Pavement materials in road building

Pavement materials

in road building Guidelines for making

better use of local materials

en :0 m en m

(J I 8 MAR 1999 � <!

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'---__ LID"; flY I � I io� _ 'b\ (LO�

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Paul Robinson Ted Oppy

George Giummarra

arOb Transport

Research

The Institution

of Engineers, Australia

ROBINSON, P., OPPY, T., GIUMMARRA, G., (1999) PAVEMEN T MATERlALS IN ROAD

BUILDING: GUIDELINES FOR MAKING BE T TER USE OF LOCAL MATERlALS. ARRB Transport Research Ltd. 180 pages including maps, photos, diagrams and tables.

ABS TRAC T: Locally available road consh'uction materials, palticularly in rural areas, are often

of marginal quality. Best performance may not always be achieved due to the often limited

technical knowledge of the material being used. The guidelines include information on how soil

types perform across Australia with information gathered from practical, local experiences;

laboratolY soil testing and case studies. Detailed advice is provided about 50 different soil

types available across Australia. Maps and references make it easy to locate soil types and

climatic information. Simple low cost techniques are described on how to test soils to arrive at

a better understanding of a given soil type. Guidance is given on how to best treat a soil for

particular use as a sub-base or base course and as a wearing course in the case of unsealed roads.

Additionally general advice is provided on stabilisation techniques and calculation of mix

blends. Appendices cover pavement design and construction and the Thomthwaite Moisture

Index. A comprehensive list of references is included to guide the reader to further information.

ISBN 0869107844

March 1999

Designed by: Vicki Jaeger, ARRB Transport Research Ltd

Technical Editing: Jan Anderson Publishing Services

The Centrespread Map is ©

Commonwealth Copyright,

AUSLIG, Australia's national

mapping agency. (1982).

All rights reserved. It has been

reproduced with the permission

of the General Manager,

Australian Surveying and Land

Information Group, Department

of Industry, Science and Tourism,

ACT. A number of other maps

and figures, where noted within

the text, have been based on

AUSLIG material © 1982

and 1992.

Maps sourced as "Bureau of

Meteorology, ©AGPS, 1989"

are " Commonwealth of Australia

copyright reproduced by

permission"

Where maps and figures within

the text have been reproduced

from other sources, the origin is

acknowledged in the text. The

authors and publishers wish to

thank these organisations for

permission to reproduce them in

this document.

It is important to note that

these Guidelines are intended

to assist those working with

local pavement materials in

situations where access to

standard materials, test

equipment and methods are

not readily available due to

reasons oj remoteness or

prohibitive cost. It is not the

authors' intention to replace

the use oj "Standard"

pavement materials and where

testing equipment and

procedures are available

and / or are already in use.

T he tests described here are

supplemental)' and in no way

take priority ovel; or

supercede, those given in the

relevant State/Territol)' or

Austroads Guidelines and

Australian Standards. Where

possible, specialist help should

be sought ji-om Road

Authorities or local

consultants who are Jamiliar

with the local area.

Although the Guidelines are

believed to be correct at the

time of publication, ARRB

Transport Research Ltd, to

the extent lawful, excludes

all liability for loss (whether

arising under contract, tort,

statute or otherwise) arising

from the contents of the

Guidelines or from their use.

Where such liability cannot

be excluded, it is reduced to

the full extent lawful. Without

limiting the foregoing, people

should apply their own skill

and judgement when using

the information contained

in the Guidelines.

ii Pavement materials in road bui ld ing - Guidel i nes for making better use of local materials

The authors appreciate the contribution and comments received on the draft copies of the

Guidelines from the members of the Steering Committee and Technical Advisory Group.

Also, thanks are due to the numerous State and Territory Road Authorities and Local

Government Councils, Consultants andARRB TranspOli Research officers who contributed

valuable information.

The encouragement and contribution of the Institution of Engineers, Australia via the

National Conmlittee on Local Government Engineering, in jointly funding, with ARRB

Transport Research Ltd, the development of these Guidelines is gratefully acknowledged.

Project Team

Team Members:

Steering Committee

Mr Paul Robinson, Principal Research Engineer, ARRB TR

Dr Ted Oppy, Consulting Engineer, Malvern East, VIC

Mr George Giunmlarra, Local Roads Coordinator, ARRB TR

Chainnan: Mr George Giummarra, Local Roads Coordinator, ARRB TR

COlllinittee Members: Mr Geoff Barrow, City of Hob sons Bay, VIC, IEAust rep.

Mr Mike Ellis, Fisher Stewati, Geelong, VIC, IEAust rep.

Mr Paul Robinson, Principal Research Engineer, ARRB TR

Technical Advisory Group

Mr Bernard Ambrose, Department of TranspOli & Works, NT

Mr StanAntczac, Blue Mountains City Council, NSW

Mr Peter Brown, Delatite Shire Council, Victoria

Mr Graham Foley, Plincipal Research Engineer, ARRB TR

Mr David Hazell, Transport South Australia

Mr Charles Lockwood, Shire of Harvey, WA

Mr Tony McDonald, Cambooya Shire, QLD

Dr Doug McInnes, Golder Associates, WA

Mr Kieran Sharp, Principal Research Scientist, ARRB TR

Pavement materials in road bui ld ing - Guidel ines for making better use of local materials iii

ACV Aggregate Crushing Value (%)

C B R California Bearing Ratio (%)

CH Clays of CH group. Heavy clay; highly plastic clay

CIV Clegg ImpactValue (1 CIV = 10 g)

CV Commercial vehicles (% ofAADT value)

D D Dry Density. (SDD i s standard dry density.)

FCR Fine crushed rock

1m Thornthwaite Moisture Index

LAA Los Angeles Abrasion value (%)

L L Liquid Limit (%)

L S Linear Shrinkage (%)

M C Moisture Content (%)

M D D Maximum Dry Density

O M C Optimum Moisture Content

P I Plasticity Index

PL Plastic Limit (%)

P M Plasticity Modulus

P P Plasticity Product

USC Unified Soils Classification System

iv Pavement materials in road bu i ld ing - G uidel ines for making better use of local materials

Acknowledgements

List of Abbreviations

List of Figures

List of Tables

Preface

Chapter 1 Introduction

1 . 1 General

1 .2 Structure of these Guidelines

1 .2 How to Use this Document

Chapter 2 Overview and Background

2. 1 Climate

2.2 Population Density and the Road Network

2.3 Moisture Sensitive Subgrades

2.4 Local Pavement Materials

2.5 Road Building and Local Pavement Materials

2.6 Case Study

Chapter 3 Material Classification

3. 1 Introduction

3.2 Classes of Local Pavement Materials

3.3 Materials Location

3.4 Materials Identification

3.4. 1 Soil Properties

3.4.2 Particle Size Distribution (Grading)

3.4.3 Plasticity

3.5 Suggested Specification Limits

3.6 In-situ Measurement of Material Strength (CBR)

3.6. 1 Description of the California Bearing Ratio

3.6.2 Field Measurement of CBR

3.7 Australia-wide Occurrence of Material Classes A - D

3.7. 1 Groups

3.7.2 Class A - In-situ Weathered Rocks

Pavement materials in road building - Gu idel i nes for making better use of local materials

III

IV

ix x

xi

1

2

5

5

5

7

7

8

1 1

1 3

13

13

14

14

14

15

17

20

2 1

21

2 1

2 1

21

22

v

3.7.3 Class B - Soft Rocks 22

3.7.4 Class C - Ridge Gravels 22

3.7.5 Class D - Transported Deposits 23 3.8 Materials Data Sheets 23 3.9 Typical Materials Classification Sheets 24

Typical Materials Classification Sheets, Class A 26

Typical Materials Classification Sheets, Class B 27

Typical Materials Classification Sheets, Class C 30

Typical Materials Classification Sheets, Class D 32

Chapter 4 Materials Extraction 35

4. l Introduction 35

4.2 Location of New Sources 35

4.3 Preliminaty Tests 36

4.3. l Characteristics 36

4.3.2 Paliicle Size 36

4.3.3 Combination of Size and Plasticity 36

4.3.4 Dry Strength 36

4.3.5 Decomposition 36

4.4 Inexpensive Tests for Assessment of Materials 36

4.4.l General 36

4.4.2 Dominant Clay Component 36

4.4.3 Strength and Durability 38

4.5 Regulations to be Observed 38

4.5. l Introduction 38

4.5.2 Landowner's Consent 38

4.5.3 Planning Regulations 38

4.5.4 State Government Regulations 38

4.5.5 Federal Regulations 39

4.5.6 Council Conditions 39

4.6 Pit Operation and Rehabilitation 40

4.6.1 Operation 40

4.6.2 Rehabilitation 40

Chaptel'S Pavement Stabilisation and Modification Techniques 43

5.1 Introduction 43

5.2 Granular or Mechanical Stabilisation 44

5.2. 1 Example: Calculating Material PropOltions 45

5.3 Cementitious Stabilisation 46

5.4 Lime Stabilisation 49

vi Pavement materials in road bui ld ing - G u idel ines for making better use of local materials

5.5 Bitumen Stabilisation

5.6 Chemical Stabilisation

5.7 Summary of Stabilisation Techniques

5.8 Geotextiles

5.8. 1 General

5.8.2 Subgrade Layer

5.8.3 Geotextile Reinforced Seals

Chapter 6 State by State Review

6. 1 Introduction

6.2 New South Wales

6.3 Northern Territory

6.4 Queensland

6.5 South Australia

6.6 Tasmania

6.7 Victoria

6.8 Western Australia

49

49

50

50

50

50

50

53

53

54

56

58

60

62

64

66

Colour photographs of materials

Australia surface rocks map (©AusJig)

69-71 and 74-75

Chapter 7 Materials Data Sheets

7.1 Introduction to Materials Data Sheets

7.2 Index of Local Materials Data Sheets - By Material Class

72-73

77

77

78

7.3 Index of Local Materials Data Sheets - By State and Map Number 80

Materials Data Sheets

New South Wales 83

Northern Territory 97

Queensland 101

South Australia 117

Tasmania 125

Victoria 129

Western Australia 133

APPENDIX 1 Pavement Design for Light Traffic 1 45

A 1 . l Introduction 145

A l . l . l General 145

A l . l .2 Terminology 147

A l .1.3 Light Traffic 146

A1.1.4 Pavement Strength 146

Al.2 Pavement Design Thickness 146

Pavement materials in road bui lding - G u idelines for making better use of local materials vii

A 1.2. l Pavement Function 146

A 1.2.2 Granular Pavements with Thin Bituminous Surfacing 147

Al.2.3 Pavements for Unsealed Roads 147

A1.2.4 Design CBR for Subgrade 148

A1.2.5 Design Cha11s 148

Al.2.6 Estimating Design Traffic 148

Al.2.7 Selection of Material Type 148

A 1.2.8 Pavement Design Example 148

APPENDIX2 Pavement Construction 151

A2.1 Introduction

A2.2 Treatment of Local Pavement Materials

A2.2. 1 General

A2.2.2 Winning Materials

A2.2.3 Drainage

A2.2.4 Compaction

A2.2.5 Preparation for Sealing

A2.3 Environmental Effects

A2.4 Selection of Plant

APPENDIX 3 The Thornthwaite Moisture Index

A3. 1 The Thornthwaite Moisture Index

A3.2 Soil Suction and Subgrade Strength

APPENDIX 4 Geological Time Scale

APPENDIX 5 Additional Materials Data Input Form

Glossary

References

151

151

lSI

152

152

152

153

153

154

157

157

157

161

163

165

169

vii i Pavement materials in road building - Guidelines for making better use of local materials

Figure 2. 1 Climate 6

Figure 2.2 Rainfall 6

Figure 2.3 Evaporation 8

Figure 204 Road network 8

Figure 3. l Unified Soil Classification system (USC) 16

Figure 3.2 PalticIe size distribution curves for various values of n 17

Figure 3.3 Properties of mechanicall y stable gradings 18

Figure 304 Key map 24

Figure 4. l Emerson ClUmb Test for dispersive soil 37

Figure 4.2 Location of access roads 41

Figure 5. 1 Graphical solution for grading distribution 46

Figure 5.2 Worked example for blending of three materials 'A', 'B' and 'C' 47

Figure 6. l Simplified surface rocks map of NSW 54

Figure 6.2 Simplified surface rocks map of NT 56

Figure 6.3 Simplified sUlface rocks map of QLD 58

Figure 604 Simplified surface rocks map of SA IX)

Figure 6.5 Simplified surface rocks map of Tasmania 62

Figure 6.6 Simplified surface rocks map of VIC 64

Figure 6.7 Simplified surface rocks map of WA 66

FigureAl. 1 Commonly used road terms 145

FigureA 1.2 Flexible pavement design system for granular pavements with thin

bituminous surfacings 147

FigureA l .3 Design chart for granular pavements with thin bituminous

surfacing (80% confidence) 149

FigureA Io4 Design chart for granular pavements with thin bituminous

surfacing (90% confidence) 149

FigureA3. 1 Climate map of Australia based on Thomthwaite Moisture Index 158

FigureA3.2 Relationship between equilibrium suction and

Thomthwaite Moisture Index 159

FigureA3.3 Map showing zones of uniform equilibrium suction 159

Pavement materials in road bu i ld ing - G u idel i nes for making better use of loca l materia ls ix

Table 3.1 Local materials by State/TerritOlY and Class 13

Table 3.2 Propelties of mixture gradings 18

Table 3.3 Suggested grading requirements for naturally

occurring granular materials 19

Table 3.4 Plasticity Index for nonstandard materials 20

Table 4.1 Identification of clays by appearance 37

Table 4.2 Strength of cohesive soil 38

Table 4.3 Strength of fragments of rock and hardened materials 39

Table 5.1 Mixture grading distribution 45

Table 5.2 Local pavement materials assessed for suitability

for stabilisation by cementitious binders 48

Table 5.3 Suitablity of stabilisation additives for various soil types 50

x Pavement materials in road build ing - Guidel ines for making better use of local materials

In the construction and maintenance of local roads, practitioners, particularly in rural areas,

are often under pressure to obtain better value from their budgets. Making best use of often

marginal or non-standard local materials can assist engineers in this task.

However, making best use of local materials may not always be achieved, because of limited

knowledge of the materials being used, pelformance under traffic loads, or the most appropriate

construction teclmiques. This is particularly so in current times as a result of numerous staff

changes due to industry restructuring and the employment of personnel who may not have

the necessary local knowledge.

Many practitioners are not employing soil testing procedures to determine the key

characteristics of a given material and they tend to have insufficient data on how to modify or

use various stabilisation techniques to maximise the potential of the locally available pavement

materials.

In recognition of this need, the Institution of Engineers Australia National Committee on

Local Government Engineering, together with ARRB Transport Research, have jointly

sponsored the production of "state of the art" Guidelines to assist local road practitioners

make better use of available local materials for road pavements in order to achieve greater

value from the limited funding available tlu'ough the provision of longer lasting pavements

with improved ride quality.

Engineers have an obligation to not only be resourceful in utilising their knowledge but to

pass that knowledge to their subordinates and colleagues. The Institution and ARRB

Transport Research Ltd. believe that these Guidelines wi II assist engineers in better serving

their communities.

GEORGE J.GIUMMARRA

Local Roads Coordinator

ARRB TranspOlt Research Ltd

DAVID A.HOOD

Director Engineering

Institution of Engineers, Australia

Pavement materials in road bui ld ing - G uidel ines for making better use of local materials xi

xii Pavement materials in road building - Guideli nes for making better use of local materia ls

1 .1 General

Road practitioners, particularly in rural and remote areas,

are often required to make best use of locally available

materials for road pavements due to budget constraints.

Local materials are often found to be of marginal quality

and not always meeting standard specifications.

H owever, these materials can nevertheless be

successfully used for road pavements providing celiain

measures are taken to ensure best value is obtained.

To assist practitioners in making better use of local

materials, this Guidelines document has been prepared

to report on the field performance of a variety of different

engineering soils around Australia. This infOlmation is

intended to complement local knowledge available and

add value to current practices.

The purposes of these Guidelines are to:

• provide a technical document on how local road

practitioners can make better use of available local

materials for their pavements;

• assist in the achievement of optimum pavement

performance through the provision of pavements

which have improved ride quality and less costly

maintenance requirements;

• present the knowledge in a manner that will be useful

for the inexperienced professional, for supervisory

personnel and for those unfamiliar with the pavement

materials of an area;

• show where similar materials are found throughout

Australia and how they are best used in their

particular locations; and

• provide guidelines for minimising any adverse

impacts on the environment.

The Guidelines provide detailed guidance on the most

appropriate use of 50 different local road making

materials throughout Australia, embracing various

climatic regions and geological provinces. These

materials seldom comply with current specifications for

major roads. The technical information includes

guidelines as to the best use of these materials as either

a sub grade, sub-base or base course under a sealed

road and also as a wearing surface in the case of

unsealed roads.

In addition, the Guidelines provide general guidance

on pavement design procedures for lightly trafficked

roads, construction, various stabilisation techniques

and how to blend mixes from the various available local

materials. Some handy hints on using simple soil testing

techniques are also provided. A comprehensive list of

references is included to guide the reader to more detailed

information.

1 . 2 Structure o f these Guidelines

The Guidelines document present practice in the use of

local materials throughout Australia in terms of both a

material "Class" and location. Advice on appropriate

current tests is described. A "Surface Rock Types" map

of Australia (Auslig 1982a) is provided in the

centrespread and this should prove useful in identifying

the occurrences of many of these materials. In many

cases, materials with similar properties occur in more

than one location and in more than one State or Territory.

Pavement materials in road bui ld ing - Guidel ines for making better use of local materials

If a particular material of interest is not described in the

Guidelines, it is possible that a similar material can be

referred to and the information provided adopted.

The Guidelines comprise seven chapters and five

appendices as follows.

Chapter 2 describes the climate and how much of the

continent of Australia is dry (arid and semi-arid with

less than 500 mm of rainfall annually), containing only

low grade rocks. Australia contains great lengths of

low volume, low cost roads. The text is supplemented

with maps of rainfall and climatic zones and the road

network. These maps emphasise the dlyness and sparse

population of much of the continent. Moisture sensitive

subgrades and the use of local materials are introduced.

Chapter 3 looks at soil properties and field identification

and then goes on to describe the various "Classes" of

pavement materials (A - In-situ Weathered Rocks,

B - Soft Rocks, C - Ridge Gravels, or D - Transported

Deposits) and their Australia-wide occurrence. Ten

typical "Materials Classification Sheets" of the more

commonly used material types are included.

Chapter 4, "Materials Extraction", describes location of

new sources, inexpensive preliminary tests and an

overview of the issues and regulations concerning

extraction, pit operation and rehabilitation.

Chapter 5 is a brief review of pavement stabilisation

and modification techniques, a subject of increasing

relevance in seeking cost effective enhancement of

local pavement materials.

Chapter 6 comprises a relatively brief overview for each

State/Territory including climate, geology and a review

of conunonly used local materials.

Chapter 7 contains 50 "Materials Data Sheets" from

specific localities around Australia. They are indexed

by State/TelTitory and Map Number (00 - 40) and also

by Material Class. Information is provided on soil

properties fol lowed by methods of extraction and

construction techniques and performance data. Other

information is included which may also be useful to a

practitioner not familiar with the district.

Appendices I and 2 briefly review pavement design for

light traffic and re levant construction issues

respectively, whilst Appendix 3 describes the

Thornthwaite Moisture Index and its relevance to soil

suction and strength. Appendix 4 contains a geological

time scale.

Blank Materials Data Sheets are included in

Appendix 5. As readers gain more information on their

own local materials they are encouraged to include such

material in their own copy of the Guidelines for use by

others. The ongoing value of these Guidelines will be

enhanced by also forwarding a copy of this additional

infonnation toARRB Transport Research for inclusion

into future updated editions.

1 .3 How to use this document

To try and improve the performance of local pavement

material it is necessary to first understand the strengths

and weaknesses of local soils and ways to best

overcome identified deficiencies.

There are two ways suggested in the Guidelines

document. These are either using preliminaty field test

methods or to make use of prior testing carried out on a

wide range of local soils across Australia.

Inexpensive Field Testing

Grading Mix

Undertake size analysis to determine any "gaps" in

patticle size, distribution (Chapter 3, Fig. 3.2).

Plasticity

Establish LL, PL and PI and see whether it is within

acceptable limits (Chapter 3 , Table 3.4).

Strength of Cohesive Soil

Use Tables 4.2 and 4.3 to help determine CBR (MPa)

values of soil mix strength.

Stabilisation Techniques

W here a local soil has identified deficiencies the

fo llowing stabilisation techniques should be

considered:

• Where there is a "gap" in particle size distribution,

try mechanical stabilisation to correct deficiencies.

2 Pavement materials in road bui ld ing - G uidel i nes for making better use of local materials

Fig 5.1 demonstrates a technique to arrive at an

appropriate blending mix design.

• For soils with high/low levels of PI use an appropriate

chemical stabilizer listed in Table 5.3.

Use of Materials Data Sheets

An assessment of a local soil can be undetiaken by use

of prior field testing undetiaken for a patiicular soil class

or by geographical location.

If material type is known (given in Chapter 3) use the

soil type that best aligns with the local material and

adopt its key characteristics and applications

techniques to obtain best results.

Alternatively, knowing the geographical location of a

road project, determine from Chapter 7, whether there is

in the vicinity a Material Data Sheet available that

provides the required soil testing information and best

application techniques in the design and construction

of the pavement.

Pavement materials in road bu i ld ing - Gu ide l ines for making better use of local materials

Introduction

3

4 Pavement materia ls in road building - Guideli nes for making better use of local materials

2. 1 Climate

The climate of Australia is mostly dlY (arid to semi arid)

and is dominated by limited and highly variable rainfall

(Johnson 1 992). The rainfaIl pattern centres on the

extensive arid core which comprises about seventy five

percent of the continent, receiving less than 500 mm

rainfall per year. Around the core is the discontinuous

margin of humid lands. In the west, aridity extends to

the coast (Figure 2. 1, "Climate"). Sununer rains dominate

in the north and winter rains in the south-west and

south. Between these areas and particularly in southern

New South Wales and the eastern half of Victoria, an

even seasonal distribution is experienced (Figures 2.2

and 2.3 - "Rainfall" and "Evaporation", respectively).

2.2 Population density and the road network

The population in Australia is concentrated mostly in

the south-east in a narrow crescent, 300 to 400 km wide,

from just north of Brisbane to Adelaide. Outside this

crescent, major urban centres are located in small

pockets of higher density settlement, on the east coast

of Queensland and in the south-west corner of Western

Australia. Rural population density is low, mostly below

5 persons per square kilometre. In the interior and in

north-western Australia, mining and service industries

create the bases for urban centres. Much of the land is

unsettled desert (Jolmson 1 992).

The road network (Figure 2.4) reflects the distribution

of population, being most extensive in the south-east

and east of the Great Dividing Range. In the interior and

west of the continent, roads are generaIly lightly

h'afficked and spaced widely apart. Networks are dense,

however, on the fringes south-east of Perth, north of

Adelaide, nOlth of the Victorian Divide and west of the

Great Dividing Range in New South Wales and

Queensland, where the climate is semi arid.

Queensland, South Australia and Western Australia,

with relatively sparse populations, have 60, 65 and 90 m

of road per person respectively compared with the

Australian average of 45 m of road per person. The

implications of this in telms of economics are clear. The

management of scarce financial resources means that

widespread use of local materials is essential for low

cost roads carrying low traffic volumes. Conventional

road making materials are scarce and can be velY costly.

Climate ultimately determines the soil type in many

regions. In time the influence of parent rock becomes

less noticeable. The bulle of the arid and semi-arid zones

contain only "soft" rocks, sedimentary and weak

metamorphic, which have been subject to extensive

climate related weathering over inunense periods of time.

There is therefore little choice in the selection of road

base materials. Pavement strength is measured in terms

of the California Bearing Ratio (CBR) which is described

in more detail in Chapter 3. Local gravels with W1soaked

CBR values as low as 60%, or even 30% in some cases,

have proven satisfactory on low traffic roads (a

"Standard" road base specification would normaIly

require material to have a CBR sh'ength of at least 80%).

These materials, although not so strong, tend to have

more plastic fines and so aid in waterproofing sub-base

and subgrade layers. The key objective is to best match

available material to the roadworks task in an operating

envirOlm1ent where water for consh'uction may be scarce

and of poor quality and where hauling is costly and can

further damage road pavements.

Pavement materials in road bui ld ing - Guidel ines for making better use of local materials 5

6

CLASStflCATlm�

S.�f,Rmtlli -Tlc;;leil

s."-,,,R'II>I,II - ht\J(91C11

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t.,lel Ihrr�11I

CLIMATIC ZONES AUSTRALIA

SEASONAL CHARACTERISTICS

SUMMER WINTER

HHI'I,ellO�ICrilU CUflill,'I"lns It.u'lIIlAcont.1 & �'I�I}.·.d,rfl!1 IIlld�)'d'n H'lif�mllr 0" H.IlH!I.COUlllmu

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IlIfi'o'llIlIl •. �IU/II,M Rtlll�·e lll.(oc.:'ml tkltA!I\·I) 1.,nklUII CfOllorlild

CLASSifiCATION SEASONAL CHARACTERISTICS

SUMMER WitHER

"_'I!lRmblll"'--'II'.t/�Ulltl IiIls1tl 11(.11 iutl\lIJr r"ft Rthltit r". • Tt-;tllt e 'un to t.!)! ItoIlIl,r--Y!mlt)

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Figure 2.1 Climate (Source: Bureau of Meteorology, © AGPS, 1989)

lEGEtlO o 0·300 g 300·.00 []]J '00· 600

� ,00·800 � 800·'''' � 1200·1600 � 1600·2400 rrnli "00'�3"'''' .� ��"&J-. '

3

�

, ,

Figure 2.2 Rainfall (Source: Bureau of Meteorology, © AGPS, 1989)

Pavement materials in road bu i ld ing - G u idel ines for making better use of local materia ls

2.3 Moisture sensitive subgrades

In semi arid inland areas, sandy subgrades take up

moisture quickly after rain and become impassable. The

same subgrades, when protected from moisture ingress,

are strong and hard.

The Thornthwaite Moisture Index (Morgan 1974) is a

fundamental descriptor which relates equilibrium soil

moisture conditions to climate and is an indicator of

soil suction. It is negative in dry environments where

annual evaporation exceeds rainfall. A general

description and map describing the Thornthwaite

Moisture Index and its relationship with soil suction

and strength is located in Appendix 3.

Equilibrium Moisture Content (EMC), the moisture

content of a material when it is in a stable state or at

equilibrium in its surroundings, is reached some time

after constlUction when seasonal moisture movements

under a sealed pavement have ceased; it will be dry of

the Optimum Moisture Content (OMC), the moisture

content at which maximum density can be achieved from

compaction equipment during constlUction. Typically,

the compacted subgrade after reaching EMC in dry

environments, will be quite firm and strong and have a

moisture content of 70% to 90% of OMC or even less.

Pavement design for lightly trafficked roads is discussed

in Appendix 1 . The design method for granular

pavements which is taken from APRG Report No.

21 (APRG 1998), is empirically based and relies upon the

strengths of pavement layers as determined from CBR

values for the compacted materials. If moisture ingress

can be prevented then subgrade strength will be

maintained and a relatively thinner base course layer

will be sufficient to spread and transfer traffic loadings

to the subgrade without causing rutting. In dry

environments CBR values of up to 30% for sub grade

soils are experienced, this being higher than is often

possible in wetter, temperate climates. With all moisture

sensitive subgrades, including expansive clay

subgrades such as are found in New South Wales, the

Northern Territory, the Kimberley region of Western

Australia, western Queensland and the Victorian

Wimmera, ingress of water has to be prevented as much

as possible by elevated road formation, adequate

crossfall, shoulder design and regular seal maintenance.

Overview and background

2.4 Local pavement materials

In the context of these Guidelines, "local pavement

materials" are generally naturally occurring weathered

rocks, soft rocks, ridge gravels, stream gravels, sands

and clays which are close to site and can usually be

won and placed by readily available construction

equipment. They can be ripped in the pit without drilling

and blasting, as distinct from fine clUshed rock, sealing

aggregate etc. which is produced in a hard rock quarry

with stationary clUshing and screening plant. Some

types of local materials however may require some

processing, e.g. sandstone, siltstone and calcrete.

Naturally occurring rocks and soils are often marginal

or non-standard in terms of strict compliance with the

material specifications for major road pavements.

By definition, waste materials from industry (slags, ash

etc.) are not a "local pavement material" but their use is

included in discussion elsewhere in these Guidelines

(for example see Chapter 5) particularly when used as

stabilisation agents for modifying a local pavement

material in a cementing process.

The Permanent International Association of Road

Congresses (PIARC) defined non-standard and non

traditional materials as:

any material not wholly in accordance with the

specification in use in a countl)1 or region for

nor1l1al road materials but which can be used

successfully either in special conditions, made

possible because of climatic characteristics or

recent progress in road techniques, or after having

been subject to a particular treatment. (PIARC 1989)

The use of local or non-traditional materials, including

naturally OCCUlTing materials, industrial by-products and

waste materials, is subject to the materials being

assessed on technical, economic, ecological and

environmental criteria or in terms of extending existing

natural resource·s. Their use should be viewed in the

context of availability of traditional and good quality

pavement materials. In arid and semi-arid areas there

are few options to choose from. The choice of pavement

and surfacing type in each paIticular case is influenced

by:

• availability of materials (there may be a few choices);

Pavement materials i n road bu i ld ing - Guideli nes for making better use of local materials 7

8

---I

EVAPORATION AVERAGE ANNUAL (inmillimelresj

E�'pmllII: CLASS A pan lllith bItd guard Ava)lablt r.cotds to 19&0 Inc:Ivs/YI(rll'Sl lKOrdS In 1961)

'IIOlaCTIO'h ,U . •• /UCONIC .. LIQU ... L ...... E ... I

'"

Figure 2.3 Evaporation (Source: Bureau of Meteorology, ©AGPS, 1989)

Road System ---- National highway ---- Major road

��"'''" TAS HOBART

Figure 2.4 Road network (Source: Auslig, 1992)

JBRlSBANf

Pavement materials in road bui ld ing - G u idel i nes for making better use of local materials

• local construction and maintenance practice and

equipment;

• environmental conditions (climate, temperature,

depth to ground water table); and

• available funding and whole of life cost analysis.

There is a lack of documented knowledge on the

selection and use of local non-standard materials in

pavement consh·uction. Although local knowledge of

these materials has been gained over a long period of

time, resulting in their correct use, this experience has

generally not been well documented, usually existing

as "unwritten practice". Extensive systematic testing

and evaluation of these materials has not been carried

out to facilitate the selection process. New specifications

which "tailor" procedures to suit locally available

materials are required. A trade-off or compromise,

however, between costs and reliability and also

variability in performance is often a reality, particularly

in low volume traffic, local road situations. In arid and

semi arid areas there may be no alternative; however,

non-standard materials have pelformed well in dry areas.

A broad view ofAush'alian practice in the development

and use of local materials for road construction and the

use of non-standard materials such as decomposed

rocks, fine grained materials, loams and sands in an

Australian context is described in Metcalf (1978 and

1989). Metcalf has stated that:

for ·wider use and acceptance of naturally occurring

and nOli-standard materials the basic engineering

principles, compacted density and probability of

failure and knowledge of local materials and

conditions are important. (Metcalf 1978)

Many kilometres of local roads have been built at

relatively low cost and still provide good service without

the benefit of sophisticated (expensive) testing and

using materials which do not meet the current specified

requirements for major road pavements. As stated by

Metcalf:

A vel)' wide variety of materials, loams, soft

sandstones, natuml gmvel, decomposed rock and

industrial residuals have been and are being


successfully used where traffic is not too heavy, the

environment is understood and properly taken into

account, where design, construction and

maintenance is appropriate to the circumstances

and quality control is adequate. (Metcalf 1978)

SouthAfi-ican work (Netterberg and Paige-Green 1988)

suggests that non-standard materials can be used in all

pavement layers provided that traffic, climatic and

drainage conditions are favourable. They suggest that

the selection of non-standard materials is based

ultimately on sh'ength and stiffness and to a lesser extent

upon strict compliance with plasticity and grading

requirements. Knowledge of these parameters is,

however, still fundamental to an understanding of the

matelial.

2.5 Road building and local pavement materials

Metcalf also stated that:

A standard (processed) granular material ji'O/n a

hard rock source has conservative properties, will

be tolerant of construction mishandling and

environmental conditions, and probably will

peljorm well in most circumstances. (Metcalf 1978).

Higher quality imported pavement materials are being

used more and more on the increasingly heavily

trafficked roads in the temperate and humid zones

because:

• they perform well on moister subgrades. Designs

based on the pavement strength parameter, California

Bearing Ratio (CBR) or Resilient Modulus, apply;

• local materials complying with quality specifications

for major roads are either exhausted or were non

existent; and

• on heavily trafficked roads the cost of processed

materials is justified and high strength is needed to

ensure design life is achieved.

Local materials which are often marginal or non

standard, are, however, being widely used on more

lightly trafficked roads because:


• The bulk of the arid and semi-arid zones which cover

most of the continent have very few suitable hard

rock sources or complying granular materials. Local

materials have to be used, as they are often the only

available source.

• Even if hard rock sources are located within haul

range, the production of manufactured granular

materials is generally too costly for lightly h'afficked

roads and the use of local materials is more cost

effective.

• Within the semi-arid areas many of the sandy deselt

soils and all of the heavy "cracking" clays are

moisture sensitive. These are, for example, typical of

cotton and beef production areas in Queensland.

Even if cost effective and available, granular

"standard complying" crushed materials tend to

pelfOim poorly, as they are generally quite pelmeable.

A more impermeable material, although difficult to

place and compact, tends to waterproof these

sensitive subgrades better.

• In arid areas, the subgrades, when carefully designed,

built and maintained at close to their Equilibrium

Moisture Content (EMC), are strong, have in-situ

Califomia Bearing Ratio (CBR) values up to 30% or

even 50% and do not need a thick overlying pavement

to transfer the loads to the lower layers. Thus

pavement material layer thicknesses of 150 mm to

200 mm may prove sufficient.

Many of the non-standard local pavement materials,

however, have doubtful durability or poor particle size

dish'ibution and it is often hard to obtain a material with

CBR values greater than 60%, which is often the

"specified" minimum for a local road base material.

Deformation under h'affic (usually in the form of rutting)

is more likely to occur within a fine grained local

pavement material, rather than pelmanent deformation

of the subgrade. Good results have been obtained by

placing subgrade fill close to the EMC which is generally

less than the Optimum Moisture Content (OMC), by

using existing roadway formations and by delaying fmal

sheeting and preparation on new formation until

moisture has stabilised.

In the past, LocalAuthorities have generally undeltaken

velY limited testing of local materials either due to the

cost or because current standard tests were

inappropriate to low cost roads. Where at all possible

and practicable, arrangements should be made for local

materials to be tested and assessed by the materials

laboratory of the local road authority office or by the

nearest local consultant or testing laboratory. Basic

testing of local materials however, should not be

unnecessarily difficult or expensive and is discussed in

Chapter 4.

1 0 Pavement materials i n road bui ld ing - G u idel ines for making better use of local materials


2.6 Case study

This case study from Victoria, by McPherson ( 1 987), gives an example of the successful use of local

non-standard material in road reconstruction. The example illustrates that even when all does not run

smoothly, a pavement constructed of local materials can perform quite satisfactorily.

Saxton Street is the main access to Numurkah township from the intensely irrigated areas to the west

and north-west and from Nathalia township . At the time of reconstruction it was carrying just under

1 ,000 vehicles per day and consisted of a 3 . 7-metre seal perched on top of a very high narrow

fOlmation with deep sullage filled drains on either side of the formation. Reconstruction involved the

relocation of in-pavement services (water etc.), installation of a maj or underground drainage system,

provision of kerb and channel on either side and the construction of a new sealed pavement

approximately 1 3 metres in width.

After pavement investigations were completed a pavement depth of 3 5 0 mm was selected. The

existing pavement was totally excavated and removed along with the old water mains. The deep side

tables were filled and compacted, the new drainage trenches were backfilled with consolidated road

making sand and the whole base was shaped and lightly compacted.

Tenders were called for the supply of material and the successful tenderer was contracted to supply

a coarse sand having typical characteristics of a Prior Stream Gravel (99% passing the 9 .5 mm sieve,

3 0% passing the 0.425 mm sieve and 4% passing the 0.075 mm sieve, PI 4). The material was

delivered continuously to the road-bed and graded, watered and compacted using an 1 8 tonne drawn

pneumatic tyred roller supplemented by road traffic.

The job was proceeding smoothly until laboratOlY tests, which were taken on the almost completed

pavement, revealed that most of the material delivered had plasticity indices as high as 1 5 and not 4

as per the approved submitted samples. Consideration was given to the possibility oflime stabilising

the top 200 mm but on the advice from the road authority laboratory at Benalla, Victoria, 50 mm of a

very hunglY dune sand was impOlted from Shepparton and intimately mixed with the top 1 5 0 mm to

reduce the PI to approximately 1 0 .

Extreme difficulty was encountered i n placing this top layer due i n part to the deep movement caused

by the heavy roller over some of the previously filled areas and to the difficulty of maintaining

Optimum Moisture Content (OMC) in the sand mixture. Eventually the sands were brought to a

state that was considered suitable for priming, at which time the job was left over the weekend with

the intention of priming on Monday. Dming the weekend 50 rnnl of rain fell and by Monday, contralY

to expectation of the excess moisture softening the pavement, the whole pavement had set sound and

hard under local traffic movement. This was probably due to the "tightening up" of the surface by

rolling with a rubber tyred roller in preparation for priming and a good camber assisting drainage. The

pavement was given a 1 4mm single coat seal and went on to give some 1 8 years of satisfactOlY

performance, receiving two reseals before consideration was given to providing an asphalt concrete

overlay.

Pavement materia ls in road bu i ld ing - Gu idel ines for making better use of local materials 1 1

1 2 Pavement materials in road bui ld ing - Guidel ines for making better use of local materials

3.1 Introduction

This chapter contains:

• a description ofthe soil propelties and components

(gravel, sand, silt and clay) which make up a road

making mateIial;

• a description of the classes of local pavement

materials (Classes A, B, C and D) according to their

sources and formation and where they may be found

throughout Australia; and

• a set of key Material Information Sheets which

describe more precisely the main materials in each

class and show the characteristics, application and

location of each of the most commonly used

materials.

Class NSW NT QLD A Grey earth, Granite Basaltic

Clay sands, clay, Black

(sealed) Laterites earths

B Sandstone, Siltstone Sandstone,

Shale Siltstone,

Calcareous

siltstone

C Calcrete, Calcrete, Silcrete,

Calcareous Iron pan Fenicrete,

soil Calcrete,

Colluvial

gravel

D P rior River gravel, River gravel,

streams Sand-clay Sand-clay

3

3.2 Classes of local pavement material

For convenience local pavement materials are grouped

in 4 classes - A, B, C and D, according to their source

and nature offormation as described by Metcalf(1978).

Most fall clearly into a group although there are

borderline cases.

Class A: In-situ Weathered Rocks (residual soils)

Mostly igneous, including decomposed basalt, granite,

granitic sand and basaltic clay but also laterite and coral.

Class B: Soft Rocks (mostly sediments) including

sandstones, shales, mudstones and siltstones, and

which can be extracted from a pit without quarrying.

Class C: Ridge Gravels (duricrusts) of pebbly or

SA TAS VIC WA

Laterites Scoria, Laterites,

Granitic Coral

sand

Sandstone, Sandstone, Sandstone Sandstone

Siltstone, Siltstone

Shale

Calcrete Quartz Limestone Calcrete,

Iron pan gravel Limestone,

Ironstone

River gravel, River gravel River gravel, Sand-clay,

Sand-clay Sand-clay, River gravel

Tertiary

gravel

Table 3.1 Local materials by State/Territory a n d Class

Pavement materials in road bui ld ing - Gu idel ines for making better use of local materials 1 3

cemented layers from soil fOlming processes including

limestone, ironstone gravels and quartz gravels.

Class D: Transported Deposits including river gravels,

prior sh'eams, sand dunes, glacial till and conglomerates.

Local materials fit into the mah'ix shown in Table 3 . 1 on

page 1 3 .

3.3 Materials location

Each of the 50 Materials Data Sheets in Chapter 7 has a

map of the district. For the purpose of consistency

there are 40 district maps (each approximately 500 km

square), taken from the 1 : 5,000,000 Auslig "Base Map

of Australia" (Auslig 1 982b). All but three cover 5

degrees of latitude and 5 degrees longitude. Each dish-ict

map is referenced with the prefix letter for the State,

material class letter, locality name (a town or physical

feature) and district map number. For example "Q-B

Winton Map 17" describes a Class B material located at

or near Winton in Queensland and appears on district

map number 1 7.

For further geological information a full colour "Surface

Rock Types" map of Australia (© Auslig 1 982a) is

located on pages 72 and 73.

An index of map sections numbered in accordance with

a Key Map (Figure 3 .4, p. 24) is listed at the start of

Chapter 7 and has the format shown at the base of this

page.

Two such listings are given, one in alphabetical order

by Material Class and the other in order by Statel

TelTitOlY and section map number.

3.4 Materials identification

3.4. 1 Soil properties

The first challenge facing road construction or

maintenance personnel, especially in rural and remote

areas, is the location of suitable pavement conshuction

materials. Now that obtaining permits to exh'act material

Map No.

34

Reference

State and Class

NSW-A-MelTimajeel

Material

Clay

is increasingly difficult and some h'aditional sources

are no longer available, it is essential to have an

understanding of the required material properties and

how to quickly recognise and assess potential sources

in the field.

Typically local materials in the context of these

Guidelines will be marginal or non-standard in terms of

standard specifications for major roads. Generally,

although not always, they will be naturally OCCUlTing

and not require fUlther processing in the pit. In some

areas locally qualTied and processed stone used in local

road construction, such as some sandstones,

limestones and shales, will also be unsuitable for major

road pavements (unless stabilised).

In road construction terms all local materials used can

be classified as engineering soils regardless of their

source. The basic soil components consist of gravel,

sand, silt and clay. These four soil components are

distinguished by limits on their particle size:

Gravel Palticle size greater than 2.36 nun

Sand 2.36 nun - 0.06 mm (note: 0.075 mm test sieve

is the closest to this)

Silt 0.06 - 0.002 mm

Clay Less than 0.002 mm .

Gravels may derive from broken or shattered rocks

which have been h'anspOlted by water and/or gravity.

River gravels may be smooth and rounded by water

action and very hard, the softer palts having been worn

away by attrition. Other gravel size soils may have been

produced in-situ by deep weathering of the parent soil

and rock. Laterites, for example, are soils formed when

iron oxides transported in solution have been

redeposited to fOlm gravelly nodules. Other soils of

gravel size which can also be useful in road conshuction

include concretionary calcrete, silcrete and volcanic

cinders (or scoria) Soft rocks such as limestones,

Location

Cobb Highway

Near Booligal

Latitude

(South)

330 4 1 '

Longitude

(East)

1440 50'

1 4 Pavement materials i n road bui ld ing - Guidel i nes for making better use of local materia ls

sandstones and siltstones generally break down to

predominantly gravel sizes during the construction

process.

Sands are mostly produced from weathering of rock

which has been transported by wind or water. Their

particles will most frequently consist of quartz particles

(silica) which are amongst the most resistant to

weathering. Some sands consist of calcium or

magnesium carbonate eg coral sands and calcrete sands.

Other sands are the product of weathering of igneous

rocks, e.g. the granitic sands of Victoria.

Silts consist of fmely divided rock. They can occur as

a residual in situ soil or more commonly as a transpOlied

soil by wind or water. Silts are often wealdy consolidated

and lack the free draining characteristics of gravels and

sands. Soils with high silt contents are likely to be highly

susceptible to erosion.

Clays, unlike gravels, sands and silts, which consist of

rounded or sub-angular particles, are the product of the

chemical weathering of rock minerals. Clays generally

consist of microscopically thin plate like particles.

Undisturbed these paIiicles lie parallel to each other.

Upon wetting the particles adsorb water and become

slippery. As clays dry out, suction forces develop

between the plates producing cohesion forces and the

shrinkage that is so characteristic of clayey soils. The

most common and in many ways least troublesome, of

the clay minerals with respect to volume change is

kaolinite .

During the weathering process the clays pass through

different forms of electro-chemical sh'ucture of hydrated

alumino-silicates which can have quite different

properties from the relatively stable kaolinite. Most

notably montmorillonite can form. This clay mineral

has plate like particles which are associated with vel)'

large volllllle changes between wet and dry condition.

This property is best represented by the highly reactive

black cotton soils found in westem Queensland and

other parts of Australia.

Soil

The actual fOlm taken by the clay minerals is dependent

upon the nature of the parent rock and on the local

climatic and topographic conditions. The most rapid

Material classification

weathering takes place in hot humid climates. In tropical

regions these processes are still active in rocks which

can be deeply weathered.

Most soils are a mixture of two or more types of these

particle size groups. Various soil classification systems

take account of these mixtures. Usually the coarser

fraction soils are classified by their paIiicle size grading.

The finer silts and clays are classified according to their

reaction to moisture (or plasticity), most commonly by

assessment of Liquid Limit (LL), and Plastic Limit (PL)

tests. Known as the Atterberg Limits, these tests were

originally developed by Atterberg for defining the

moisture content range over which agricultural soils

could be tilled. No longer used by agriculturalists they

have been adopted by engineers as a useful and rapid

way of characterising silt and clay soils (Millard 1 993).

Linear Shrinkage (LS) is also a useful test in this

category.

The Atterberg Limits tests are described fully in

Chapters 3 and 4 . One classification system based on

particle size and Atterberg Limits is the Unified

Classification System CUCS), Figure 3 . 1 .

3.4.2 Particle Size Distribution (grading)

The quality of pavement material depends upon paliicle

size distribution (grading) and plasticity of fines.

Secondary considerations include the hardness of the

source rock and its durability. Research carried out by

Fuller, and later confirmed by Rothfuchs and others (in

Soil Mechanics/or Road Engineers, RRL 1 968) showed

that a granular material has a relatively high dry density

when its grading follows a certain law. The limits of

many intemational specifications have been shown to

approximate to the "Fuller" curves, obtained by the

formula:

where: p

p

percentage of particles smaller than

sieve size d;

percentage of particles smaller than

sieve size D; and

n = an exponent whose value is between

0.3 and O.5.


--

Field Identification Group

Typical Names Symbol --

:!2 '0 CfJ al C .� (!J ., l'! '" 0 u

!!J. §i al c .� (!J ., C ir:

wide range in grain size and substantial GW well graded GRAVEL

ffi � amounts of all interm. sizes w _ ., >

Vl �E - Ol ,, � predom. one size or a range of sizes with GP poorly graded GRAVEL Qj .!!! E Ol � E .!i) � � N some interm. sizes missing Ol E '0 ;,� � o c CfJ (!J ill '" .0 . al 1\ £ Vl non-plastic fines (see ML below) GM SILTY GRAVEL .p O � W ..c VJ C > .� � o' 1\ .� :is .!a � � :.:: plastic fines (see CL below) GC CLAYEY GRAVEL " E (!J .5 E d> l'! wide range in grain sizes and substantial SW well graded SAND � g '" 0 w C Vl amounts of all interm. sizes � v U ", '0 'iii 'E <Il C - '" � � E " VI predom. one size or a range of sizes with SP poorly graded SAND

C O '" some interm. sizes missing ro � c CfJ :i! l1 A - � ..c: � non-plastic fines (see ML below) SM SILTY SAND � m '� � plastic finp.s (see CL below) SC CLAYEY SAND

(1 ) (1) Shine Dilatancy Toughness

none to quick to slow none ML INORGANIC SILT very dull

� E 0 moderate none to medium CL INORGANIC CLAY of low to III very slow medium plasticity "' E v E <o '0 Vl >-0 CfJ none to slow slight OL ORGANIC SILT & CLAY of low .0 . >-

0 0 al '" E <§' v i3 very dull plasticity :i! .!!l C :.J .� '0 C '0 c E (!J '" '5 dull slow to none slight to MH INORGANIC SILT of high .5 E Q, VI 0' '" :.J medium plasticity � g C Vi ir: � v g very none high CH INORGANIC CLAY of high " glossy plasticity

moderate none to slight to OH ORGANIC CLAY of medium to tO Y. glossy very slow medium high plasticity

Highly identified by colour, odour, spongy feel Pt PEAT and other highly organic Organic Soils and fibrous texture soils

A. The system excludes the cobble and boulder fractions ( > 60 mm) of the soil for classification.

B. It adopts the particle size limits given In AS1 289 C. For laboratory classification the closest AS sieve to sizes shown should be used.

Procedures for Fine-Grained Soils or Fractions ( 1 ) Dilatancy (reaction t o shaking):- Toughness: (consistency near plastic limit):-1) Prepare pat of moist soil, adding water to make soft - but 1) Mould sample to consistency of putty, adding water or air

not sticky. drying as required 2) Place pat in palm of hand, shake horizontally by striking 2) Roll to thin (3 mm) thread, fold and reroll repeatedly until

vigorously against other hand thread crumbles at plastic limit 3) Knead together and continue until lump crumbles

Positive Reaction: appearance of water on surface of pat, which becomes glossy Diagnosis: when squeezed between fingers, water and gloss disappear, a tough thread and stiff lump indicate high plasticity, a weak pat stiffens and may crumble thread and lump low plasticity clays

Figure 3. 1 Unified Soil Classification sy stem (USC) (simplified and metricated)

1 6 Pavement materials in road bui ld ing - Gu idel i nes for making better use of local materials

Granular materials, whose particle size distributions

resemble the theoretical distribution when the exponent

11 lies in the range of 0.3 to 0.5 (Figure 3.2), are considered

more likely to pelform satisfactorily. The limits of patticle

size distribution adopted by most authorities in standard

specifications for pavement materials, approximate to a

distribution calculated by applying these values of 11,

and specifying an appropriate maximum patticle size

frequently 19 mm.

The effect of patticle size dish'ibution on density is palt

of the justification for its use as an indicator of likely

performance. It has been observed that in relation to

similar soils similarly compacted, those soils with the

highest in situ densities provide the highest stability,

lowest permeability and best long-term perfOlmance. It

is also known that soils with maximum density gradings

are generally more workable and easier to place.

Table 3.2 illush'ates the general properties of various

material mixtures.

1 00 .075 80 60 40

� � 20 -----

� t:=== o 75 1 50

0.425

In - 0.30 /"

/ � � n - 0.45 0 --

------------..---------/

300 425 600

Y �

1 . 1 8


The general properties of mechanically stable gradings

for pavements under various traffic loading conditions

are illush'ated by Figure 3.3.

VicRoads has suggested the following grading

requirements for naturally occurring granular materials

(Table 3.3).

3.4.3 Plasticity

Consistency limits are based on the concept that a fine

grained cohesive soil can exist in four states, depending

upon its water content. Thus a soil is solid when dry,

and with the addition and incorporation of water will

proceed through the semi-solid, plastic and liquid states.

The explanation for these changes lies in the interaction

of the soil palticles. The greater the amount of water a

soil contains, the less interaction there will be between

adjacent palticles, and the more the soil will act like a

liquid. The water contents at the boundaries between

adjacent states are termed the Linear Shrinkage, Plastic

2.36 4.75 9.5 19 5 38 50 1 00 //

� Ij

/

� �rn - 0.50 I

/

2.36 4.75 9.5 20 28 38 50

8 o

60 40 20 o

Australian Standard Sieve Sizes

Figure 3.2 Particle size distribution curves for various values of n (Source NAASRA 1 976, figure3)


� Coarse stone, Well graded Excess

Property low fines coarse to fine fines

Compaction Difficult Moderate Easy

Flexibility Relatively stiff Moderate Relatively pliant

Stability Variable Good Fair

Drainage Good Low Variable

Effect of water on strength Not much Moderate Vety significant strength loss

Chemical stabilisation Not very suitable Suitable Very suitable

Dust Low Moderate High

Roughness High Moderate Variable

Capillary (suction) effects Vely low Beneficial suction High suction, risk

1 00

90

80

70

60

50

40

30

20

1 0

0

1 8

Table 3.2: Properties of mixture gradings

0.075 200

0.425 36

of potential instability

BS Sieves

2.36 4.75 9.2 1 9 37.5 75 7 3/1 6 3/8 3/4 1 -1 /2 3

1 1 1 1I1 1 1 ./ I I ./V � I f--+--f-t--t-H+t+----+-+-+-++++t+--+--+ I I I I I I I I I / I Unstable in wet / / ° 1 f---+--+-+-+-1-++++--+-+-+-!-+-1-H-1f---+-+ bitumen or cement +-M--t+1-t--t-+-H'tttHl--t!- o�Cj +++++1

t--+-+-+-+I-+tt+--+-+-+-1-+1-tHf---+-+ stabilisation 7 >J .-/ / V-+-++-H+I / / !-G:J0 �-Q�0 t--+-+-+-+I-+tt+--+-+-+-1-+1-tH--+-+-+-+I-+tt+-7��--+�/+-�K+t--+.A- oV / �v --+-+�H4� V / v 'Ii f---+--+-+-+-1-++++--+-+-+-!-+-1-H-1--+--+-+-+-1--t-b0i4--+-:A-+-f--hI-l+f----)f- . >;-0" � -+--+7i-t+-H-H t--+-+-+-+I-+tt+--+-+-+-1-+1-tH--+-+-+�H+++--��/ -+-r,�++_�/� 0�� , ��-��/'-r++H+1 ,,/ �\(j � •. v � ./f 1/' -<-0f1y_-A-V--+--+�H4�

/ �'l>� $' / / t('\. ><S t--+--+-t-rH-++t--+-+-+-H--K+t--t--+-+-+I-71+t--+ 0C!i_7' �"\ / / / f---+--"-...J.......j....;....uCW---'--'-+-+++++¥--+--+---t---.I�+++-+-7'/'-t-h �0 / / --

0.0001

Unstable in wet due to -+-++--H'H--+---b"'I--f-H+H---'!«/'--+-+--boI"++++-"'/'-+-+-+-+-1-tlr-t+ Harsh mixtu re high volume change ./ ,,/ /' difficult to shape slippery when wet V V II and compact

0.001 0 . 1 1 0

Particle Size (mm)

Clay Fine Medium Coarse Fine Medium Coarse Gravel Silt Silt Sill Sand Sand Sand

Figure 3.3: Properties of mechanical ly stable gradings (Woolorton 1 947)

1 00

Pavement materials in road bui ld ing - G u idel ines for making better use of local materials


Nominal Size (mm), Suggested uses

Sieve 25 Sealed 25 Unsealed 20 Sealed 20 Unsealed 10 Sealed 10 Unsealed size base, base, base, base, base, base,

AS (mm) sub-base sub-base sub-base sub-base sub-base sub-base

26.5 100 100

1 9.0 86 - 1 00 89 - 100 100 100

9.5 6 1 - 82 65 - 82 70 - 88 74 - 88 100 100

4.75 42 - 66 48 - 66 48 - 7 1 5 5 - 7 1 70 - 90 74 - 88

2.36 28 - 54 34 - 54 34 - 57 40 - 57 48 - 73 48 - 7 1

1 . 1 8 2 1 - 44 25 - 44 24 - 46 28 - 46 34 - 60 40 - 57

0.425 1 2 - 30 1 6 - 30 1 4 - 33 1 8 - 33 1 9 - 42 25 - 42

0.075 5 - 1 8 8 - 1 8 6 - 20 9 - 20 8 - 25 1 2 - 24

Table 3.3 Suggested grading requirements for naturally occurring granular materials (Based on VicRoads 1 998)

Limit and Liquid Limit respectively. These limits are

defined in an empirical manner, and determined by

standard test procedures. They give an indication of

the amount and activity of the clay present in a soil.

NAASRA's Natural Gravel, Sand-clay and Soft Fissile

Rock (NAASRA 1 980) Pavement Materials, Part 2,

describes the consistency limits as follows.

The Plastic Limit -The Plastic Limit (PL) is defined as

that moisture content (expressed as a percentage) at

which a thread of soil passing the 0.425 mm sieve can

be rolled without breaking until it is only 3 nm1 in

diameter. It is dependent on both the type and amount

of clay present. At the Plastic Limit sufficient water is

required to wet all the surfaces and reduce cohesion so

that the particles can move past one another under

stress, but maintain a new moulded position. A high

Plastic Limit may indicate the presence of an undesirable

amount or type of clay.

The Liquid Limit - The Liquid Limit (LL) of a soil is

usually defined as the moisture content (expressed as a

percentage) at which the soil passing the 0.425 mm sieve

is sufficiently fluid to flow a specified amount when

jarred 25 times in a standard apparatus. It is dependent

upon both the type and amount of clay present, but is

more sensitive to the type of clay than is the plastic

limit. At the Liquid Limit, a soil is water-saturated, and

the distance between particles is such that the forces of

interaction between the clay palticles are sufficiently

weak to allow easy movement of the palticles relative to

one another. The Liquid Limit of a soil generally increases

with an increase in the amount of flaky, fibrous or organic

p31ticles present. It therefore often gives us a useful

waming of the presence of undesirable components

which may affect packing, interlocking and cohesion of

the soil particles, leading to poor stability of the

compacted soil mass.

The Plasticity Index - The Plasticity Index (PI) is the

numerical difference between the Liquid Limit and

Plastic Limit for a particular material and indicates the

magnitude of the range of moisture contents over which

the soil remains plastic. Except where a clay has unusual

propelties, the Plasticity Index generally depends only

on the amount of clay present. It gives a measure of the

cohesive or binding qualities resulting from the clay

content. Also it gives some indication of the amount of

swelling and shrinkage that will result from wetting and

drying of that fraction tested.

Pavement materials in road bui ld ing - Guidel ines for making better use of local materials 1 9

As some soils do not have sufficient mechanical

interlock, they require a small amount of cohesive

material to give a satisfactOlY perfOlmance. A deficiency

of clay binder may cause ravelling of gravel wearing

courses during dlY weather and excessive permeability.

An excess of clay results in softening of the binder and

loss of stability when the gravel becomes wet. Materials

with an excess of clay are also difficult to work.

Linear Shrinkage - The Linear Shrinkage (LS) is the

percentage decrease in volume of the fine fraction of a

soil when it is dried after having been moulded in a wet

condition, approximately at the Liquid Limit. Like the

Plasticity Index it gives some indication of the volume

change that is likely to occur in a soil when moisture

content changes. It is a useful test for soils with low

clay contents on which the Liquid and Plastic limits and

hence the Plasticity Index, are often difficult to measure.

An approximate estimate of the Plasticity Index can be

made by measuring the Linear Shrinkage. The Plasticity

Index is then approximately two and a half times the

Linear Shrinkage.

3.5 Suggested specification limits

Suggested specification limits for LL and PI for non

standard sands, gravels and ripped rocks used for

various applications under different rainfall regimes

have been proposed by VicRoads (1998) in Table 3.4.

Other Road Authorities may have their own preferred

specification limits.

Following are recommendations for using grading and

plasticity information based on TRL (1993).

The normal maximum specified PI for a pavement base

material is 6. The material passing the 0.075 rrun sieve

should be chosen according to the grading and

plasticity of the fines. For materials with non-plastic

f ines, i.e. processed or crushed aggregate, the

proportion passing the 0.075 mm sieve may approach

12%. If the PI approaches the upper limit of 6, it is

desirable that the fines content be resh'icted to the lower

end of the range. To ensure this, a maximium Plasticity

Product (PP) value of 45 is recorrunended where:

PP = PI x (% passing the 0.075 mm sieve).

W hen using naturally occurring granular materials

as road base, the fines should preferably be non-plastic

but again should not normally exceed a PI of 6. As an

alternative a Linear Shrinkage not exceeding 3% is

recommended.

If the PI approaches the upper limit of 6 it is desireable

that the fines content be restricted to the lower end of

the range. To ensure this, a maximum PP of 60 is

recommended or alternatively a maximum Plasticity

Modulus (PM) of 90 where:

PM = PI x (% passing the 0.425 mm sieve).

In arid and semi-arid areas where average rainfall is less

than 500 mm per annum, and where evaporation is high,

the allowable PI could be increased to 12.

In order to meet these requirements in either of the above

cases, it may be necessary to modify the material

Annual rainfall (mm)

Material use < 500 > 500

IL PI IL PI

Unsealed base/shoulder 35 (max) 4 - 15 35 (max) 4 - 9

Sub-base for unsealed pavements 35 (max) 18 (max) 35 (max) 12 (max)

Sealed base/shoulder 25 (max) 2 - 10 25 (max) 2 - 6

Sub-base for sealed pavements 25 (max) 2 - 12 25 (max) 12 (max)

Table 3.4 Plasticity I ndex for non-standard materials (Source: VicRoads 1998)

20 Pavement materia ls in road bui ld ing - Guidel ines for making better use of local materials

properties by adding a small proportion of cement or

lime. Where the PM (PI x % passing 0.425 mm sieve)

does not exceed 1 000, a wide range of plant has been

found to be effective in mixing these soils including

tractor towed disc harrows, graders and pugmills (Odier

e/ al. 1 97 1 ). Further details on soil stabilisation are

given in Chapter 5.

3.6 In-situ measurement of material strength (CBR)

3.6.1 Description of the California Bearing Ratio

The most common measure of the strength or support

value is the Californian Bearing Ratio (CBR) and is used

in these Guidelines. The CBR test was originally

developed in the Uni ted States using a crushed

Californian limestone as the standard material. The test

consists of measuring the force required to push a

cylindrical plunger of 49.6 mm diameter at a rate of I nun

per minute, 2.5 mm and 5 mm into the laboratory

compacted sample. This force ( 1 9.5 kN) was assigned

the value of 1 00% and became the base line against

which all other soil strength measures could be recorded.

Tests are carried out either unsoaked (at OMC or EMC),

or soaked (a weaker state of the material, normally after

four days soaking in water). Hence soft soils may have

CBR values as low as I % and good quality crushed

rock 1 00% or more.

The value of the CBR method of pavement design is its

widespread use over the past 50 years or so. Full CBR

testing, both in the field and in the laboratory are seldom

carried out for light trafficked roads because of time

and cost.

3.6.2 Field measurement of CBR

The Dynamic Cone Penetrometer (DCP) and Clegg

Hanmler are devices which measure shear strength

indirectly and can be calibrated to give an indication of

CBR

The DCP, which is documented in the Sealed Local Roads Manual (ARRB 1 995) is suitable for assessing

subgrades and some fine grained sub-base materials.


The Clegg Hammer is suitable for rapid assessment at

low cost, of compacted sub-base and base materials

including gravels. Use of the Clegg Halruller on similar

pavement material in a well-performing road nearby at a

similar equilibrium moisture condition will give an

indication of the in-sih! CBR which can be expected.

The Clegg Hammer was devised in Western Australia

by Doctor B. Clegg in 1976 and has been modified and

developed since. Whilst there are several models now

available, the best Imown is the Standard Clegg Hanmler

which consists of the 4.5 kg hammer used in the heavy

or modified compaction test, dropped tlu'ough a guide

tube f)'om a height of 450 mm on to the pavement sUlface.

The equipment is fitted with an accelerometer and the

dynamic response is measured by the peak deceleration

which is relayed directly to a gauge calibrated in units

of gravitational acceleration. The units are Clegg Impact

Value (ClV), where 1 ClV = 1 09 (g is the unit of

gravitational acceleration), which is normally recorded

on the fourth blow of the hatruner. It is useful as a rapid

field control test of materials and their compaction. Since

the Clegg Hammer impacts on just a small surface area,

the results are susceptible to scatter where there is a

significant stone content with sizes in excess of 1 5 nml

diameter.

A relationship between CBR and ClV has been

developed following research by a number of

researchers over a variety of materials (PlARC 1 995):

CBR (%) = 0.07 x (crvy. Another comparison gives:

CBR = 2.5 x crv - 25 (for CBR < 30).

3.7 Australia-wide occurrence of material classes A - D

3.7.1 Groups

The local pavement materials, grouped according to

their mode of formation or source in Classes A, B, C and

D, are each represented in most States and may be

generally described as follows:

Pavement materials in road bui ld ing - G uidel ines for making better use of local materials 2 1

3.7.2 Class A - in-situ weathered rocks (residual soils)

Weak or poorly cemented residual soils consist of the

material remaining after a rock has been removed by

chemical weathering processes such as solution or

leaching in tropical conditions. White Rock is a leached,

low strength, kaolinised sandstone or weathered

mudrock; it is used in parts of cenh'al Queensland. It

occurs in the lower slopes of mesas or remnants of

mesas (flat topped outcrops or hills). DuriclUst is formed

by precipitation of minerals (iron oxide, silica or calcium

carbonate) from solution under the influence of seasonal

climatic variations. They can be found as cap rock in

mesa terrain of western Queensland. This rock can be

broken down by crushing or grid rolling. This massive

form is not so common in occurrence in Australia as the

pisolithic (pea gravel) form, which is refetTed to as a

ridge gravel Class-C laterite below.

Volcanic scoria deposits occur in south-eastern

Australia. They are vesicular cinders resembling blast

furnace slag but weaker. This material has been used in

IUral Victoria. It is relatively easily worked and well suited

to use in construction of local low trafficked roads.

Granite sands are fotmed £i'om the weathering of ancient

granite intrusions and are found on the slopes or

foothills of the present granite outcrops. They are used

most widely in Victoria on all roads except the busiest

State highways.

Expansive clays containing the mineral montmorillonite

can be patticularly troublesome in road constlUction.

This is due to its large volume change between wet and

dry states. The black soils of western Queensland, New

South Wales, the Northern Territory and the Kimberley

region of Western Australia fall into this category. The

seasonal expansion and contraction can cause a

considerable volume change. Deformation of the

pavement surface and longitudinal cracking a metre or

so from the pavement edge are telltale signs that the

subgrade is an expansive clay. This effect can be

overcome by lime stabilisation of the upper layer and

by installing moisture barriers either side of the

pavement but this can be an expensive process. Keeping

the moisture variation to a minimum will in turn reduce

the volume changes, i.e. reduce rainfall ingress and

evaporation. Use of geotextiles rolled out over a base

of such material and covered in a light bituminous chip

seal has been successfully trialed in NSW. A wider

formation width has also been found to work well in the

Kimberley region.

3.7.3 Class B - soft rock

Soft rock is mostly sedimentary rocks comprising two

main groupings:

• fine grained or argillaceous, comprising very fine

patticles and having a fine texture, when weathered

becomes mainly clay minerals or silts. Rock types

include siltstone, shales and mudstone; and

• coarse grained or arenaceous, comprising silica

(qUattz) grains, usually cemented together by other

minerals and having a medium to coarse texture. Rock

types include sandstone, conglomerate, tillite and

breccia.

Sedimentary rocks are formed by the deposition from

either water or air, of the organic remains of plants and

animals and by the crystallisation of soluble materials

£i'om solution. The granular material is usually the result

of weathering of other rocks. Although cemented as

part of the formation and hardening process,

sedimentary rocks are usually mechanically weak and

can be ripped and grid rolled. They tend not to be

widely used in road building. Victoria has been the

largest user of weak sandstone along with parts of south

eastern New South Wales; in the absence of better

material, decomposed sandstones have been used in

westem Queensland. Shale and siltstone have also been

used in some locations including south-east New South

Wales.

3.7.4 Class C - ridge gravels

Ridge gravels, angular fragments comprising the

weathered remnant of more resistant rocks, occur

extensively and have been of great value in road

construction for unsealed gravel surfacing and as a road

base for sealed roads. Found on higher ground, often

in association with clay binders, they are usually the

result of in-situ weathering of sedimentary or

metamorphic rocks and are technically residual rocks.

They can be very variable and may require ripping,

22 Pavement materials in road bu i ld ing - G u idel ines for making better use of local materials

screening and grading control (Lay 1 985). These include

quartz rich sedimentary gravels, harder weathered

metamorphic and pisolithic (groundwater) lateritic

gravels. Lateritic gravels generally occur in isolated

deposits, bedding horizontally and can range from I to

5 metres thick generally. They may stand out as low

humps in the surrounding countryside and tend to

support particular types of vegetation. (Detection by

aerial photography is a possible means of rapid

assessment when searching for materials based on the

topographic and vegetational key indicators.)

When used as a road base under a bituminous seal the

gravel will remain in place for the life of the pavement

but when used as an unsealed surfacing the material

will be lost in a few years as a result of traffic and climatic

effects (wind and rain).

Lateritic gravels of this class sometimes have a palticular

characteristic gap graded particle size distribution. As a

class they are sandy or clayey gravels consisting of

rounded particles (pisoliths) of between 6 and 20 mm

embedded in a matrix of fine textured soil. The pisoliths

are concentrations of iron oxide which may display by

concentric layers of iron oxide precipitation or may be

quite amorphous. The gravels are suitable as a wearing

surface generally. Skid resistance can be a problem

with a loose cover of pisolithic gravel. Should testing

facilities be available, the best gravels are those with a

Los Angeles Abrasion value less than 45% after being

soaked in water for at least 24 hours. Laterite gravels

tend to harden fulther or self harden when built into the

road. This is probably due to continuing compaction

by traffic, reduction in clay content by 'dusting' effect

of traffic and suction in the remaining clay fraction as

the soil dries out. In the presence of water these

pavements will be weakened considerably and may

benefit from either lime or cement stabilisation in more

heavily trafficked applications.

Other concretionaty materials located palticularly in arid

areas and usually not far from their source rocks include

calcrete (formed from migration of calcium and

magnesium carbonate) and silcrete (formed from

migration of qU31tz -silica). They may also be known as

kunkar, or coffee rock. They may occur as pans around

salt lakes. Calcrete can occur in various forms, as quite


massive beds, nodular gravel, calcified sand, or fine

powder. Massive calcrete can develop in sheets thick

enough and hard enough to require quanying. With

appropriate processing, base course quality crushed

rock can be produced. The weaker forms would generally

be used only where no other stronger materials are

available. Silcretes occur less frequently. Both calcrete

and silcrete may be modified by stabilisation with cement

or lime. Powder silcrete however may undergo an extreme

alkali-silica reaction if stabilised with lime causing "blow

outs" of portions of the pavement due to rapid

clystallisation and expansion of the material over a vety

short period of time.

3.7.5 Class D - transported deposits

Rounded alluvial gravels occur alongside both existing

water courses and the paths of ancient prior streams.

These gravels can be very hard, consisting of igneous

or metamorphic rock. Due to their rounded nature they

are best crushed before use as a road base.

Deselt soils consist predominantly of wind blown sands.

As such they tend to be poorly compacted with low

field densities. Pavements formed with these soils may

support very low levels of light traffic but will break

down and rut or turn to dust very rapidly as traffic

increases. Compaction is required to improve the

strength of a sand base but in areas of little or no water

this can be a real problem. Some chemical binders/dust

suppressants (Foley et al. 1 996) have been used

successfully to reduce the amount of water required for

wetting of the soil. By lowering the surface tension of

the water its wetting powers are increased, improving

the lubrication between the sand particles and thus

lowering the Optimum Moisture Content for compaction.

The use of heavy impact rollers on poorly compacted

soils has also been found to be effective on such soils.

Cement and lime stabilisation of these soils is not

generally effective. Bitumen stabilisation of the surface

layer to approximately 1 50 mm has proved to be

effective.

3.8 Materials Data Sheets

Materials Data Sheets for 50 individual sites are located

in Chapter 7 and are grouped by State/TelTitOlY and

Material Class. The data sheets contain site specific

Pavement materials in road bui ld ing - Guidel i nes for making better use of local materials 2 3

details on properties and handling of the material. A

Key Map, Figure 3 .4, shows how Australia, which covers

a land area of about 8 mil lion sq km, has been divided

into 40 smaller areas for reference purposes.

3.9 Typical Materials Classification Sheets

The common properties of 10 of the key pavement

materials types found:

.--- - 1 0

______ -1 5

6 I

•

1 3 1 4 : 1 I

7

•

•

Class A White Rock, Granitic Sand;

Class B Sandstone, Shale, Ripped Sedimentary Rocks;

Class C Calcrete, Lateritic Gravel; and

Class D River Gravel, Prior Stream Gravel, Sand-clay

are listed in the Materials Classification Sheets which

follow.

1

I

• • . . - , . •

r - - - - - - - - - -23 : 24 25

I

22 : 26 I I I- _ _ _ _ I

• I I • I II 35 I

• •

_________ -40 1 35

24

LEGEND

� Location Map Soil sample

1 40 1 44 1 50

Figure 3.4 Key map (Source: Base Map of Australia, Auslig © 1 982)

Pavement materials in road bu i ld ing - G u ide l ines for making better use of local materia ls

Class • liranitic Sand

Granitic san ds pit at Mt Bolton, Victoria

Key characteristics

These sands represent granitic derived colluvial deposits as distinct from alluvial sands and in-situ weathered granite.

Application

Widely used where granite outcrops are available. Increased traffic loadings and environmental pressures on the

working of these pits have seen a decline in their use. Used in their areas of OCCUlTence on light to moderately

trafficked roads.

Subgrade, suitable as capping material over soft subgrades.

Sub-base, formerly used on main arterial roads/highways in wetter parts of the State.

Base. Suitable as road base on low to medium traffic municipal roads, granitic sands. Also used as an additive to

coarser river gravels to improve grading and impart some plasticity,

Typical grading and plasticity characteristics, for Victorian samples, range as follows:

Sieve size (mm)

Location 4.75 2.36 .425 .075 LL % PL %

Tooborac 96 82 43 27 21 16

Tooborac 93 70 32 21 18 15

Pyalong 90 60 39 22 38 27

Pyalong 79 50 21 1 1 33 20

Langi Ghiran 55-100 45-90 25-50 6-25 25

Mt Bolton 100 75-90 30-50 18-25

Stabilisation by mechanically blending with coarser gravels is most effective.

Compaction

PI

5

3

12

13

4-8

LS %

2

0

4

5

Avoid very thin layers as "compaction planes" can develop causing delamination. The material is easy to work.

Simply spread, water and compact at OMC and using smooth drum heavy roller. Will not nOimally respond to

vibration.

Wearing surface.

Suitable as a wearing surface only on lightly trafficked roads. Not suitable under heavy commercial vehicle loadings.

Care is required in preparation of the base for sealing; a uniform mix of moisture must be achieved throughout the

material.

Pavement materials in road bui ld ing - G u idel ines for making better use of local materials 25

Class • White Rock

Key characteristics

Low sh'ength, often silicified kaolinitic material formed by the leaching of iron and alwninium from siltstone, shale and

mudstone. Generally formed in the mottled and pallid zones below a present or former duriclUst surface. Examples are

White Rock from south-eastern Queensland near Goondiwindi and the Mesa White Rock from the central west.

Application

Suitable as a base or sub-base depending upon material quality. Typically used in moderate to low rainfall areas (500-

SOO mm per year) for a range of traffic conditions up to 5 x 106 ESAs over a 20-year design life. Pelformance evaluations

have shown that this material contirlUes to maintain good shape and riding qualities throughout its life.

No grading data available.

Construction

Selection of material for base/sub-base is based upon its ease of excavation and stockpiling. In higher traffic situations,

a 250 kW (DS) dozer should not produce more than 1 50 m3 per hour. This ensures that the material is not too soft. For

lower traffic situations a front end loader should be capable of winning satisfactory material. Use of grid rollers and

rock busters to reduce oversize is practised. Strength is very dependent upon cohesion. Performance moisture

content is therefore critical, with the greatest sh'ength gains resulting from reduction in moisture content. In common

with some other residual materials, reworking of the material will greatly reduce strength so that care must be taken to

ensure that any such reworking is kept to an absolute minimum.

Stabilisation options.

Processing by addition of sand results in some strength gains. Up to 15% by weight of sand is usually added to the

White Rock to improve the grading and reduce the Plasticity Index (the local specification requires PI not more

than 1 0).

Wearing surface

Harder fractions have been used on Shire unsealed roads as a running surface; however, it is not generally suitable as

a wearing surface. New pavements should be sealed at or below the design moisture content, typically 60 - 70 % of

OMC.

26 Pavement materials in road bui ld ing - G u idel ines for making better use of local materials

Class B Sandstone

Key characteristics

The most abundant, easily worked and easily won material. Extremely variable in quality and wet/dry strength.

Sandstones do not generally meet standard specification requirements unless modified or stabilised.

Application

Widely used in their areas of occurrence unprocessed on light to moderately trafficked roads. Areas of use range from

North West Queensland where weak Winton sandstones have been used, to SE NSW where sandstones provide a

medium to good quality material and on to SA where the quartzites of the Adelaide Hills provide good quality

roadstone when cement treated. Sandstone scree gravels (loose gravel accumulated at the foot of hills lopes) are also

used in the Kimberley of WA.

Material is generally free draining in situ and suitable as capping material over soft subgrades.

Use as a sub-base, material either "as won" or with some modification of grading by crushing and / or by additives,

usually cement.

Base. Suitable as road base on light to medium trafficked roads and with cement or bitumen stabilisation on heavily

trafficked roads. Cement treated quattzite is used extensively on main roads in South Australia as a sub base and base

course.

Gradings from QLD and NSW show the variability of sandstone gradings:

Locality

Winton

Nowra

37.5 19

100 76

9.5

54

Sieve size (mm)

4.75

100

46

2.36

41

Suggested conventional specification gradings for light and heavy traffic:

Sieve 37.5 19

light traffic 70-100 53-100

heavy traffic 70-100 53-1 00

9.5

40-100

40-90

Sieve size (mm)

4.75

30-87

30-75

2.36

26-75

26-58

.425

94-98

33

.425

14-50

14-30

.075

25-30

9

.075

7-30

7-28

PI

6-12

0-2

PI

2-6

2-6

Stabilisation by treatment of harder material by crushing, and of all types by cement or bitumen stabilisation is the

most effective.

Compaction at/or slightly dlY of OMC with grid roller, smooth drum, vibrating smooth drum and pneumatic tyred roller.

This will produce a strong, stable pavement. Blending with 2% - 4% cement will produce CBR values in the range 30%

to 90%, indicating suitability as a sub-base or base on most standard specifications. Beware of cracking with higher

cement contents. Softer sandstones typically require placing and compaction in thick lifts (up to 200 mm); avoid

reworking. Some harder crushed sandstones are suitable for use as a wearing surface. Addition of sufficient plastic

fines to improve binding, can provide a reasonable unsealed wearing surface but they are generally too susceptible to

wet-dry strength variations to be used as a sealing aggregate.


Class B Shale

Ripped sha le, Copley, SA (TSA)

Key characteristics

Usually grey/black, predominantly fine grained relatively weak mudstones or siltstones, may be fissile (with cleavage)

and can VaJY from relatively weak to hard when in the unweathered state. May have clay fractions or bands which tend

to weaken when wet.

Application

Generally can be won in the pit by ripping with a dozer. Suitable as a base course layer in low and medium trafficked

roads (up to 2,000 vehicles per day). This material is won by blasting, and further mixing by windrowing to blend in

clay fines. Grid rolling may sometimes be required to achieve a "workable" size distribution. Performs best in areas

where annual rainfall is low, below 400 nun.

Subgrade and sub-base

Suitable for use as select subgrade and sub-base in roads up to medium traffic loads and in areas where subgrades are

free draining. In poorly drained wet conditions, can soften quite rapidly.

Usually suitable as base on lower traffic sealed roads only. Stabilisation with lime or cement may improve propeliies,

depending upon the constituent mineral composition of the pavement material.

Typical grading and plasticity for 40mm maximum size shale (low plasticity si Itstone) from Tomerong, just south of

Nowra;

Sieve (mm) 19

T40 76

9.5

54

4.75

40

2.36 .425

32 20

.075 LL % PI LS %

1 1 1 8 3 0.5

Compaction should be carried out at or below optimum moisture content. Shale is generally more moisture sensitive

than sandstones. Rapid loss of strength may result if too wet. Typically compact to only 1 00% density relative to

standard compaction. Excessive compaction may cause breakdown of the material. Minimum CBR 20% with weak

well-compacted shales to in excess of CBR 60% for more massive siltstones. EMC should be some way below OMC

for best results; i.e. ensure a well-drained foundation.

Wearing surface

Unsuitable as a sealing aggregate.

28 Pavement materia ls in road bui lding - G u idel i nes for mak ing better use of local materia ls

Class B Ripped Rocks

Key characteristics

Ripped sandstone and dolomite, Mt Lofty Range, SA

A wide spectrum of arenaceous and argillaceous sedimentalY rocks. Most are used "as ripped". Some harder materials,

however, require some degree of crushing.

Application

Used extensively in areas adjacent to highlands of eastern and southern Aush'alia because of their widespread

geological occurrence, and with the declining reserves of "gravels" due to depletion and environmental constraints,

in future it is anticipated that greater use will be made of sedimentary rocks - particularly the softer types that can be

won at relatively low cost by ripping.

Following are examples of grading and other properties of a number of Victorian ripped rocks:

Sieve size (mm)

Type and location 19 9.5 4.75 2.36 .425 .075 LL% PI LS % CBR % OMC %

Conglomerate, Gisborne 100 71 5 1 40 23 10 20 6 3 60 5.5

Quartzite/Tillite, Myel' 100 77 58 47 33 23 16 3 95 7.8

Siltstone, Winton 100 73 53 39 20 12 27 8 3 65 9.0

Mudstone, Irvine 100 73 58 47 33 24 22 5 3 45 9.2

Tuff, Manifold 100 95 78 70 26 8 NP 0.4 50 19.8

Additional testing for durability should be carried out if facilities are available including LosAngelesAbrasion Value

and/or Aggregate Crushing Value and wet/dry strength comparisons.

Stabilisation. Where necessary, cement stabilisation of ripped material, possibly subject to fUliher processing by grid

roller or rockbuster, will in most cases produce a high strength base course material for use on more heavily trafficked

roads.

Construction

In areas where other economic alternatives are not available, rippable sedimentary rock is used for base course

provided the Plasticity Index is <6 in wetter areas, though in drier areas Plasticity Indices of up to 1 0- 1 5 may be sealed.

For base course construction the hardness of the source rock must be such that excessive degradation to its constituent

grain size does not occur during compaction. Ripped and crushed sedimentary rocks tend not to be used as base

course on heavily trafficked roads - particularly in wetter areas due to this durability problem.

Pavement materials in road bui ld ing - G u idel ines for making better use of local materials 29

Class C Calcrete

Calcrete stockpile, Tailem Bend, SA

Key characteristics

Variable calcareous material generally Class C or occasionally B, ranging from hard limestone conglomerate through

rubbly "limestone" to soft chalky sands. Alternatively known as kunkar, kopi, "limestone".

Application

Used in low rainfall areas on unsealed roads. Also suitable as a base course layer, unprocessed on light to medium

trafficked sealed roads (up to 7 X 1 05 ESAs) or cement stabilised on more heavily h'afficked roads. Also suitable for use

as select sub grade and sub-base. Provides a generally good subgrade with CBR values in the range of 8% to 20%.

Used extensively as sub-base and base material in drier parts of the NT and in NSW, SA, western Victoria. Calcrete has

a wide range of propelties from cemented sands to nodular limestone. Typical grading and index propelties from

south- eastern South Australia are:

Sieve (mm) 19

66

9.5

56

4.75

50

2.36

46

.425

31

.075

12

LL %

22

PI

NP

LS %

1 .5

A suggested specification for this material, a 5 5 mm Quarry Rubble, from South Australia is:

Sieve (mm) 26.5

6 1-85

13.2

41-65

4.75

22-44

2.36

1 6-34

.425

6-18

.075

3-9

LL%

28

PI

1 -8

LS %

4

Typically, plasticity requirements can be increased by as much as 50% above normal requirements in the same climatic

regime with little deh'imental effect on performance.

Stabilisation. May be partially stabilised with 2% cement or prepared as a cement treated base at 4% cement. Lime

stabilisation is not appropriate.

Construction

Usually won using a dozer (nominally Cat D7) to rip and stockpile. Compaction with grid roller, smooth and pneumatic

tyred roller; processing of harder calcretes after crushing or breaking up with a rockbuster. CBR values range between

approximately 25% and 90% at 95% of OMC. When dried back to 75% of OMC, values increase to 1 20% or more.

Wearing surface

Harder calcretes are suitable as a wearing surface although they may require some blending with fines to provide

acceptable grading for unsealed roads. Will tend to pothole if unevenly mixed. Calcrete gravels have been processed

as a short term sealing aggregate where no other material is readily available.

30 Pavement materials in road bu i ld ing - Guide l ines for making better use of local materials

Class C lateritic IiravHI

Key characteristics

, . •• " " • , 4 : . :.. · · '

.. � . ' ;

. .... \ . '.� � ) , :., '.

Lateritic gravel pushed up i n pi t near Kalgoorlie

Variable quality red-brown rounded (pisolithic) gravels and mottled red/greenish laterite gravels (ferricretes) overlying

the massive laterites (duriclUst) that in turn overlie the weathered bedrock. Extensively available in IUral WA and Palts

of Qld, SA and NT.

Application

Suitable for use in low and medium trafficked roads (up to 5,000 vehicles per day). This naturally variable material

should be pushed up by dozer in the pit to ensure mixing. FUlther mixing by windrowing to blend in the sand and clay

fractions is desirable.

Subgrades are typically sandy clay with a grading similar to that shown and will be moisture sensitive.

Sieve (mm) 2.36

96

.425

78

.075

45

LL%

36

PL % LS %

15 10

When protected from moisture intlUsion, they have performed satisfactorily. Lime stabilisation will reduce water

penetration. Detailed data, where available, is given with location data sheets.

Suitable as a sub-base. To avoid moisture problems, performance is better when formed up to 300 mm above natural

surface.

Suitable as base course in drier climates. In wetter areas performs satisfactorily provided sealing of the surface is

carried out to waterproof and prevent softening by moisture entry.

Tends to "self stabilise" by compaction, loss of clay fraction and chemical migration. Stabilisation with small amounts

of cement and lime has sometimes been used in order to reduce moisture sensitivity. PerfOlms best if blending with the

more plastic fines is carried out in the pit. Provides a suitable wearing surface but can break down if too wet. The

rounded "pisolithic" gravels provide good surface sheeting (and fair short telm sealing aggregate).

Successful constlUction has been achieved with a range of grading and plasticity as shown in the following example:

Sieve (mm)

GEH

SCH

19

99

97

9.5

89

80

4.75

71

49

2.36

62

32

GEH = Great Eastern Hwy, SCH = South Coast Hwy

.425

44

23

.075

1 8

1 2

LL%

23-27

19

PL

14- 17

16

LS %

2-9

Compaction at moisture close to OMC for a "tight" surface and reduced risk of moisture ingress. Tendency to soften

to clay if over wet. Cure with moisture close to, but not above, OMC before compaction. Typical laboratory compaction

95% MDD at 6-7% moisture content. Grading and index limits are variable. Not normally suitable as a sealing

aggregate.

Pavement materials in road bu i ld ing - Guidel ines for making better use of local materials 3 1

Class • River liravel

Key characteristics

River gravels are often "over sanded", non-plastic and can have poor cohesion and high permeabilities unless

modified by blending. The sphericity of many gravels detracts from their mechanical interlock strength.

Application

Widely used in their areas of occurrence; unprocessed on light to moderately trafficked roads.

Subgrade, suitable as capping material over soft subgrades.

Sub-base, used in VIC and southem NSW as a sub-base material.

Base. Suitable as road base as dug with some additive to promote cohesion and reduce permeability, or paltly crushed

to increase mechanical interlock and with the addition of plastic fines, such as granitic sands, on heavily trafficked

roads.

Typical natural grading and plasticity of Wodonga river gravels:

Sieve size (mm)

53 37 19 1 3.2 9.5 4.75 2.36 .425 .075 PI

100 95-100 75-95 65-85 55-75 45-60 35-50 1 0- 15 0-3 NP

Recommended conventional specification grading:

Sieve 19 1 3.2 9.5 4.75 2.36 .425 .075 PI

Sub-base 100 83 71 50 35 15 6 2-6

Base 100 84 72 52 37 16 7 2-6

Stabilisation

Treatment by pmtial crushing andlor mechanical stabilisation by blending as noted above is the most effective.

Compaction

Compaction at or slightly dty of OMC with grid roller, smooth drum, vibrating smooth dnlln and pneumatic tyred roller.

This will produce a strong, stable pavement. Partial crushing will produce gradings with compacted CBR values of at

least 60% or more, indicating suitability as a sub-base or base on most standard specifications.

Suitable as a wearing surface, although they may require some crushing and blending with fines to provide acceptable

grading for unsealed roads. River gravels have been processed as a sealing aggregate but can be of variable quality

due to their roundness.

32 Pavement materials in road bui ld ing - Guidel ines for making better use of local materials

Cia s D Prior Sireanl liravel

Key characteristics

Prior stream gravels (also known as sandy loams in some areas) comprise clayey sandy gravel (formerly stream bed

deposit). Generally fine graded with a small amount of stone comprising rounded qumiz pebbles. Typical subgrade is

silty clay. Present-day streams often flow transverse to the "old gullies" in which these gravels are located.

Application

Generally have satisfactory LL, PL and PI values making them suitable as a pavement material up to base course layer

for low to medium trafficked roads.

Base

Suitable as base on low traffic roads provided sealing of the surface is carried out to waterproof and prevent softening

by moisture entry. If PI is too low it is difficult to compact without flooding the material. If too wet, problems can

develop after sealing with the buildup of moisture unable to escape by evaporation. Shoulders should be spray

sealed.

On lightly trafficked roads can be used as a surface course without a bituminous seal. It must contain sufficient clay

to bind the palticles but not so much as to cause swelling in wetter conditions. Given regular maintenance grading

these roads can perform well under light h·affic. There is a tendency for loss of fine material as dust during sunune11ime,

leading to surface cortugation. This may necessitate the replacement of gravels every three years or so. Sheeting with

a fine crushed rock material has been carried out to impart additional mechanical strength.

Typical grading and plasticity for materials from Narrandera NSW and Numurkah VIC:

Sieve (mm)

Narrandera

Numur\<ah

9.5

100

100

4.75

99

99

2.36

97

93

.425

57

28

.075

30

4

LL %

22

PI

9

NP

LS %

Stabilisation of unsealed base with cement prior to sealing has proven effective in eliminating the adverse effects of

the higher plasticities necessary in unsealed bases.

Construction

The best reserves of this material are often covered by several metres of plastic silty clay overburden which must be

removed. EXh·action by scraper, fi·ont end loader or dozer. Thorough mixing is required prior to placement. Consh·uction

of the Narrandera material at 80% OMC, MDD of 2. 1 0 t/m3 at OMC 8.5%. CBR at EMC is 25%. Compaction may be

achieved by vibrating sheepsfoot, vibrating smooth, smooth or pneumatic tyred roller.

Suitability as a wearing surface on lightly trafficked roads only.

Pavement materials in road bui lding - Gu idel ines for making better use of local materials 33

Class D Sand-Clay

Sand-clay road base, Victoria

Key characteristics

These materials are generally fine grained slightly clayey sands (Unified Soils Classification ofSW, SP, SM, or SC:

see Figure 3. 1 in Chapter 3) of river channel, flood plain or wind blown origin. Tend to be composed of rounded to

sub-angular quartz grains coated with a mixture of iron oxides and clay minerals.

Application

Used for subgrade, sub-base and base with varying success on light to moderately trafficked roads (AADT up to

500). Restricted to areas with an annual rainfall less than 500 mm . The materials tend to be very moisture sensitive

with typical CBR values of 30% to 35% at OMC, 5% to 1 0% at l % OMC + 1% andin excess of60% when dry ofOMC.

Plasticity Index should generally be less than 10.

Subgrade, may be compacted. Suitable as capping material over soft subgrades.

Sub-base, should have a CBR >30% to enable a minimum thickness of base course to be placed.

Base. Suitable as a sealed road base but shoulders should also be sealed to reduce moisture ingress and inhibit

erosion of fines from the pavement edge.

Grading specifications tend to vary between States, but this WA specification would be fairly representative for

sand-clay basecourse:

n'affic 4.75

< los ESA 100

< 3 x l04 ESA 100

Stabilisation

2.36

70-100

70-100

Sieve size (mm)

.425

30-56

30-84

.075

13-31

l 3-35

lL

< 20

< 20

PL I.S

< 8 1-3

<8 1-3

Treatment by stabilisation with bitumen emulsion may be effective but relatively costly. Stabilisation with chemical

polymer additives has been trialled in WA.

Compaction

Construction procedures need to be carefully controlled with the compaction moisture content between OMC -2%

and OMC. Drying back of the material prior to priming for 2-3 days, typically to 80%, or less, of OMC, enhances

strength.

34 Pavement materials in road bui ld ing - G u idel ines for making better use of local materials

4. 1 Introduction

This chapter contains information on the following:

• how to locate new sources of materials;

• field tests - these tests are partly to identify the origin

or "Class" of the material, but more particularly to

assess quickly in the field whether it is likely to be a

satisfactory material for road use;

• inexpensive tests - these are further tests to help in

assessing suitable materials;

• regulations - whether operating from an existing pit

or source, or in opening a new pit, there are many

regulations to be observed. Both economic and

environmental considerations are impOliant; and

• pit operation and rehabilitation - an operating plan

will be needed. This section gives some guidance

on making an operating plan and also considers

environmental and rehabilitation issues.

4.2 Location of new sources

In considering the procedure for locating and evaluating

new sources of materials, NAASRA's Pavement

Materials, Part 1 - Search (NAASRA 1 982) is a very

useful reference. A search of existing available

infOlmation is also useful. Local GovermnentAuthorities

will have infOlmation on existing sources of road making

materials from private propeliy, gravel reservations and

Council owned pits. State Government Lands and

Minerals Depaliments will have information on quarries,

mines and extractive industries involving aggregate

production for roads. Any topographical maps, bore

hole information, and geological maps of known sources

may be useful. Possibly large scale searches have been

made with aerial photographs or with remote sensing

using infra red photography. Infra red photography has

been used to locate near surface gravels and sands

(providing they are not water bearing). Forestly Officers

will have information about materials used for surfacing

their own roads.

Field reconnaissance oflikely areas should take note of

all existing:

• excavations - dams, chatUlels, road cuttings, eroded

gullies and animal burrows;

• outcrops of rock formation which may be the source

of weathered deposits; or

• ridge gravels at higher levels and on colluvial slopes.

Local knowledge is most useful. Vegetation native to

the area provides clues. For example, stands_ofironbark

trees may be found on gravelly ridges. Bracken fern

may indicate fine sandy gravels and sparse areas may

indicate rock, sand or gravel at shallow depth. Celiain

shrubs exist where shallow sandstones are present.

Deposits beneath overburden and productive soil are

hard to detect but farmers, for example, may know the

course of ancient streams below their land which contain

"prior stream gravel". Sometimes the aspect of the site

is important; e.g. granite sands are often deeper on a

northern slope, possibly because of deeper weathering

in the warmth of northern sunlight. Ironstone gravels

may stand out as low humps in the surrounding

counttyside and tend to support little in the way of

vegetation, which may be apparent from aerial

photography.


At an early stage some preliminary drilling with tractor

mounted auger, or backhoe trenching, will identify

suitable deposits. Where resources are available, the

extent of the deposit may be verified by geophysical

methods such as seismic refraction or electrical

sensitivity methods.

4.3 Preliminary tests

4.3.1 Charactelistics

For local materials the important characteristics are

p311icle size, plasticity and durability, even though the

requirements or standards for size and plasticity are

less sh'ingent on low volume roads, pa11icularly in arid

and semi-arid areas.

4.3.2 Particle size

Sieving in the laboratory is necessary to accurately

determine the combined silt and clay fractions in the

size range of <0.075 nm1. With some practice it is possible

to classify the gravel with the Unified Soils Classification

System (USC) symbol by appearance and feel (without

sieving), and with the aid of some simple tests - shaking,

dry strength, crushing and toughness. The Unified Soils

Classification System (USC) is shown at Figure 3 . 1 in

Chapter 3 .

4.3.3 Combination of size and plasticity

The simplest measure of plasticity is the Linear

Shrinkage (LS) test on the portion finer than 0.425 nm1

sieve. A higher LS can be tolerated (even desired) where

the percentage passing the 0.425 mm sieve is small (say

< 1 2%). Where the percentage passing the 0.425 mm

sieve is less than 1 2%, there is little value in calTying

out the LS test because extra fines will have to be added

to the material to obtain a workable stable gravel.

However, a well-graded material can be assessed by

"wetting and squeezing" a handful of soil where

particles greater than 5 mm have been first plucked by

hand. It will:

• feel gritty;

• form into shapes;

• only slightly discolour the hands; and

• compact into a dense cake, that cannot be penetrated

readily by a blunt stick the thickness of a pencil.

Any damp material that sticks to the hands should

contain both sand and clay and not clay alone.

4.3.4 Dry strength

A typical inorganic silt possesses only slight dry

strength - a typical silt has the smooth feel of flour.

Silty gravels lack cohesion, are hard to compact and

consequently lack strength. They also lose strength

quickly as moisture content increases beyond optimum

(OMC). Dry strength can be gauged by drying a part in

the oven and crumbling in the fingers (or crumble the

remnant of the LS test). High dry strength is

characteristic for clays of the CH group. Unlike silts,

the clays are not "moisture sensitive" and take up water

very slowly.

4.3.5 Decomposition

Highly micaceous gravels are usually unstable because

of the plate like particles. Some igneous rocks can

decompose chemically and revert to plastic clays.

Personnel with local experience (e.g. from a local

authority or local contractor) should be consulted

regarding which materials, that appear suitable at first

sight, have not performed well in practice. Other soft or

decomposing rocks or gravels may break down in the

pavement. Those that decompose chemically or break

down mechanically are said to have poor durability.

4.4 Inexpensive tests for assessment of materials

4.4. 1 General

There are a few inexpensive tests which can be carried

out with a minimum of equipment to carry out a rapid

assessment of material quality. An initial appraisal of a

material should include its colour, texture, shape,

hardness and durability.

4.4.2 Dominant clay component

Colour can be of significance in that it may be an indicator

of the dominant clay component. Reliance should not

be placed on colour alone however, and this must be

confirmed by further testing as necessary. The

predominant colour plus any secondary mottling should

be noted when both wet and dry. The following table-

36 Pavement materia ls in road bui lding - G u idel ines for making better use of local materials

Materials extraction

Obsenration Dominant Clay Component

Mottled clays, red-orange-white mottle Kaolinites (non expansive)

Mottled clays, yellow-orange-grey mottle Montmorillonites (expansive, dispersive)

Medium to dark grey and black clays Montmorillonites

Brown and red-brown clays Appreciable i l l ite some montmorillonite

White and l ight grey clays Kaolinites and bauxites

Discrete micropaIticles of high reflectance Micaceous soils

Discrete microcrystals, easily crushed Gypsum-rich soils (sulphate salts)

Soft nodules, acid soluble, disseminated Carbonate soils (lime rich)

Hard nodules, red-brown Ironstones, laterite

Table 4.1 Identification of clays by appearance (Source: Ingles and Metcalf, 1972)

(Table 4.1) shows how different colours observed may

indicate the dominant clay or mineral.

A method of determining clay mineral type is the

Emerson Cnunb Test (Emerson, 1 967) which can be

employed to determine a number of soil types and

propert ies , notably whether the clay fract ion i s

expansive/dispersive or not. The procedure requires

good quality water; either distilled water or clean

NB: Siakes- combines chemically with water. 'If the crumbs are not air dry at first immersion, the scheme is still valid but this category will contain the nonsaline illites and montmorillonites as well as organic soils . .. Dispersio n is most readily detected by the formation of fine misty halos around each crumb, easily visible against a dark background. The more pronounced the halo, the more dispersive the soil. + The presence of carbonate, if not already recognised, can be readily verified by effervescence in the soil when a drop of acid is placed on it (battery acid or dilute hydrochloric acid will suffice). ++ Settling to a clear supernatant liquid (liquid on top) in less than 10 minutes is to be regarded as non dispersion.

Slakes

Complete Partial Dispersion Dispersion

(halos)� (halos)� Saine Saine f\o1ontmorillonites Illites often carbonates also

rainwater will suffice. No dispersant or wetting agent

must be added. The procedure is to place a small air-dlY

crumb (about the size of a bean), broken directly out of

the soil, into a glass or clear plastic container filled with

distilled or rainwater. It.is important that the crumb

should not be worked in any way by hand before

immersion. Observe the behaviour of the crumb after

immersion for several minutes (up to 1 0 minutes),

according to the following figure (Figure 4.1).

No Dispersion

Disperses Illite

Disperses Illite

Irrmerse Air Dry Crumbs in Water

Does not Slake --�-

Swells' I Does not swell

Organic Soils Laterised days

Take fresh crurrbs and moisten, remould lightly and immerse

- --------, Does not disperse

Carbonate and Gypsum absent

Shake vigorously

Does not disperse #

Kaolinite aJlorile

Carbonate and Gypsum present' CaIfv'g Illite CaIfv'g f\o1ontmorillonite

Figure 4.1 Emerson Crumb Test for dispersive soil (Source: Ingles and Metcalf, 1972)

Pavement materials i n road build ing - Gu ide l ines for making better use of local materials 37

4.4.3 Strength and durability

A very easy and quick test is to place a sample of the

selected material in a bucket of water overnight.

Inspection the next day will give a good idea of the

relative strength and durability.

The likely strength and durability of the material can

also be assessed with inexpensive testing. Refer to

Tables 4.2 and 4.3 following.

4.5 Regulations to be observed

4.5.1 Introduction

Regulations regarding the winning oflocal materials for

road construction vary in detail between States and

Territories but apply generally as follows:

4.5.2 Landowner's consent

Thi s is necessary before carrying out any preliminary

field reconnaissance or test hole drilling and sampling.

No pits can be started within close proximity of the

owner's dwelling or outbuildings; nor can they be

started in an orchard or other plantation. Owners have

sometimes made plantations of hardy trees (for example,

pine trees) on gravelly areas to prevent gravel removal.

On the other hand, if co-operative, the long establ ished

property owners are very knowledgeable. If a new pit

appears likely to eventuate, agreement on compensation

will have to be reached.

4.5.3 Planning regulations

Council plmming schemes will indicate the zones where

extractive industries are prohibited. Applications for

permits to open a pit in other areas will be considered

by Council on the grounds of visual unsightliness,

nuisance of noise and dust, sensitivity of other nearby

land users, damage to the environment through clearing,

soil erosion, stream contamination etc. The Council

may place conditions on the permit to ensure that

nearby ratepayers are not adversely affected, nor

ratepayers in general (e.g. by damage to Council roads),

in which latter case compensation payments may be

required by Council .

4.5.4 State Government regulations

State Government regulations usually forbid extraction

from permanent reservations. State authorities (Forestty,

Lands, Conservation) may i ssue permits to remove

material from Crown lands subject to arrangements

ranging from compensation to pit restoration, or both.

In all cases where the size or depth of face or hardness

of rock (drilling and blasting) means that the "pit" is

legally a "quarry" then the operation has to be l icensed

and subject to government safety regulation as an

extractive industry.

Term Undrained Approx. Field Test shear eBR

strength ("/0) (kPa)

VelY Soft =< 12 < 1 Exudes between fingers when squeezed in hand.

Soft 12 -25 1 -2 Easily penetrated by thumb. Moulded by l ight finger pressure.

Firm 25 -50 2-4 Penetrated by thumb with effort. Moulded by strong finger

.pressure.

Stiff 50 -100 4-7 Indented by thumb. Cannot be moulded by fmgers.

Very Stiff 100 -200 7 - 1 0 Indented b y thumbnail . Penetrated b y knife to about 1 5 mm .

Hard > 200 > 1 0 Can b e indented with difficulty b y thumbnail .

Table 4.2 Strength of cohesive soil (Source: after AS 1726-1 993)

38 Pavement materials in road building - Guidelines for making better use of local materia ls


Tenn Point Load Index (MPa) Field Test

EXh'emely Low <0.03 Easi ly broken by hand to a material with so i l

properties.

Very Low 0.03-0.1 Broken by leaning on sample with hammer. Cmmbles

under firm blows with a pick. Can be peeled with a

knife.

Low 0. 1 -0.3 Broken in hand by hitting with hammer. Easily scored

with knife. Sharp edges may be friable.

Mediwn 0.3-1.0 Easily scored with a knife. Broken against solid object

with hammer.

High 1-3 Difficult to break against solid object with hammer,

rock rings under hammer.

Very High 3-10 Requires more than 1 blow of hammer to fracture

sample, rock rings under hammer.

Extremely High > 1 0 Sample requires many blows with a hammer.

Table 4.3 Strength of fragments of rock and hardened materials (Source: after AS 1 726-1 993 and Geological Society Engineering Group 1 990)

4.5.5 Federal regulations

Federal regulations may apply in the Northern TerritOlY

and in the various States where heritage or sacred sites

exist or where relics are unealthed during the operation.

4.5.6 Council conditions

I n the case of a pit (not quany) on private property

Council may impose conditions on the granting of a

Plalll1ing Permit including:

• construction of haul road and maintenance to

eliminate dust nuisance to the landowner;

• fencing haul route to protect stock;

• adequate compensation for a neighbour where the

haul route continues through the neigh,bour's

property;

• rehabilitation of the pit area including fencing off

from stock while vegetation is being generated;

• stockp i l i ng of stripped top s o i l to ass i s t i n

rehabilitation;

• constmction of silt ponds downstream of the pit to

prevent turbidity in nearby streams; and

• prohibition of calting at celtain times of the year.

Where there is a considerable quantity of gravel to be

hauled over Council roads, it is usual for Council to

place celtain conditions, l isted below, on the permit for

the operation:

• to restore the public roads to the "pre-carting"

condition as determined from joint inspections by

Council and operator representatives (which is

usually sufficient on unsealed roads and low volume

roads); or

• in the case of a sealed road, to pay a sum to Council

for the additional maintenance during the operation,

and for the shortened life of road due to the increased

amount of axle loading as calculated for a life cycle

analysis.

The above emphasises the importance of minimising

haul and using nearby materials where possible. When

deciding on the most economic material total, costs have

to be taken into account. However, in general the closest

satisfactory material (not the best available in the

locality) will be economic even ifthis means opening a

new pit near the works site.

Pavement materia ls in road building - Guidelines for making better use of local materials 39

4.6 Pit operation and rehabilitation

4.6.1 Operation

A material borrow pit is only a temporary land use and a

clear operation and rehabilitation objective, consistent

with the proposed future land use of the area, must be

defined. From the outset this objective should be

established in consultation with relevant govemment

departments, local Councils , landowners etc. An

operating plan will be needed. This plan should detail

the extent of the extraction work, both in area and volume,

and identify at which time and for how long, sub-sections

of the pit area are to be progressively worked over the

expected l i fe of the pit . Detai ls of progressive

rehabilitation/revegetation should also be provided in

the plan.

The following procedures are good practice, in addition

to promoting safe operation and in consideration of

future rehabilitation. Where the topography allows:

• work the pit clear of a major gully and prevent run

off water from entering the pit by diversion drains;

• slope the floor of the pit away from the face in order

to keep the working face and plant operating area

near the face in a dry condition;

• because most natural materials are variable, mixing

and blending to obtain a homogeneous mixture will

usually be required. In the pit it is important to doze

downwards through the entire depth of the face, and

then move material parallel to the face to ensure

thorough mixing. If placed unsorted on the road

formation, mixing by windrowing and backblading

with a grader will be required;

• where hard lumps of material are being broken down

with a "rockbuster", there may be room to use the

rockbuster on the pit floor and then transport a

blended product to the road bed. In some cases a

grizzly (a crude screen often using parallel rail lines

to screen off oversize material) and jaw crusher can

be used to blend the hard and soft material;

• fine grained material for embankments is best moved

quickly - extracted and placed at in-situ moisture

content to save watering, and because it may already

be near EMC; and

• water from the pit floor and cut-off drains should be

directed to a silt pond before being discharged to a

watercourse.

4.6.2 Rehabilitation

There is a range of legislation concerned wholly or in

part with matters related to s i te rehabi l itation .

Administrative arrangements between government

agencies differs from State to State. Liaison between

these agencies should, in the first instance be via the

local govemment and state/territory departments of

Mines or Environment or in accordance with state

administrative procedures for material extraction.

The rehabilitation programme may involve:

• restoration of the area so that pre-extraction

conditions are replicated;

• reclamation ofthe area so that the pre-extraction land

use and ecological values can be re-established in

similar conditions; and

• remodelling ofthe area so that it is retumed to a use

substantially different to that which existed prior to

extraction.

The risk of soil erosion increases with rainfall intensity,

particularly where vegetation has been removed. The

final objective of rehabilitation of the site should be

reinstatement to a safe, stable and non-erodible

condition. On land used for agriculture or forestry the

aim could be to reinstate the land to its pre-extraction

level of productivity. At the very least, the objective

should be to restore the area as nearly as possible to its

original condition.

A survey of the site is essential to provide a baseline

standard for later rehabilitation. The significance of

various factors wi 11 vary between sites; c l imatic

conditions, particularly rainfall and soil characteristics,

are invariably of direct significance to site rehabilitation

procedures.

A site survey should include information on:

• land form and surface geology;

• soil types;

• surface and ground water;

• land use; and

• flora and fauna.

40 Pavement materia ls in road bu i ld ing - Guidel i nes for making better use of local materials


Quarry site Quarry site Quarry site area

§;j?j r--O

§;j?j

n area 0

§;j� J!:; £:} i �£:}c:::v�

area

c:::v 0 £:}

0�_ q

� i � �Di �� (a) (b) (c)

Not Recommended Recommended

Figure 4.2: Location of access roads (Source: AMIC 1 989)

Even on a relatively small scale, quarrying of materials

can result in local changes to the physical enviromnent

such as effects on vegetation, and on surface and

groundwater, and also in terms of dust. These changes

need to be managed so as to avoid adverse

environmental impacts such as erosion by wind and

water, introduction of weeds and visual degradation.

Care is required in the removal and storage of topsoil

and overburden. Many of the potential adverse impacts

of materials extraction from pits and quarries can be

avoided or reduced by careful siting of access roads

and creation of nature sh·ip buffer zones. Some examples

are il lustrated in Figure 4.2.

Good plaiUling and operating procedures will minimise

the adverse impacts of the extraction operation .

"Rehabilitation" refers to the operations whereby the

unavoidable impacts on the environment are repaired.

To the extent practicable, rehabilitation should be

concurrent with extraction, paliicularly on larger pits

and quarries.

The following basic procedures should be followed:

• Prepare a rehabilitation plan before commencing

extraction.

• Be aware of any statutory requirements and ensure

that these are met in the plan.

• Always remove and retain topsoil for subsequent

rehabilitation.

• Rehabilitate the site progressively wherever possible.

• Ensure the site is made safe; restrict public access

where possible.

• Reinstate natural drainage patterns where they have

been affected.

• Ensure the reshaped land is formed so as to be

inherently stable, adequately drained and suitable

for the desired long term use.

• Minimise long term visual impact by creating land

forms compatible with the landscape.

• Be aware that topsoil will generally not adhere to

slopes steeper than 27°(1 in 3 . 5) and CaiUlot normally

be placed by machine on slopes greater than 19°

(I in 5).

• Minimise erosion by wind and water during both the

extraction and rehabilitation processes.

• Remove all facilities and equipment from the site

unless approval has been obtained from the

regulatory authorities or affected land holders to do

otherwise.

• Remove all mbbish.

• Revegetate the area with plant species that will control

erosion and provide vegetative diversity compatible

with the local ecosystem.

• Prevent the introduction of weeds and pests. In some

areas, notably in WA and SA, "dieback" fungal

organisms cail be a major problem requiting patiicular

care in topsoil clearing and storage.

• Monitor rehabilitated areas until they are self

sustaining or at a stage which meets the satisfaction

of the landowner or responsible government

instrumentality.

Pavement materials in road building - Guidelines for making better use of local materials 41

42 Pavement materials in road bu i ld ing - Gu idel ines for making better use of local materia ls

5.1 Introduction

The availability of suitable materials for pavements is

becoming increasingly difficult as conventional road

construction materials are being depleted in many areas.

Compounding the increasing scarcity ofthe materials,

the cost of hauling them from fmiher away is increasing.

A possible solution to these problems, which i s

becoming more cost-effective with time, is the utilisation

of various stabilisers and stabilisation techniques to

improve the quality of local materials which do not

conform with the ex is t ing specifica t ions and

requirements for roads.

Naturally occurring materials can be improved/modified

by the addition of chemical stabilising agents or by

blending and mixing to improve their perfOimance as

pavement materials. In general, stabil i sation is a

treatment to i mprove and mainta in strength,

permeabi l i ty, volume stab i l i ty and dura b i li ty

characteristics ofthe materials used in road construction.

The stabilisation treatment not only rectifies pavement

material deficiencies in strength, moisture sensitivity,

workability, erodibility etc. to improve its performance

in the pavement but it also extends the range of materials

available for selection, and at the same time has the

potential to reduce costs. Non-standard, readi ly

available materials can also be stabilised as a cheaper

option to reduce the construction costs. Climatic

conditions and the properties of the non -standard

material will determine the choice of stabilisation

method .

Cement treated sandstone sub-base (SA)

Stabilising additives corrunonly used are:

• plastic fines (loam, clay);

• granular materials;

• POliland cement;

• lime (hydrated lime and quick lime);

• cementitious blends;

• bitumen including emulsions; and

• chemicals, including polymers.

Cementitious blends include products such as flyash,

slag (ground granulated blast furnace slag), and other

similar materials blended with hydrated lime or cement

(Wilmot 1 99 1 ).

Cementi t ious addit ives are the most common

stabi l i sation agents used in Austral ia . However,

stabi l isation of materials can increase the cost of

Pavement materials in road bu i lding - Gu idelines for making better use of local materials 43

construction and where cementitious chemicals are

utilised, the material carmot be re-worked after a short

time-span has elapsed. It is thus essential to ensure

that the correct stabiliser for the material is selected, the

correct application rate of stabiliser is used and the

construction plant and technique employed are suitable

before use.

Readers are referred to the Austroads' Guide to

Stabilisation in Roadworks (Austroads 1 998), which

provides detailed practical advice to those involved in

the design, materials characterisation, construction and

maintenance of pavements incorporating stabilised

layers. It includes advice on behalf of binder types,

materials testing and field techniques. The Guide

replaces the 1 986 NAASRA (National Association of

Australian State Road Authorities) publication Guide

to Stabilisation in Roadworks (NAASRA 1 986) and

incorporates advancements in stabilisation technology

and design that have occurred since the NAASRA

Guide was published. The objective ofthe Guide is to:

provide systematic guidance to practitioners in best

practice for the selection, design and construction

of stabilised pavements for ne w road pavements as

well as the maintenance, rehabilitation and

recycling of existing road pavements. (Austroads

1998).

The notes below provide general information on the

more typical stabilisation techniques used.

5.2 Granular or mechanical

stabilisation

In low volume roads, improvement to granular materials

is most frequently done by granular or mechanical

stabilisation (mixing of two or more non-complying

materials) rather than by chemical or bitumen stabilisation

because of the specialist equipment needed and often

high costs involved. The blending is usually done to

improve both grading and plasticity - the design being

most often done on the basis of meeting a grading

specification. A dense well-graded mass offers the

maxinlllm resistance to lateral displacement under a load.

The mechanical strength of the mass is due to the

internal friction of the coarse p31ticles (gravel, sand and

silt) combined with the cohesion of the fillest particles

(clay). The moisture content of the material is critical in

obtaining maximum compaction. At the Optimum

Moisture Content (OMC) the material will attain its

maximum density for a given compactive effOlt. Strength

loss, as well as reduced density, will result from too

high a moisture content in the soil during compaction.

The addition of granular materials, such as sands, clays,

quarry products etc . , modi fies the particle s ize

distribution (grading), plasticity, strength or shrinkage

characteristics. Granular stabilisation may be applied

to base and sub-base materials for sealed or unsealed

roads. Granitic sand, fine sand and plastic loam are

some of the granular stabilising agents added to crushed

rock, limestone, scoria etc. to modify plasticity and

cohesiveness. Adding a combination of sand and clay,

in suitable propOltions, to a granular material lacking in

fines improves particle size distribution and hence

binding and compaction. This is particularly so for

unsealed pavements where a higher plasticity index is

required to provide a well-bound wearing surface to

better resist wheel abrasion effects and minimise water

penetration into the pavement.

Specification (plasticity, particle size distribution etc.)

for mechanica l stab i l i sat ion should take into

consideration the type of natural material available and

climatic (environmental) conditions. The plasticity of

the binder is an impOltant factor contributing to the

satisfactory performance of the material. Austroads

( 1 998) recommends limits for plastic properties of

granular stabilised bases for sealed pavements, e.g.

Liquid Limit of25% and Plasticity Index not exceeding

6. For surfacing mixtures on unsealed roads a slight

relaxation of this would provide greater cohesion to

bind the material and help offset the moisture lost by

evaporation. In this case LL should not exceed 35%

and the PI should l ie between 6-9. As a note of caution,

this difference in LL and PI between sealed and unsealed

bases must be taken into account when considering

sealing a previously unsealed road. The higher LL and

PI may result in softening of the base beneath the seal

and premature failure caused by the higher moisture

content being trapped beneath the impervious seal and

unable to evaporate. Hence to achieve the desired LL

and PI when sealing an unsealed road, further material

may have to be added.

44 Pavement materia ls in road bu i lding - Gu idelines for mak ing better use of local materials

One method to use in calculating material proportions

for mechanical stabilisation is Rothfuch's graphical

method (in RRL 1 968). This is a reasonably quick,

accurate and simple method.

• Using the desired particle size grading limits, plot a

graph using the usual ordinates for the percentage

passing but choosing a scale of sieve size such that

the particle size distribution plots as a straight line.

This is readily done by drawing an inclined straight

line and marking on it the sizes corresponding to the

various percentages passing.

• The particle size (grading) curves of the materials to

be mixed are plotted on this scale. It will generally

be found that they are not straight lines.

• With the aid of a transparent straight edge, the straight

lines that most nearly approximate to the paiticle size

distribution curves of the individual materials are

drawn. This is done by selecting for each curve a

straight line such that the areas enclosed between it

and the curve are a minimum and are balanced about

the straight line.

• The opposite ends of these straight lines are joined

together and the proportions for mixing can be read

off from the points where these joining lines cross

the straight line representing the required mixture.

Pavement stabilisation & modification techniques

5.2.1 Example: calculating material proportions

The actual procedure will be apparent from the following

example (RRL 1968):

Referring to Table 5 . 1 , columns 4,5 and 6 give the

particle size distribution ofa crusher run aggregate (A),

a sand (B) and a silty clay ( C) that is required to be

mixed to produce the stabilised mixture. Column 3 gives

the required average percentage passing at each sieve

SIze.

• The required size distribution is represented by the

diagonal O-O'ofa rectangle (Figure 5 . 1 ) . The veitical

scale is graduated to show percentages 0- 1 00. The

horizontal scale for sieve apeiture size is graduated

by drawing for each sieve size, a veitical line that

cuts the diagonal at a point where the value equals

the percentage passing that sieve, ie. 1 00% for 25

mm , 92% for 1 9 mm, 82% for 9.5 mm and so on.

• The size distribution of the aggregates to be mixed

(Table 5 . 1 , cols 4, 5& 6) are plotted on this scale

(Figure 5 . 1 ) giving the lines BAO' (crusher run), BFE

(sand) and OG (silty clay).

• The nearest straight lines to these size distributions

are drawn using a transparent straight edge by the

"minimum balance areas" method described above.

Percentage passing

Aggregates available

Mixture 37%A, 4 1 % B, 22%

Sieve Si ze Speci fied Average (A) (B) ( C) From

Limits % Crusher Sand Clay ChaIt %

1 2 3 4 5 6 7

25 1 00 1 00 95 - - 98

19 85 - 100 92 70 - - 89

9.5 65 - 1 00 82 21 - - 75

4.75 55 - 85 70 II 1 00 - 67

2.36 40 - 70 55 7 85 - 58

0.425 25 - 45 35 2 55 - 43

0.075 1 0 - 25 18 nil nil 1 00 22

Table 5.1 Mixture Grading Distribution (Source: based on RRL 1968)


E

F

22% Si lty clay C - .. -- I �------------�--.. ��--. -- --�---'----'------�------��--�----��

0.425 2.36 9.5 19 25

Sieve Sizes (Scale proportionate to % passing sieve)

Figure 5.1 Graphical solution for grading distribution (Source: based on RRL 1968)

They are the lines CO' , BD and OG (the last being

coincident with the actual size distribution).

• The opposite ends of these lines are joined, giving

the lines CD and BG (in this case the latter coincides

with the >O.075mm sieve point). Points L and M

are where these I ines cross the required size

distribution line. The propOltions in which the three

aggregates should be mixed are obtained from the

differences between the ordinates of these points and

are shown on the right-hand side of Figure 5 . 1 .

The palticle size distribution that will result from mixing

the materials in these proportions is given in column 7

of Table 5 . 1 . Although not identical with the required

size distribution given in column 3 it is within the

specified limits shown in column 2 (Figure 5.2).

The above example is also presented plotted on a

standard grading chart in Figure 5 .2 .

5.3 Cementitious stabilisation

• TheAustroads Guide to Stabilisation in Roadworks

(Austroads 1998) makes a clear distinction between

two classes of material which may result from the

incorporation of cementitious binders into granular

material. These two classes are:

• Modified granular material - achieved by adding small

amounts of cementitious binder and/or the granular

material . This process is undertaken to remedy

deficiencies in the granular material (e .g . high

plasticity, low shear strength etc.). The amount of

binder added is insufficient to convert the granular

material into a monolithic slab with significant tensile

strength. Hence, for design purposes, the modified

material is considered to be (improved) granular

material.

• Cemented granular material - achieved by adding

greater amounts of cementitious b inder to the

granular material. The resulting material is monolithic

in nature and possesses a significant tensile strength,

together with relatively high stiffness. Cognisance

is taken in the design process of both of these

properties .

It is unlikely that a cemented layer would be appropriate

in a road with design traffic less than 5 x 105Equivalent

46 Pavement materials in road build ing - Guidel i nes for making better use of local materials


100 75)lm 0.425 600)lm 1.18mm 2.36 4.75 9. 5 38 50mm 100 90 rC' Clay /� y, 90

1 "s'SaJid //, � "'V/I ,I 8ott ______ �----�_r--�==��--��--��r_�--+_--__;80 70tt-----�----+--+---r--�rl�-····-··��'-·�" ·��9·r· /r;�-'--71�--_+--r_---;70 6011 ----===r==��t__-*I:::.."..-/--+..-""� ')+-r("..y"'=--"'/ .f-V_4-+-+-+�60 rr- ISpecilicalion Limits L V � . � I " ./ 501t---- -+-_-+-+-l.K __ ·· �7'f-��L+-K-'.,-� __ "i��""/4V-_+_---+-/�___+___t___f50 40H--_---+_� •. ��'/+_f(� .... .__I___�---.:�\�\�__+�� .�._;*y�--=r A=f+=B+ =C'=Mi=xtU'Fre=-I f--/---1-+_+-+-_�40 301+--�/-+--<I<4?_ ·/-4:-��_�b'\. A;:::»--+V _-+-_+-_+-r/_-+-+---+--+----f30

L---< � X""'" f'\. / ,� 20 �/ '\ .r\ '\. V I,

10 r "' ...... :� V " ./ \ � /' 'A' Crusher Run

- - - - -e.- ----

20 10

O�-=-=��-� -�� -�� __ �� __ ��*-__ �� ____ �� __ �� __ �O 75)lm 150 300 425 600)lm 1.18mm 2.36 4.75 9.5 19 25 38 50mm Auslralian Standard Sieve Sizes Figure 5,2 Worked example for blending of three materials: 'A', '8' and 'C'

Standard 8 tonne Axles (ESAs). Only lIIodified granular

materials are conside r ed under c e m e ntitious

stabilisation in these Guidelines.

General-purpose cement, which includes Portland

cement (Type GP) and blended cement, is generally used

to stabilise pavement materials, Other cement types

may also be used for specific jobs (Matthews 1 99 1 ).

Cements are classified as general-purpose cements or

special-purpose cements. Australian Standard AS 3972

(SA 1 99 1 ) deals with specific requirements for P0l11and

and blended cements. A variety of cement and cement

blends with different properties and characteristics are

commercially available.

and bound layers (depending upon cement content), in

thicknesses ranging from 250 to 350 mm. At these

thicknesses fatigue cracking is likely to be minimised.

A prime coat of cutback bitumen as initial treatment

can help curing of the stabilised layer and reduce

reflection of shrinkage cracks to the surface (Odier e t

al. 1 971). Reduced cement content may also be

considered to minimise cracking, provided all other

requirements can be met.

Cement stabilisation involves mixing of a small

percentage of Portland cement or blended cement in a

variety of soil materials ranging from non-cohesive

sands and gravels, to plastic clays and silts, to reduce

the moisture susceptibility and to increase the strength,

Cement is used to stabilise both plastic and non-plastic

soils (Odier et at. 1 97 1), Cement stabilisation is used in

sub-base levels under granular, asphalt or concrete base

layers (Bethune 1 986), and in base layers in lightly

trafficked roads and in rural highways as both modified

Cementation is the formation of cementitious hydrates

which keep the soil particles together. The hydration is

independent of any chemical reaction between cement

and aggregate. Cementation increases the cohesion

between the pat1icles. Mechanical prope11ies of cement

stabilised materials improve with cement content and

strength, cement modified materials and cement bound

materials. Strength properties, test methods and other

requirements are given in Austroads ' Guide to

Stabilisation in Roadworks (Austroads 1 998) and in

Sherwood ( 1 993). Cement contents for vatious soil types

and typical properties of cement stabilised soils are

given in Lay ( 1 984),

Pavement materials in road bu i ld ing - Guideli nes for making better use of local materia ls 47

Although cement stabilised materials are susceptible to

shrinkage cracks and brittleness, recent developments

with blends of cementitious and/or bituminous materials

significantly reduce problems associated with cracking.

Flyash, lime, slag and bitumen emulsion or foam are

common materials used in blends. Triple blend

stabi lisation which involves a mixture of Type GP

Portland cement, ground granulated blast fumace slag

and flyash is repOlted to be less susceptible to delay in

compaction and more economical than conventional

Portland cement (Bullen and Suciu 1991). Flyash in a

soil/cement mix is reported to reduce the Optimum

Moisture Content for compaction (Wilmot 1 989). Clay

based soils or high clay content gravels can be stabilised

MAP MATERIAL BINDER

39 Granitic sand, well graded SL

39 Granite conglomerate, CF 70/30 poorly graded

39 Granitic sand/clay C or CF

38 Volcanic scoria C or CF

40 Basalt gravel, poorly graded, silty C

40 Well-graded gravel C

38 Limestone gravel, poorly graded CF or CFl

33 Well-graded gravel CF or CFl

29 Calcareous sand, poorly CF

graded aeolian

29 Lateritic gravel, poorly graded CF

1 1 Sand-clay, poorly graded CS

2 Clayey gravel, poorly graded C

15 Calcrete, poor quality C or CF

15 Sand clay C

28 Well-graded gravel C,CF,CSI

9 Silty l imestone gravel, C,CF, CSI

poorly graded

18 Clayey gravel C or CF

28 Well-graded gravel C or CF

9 Pea gravel, poorly graded CSI

with cement and lime. According to Wilmot ( 1 99 1 ),

the lime stabilisation should be carried out preferably

24 hours prior to cement stabilisation.

Research has been carried out by Symons and Poli

( 1 996) on stabilisation of a variety of materials by

cementitious b inders . The research proj ect has

produced a considerable amount of data on the

properties of soils stabilised with twenty cementitious

binders. The propelties vary according to the source

of the soils and the binders and this emphasises the

improvement which can be achieved by mixing with small

quantities of cementitious binders (Symons et al. 1 996).

The number and type of materials treated in this manner

indicate the potential for improving existing pavements

% L OCATION S TATE

4 Bega,Snowy Mountains Hwy NSW

4 Catherine Hill Bay Pacific NSW

Highway

4 CannValley VIC

4 Deninallum VI C

4 Bass Hwy (NW Tas) TAS

4 Frankford TAS

4 Bordertown, Dukes Highway SA

4 Kimba, Eyre Hwy SA

4 Mandurah, Bunbury WA

Highway

4 Brookton Highway near Pelth WA

4 Exmouth BuUara - Giralia Road WA

4 Hayes Ck Stuali Hwy NT 1 75km S of Darwin

4 Santa Teresa Road 50km

SE of Alice Springs NT 4 Maryvale Rd at Deep Well NT

40km S ofA.S.

4 Cunningham H wy near Walwick QLD

>4 Burke Dev. Road l l km QLD

East of Chillagoe

4 GregOly Highway near Emerald QLD

4 Mt Pine Quany, near Brisbane QLD

4 Gulf Dev. Road 1 5km QLD

West of Croydon

SL = Blast furnace slag / Lime, 50/50 blend C = Portland cement (type GP)

CF = Cement / Flyash 70/30 blend CF l = Cement / Flyash 80/20 blend

CS = Portland Cement / Slag 35/65 blend CS I = Portland Cement / Slag 40/60 blend

48

Table 5.2 Local pavement materials assessed for suitability for stabilisation by cementitious binders. (Source: Symons and Poli 1 996)


with minimal importation of new materials. Table 5 .2

lists local pavement materials which have been assessed

for suitability.

5.4 Lime stabilisation

The physical properties such as plasticity, grain size

and resistance to moisture penetration etc. of the

pavement material are changed by lime modification.

The state of aggregation of the clay particles is changed

due to cationic exchange. Hydrated lime (calcium

hydroxide, Ca(OH)2 ) is a common lime stabiliser, but

quick lime (calcium oxide, CaO), monohydrated dolomitic

l ime (CaO.MgO), and dolomitic quick lime have also

been reported as lime stabilising agents (Sherwood

1 993). Lime stabilisation can increase the Plasticity Index

of materials. With clays the Liquid Limit will be reduced

and with silts the Liquid Limit will increase. Lime can be

used to break down clays on very wet heavy sites and

dry out the ground. This can be useful for construction

or haul roads. Another effect of lime stabilisation on

clayey materials is that it al lows the compaction

requirement to be achieved over a larger range of

moisture contents by "flattening" the moisture/density

or compaction curve by increasing the "plastic phase"

component in the mixture. For the most effective lime

stabilisation, the soil should preferably have a Plasticity

Index of> I 0 per cent, and should contain clay minerals

rather than sands or silts (Odier et al. 1 97 1 ).

Plastic soils and gravels stabi l ised with lime have

improved strength and permeability, with reduced

plasticity and moisture sensitivity. High lime contents

(about 6-8 per cent) give high tensile strengths. Increase

in strength is a function of curing time and is sensitive

to temperature (NAASRA 1 986). Mechanical properties

of lime stabilised materials are evaluated in the same

way as for cement stabilised materials. Care should be

taken to avoid the use oflime on inappropriate matetials

such as high silica content material, e.g. silcretes which

can result in an extreme form of alkali-silica reaction.

Proper safety precautiolls should be adhered to with hydmted lime all(l quick lime because of (lust alld the corrosive actioll of these lIlaterials. According to

Wilmot ( 1989), it is more economical to produce hydrated

lime, on site, by mixing quick lime with water (slaking).


5.5 Bitumen stabilisation

Bitumen stabilisation is effective on granular materials

and sandy soils. Soils pre-treated with l ime may also

be stabilised with bitumen. Bitumen, cutback bitumen,

bitumen emulsion and foamed bitumen are used in

bitumen stabilisation. These stabilising agents act as

cohesion agents in granular soils and as waterproofing

agents in clayey soils. Thin films of bitumen produce a

stronger material and thicker fi lms create a weaker, less

permeable material . The performance of crushed rock

bases stabilised with bitumen/bitumen cement have

been reported to be related to the amount of additive

and level of compaction (Vuong et al. 1 995).

Foamed bitumen stabilisation is a common technique

employed. When water in the form of steam is added to

hot bitumen under controlled conditions, a temporary,

thick foam occupying about 1 0 to 1 2 times the volume

of bitumen is formed. Injection of cold water can also

produce the foaming action. Foamed stabilisation is

reported to have improved wetting characteristics at

the bitumen/aggregate interface, even on fines which

have larger surface areas, by waterproofing fines and

providing cohesion.

S tabi l isation with bi tumen emulsion, which is a

suspension of bitumen particles in water, improves

cohesion and waterproofing of granular, low cohesion,

low plasticity « 6 per cent) materials. According toAPRG

( 1 992), Cationic Slow Setting (CSS) and Anionic S low

Setting (ASS) emulsions are used in stab i lisation

treatments. Field trials incorporating low concentration

bitumen emulsion to stabil ise non-plastic fine crushed

rock and laterite gravels have been reported in the

Northern Territory (Hornsby 1 994).

5.6 Chemical stabilisation

Chemical stabilisers include chlorides of sodium and

calcium, calcium sulphates, lignin derivatives, polymeric

resins etc. (Austroads 1 998). Not all these materials

have been ful ly evaluated and their performances

assessed. According to Wilmot ( 1 994) , po lymer

stabilisers act as waterproofing agents when added to

soils and gravels containing over 1 0 per cent silt or clay

fines and other granular materials. They repel moisture

from the fines in the soils and gravels, thus maintaining


Additive Crushed Well-Graded Silty/Clayey Sand* Sandy/Silty Heavy Clays

Rocl< Gravel Gravel Clays

Cement A A A B B N

Cementitious A A A A A B

blends

Hydrated lime B B A N B A

Hydrated lime N N B N B A

plus cement

Polymers B A A B A B

Bitumen A A B B N N

A = Usually very suitable B = Usually satisfactory N = Usually not suitable

*Depends on grading. Single sized sands require higher additive contents.

Table 5.3 Suitability of stabilisation additives for various soil types (Source: Wilmot 1 994)

the dry characteristics of the material . Polymer

stabilised pavements may be worked for an extended

period. Proprietary polymer products are available for

polymer stabilisation.

5.7 Summary of stabilisation

techniques

Criteria for the selection of materials and typical results

with conUllon methods of stabilisation are given in Table

5 .3 (Wilmot 1994). Guidelines on preliminalY selection

of materials and type of stabilisation treatment, based

on particle size distribution and Plasticity Index, are

described in NAASRA ( 1 986).

5.8 Geotextiles

5.8.1 General

Geotextile materials are commonly used either as a layer

between the subgrade and sub-base or to reinforce seals

when local pavement materials do not conform to the

desired requirement.

There is a vast range of geotextiles now available, but

generally the polyester, non-woven, needle punched

geotextiles are preferred because they do not melt when

sprayed with hot binder.

5.8.2 Sub grade layer

In locations where there is a high sub grade moisture

content and a high potential for fines from the subgrade

to be "pumped up" by passing traffic into the pavement,

use of a geotextile layer can provide beneficial results.

The geotexti le layer restricts the ingress of fines

patiicularly into the sub-base and base materials, thereby

avoiding adversely affecting the grading of the

pavement materials.

5.8.3 Geotextile reinforced seals

Geotextile reinforced seals are generally based on the

normal binders and aggregates used in sprayed sealing

and may be used as an initial treatment or as an

alternative reseal in place of a Strain Al leviating

Membrane (SAM).

50 Pavement materials in road building - Guideli nes for making better use of local materials


�. �!\ - .. ---

Field evaluation with the Accelerated Loading Facility (ALF) , Q ld .

Geotextile reinforced seals may be used as an initial

treatment to seal extremely poor quality pavements and

sometimes directly on the clay sub grade which calmot

be successfully treated by normal sprayed seal

treatments, or where it is uneconomical to bring in

acceptable natural or crushed granular type pavement

materi a l s on very long leads , and treated with

conventional seals. These conditions are prevalent in

many palis of outback Australia . The RTA NSW have

constructed long lengths of this type of treatment to

date. Field evaluation tests using the Accelerated

Loading Fac i l ity equipment indicate this type of

pavement construction is economic in a hot and dry

enviromnent.

More detailed information on guidelines on the use of

geotextile seals in expansive clay soils can be found in

the references section (RTA NSW 1 992).

Geotextile seals have also been used successfully and

economically when applied directly to stabilised clay

subgrades . One of the important aspects of the design

is also to ensure that the pavement surface is extremely

well drained, better than normally specified for a low

traffic facility. A successful geotextile seal was placed

directly onto a clay embanlG11ent at Merrimajeel Creek

in cenh'al NSW in 1 985. The area between Booligal and

Mossgiel on the Cobb Highway has few conventional

materials. Pati of the job was done with rubber bitumen

instead of the geotextile and thi s section has also

performed well . For fmiher details refer to Materials

Data Sheet, NSW-A-Merrimajeel, Location Map No.

34 . This type of pavement has also been successfully

used in urban areas including a car parking area in an

outer Melbourne suburban area, using a two-application

seal over the geotextile. The second application seal

was delayed by about 1 2 months to provide an

opportunity to repair any failures. Only a couple of

very small areas needed repair prior to applying the

second coat.

Pavement materials in road build ing - Gu idel ines for making better use of local materia ls 5 1

52 Pavement materials in road build ing - Guidel ines for making better use of local materials

6.1 Introduction

This chapter includes a brief overview of the climate,

geology and available pavement materials for each State/

TerritOly. A simplified SUlface Rocks map for each State/

Territory i s included (based on Auslig 1 982a) for

infonnation. A more detailed, full colour, "Smface Rock

Types" map (© Auslig 1 982a) is located on pages 72

and 73 of these Guidelines. The State overviews are

presented as follows:

6.2 New South Wales including the Australian

Capital Territory;

6.3 Northern Territory;

6 .4 Queensland;

6 .5 South Australia;

6.6 Tasmania;

6 .7 Victoria; and

6.8 Western Australia.

Full details of all references provided under "Published

Data" sections for each State/Territory can be found in

the References section at the end of these Guidelines.

Laterite sheeting over sand base, Esperance, WA

Pavement materials i n road build ing - Gu idel i nes for making better use of local materials 53

6.2 New South Wales including the ACT

1 1 1- - - - - - - - - - - - - - - _ /

1 1 1 � . . . 1 ' :

db • .

'-.. '"

\ � ,- f . --r-i :--: 0 : ' : ' : ' : ' : ' : " : - : ' : - : ' :-" : ' : ' : - : ' : -

�" <T :6�:4T D Igneous/metamorphic ("hard" rocks)

EIl Limestone & calcrete

[J Sedimentary

lSi Laterite D Surface deposits, sand, clay

Figure 6 . 1 Simpl ified surface rocks m a p of NSW (Source: based o n Aus l ig 1 982a) Key Map Nos: 34, 35, 36.

6.2.1 Comments

In NSW there are 1 00,000 km of unsealed roads, 70% of

which are in arid or semi-arid areas. A wide variety of

materials are utilised. Around Sydney the prevalence of

non-standard materials has encouraged the introduction

of alternative non-natural materials such as slag and

flyash to stabilise and improve these materials in areas

close to the industrial sources such as Wollongong

and Newcastle.

6.2.2 Climate

East of the Great Divide the climate is moist temperate

with warm to hot summers. Rainfall ranges between 800

and 1 200 mm per annum. West of the Divide the climate

ranges from semi arid to arid. Rainfall figures decrease

rapidly from 600 to less than 200 mm per annum in the

arid far west. Rainfall occurrence varies across the State,

with a winter maximum in the south-west and a sunU11er

maximum in the north-east.

6.2.3 Geology

New South Wales is similar in geological structure to

the other eastern States, with a narrow discontinuous

coastal strip, inland from which are the uplands of the

Great Divide containing abundant hard rock sources.

Farther inland still are the highly eroded, low lying

riverine plains with limited hard rock outcrops. The

extent of volcanic and plutonic rocks compared to the

vast expanse of riverine plains are shown on the map

above.

6.2.4 Available materials

Along the coast and into the Dividing Range, various

pavement materials are available. In the south-east

region from Bega, across to Kosciusko and north to

Bateman's Bay, the most common pavement material is

igneous granitic gravel of variable quality. This often

requires stabilisation. In the Albury-Wagga Wagga

region, river gravels are utilised to a large extent with

local shales and granitic materials as alternatives.

54 Pavement materials in road bu i lding - Gu ide l ines for making better use of local materials

Further north from Shoal haven through the Sydney

Region and on to Newcastle, sandstones and shales or

siltstones have been a common source of road making

material for almost 200 years, although strictly non

standard in many cases. NSW led the way in the use of

softer rocks (shales) in road works, the key being to

protect base layers of pavement ii-om wet and dty cycles.

North of Newcastle, inland to Narrabri and on to the

Queensland border, avai lable materials comprise

igneous, metamorphic and sedimentary rocks of varying

quality.

At Lismore for example, the h'aditional road conshuction

material has comprised decomposed basalt and crushed

basalt. The decomposed basalts occur on ridges and

provide material suitable for road shoulders and gravel

pavements for low to medium trafficked roads. The

crushed product is utilised on the more heavily h'afficked

roads. The Teven Shale, a "soft" shale of metamorphic

origin, occurs east of Lismore. This has perfonned well

on lightly trafficked and subdivisional roads and on

more heavily trafficked roads when stabilised with lime.

To the south and north-west of Lismore the Clarence

series sandstone has been used stabilised with lime on

some subdivisional roads and as a sub-base on main

roads.

Inland of the Great Divide the landscape is dominated

by the Riverine Plain comprising the plains of the

Murray, Murrumbidgee, Goulburn and Lachlan Rivers

and their tributaries. There are few ridge gravels and a

principal feature of the plain are the "prior streams".

Rising in the mountains to the east and spreading out

in distributary fans on leaving the foothills, these were

responsible for deposition during Pleistocene times of

State by State review

most of the sediments of the Riverine Plain. The depth

to bedrock can be as much as 300 metres. Comprising

coarse to medium sands plus silts and clays, these prior

stream gravels have provided satisfactory service as

pavement sub-base and base materials in the arid

climate.

A most revolutionary advance was in sealing specially

prepared clay surfaces ofthe Namoi River plains without

any granular pavement material at all , by using a

geotextile to reinforce the seal . The method was

originated in Walgett Shire and then trialed by the RTA

on main roads in central north-western NSW.

In the west and far west widespread use has been made

of "soft" calcrete materials and higher quality hard pan

"kunkar" similar to that used in SA and western Victoria.

Once again although non-standard, these materials have

petformed quite well, not only on lightly h'afficked roads

but also on the Sturt Highway between Balt'anald and

Mildura (Victoria).

6.2.5 Published data

Ingles ( 1 984), Sydney sandstones as paving materials.

Lancaster ( 1 984), Pavement materials used by Lismore

City Council.

Smith and Hawkins ( 1 982), Utilisation of calcrete for

road pavement consttuction in the arid western area of

NSW.

Suine ( 1 987), Fine grained pavement materials in the

central Murray Division.

Sutherland ( 1 987), Geotextile reinforced seals on an

expansive clay pavement.

Pavement materia ls in road building - Guidelines for making better use of local materia ls 55

6.3 Northern Territory

1 1

�s::1 � 1 �'\;\ 4 � �

cP

o Igneous/metamorphic ("hard" rocks)

[] Limestone & calcrete

[J Sedimentary

I!!l Laterite

D Surface deposits, sand, clay

Figure 6.2 Simpl ified surface rocks map of NT (Source : based on Auslig 1 9828) Key Map Nos: 2, 7, 8, 1 5, 1 6, 24, 25.

6.3.1 Comments

The Northern Territory consists of 1 ,346,000 square

kilometres with a road network of approximately 22,000

lan, ranging from flat bladed tracks through formed and

gravelled roads to sealed national and urban 31ierial

highways. It has a long history of using natural gravel

as its primary road making material . The Northern

Territory Department of Transport and Works has

opted, wherever possible, to achieve low cost designs

using locally available natural materials.

Use of such materials suits its tropical and arid climates

and sparse popul at ion rather than the use of

conventional and often expensive construct ion

materials to develop these rural roads. Ambrose ( 1 998)

has commented that handling and compaction of softer

materials is an important aspect of achieving the best

results. Otherwise suitable material can be ruined by

excessive handling and over-compaction. Blending of

naturally occurring and processed (crushed) materials

can be a way of making expensive processed materials

go fmiher.

6.3.2 Climate

The climate and geography are diverse ranging from

the moist tropical north near Darwin with an annual

rainfall in excess of 1 ,600 mm (all of which falls between

November andApril) through the semi-arid zone, with

400 mm - 800 mm per annum, extending from Tennant

Creek, to the dry arid interior aroundAlice Springs with

an annual rainfall of only 200 mm. Rainfall tends to occur

in the summer months throughout the Territory.

56 Pavement materials i n road bu i ld ing - Guidel ines for making better use of local materia ls

6.3.3 Geology

Hard rocks exist in h'opical zones where they are subject

to quite rapid chemical and mechanical weathering

under the influence of the hot humid climate and high

rainfall. Suitable hard rocks for road making are generally

scarce.


Many of the northern flood plains consist of extremely

expansive clays ("black soil"). The Victoria Highway

from 90 km west of Katherine towards the WA border

crosses these . This material is often used for the

purposes of forming the road prior to pavement

construction. Sealing with the use of plastic membranes

over the formation helps to control moisture content

changes in the material below the pavement.

The use of lateritic gravels for most road work is based

on a significant selvice histOlY. These materials are quite

readily available especially in the regions north of

Tennant Creek. Victoria and Stualt Highways around

Katherine are examples oftheir use.

In the arid region of Central Australia, where laterites

are not so abundant as in the rest of the Northern

Territory, sand-clays and calcrete are commonly used

as pavement materials and pelform well. On the Lasseter

Highway, the main highway to Ulara (Ayers Rock), two

distinct zones are crossed. A calcrete plains section

between the Stuart Highway and Curtin Springs


(Stage I) and a section through undulating sand dunes

from Curtin Springs to Ulara (Stage 2). Construction

materials in Stage I comprised dune sand as a select

subgrade with calcrete and indurated siltstone the sub

base and base materials. Problems with blistering

bitumen seals were encountered on the calcrete due to

dusting and possibly salt crystals from the compaction

water. In Stage 2 the pavement construction was of a

70% sand 30% clay mix which produced CBR values of

50% and 23% unsoaked and soaked respectively.

Preliminary h'ials using naturally occurring salt deposits

as a stabilising agent in laterite pavements have been

carried out with promising results. This is also being

tria led with calcrete and sand-clays.


Ambrose ( 1 998), Transport and Works, NT. Personal

communication.

Duffy ( 1 984), Consh'uction and maintenance in remote

areas.

Gamon ( 1 987), The use of granitic soils as a road

construction material.

Hornsby ( 1 994), Fit for purpose rural roads.

Wylde ( 1 978), Use of mechanically weak rocks as

pavement material.

Pavement materials i n road build ing - Guidelines for making better use of local materials 57

6.4 Queensland

D Igneous/metamorphic ("hard" rocks)

OJ Limestone & calcrete

IS] Sedimentary

� Laterite

o Surface deposits, sand, clay

Figure 6 .3 Simpl ified surface rocks map of OLD (Source: based on Ausl ig 1 982a)

Key Map Nos: 4, 9, 1 7, 1 8, 26, 27, 28.

6.4.1 Comments

Queensland has a great variety of geology, topography

and climate. Inland pavement materials are scarce. A

great deal of research has been carried out into non

standard materials in this State.

6.4.2 Climate

Much of Queensland is arid and semi-arid west of the

Great Divide with median annual rainfall less than 600

mm. East of the Divide the climate is moist tropical in

the north and moist temperate with hot summers in the

south. Rainfall averages between 800 mm and greater

than 1 ,600 mm per annum; at Cairns annual rainfall can

exceed 7,000 mm. Rainfall in western Queensland is very

variable and dry spells may last for up to 1 0 years.

Median rainfall over a long period (>30 years) i s

probably the best guide. Rainfall tends to occur with a

marked sununer maximum throughout the State.

6.4.3 Geology

Geological structure in Queensland comprises a narrow

discontinuous coastal sh'ip, inland from which are the

uplands of the Great Divide containing abundant hard

rock sources. Fatther inland still are highly eroded, low

lying plains of the Great Attesian Basin with limited

hard rock outcrops . Within the basin however are linear

ridges of tertiary gravels and mesas with duricrust

58 Pavement materials in road bu i ld ing - Guideli nes for making better use of loca l materials

cappings. In the far west, only around Mt. Isa do hard

rocks both igneous and metamorphic outcrop at the

surface.


The State may be divided into many groupings. Each

offer opporhmities for winning pavement materials of

various types and quality.

Discontinuous coastal plains of the east coast and the

Gulf country with alluvial plains in the south and

mudflats, saltpans, dunes in the nOlih. Sand/clays and

sand/silts (loams) developed on sandstones have been

utilised in the Brisbane area and the Burke Development

Road in the Gulf country was constructed utilising sandi

clays to provide unsealed surfaces because other

feasible options do not exist.

Complex granites, basalt plateaux, sedimentary and

metamorphic rocks comprising the tablelands, plateaux,

hilly uplands and coastal ranges. It is providential that

the more densely trafficked roads are located where

supplies of high quality paving material are abundant.

At Mareeba a colluvial gravel has been utilised.

Deep sandy soils within the tableland-lateritic rim. In

the Barcaldine area "kopi" ( calcrete) and sand/silt loams

have been utilised, performing well as a sub-base on

lightly trafficked roads.

Rugged parallel ranges and narrow lowlands developed

on metamorphic and igneous rocks, minor laterite areas

and plateaux with widespread laterite developed on

sandstone and s iltstone parent rocks, clayey sand. The

naturally occurring materials in this large and remote

grouping have good properties and can be made to

comply with specifications relatively easily. In central

west Queensland various non-standard materials are

utilised at Kingaroy and Toowoomba (fine ironstone

gravel) , Kyuna (crushed s ilcrete) . Jacobs Bore

(colluvial), Julia Creek (limestone), Coleraine (siltstone),

Croydon (ironstone) and extending to Normanton

(ironstone).

The west exemplifies the problem of low cost roads in

dry areas with only soft rocks available. Flat to gently

undulating "black" soil plains, developed on sandstone,


mudstone and alluvium and sloping sandy plains, patily

lateritic, with minor clay plains along distributary

systems. A huge area with little or no prospect of

producing natural materials which can comply with

standard specifications. There are 3 areas of expansive

"cracking clay soils" (black eatih and grey-brown clays)

- the Rolling Downs, Fitzroy Basin and the Darling

Downs. "The impOliance that has been placed on the

CBR of paving materials (granular) has influenced

people to choose high permeability materials which have

subsequently produced poor performance when used

on expansive subgrades" (Kapitzke 1 989). It was found

that seasonal moisture variation extends as much as 1

m under the edges of sealed pavements. A non CBR

specification was devised for local materi a ls at

Longt·each. The soft Winton Sandstone has been the

subject ofARRB TR's ALF trials (Vuong et al. 1 99S).

Black clay plains separating sandy rises and laterised

sandstone and the stony b lack so i l p la ins with

widespread silcrete and ferricrete capped mesas: minor

alluvial and sandy tracts cover a huge area ofthe south

west ofthe State from Goondiwindi on the NSW border

to Toolebuc near Mt. Isa. White Rock (soft laterised

sandstone) has been used successfully on low-medium

traffic roads.


Kapitzke ( 1 989), Development of paving material

specifications in Barcaldine district.

Kerr ( 1 994) DMR QueenslandWorkshop on pavements

in dry envirornnents, Longreach.

Martin, Drew and Reeves ( 1 989), Assessment of non

standard materials (White Rock and Winton sandstone).

McLennan ( 1 984), Use of natural materials in pavement

construction in north Queensland.

Murphy, H.W. ( 1 976), Use of non standard materials in

pavements.

Vuong et al ( 1 995), The performance of recycled

sandstone bases under accelerated loading.

Wallace ( 1 988), Design of low cost roads on cracking

clay soils.


6.5 South Australia

D Igneous/metamorphic ("hard" rocks)

QJ Limestone & calcrete

E3 Sedimentary

� Laterite

o Surface deposits, sand, clay

Figure 6.4 Simpl ified surface rocks map of SA (Source: based on Ausl ig 1 982a)

Key Map Nos: 24, 25, 32, 33.

6.5.1 General comments

South Australia is probably the driest State of all . Hard

rocks are extremely limited in occurrence. In outback

areas a wide range of marginal or non-standard local

materials are utilised.

6.5.2 Climate

Except for the south-east corner, the remainder is wholly

arid or semi-arid. North of the lower Eyre and Yorke

Peninsulas, median annual rainfall is generally less than

200 mm uniformly spread throughout the year, except

for a small strip parallelling the coastline of the Great

Australian Bight and Spencer Gulf, which receives 200

nun - 400 mm as winter rains. The south east corner

inciudingAdelaide has dlY summers with median a rulU a I rainfall of only 400 mm - 800 mm, mostly in the winter

months.

6.5.3 Geology

Hard rocks are extremely limited in OCCUlTence. Igneous

rocks occur in some small outcrops in the central and

far north-west of the State. Basalts occur near Mt

Gambier. Metamorphic hard rocks are to be found in the

Eyre and Yorke Peninsulas and Mt Lofty/Flinders

Ranges. Otherwise sedimentary and superficial surface

materials cover the state. According to Hazell ( 1 998),

calcretes, with or without processing, are extensively

used and perform extremely well. In outback areas a

wide range oflocal materials are utilised including high

gypsum content rubbles, shales, tableland stone, iron

pan, river gravels and clays. These materials are made

good use of by local gangs who work in these remote

areas and have learned to use them to best advantage.

60 Pavement materials in road bu i ld ing - Gu idelines for making better use of local materia ls


The availabi l ity of pavement materia ls in South

Austral ia can be divided into nine areas:

1. Lower South-East

The south-east region is well served with good

quality basalt at Mt. Schank near Mt. Gambier. A

variety of other materials are available, some of which

may be classed as non-standard. Basaltic lava flows

and associated volcanic rock are available and the

non-standard shelly limestone referred to as Mt.

Gambier limestone has been used successfully. Other

basaltic material from the Mt. Burr area requires care

i n use due to the presence of secondary

mineralisation.

2. Upper South-East

A lime sandstone is available in the Naracoorte area

and calcrete is available in the Bordertown area.

3. Murraylands

The southern part of the region has a number of

basement granite outliers; e.g. a variable quality

migmatite granite is available at Murray Bridge. In

the Mallee and Riverland areas a well-developed

calcrete caprock is the most suitable source. At

Loxton, limestone is quarried; it is suitable as a

crushed product but not for sealing.

4. Flinders Ranges and Mount Lofty Ranges

Mass ive and i ndurated (hard) s a ndstones ,

limestones and siltstones. The quartzite sandstones

tend to be limited by hardness and are unable to

achieve the specification Los Angeles Abrasion value

of <30%. Dolomitic and metamorphosed siltstone is

capable of meeting all standard specifications when

processed. Limestone/dolomite is suitable as a

crushed rock aggregate and a lso as a sea l ing

aggregate. Numerous dolomitic si ltstone quarries

supply crushed rock and sealing aggregate to the

Adelaide Metropolitan region.


5. Yorke Peninsula and Lower North

Dolomite is available as a quarried product or as by

product from mining operations at Ardrossan, Bute

and Clare. Qualizite sandstones of varying hardness

are a lso avai lable from Clare, Port Pir ie and

Warnertown.

6. Stuart Shelf

There are dolomite outcrops north Of POli Augusta.

Problems re lated to deep weathering and

groundwater activity are encountered.

7. Eyre Peninsula

The highland region of the lower Eyre Peninsula near

Port L incoln has been a source of high grade

metamorphic granite and gneiss; however, these

require crushing and processing. Calcrete and

calcareous sandstone is extensively available across

the upper Eyre Peninsula.

8. Nullarbor and FarWest Coast

The main sources of crushed rock and sealing

aggregate are the Nullarbor Limestone f0l111ation and

calcrete caprock l imestone with a commercial quarry

at Ceduna.

9. Far North

This area is very poorly served with hard rock; some

dolerites in the Musgrave block and Gawler Ranges

are available. Iron pan has been used as a marginal

quality local material for substantial lengths of the

Stu31i Highway.


Beavis ( 1 973), Observations on 4 sites in WA and SA.

Harvey ( 1 995), Granular materials.

Hazell ( 1 998), Transport South Australia, Personal

communication.

Sandman, Wall and Wilson ( 1 979), Use of natural

materials for pavement construction in SA.

Pavement materia ls i n road build ing - Gu idel i nes for making better use of local materials 6 1

6.6 Tasmania

o Igneous/metamorphic ("hard" rocks)

GJ Limestone & calcrete

[] Sedimentary

� Laterite

D Surface deposits, sand, clay

Figure 6 .5 Simpl ified surface rocks map of TAS (Source: based on Ausl ig 1 982a)

Key Map No 40.

6.6.1 Comments

Tasmania is unable to take advantage of the strong

subgrades in arid areas where water tables are deep and

EMC is velY much less than OMC. As if to compensate,

Tasmania has good sources of pavement material . Its

pavements are therefore more granular and also more

permeable than many of those of the mainland.

6.6.2 Climate

While much ofthe mainland ofthe continent is arid and

semi-arid, there are no dlY areas in Tasmania, which has

a moist temperate ciin1ate with waJm summers. The rainfall

pattern is divided between east and west. The western

half receives median annual rainfall ranging from 1 ,200

mm to in excess of 1 ,600 mm. The eastern half is in rain

shadow receiving approximately 600 mm to 1 ,000 mm

per annum. The north tends to receive seasonal winter

rains, while in the south rainfall is more uniformly spread

throughout the year.

6.6.3 Geology

Tasmania is comparatively well offfor good source rock

and has more of its surface covered with igneous rocks

(both lava and plutonic rocks) than the mainland States.


Tasmania has little problem in availability of pavement

quality materials except for the cost of crushing and

processing. In the Hobart area, igneous rocks are

abundant with basalt, dolerite and hornfels, all of which

are suitable as pavement materials. The dolerite is also

suitable as a sealing aggregate. Quarried mudstones

and red gravels are also utilised on local roads as the

natural gravels available in the nOl1h are not extensive

in the south. Crushed dolerite and quartzite gravels

have been used in the north-east near Launceston. In

the nOl1h west around Burnie the road making materials

comprise Precambrian qUaJ1zites and slates from the

Round Hill area. Natural gravels are plentiful in nOl1hern

62 Pavement materials in road bu i lding - Guidel ines for mak ing better use of local materials

Tasmania. The main problem with these natural gravels

is a lack offines, thus requiring mechanical stabilisation.

For the addition of a relatively small amount of high

quality material, an existing pavement can be improved

to sealing standard without requiring reconstmction.

In an effort to offset the high cost of materials

processing and in view of declining road funding, in

situ stabilisation has been carried out with a variety of

polymer products. Recently a badly mtted, failed section

ofthe Midland Highway at Cleveland, about 30 km south

of Launceston has been recycled and stabilised with

bitumen emulsion, one ofthe first uses ofthis technique

in Tasmania.



Morris ( 1 975), Further studies on existing constmction

subject of heavy log traffic.

Morris and Meyer ( 1 974), A study of existing and new

constmction on a main road subject to heavy log traffic.

Nolan ( 1 989), Pavement design using local materials.

Stevenson ( 1 975) , The evaluation of sources of

roadstone rock in Hobart.

Threader ( 1 975), The quanying of road making material

in the Burnie district.

Pavement materia ls in road bu i ld ing - Gu idel ines for making better use of local materials 63

6.7 Victoria

I I I � - � I '\

\ I '\ __

1 -/ \ I \ I " " I "

" I '\

D Igneous/metamorphic ("hard" rocks) EtI Limestone & calcrete

[3 Sedimentary

II! Laterite

o Surface deposits , sand , clay

I '\ - ....... ___ J --- . . . . . . . . . . .

� --;"' :"'-: -"'<-' : ' . : : : : : : : : : : : ,: : : I

I I

: : : : : : : : : : : : >i. : : : : : : : : : : : : : : : i . . . . . . . .

· . . . . · . . . . · . . . . · . . . . · . . . . · . . . .

Figure 6 .6 Simpl ified Surface Rocks Map of VIC (Source: based on Auslig 1 982a) Key Map Nos: 34, 38, 39.

6.7.1 Comments

Victoria is the most densely populated State in Australia

having, along with Tasmania and New South Wales, 30

m of road per person compared with 90 m in WA. Locally

won pavement materials from a variety of sources, often

not wholly complying with specifications cutTent at the

time, have been utilised to good advantage on light and

medium trafficked roads.

6.7.2 Climate

Victoria has a moist temperate climate with warm

summers except for the nOlth-west which is semi arid

with winter rains. Regular year round rainfall occurs

south of the Great Dividing Range, averaging 600 mm -

1 ,200 mm per annum. In the mountains, precipitation

can range fi-om 1 ,200 mm to 1 ,600 mm or more, falling as

either rain or snow in winter. North and west of the

Great Dividing Range, the climate is semi-arid to arid

in the nOlth-west with marked winter rains ranging from

400 nun - 800 mm per annum.

6.7.3 Geology

There is no shOltage of hard source rocks in the south

and east p31ticularly and also a wide range of naturally

occurring gravels . In the north-west of the State

however, the Wimmera and Mallee districts are semi

arid to arid and like most dlY areas suffer from a shOltage

of hard rocks, tend to have moisture sensitive clays

and have low traffic volumes.


A wide range of naturally occurring gravels have been

used for construct ion of local road pavements

throughout Victoria, including:

1. Granitic Sand

Both semi transported and in-situ decomposed

material, the fOlmer being of higher quality than the

latter. The best granitic sand (semi transported with

much clay leached out and deposited at the base of

slopes with a generally northern aspect) is now

somewhat depleted.

64 Pavement materials in road bui ld ing - Gu idelines for making better use of local materials

2. Hill Gravel (01· ridge gravel)

Relatively thin layers on higher ground. These have

been mostly worked out.

3. PariUa Sand (Wimmera sandstone)

Common source of material in the Wimmera and

Mallee . I t comprises an orange-red sandstone

beneath 2-3 metres of clayey overburden. The upper

metre or so is often strongly cemented with silica or

iron minerals, forming a hardcapping over softer sand

deposits.

4. River Gravel

Generally restricted to NOlih-east Victoria where

immense quantities occur in former water courses

and flood plains. Comprises a loose mixture of

rounded pebbles, mainly quartz and coarse sand.

Requires addition of more plastic fines.

5. Tertiary Gravels (quartz gravels)

Usually occur as hill cappings in central Victoria and

Gippsland. The better quality deposits have been

worked out. Tertiary gravels are sourced from pits in

central Victoria between Seymour and St . Arnaud.

6. Buckshot Gravel (ironstone gravel)

Once found relatively frequently in Western Victoria.

Consisting of thin layers concretionary lateritic

material containing rounded pebbles, sand and dust,

derived from basaltic soils. Now mostly worked out.

7. Travertine Limestone (limestone rubble)

Widely distributed in the NWVictorian Mallee (and

in SA).A concretionaty gravel, usually poorly graded

with high plasticity, occurs in thin layers near to the

surface.

8. Dune Limestone

Found in western Victoria as soft deposits in coastal

areas. Often blended with volcanic scoria to improve

grading. Used with success on light trafficked roads.


9. Scoria and Scoria Tuff

Widely distributed just north of Melbourne and in

SW Victoria. Was widely used in road construction

but care is needed with this variable quality material.

10. Ripped Rock Gravels

Widely avai lable and becoming increasingly

important as other material resources diminish.

Mainly comprise highly jointed sandstones, shales

and s i l tstones but a l so i nc ludes cherts

(a concretionary silica rock).

Stabil isation by various means, mechanical, l ime,

cement, bitumen, chemical polymers may be canied out

as appropriate to improve pelformance of these materials.


Bethune ( 1 97 1 ), Soft sandstones and limestones in

northwest Victoria.

Glazebrook ( 1 987), The use and limitations ofTertialY

gravels in central Victoria.

Hall ( 1 987), Fine grained versus standard pavement

material.

Pryor ( 1 966), The use of sandstone as a pavement

material in the Wimmera

Turner ( 1 987), Fundamental properties of gravel

materials.

VicRoads ( 1 998), Guide to general requirements for

unbound pavement materials .

Wylde ( 1 979), Marginal quality aggregates used in

Australia.

Pavement materials i n road bui ld ing - Guidel ines for making better use of local materials 65

6.8 Western Australia

I @I I

� I

� D Igneous/metamorphic ("hard" rocks)

Figure 6 .7 Simpl ified surface rocks map of WA (Source: based on Auslig 1 982a)

Key Map Nos: 5, 6, 1 1 , 1 2, 1 3, 1 4 , 20, 2 1 , 22, 23, 29, 30, 31 .

6.8.1 Comments

Western Australia the largest State, is immense and

sparsely populated, covering one-third of the continent

and having a population of only 1 .6 million. Apmt from

the more developed south-west corner, the main road

system of 1 5 ,000 km is generally situated around the

State perimeter. The vast majority of the 1 50,000 km of

secondary and local roads are constructed of non

standard materials.

6.8.2 Climate

Except for the south-west corner which has dlY smruners

with winter rainfall, and the moist tropical far n01th, the

vast majority ofWA is semi arid or arid. In the far north

and south-west corner including Perth median annual

rainfall ranges from 600 lrun to more than 1 200 mm.

Much of the remainder of the State receives less than

400 mm, with the interior receiving less than 200 mm.

Rainfall is seasonal with summer rains in the north and

winter rains in the south.

6.8.3 Geology

There are developed hard rock sources in the Darling

Ranges in the SE of the State. In the inland arid deselt

areas however, there are few hard rocks. WA has an

ancient stable, subdued topography. Weathering and

erosion have produced a complex series of in situ and

transpOlted soil and rock types. Weathered rocks can

be 30 m thick over parent material. The extent of volcanic

and plutonic rocks is shown on the map above.

66 Pavement materials in road bui ld ing - Gu idel i nes for making better use of local materia ls


More than 90% of roads in WA are made with in-situ

weathered rocks, laterites and calcretes. In common

with South Africa, this is in contrast to other parts of

the world such as North America and Europe where

most basecourse materials are derived from transpOlied

materials such as river gravels, marine gravels or from

local crushed rock.

The use of crushed rock base as a structural layer in

pavements is largely restricted to the Pelth metropolitan

area where it is obtained from the granite quarries along

the face of the Darling Scarp. This material is only used

in rural highways where satisfactory materials are

unavailable. In the Eastern Goldfields hard rock is

obtained from a quany just south ofKalgoorlie-Boulder.

The natural gravels used in pavement construction

elsewhere are primarily those of pedogenic origin (i .e.

chemically altered soils) and include ferricretes (lateritic

gravels), calcretes and silcretes.

The Tamala l imestone, a coastal dune deposit, occurs

along the western coastal strip from Augusta to

Geraldton including the Pelth metropolitan area. It is a

non-plastic material of moderately high strength and is

used extensively as a sub-base material. It can be

stabilised with bitumen for use as a base course. A

weakly cemented shelly limestone gravel also occurs

along the low lying coastal belt derived from a

Pleistocene marine deposit. This material was used as a

basecourse for the reconstruction and widening of the

Eyre Highway between Madura and the State border

with SouthAustralia.

The ferricretes or lateritic gravels have had the greatest

use in WA. Indurated ferricretes and associated red

brown pisolithic gravels are the most common surface

rocks found i n WA. They extend from the warm humid

south-west to the hot semi arid north and include the

immense Yilgarn plateau, a Precambrian granite intrusion

which covers some 700,000 square kilometres and

stretches from Albany in the south to Meekatharra in


the north, and from Gingin in the west to Kalgoorlie in

the east, with isolated sources near Newman and Fitzroy

Crossing.

Cal crete or "popcorn grave l" , developed over

calcareous sedimentary rocks to the south of the

Kimberley, has been extensively used as a base along

the Great NOlthem Highway and the NOlih West Coastal

Highway.

Scree gravel, transported gravel size weathered rock

(qualtz, chelts and banded ironstones) accumulated at

the foot of hillslopes, has been used in the dry northern

palts of the State as base on low to medium traffic roads.

River shingle is also used as a base course throughout

the Pilbara and Kimberley regions. The material requires

blending with sand and clay to provide binder.

Sand-clay (Pindan), a well-sOlied fine to coarse grained

fenuginous material has been used as a base and sub

base in the Kimberley, Pilbara and Murchison, e.g. the

Hamelin to Denham Road.


Cocks and Hamory ( 1 988), Road construction using

lateritic gravel in Westem Australia.

Hamory and McInnes ( 1 972), Compressive strength

assessment of road materials.

Jewell ( 1 968), An evaluation of criteria for selection of

pavement basecourse materials in WA.

McInnes ( 1 970), The requirements for base course

materials - Western Australia

McInnes ( 1 972a), In-situ base course conditions,

Westem Australia.

McInnes ( 1 972b), Factors influencing the perfOlmance

of rural road shoulders.

Metcalf and Wylde ( 1 984), A re-examination of

specification parameters for sandy soi l road base

materials.

Pavement materials in road bui ld ing - Guidel i nes for making better use of local materials 67

68 Pavement materials i n road bui ld ing - Gu idelines for making better use of loca l materia ls

Colour photographs & map

Local roads may be in an urban setting

Or in a rural environment

Pavement materials in road bui lding - Guidel ines for making better use of local materials 69

Site investigation is vital in provid ing information on local materials

Borrow pit or quarry operation today requ i res strict compl iance with regu lations

70 Pavement materials i n road bui ld ing - Guidel ines for making better use of local materials


Deta i l of pisolithic lateritic gravel

Laterite surfaced road , Kalgoorlie, WA

Pavement materials i n road bu i ld ing - Guidel i nes for making better use of local materials 7 1

\ 72

Rolalively deep surficial deposits (tMgely unconlolidated) end doop-weothoring mantles (with or ... /ithou! d�IClUSti. § Clay. sill. minOf sBnd ilnd Ilfovel:

Alluvial. ruidutJl, minor ,fdal swamps

Sand. sile. cl;)y. �aYI!I; Alluvial, colltJViaJ Ouarll ,and: DI.Irn!$, a�iJ(I and residual sa04llBiiu. minClf OtIllvash plams

Evaporite: Gypsum, hll/,/o fJnd minor ciay, sdlandsand

laU�nte: Fvruotnous to aluminow nodvIiJI' dUfiausI, fubbly IIIpllJC;oS

Silcrete: Sificoous dtlicrusl CalerOfO: ClIlClJrtJOUS dur/cru,'. fubblyinpillces

Calcarenife: CalCiJfeOU$ sand, cemented in PBlt

\

o c N

In oroos of each defll'lBd type, minOf B101lS 0' othflf sedimentary focts may occur: 'Of example. fine-galned sandstone OCCIXS in many areas of siltstone, shale, mudstone. D Siltstone, shalll, mudslono

D &ndstooe

• Cooglomefato. IlIlite. breccia

D limellooe. dolomite

• Banded iron fOfmation

D Mi.otedsl!dimerlf"'Vrocks

T I M 0 R S E A

METAMORPHIC ROCKS IGNEOUS ROCKS

• Low-grade metamorphic rocks: VOLCANIC SlalB. phyllite, low-f1IIJde schist. D Acid to Inlermedillle: Rhyolite, Olhff (mfflOl) melaseOments difcit&. andesil�. minor porph)''Y. luff

• Medium-grade to high-grade metamorphosed liiecllm&ntary and Y�canicrocks: $chis!. gneiss, minorlJffiphjbollt�. q1Jarllite. aranufJre

Basic to III t tabule: 8asall. minor agglomHB,e. luff

INTRUSive • Acid to intermediato; Granile. IIdaffillllile, granodiorite. minor • Medium-grade to high-grade diorite

metamorphosed il)fleous and minot sedimenurv rocks; Gneiss, • migma/ile, mmBmphlbolite Basic to uluabasie: Dolelfle,

nrp�nlinile. minot norile, gabblo

SOURCES AflO ACI(Uo\\UD<iEMENTS: Pltp,," by the 0i\;1Iion 01 ""ion" Mapping " 1980-81 undu lhe ()IIl$n(. 01 W. D. Pa.'fre\TTlIll. 8�"", 01 Minflal Ruo .. nu, �, and GHlPhysks. Canbur •. Blud on �uI mfP$ 'I t:2150 000 ItId lhe ITl3PI 'Auwe!ia: Geology' 11982. 1:15000 0001 of INs Alln ""d '(N.oIogy of Austrah' 18MA. 1976. 1;25oo ooo) lupplemenled by regt.oNJ IIld Stet, g.eoIogi:ea1 m�t II 1:600 000 to 1:2 600 000,



Pavement materials in road bui ld ing - Guidel i nes for making better use of local materials 73

Cement treated sandstone rubble - note contamination with sand subgrade

Limestone gravel stock pile

74 Pavement materials in road bui lding - Guidel ines for making better use of local materials


Calcrete stockpi le (SA) : segregation of materials shows poor blend ing

Ripped shale stockpi le

Pavement materials in road bui ld ing - Guidel i nes for making better use of local materials 7 5

Mixing and breaking down on the pavement requir ing appropriate use of plant

Watering and compaction of prepared base course

76 Pavement materials i n road bu i ld ing - Gu idel i nes for making better use of local materials

7.1 Introduction

This chapter contains Material Data Sheets detailing

information on fifty specific local materials sites.

Information has been drawn from many sources

including numerous technical papers and the individual

contributions from many local govenunent engineering

practitioners and consultants. Location maps on each

data sheet are based on The Australian Base Map © AUSLIG 1 982. The report by Reeves ( 1 99 1 ) detailing

material collected for theAPRG natural materials register

has been a patticularly valuable source.

These are arranged in order of State/Territory with

individual locations in order of Map number within each

State/Territory:

1. New South Wales inc luding the Austra l ian

Capital Territory;

NOithern TerritOlY;

Queensland;

South Australia;

Tasmania;

Victoria; and

Western Australia

Calcrete borrow pit, near Ceduna, SA

2. Locat ion, i ncluding Latitude and Longitude

information related to the location of the nearest town

or significant feature.

3. Each Material Data Sheet Ln this chapter describes

the source rock and soil formation process for the

particular material . It also shows, where available:

• cl imate at the road s ite and whether annual

evaporation exceeds rainfall (in which case the

Thornthwaite Index is negative);

• sub grade at the road bed, i .e . type of clay and

drainage conditions;

• methods of extraction and construction teclmiques

which have been shown to be successful; and

• other information which may be useful to a

practitioner not familiar with the district.

4. Sections 7.2 and 7.3 are Indices of Materials Data

Sheets by Material Class and Location (Map

Number).

Pavement materials in road bui ld ing - Gu idel ines for making better use of local materials 77

7.2 Index of local materials data sheets - by material class

Map Reference Material Location

CLASS A

28 NSW-A-Lismore Decomposed Basalt Lismore

34 NSW-A-Menimajeel Clay Cobb Highway near

Booligal

2 NT-A-Cullen Granite Sand Stuali Highway

200km S Darwin

1 5 NT-A-Devils Marbles Granite Sand Stuart Hwy S of

Tenant Creek

37 SA-A-Rocky River Lateritic Gravel South Coast Road

Kangaroo Island

38 VIC-A-Mt Bolton Granitic Sand Mt Bolton near Waubra

30 WA-A-Carlingup Laterite West of Esperance

00 WA-A-Cocos Coral Coral Sand/Gravel Cocos Island

2 1 WA-A-Doolgunna Laterite North of Meekatharra

29 WA-A-Gingin Laterite North of Perth

29 WA -A -Menedin Laterite South of Menedin

CLASS B

36 NSW-B-Attunga Soft Limestone Attunga near TamwOlih

36 NSW-B-Nowra Shales South ofNowra

36 NSW-B-Nowra Sandstone South ofNowra

Sandstone

17 Q-B-Coleraine Siltstone Richmond-Winton Rd

17 Q-B-Garonna Soft Limestone Near Julia Creek

28 Q-B-Goondiwindi White Rock Leichardt & Barwon Hwy

17 Q-B-Silver Hills Soft Limestone Near Richmond

1 7 Q-B-Winton Weak Sandstone Landsborough Hwy

33 SA -B-Woomera Sandstone Gravel Pimba near Woomera

40 TAS-B-Round Hill Sandstone/Slate Round Hill near Burnie

2 1 WA-B-Mt Magnet Silt-clay (Coffee Rock) Between Mt Magnet

& Meekathana

Latitude Longitude

(South) (East)

28° 49' 1 53 ° 16'

33° 4 1 ' 144° 50'

1 3 ° 22' 1 3 1 ° 1 3 '

20 ° 39 ' 1 34 ° 1 3 '

35 ° 57 ' 1 3 6 ° 44 '

3 7 ° 22' 143 ° 38 '

33° 55, 1 20° 02'

1 2° 1 1 ' 96° 50'

25° 40' 1 1 9° 1 1 '

3 1 ° 2 1 ' 1 1 5 ° 55 '

3 1 ° 37 ' 1 1 8° 32 '

3 1° OS ' 1 50° 56'

34° 53' 1 50° 36'

34° 53' 1 50° 36'

21 ° 1 5 ' 143° 00'

20°40' 141°45 '

28 33 1 50 1 8

20°44' 143° 08'

22° 23 ' 143° 02 '

3 1 ° 1 2 ' 1 3 6° 49 '

41 ° 04' 145° 54'

28° 04' 1 1 7° 5 1 '


Materials data sheets - index

Map Reference Material Location Latitude Longitude

(South) (East)

CLASS C

34 NSW - C-Menindee Calcareous Soil 53km East ofBroken Hill 32°09' 141° 55'

34 NSW-C-Euston Calcrete (kunkat") Near Euston NSW 34° 35' 142°44'

34 NSW-C-Wilcannia Calcrete (nodular) BalTier Highway 3 1° 34' 143°22'

15 NT-C-Ti Tree Sand Clay Stuart Highway Ti Tree 22° 07' 1 33°25'

17 Q-C-Area U Colluvial Gravel West of Kyuna 2 1 ° 35' 142°00'

9 Q-C-Croydon Ironstone Soth East of Norman ton 1 8° 12' 142° 1 5 '

18 Q-C-Durrandella Sand Clay Alpha-Tambo Road 24° 07' 146° 35'

17 Q-C-Jacobs Bore Colluvial Gravel West of Kyuna 21° 16 ' 141° 17 '

28 Q-C-Kingaroy Lateritic Gravel Homleigh & 26° 32' 1 5 1 ° 50'

Mt Wooroolin

17 Q-C-Kywla Silcrete KelTs Table Mountain 21°44' 141 ° 55'

10 Q-C-Mareeba Colluvial Gravel Atherton Tableland 16" 59' 145° 25'

9 Q-C-Normanton Ironstone Normanton 1 7° 40' 14 1 °04'

32 SA-C-Ceduna Limestone Multee Road Pit 32° 08' 133°4 1 '

conglomerate

38 SA -C-Lameroo Sand Clay West of Pinaroo 35° 1 3 ' 1 40° 20'

34 SA-C-Loxton Calcrete South-west of Renmark 34° 27' 1 40° 28 '

33 SA-C-Yaninee Calcrete South-east of Ceduna 32° 57 ' 1 35° 1 6 '

40 TAS-C-Pipers River Quartz Gravel North ofLaunceston 4 1 ° 06' 1 47° 05'

38 VIC-C-Pyramid Hill Sandstone & Crushed Pyramid Hill & West 36° 03 ' 144° 07'

Granite

6 WA-C-Kimberley Calcrete Gravel Great NOtthem Hwy 1 8° 1 1 ' 1 25° 36 '

29 WA-C-Tamala Limestone Pelth Coastal Plain 3 1 ° 45 ' 1 1 5° 48'

CLASS D 35 NSW -D-Narrandera Prior Stream Gravel Mun'umbidgee plains 34° 45 '

- 1 46° 33 '

34 NSW-D-Booligal Prior Stream Gravel Booligal Station 33° 52' 144° 52'

35 NSW-D-Dubbo Sandstone Gravel Frasers Pit near Dubbo 3 1 ° 59 ' 148° 38 '

34 NSW-D-Tocumwal Prior Stream Gravel Varley's Pit Tocumwal 35° 49' 145° 34'

28 Q-D-Brisbane Silty Sand (loam) Coastal areas nOlih 27° 00' 1 53° 00'

of Brisbane

38 VIC-D-Guildford Tettiary Gravel Kays Pit near Guildford 37° 09' 1 44° 1 0 '

5 WA-D-Broome Sand-clay (Pindan) Cable Beach Road 1 7° 58 ' 122° 1 4 '

20 WA-D-Hamelin Red Deselt Sand South of Shark Bay 26° 24' 1 1 4° 00'

Pavement materials in road bui ld ing - Gu idel ines for making better use of local materials 79

7.3 Index of local materials data sheets - by State and map number


(South) (East)

NSW

28 NSW-A-Lismore Decomposed Basalt Lismore 28° 49' 1 53° 1 6 '

34 NSW - C-Menindee Calcareous Soil 53km east of Broken Hill 32° 09' 1 4 1 ° 55 '

34 NSW-A-Merrimajeel Clay Cobb Highway near 33° 41 ' 1 44° 50'

Booligal

34 NSW-C-Euston Calcrete (kunkar) Near Euston NSW 34° 35 ' 1 42° 44'

34 NSW-C-Wilcannia Calcrete (nodular) Barrier Highway 3 1 ° 34' 1 43° 22'

34 NSW-D-Booligal Prior Stream Gravel Booligal Station 33° 52' 144° 52 '

34 NSW-D-Tocumwal Prior Stream Gravel Varley's Pit Tocumwal 35° 49' 1 45° 34'

35 NSW -D-Narrandera Prior Stream Gravel Munumbidgee plains 34° 45' 1 46° 33 '

3 5 NSW-D-Dubbo Sandstone Gravel Frasers Pit near Dubbo 3 1 ° 59 ' 1 48° 38 '

36 NSW-B-Attunga Soft Limestone Attunga near Tamworth 3 1° 05 ' 1 50° 56 '

36 NSW-B-Nowra Shales South ofNowra 34° 53 ' 1 50° 36'

36 NSW-B-Nowra Sandstone South ofNowra 34° 53 ' 1 50° 36'

NT 2 NT-A-Cullen Granite Sand Stuart Hwy 200km 1 3° 22' 1 3 1° 1 3 '

S Darwin

1 5 NT-A-Devils Marbles Granite Sand Stuatt Hwy 20° 39 ' 1 34° 1 3 '

S o f Tenant Creek

1 5 NT-C-Ti Tree Sand Clay Stuatt Highway Ti Tree 22° 07' 1 33° 25'

QLD 9 Q-C-Croydon Ironstone Soth East of Norman ton 1 8° 1 2 ' 142° 1 5 '

9 Q-C-Normanton Ironstone Normanton 1 7° 40' 1 4 1 ° 04'

1 0 Q-C-Mareeba Colluvial Gravel Atherton Tableland 1 6° 59 ' 1 45° 25 '

1 7 Q-B-Coleraine Siltstone Richmond-Winton Rd 2 1° 1 5 ' 1 43° 00'

1 7 Q-B-Garonna Soft Limestone Near Julia Creek 20° 40' 1 4 1 ° 45 '

1 7 Q-B-Silver Hills Soft Limestone Near Richmond 20° 44' 1 43° 08 '

1 7 Q-B-Winton Weak Sandstone Landsborough Hwy 22° 23 ' 1 43° 02'

1 7 Q-C-Area U Colluvial Gravel West of Kyuna 2 1° 35 ' 1 42° 00'

1 7 Q-C-Jacobs Bore Colluvial Gravel West of Kyuna 2 1° 1 6 ' 1 4 1 ° 1 7 '

1 7 Q-C-Kyuna Silcrete Kerrs Table Mountain 2 1 ° 44 ' 1 4 1 ° 55 '

1 8 Q-C-Durrandella Sand Clay Alpha-Tambo Road 24° 07' 1 46° 3 5 '

80 Pavement materials in road bu i ld ing - Guidel i nes for making better use of local materials

Materials data sheets - index


(South) (East)

28 Q-D-Brisbane Silty Sand (loam) Coastal areas north 27° 00' 1 53° 00'

of Brisbane

28 Q-B-Goondiwindi White Rock Leichardt & Batwon Hwy 28° 3 3 ' 1 5 0° 1 8 '

28 Q-C-Kingaroy Lateritic Gravel Hornleigh & 26° 32' 1 5 1 ° 50'

Mt Wooroolin

SA

32 SA-C-Ceduna Limestone Conglomerate Multee Road Pit 32° 08 ' 1 33° 4 1 '

33 SA -B-Woomera Sandstone Gravel Pimba near Woomera 3 1° 1 2 ' 1 3 6° 49'

33 SA-C-Yaninee Calcrete South-east of Ceduna 32° 57' 1 35° 1 6 '

34 SA-C-Loxton Calcrete South-west of Renmark 34° 27' 1 40° 28 '

37 SA-A-Rocky River Lateritic Gravel South Coast Road 35° 57' 1 3 6° 44 '

Kangaroo Island

38 SA -C-Lameroo Sand Clay West of Pinaroo 35° 1 3 ' 140° 20'

TAS 40 TAS-C-Pipers River Quatiz Gravel North of Launceston 4 1 ° 06' 1 47° 05 '

40 TAS-B-Round Hill Sandstone/Slate Round Hill near Burnie 4 1 ° 04' 1 45° 54'

VIC

38 VIC-C-Pyramid Hill Sandstone & Pyramid Hill & West 36° 03 ' 1 44° 07'

CtUshed Granite

38 VIC-A-Mt Bolton Granitic Sand Mt Bolton near Waubra 37° 22' 1 43° 38 '

38 VIC-D-Guildford Tetiiary Gravel Kays Pit near Guildford 3 7° 09 ' 1 44° 1 0 '

WA

00 WA-A-Cocos Coral Coral Sand/Gravel Cocos Island 1 2° 1 1 ' 96° 50'

5 WA-D-Broome Sand-clay (Pindan) Cable Beach road 1 7° 58 ' 1 22° 14 '

6 WA-C-Kimberley Calcrete Gravel Great Northern H wy 1 8° 1 1 ' 1 25° 36'

20 WA-D-Hamelin Red Desert Sand South of Shark Bay 26° 24' 1 1 4° 00'

2 1 WA-A-Doolgunna Laterite North of Meekatharra 25° 40' 1 1 9° 1 1 '

2 1 WA-B-Mt Magnet Silt-clay (Coffee Rock) Between Mt Magnet 28° 04' 1 1 7° 5 1 '

& Meekatharra

29 WA-A-Gingin Laterite NOtih of Perth 3 1 ° 2 1 ' 1 1 5° 55 '

29 WA-A-Merredin Laterite South of Merredin 3 1 ° 37 ' 1 1 8° 32'

29 WA-C-Tamala Limestone Perth Coastal Plain 3 1° 45' 1 1 5° 48'

30 WA-A-Carlingup "Lateritic" Gravel West of Esperance 33° 55 ' 1 20° 02'

Pavement materials in road bui lding - Gu idel ines for making better use of local materials 81

82 Pavement materials in road bu i ld ing - Gu idel ines for making better use of local materials

New South Wales

- --

-1" -

140

•

126 27 • • .--------------- .;

•

1311 • 35 • • • i" - ....

• \ ...

, ... • ... ) ... .. I; .... - .......

3 �� .. -.. 145 150

LEGEND

� Location Map • Soil sample

-25-

-30 ---

-35 ---

155

Map number 28

SITE

Location. Lismore NSW. Lat 280 49' south, Long

1530 16' east. Material is decomposed basalt and crushed

weathered basalt.

Climate. Sub tropical humid. Average rainfall 1400 Jmn! year which mostly occurs between late summer and

autumn. Water table varies.

Moisture Index Jm = +20 (from map).

Topography. Variable relief.

PROPERTIES

Decomposed basalts are notoriously variable and PI values in excess of 8 are common. May contain zones

of secondary alteration as expansive montmorillonitic

clays.

Source Rock: Volcanic lava flows of the Tertiary period

forming Lismore and Blue Knob Basalts and Nimbin

Rhyolites. Decomposed and crushed basalts are won

from ridges.

Sub grades in the Lismore area comprise: A heavy clay within the floodplain, PI 55, LS 25, CBR 2. Elsewhere a decomposed basalt to the north and west

and decomposed basalt with well draining red soil areas to the east.

- "

._--]&

USAGE

Decomposed basalt has mainly been used for road

shoulders and gravel pavements. Blending with fresh

crushed basalt to reduce PI and allow use as a sub base in bitumen sealed pavements has also been trialed.

Suitable for light traffic below anAADT of 250 but can

suffer edge failures under more heavily trafficked

pavements in locations of poor drainage.

PERFORMANCE

Performance beneath seal is satisfactOlY but the material

rapidly deteriorates on wetting. Pavement failures are conUllon mostly in old work. Performance is best where

used on a free draining sub grade such as the local red

soil areas. Edge failures are quite common within 1

metre of the pavement edge requiring widening of seal

or additional longitudinal subsoil drainage and increased pavement crossfalls.

Treatment by crushing to 30mm minus to reduce the PI,

remove oversize and provide some strength from stone

interlock. PI values have been reduced to a maximum of 10 generally.

84 Pavement materials in road building - Guidelines for making better use of local materials

SITE

OIli�IUlltil 1 I I

, flO

· '- l=j� " i tl to . """'r--' .' Wil(l.,,:h /1

Location, Stmi Highway immediately west of Euston,

Lat 340 3 5' south, Long 1420 44' east Local material is

calcrete gravel in a massive hardpan (kunkar) calcrete

deposit fonned through secondary cementation. The

hardpan was blended in the pit with mbbly limestone to form a well graded material.

Climate, SemiArid. Water table> 5 metres below natural

smface. Moisture Index -30. In MlUTay River flood plain.

PROPERTIES

In a dry environment the calcrete without clUshed kunlcar

is satisfactory. With cmshed kunkar included it comes

close to meeting highway specification.

19 9.5 4.75 2.36 .425 .075 100 85 66 55 36 18

Linear Shrinkage = 2.5

Product PI x .425 > 200

IL 21

PL 13

Map number 34

SOUl'ce Rock: Surficial deposits of Tertiary Age generally more than 5m thick.

USAGE

Traffic near Euston is quite high with AADT of

around 2000.

Extraction: Pits are worked to a depth of approximately

1 metre. The hard pan is cross ripped in the pit, spread

and given four passes with a rockbuster impact breaker. This is more safely done in the pit than on the road,

which remained open to traffic. Use of the rockbuster

improves the final sand size particle content; otherwise it tends to be gap graded with coarse particles in a

powdery matrix. The compaction process leads to a

matelial significantly finer than pre compaction.

PERFORMANCE

Materials such as that used at Euston have performed

well for many years; an exception is in ilTigated areas. In

service the Equilibrium Moisture Content of the pavement is approx 5%. At the expected moisture

contents the Texas Classification procedure confirms

the material as base quality.


Map number 34

SITE

Location. Broken Hill- Menindee Highway 53 km south

east of Broken Hill, near Quondong, Lat 320 09' south,

Long 14 1055' east.

The local material is weakly cemented calcareous soil

(similar to sandy loam), which has been modified by addition of sand from an adjacent creek bed.

Topography is undulating.

Climate. Arid.150mm per year. Water for construction often unavailable. Water table is >5metres below natural

surface.

Moisture Index 1m = -50.

PROPERTIES

The effect on plasticity of adding sand is small but

grading is improved.

9.5 4.75 2.36 .425 .075 IL PL

CS 98 97 95 80 40 23 12 Sand 99 97 90 22 2 NP Mix 99 99 96 57 25 22 11

PI = 11% Linear Shrinkage = 4%

Laboratory OMC 10%.

.470

) V/ iltlJlin , .-- I --- :

· .. ·--r-t " i�,l l, ··""T'· �

W,ltlnci. /

Source Rock: Ancient surficial deposits of Cretaceous Period more than 5 m thick, site close to Ordovician

sediments.

USAGE

Traffic light, AADT around 200.

In the field trial, sections of calcareous soil were untreated; some had 1 % and 2% cement added. In

practice there was little change in plasticity at the 1 %

cement level. However PI reduced to approx 8 with

addition of 2% cement.

PERFORMANCE

All test sections showed longitudinal cracking (common

to the area); all displayed no rutting and a good

subjective ride quality (even after as much as 18 years

of service). The shoulders were widened and sealed in 1979. The materials would be suitable for use in dry conditions where rainfall is less than 250 mm/year .


SITE

Location. Clay embanlGnent between 3 bridges over Merrimajeel Creek on the Cobb Highway between

Booligal and Mossgiel in Central NSW. Lat 330 41' south,

Long 1440 50' east. Conventional road materials are

scarce. The clay pavement was sealed with ageotextile reinforced seal. The base is a thin layer of sandy clay over a sub grade of grey clay.

Climate. Arid. Rainfall 250mm per year. At times there

can be a build up of floodwater from the Lachlan River

and water may stand close to road level for a month or

more in wetter years. The permanent water table is

< 5 metres below natural surface.


PROPERTIES

Source Rock. No hard rock nearby. Deep surficial deposits of the Permian period generally more than

5 metres thick.

Map number 34

USAGE

In-situ CBR results for the grey clay varied from 7% at 95% compaction and 110% OMC, to 20% where

moisture is less than 90% OMC.

A 1.0 m shoulder width was included in the geotextile

seal design to minimise edge wear and moisture ingress

laterally.

PERFORMANCE

The clay pavement was sealed in 1 9 85. The geotextile

reinforced seal performed well.

The procedure was to apply a tack coat, roll out 5.3 m

wide fabric, blind wheel tracks with 7nml aggregate, then

spray binder and cover with 10nml aggregate.

Part of the job was trialed with rubber bitumen instead

of the geotextile. T his was also reported to have

performed well.


Map number 39

SITE

Location. Newell Highway between Finley and Tocumwal, on the NSW - Victoria border. Lat 350 4 9 '

south, Long 145034' east.

The local material used is a prior stream gravel obtained from Varleys Pit.

Topography is typical of the Riverina Plains.

Climate. Semi Arid. 300mm per year. Water for

constmction often unavailable. Water table is >5 metres

below natural surface.


PROPERTIES

The particle sizes of this source material and others in

the district are:

9.5 4.75 2.36 .425 .075 IL PI

V 99 94 59 25 7

B 97 88 40 24 10

Y 100 100 62 41 17

V = Varley's Pit, B = Balranald, Y = Yorks Pit

Source Rock: Surficial deposits of the Riverina Plain,

generally> 5m thick. (See also NSW-D-Booligal)

USAGE

Traffic expected traffic on the Newell Highway over a 20 year period is 1 x 107 ESA.

Varley's Pit has 25% passing the 0.075 sieve and 15% passing the 0.0 13 sieve and is a fme silty sand of medium

plasticity. Details of pit operation are as for NSW-DBooligal.

PERFORMANCE

The material is expected to perform well where high

moisture contents and lateral stresses are absent.

Prior stream gravels are probably the finest grain sized

materials used in NSW as a base material. They have been used successfully in Central MUlTay Division for many years. It is expected that their widespread use will

continue.


SITE

Location. Barrier Highway west of Wilcannia,

approximately 125 \an east of Broken Hill. Lat 31034'

south, Long 143022' east.

The local material is calcrete gravel in nodular fOlm. "Pit

known as the 7 7 . 9 Mile deposit." Has been used for many years and is satisfactory in a dry environment

under medium traffic. Has high porosity and high

Atterberg Limit values. Some attempts at bitumen

stabilisation were made in the late 1 960's.

Climate, Arid. 200mm per year. Water for conshuction

often unavailable. Water table is >5 metres below natural

surface.


PROPERTIES

Tends not to be well graded and is highly absorptive.

1 9 9.5 4.75 2.36 .425 .075

100 <Xl 80 73

Linear Shrinkage = Nil

LaboratOlY OMC 23%.

43 20

LL PL

35 27

Map number 34

Equilibrium moisture in field not known, possibly close

to 5% as at Euston.

Source Rock: Ancient surficial deposits of Petmian,

Carboniferous and Devonian Periods. Generally more

than 5m thick. Samples of the nodular deposits contained

26% of CaCO).

USAGE

Traffic west of Wilcannia is medium with anAADT of

around 400.

Modification with bitumen emulsion in the propOliions 1 (emulsion): 2 (water).

Surface should be primed and sealed as soon as

possible.

PERFORMANCE

All sections on the road petformed well whether bitumen

stabilised or not. In such a dry environment at modest

traffic levels, stabilisation may be unnecessary.


Map number 34

SITE

Location. Booligal on the Cobb Highway approx 80 km north of Hay. Lat 3 3 0 52' south, Long 144 0 52' east.

The local material is a prior stream gravel obtained from

BooJigal Station Pit.

Topography is typical of the Riverine Plains.

Climate. Semi Arid. 1 50mm per year. Water for

construction often unavailable. Water table is >5 metres

below natural surface.


PROPERTIES

Typical of "prior stream" gravel deposits.

T

B

9.5 4.75 2.36 .425 .075

100 95 70 40 100 75 63 40

T = typical grading; B = Booligal Pit

lL PI

15

13

Most of the area comprises Quaternary sands, silts,

clays of alluvial (and some aeolian) origin. Prior stream

deposits formed in the Pleistocene when earlier rivers

deposited sediments in fans on the Riverine Plains on leaving the high country. The depth to bedrock is up to

300m. There are few hard rocks in the Central Murray Division.

USAGE

Traffic light, AADT around 200.

The material is mixed down the face of the pit and then

cross mixed prior to stockpiling.

Allowable plasticity under a relaxed specification for

arid and semi arid areas is:

RainfaU

< 250mm

250- 350mm

PI Max

15

12

> 350mm 8

PERFORMANCE

A lack of alternative materials means prior stream gravels

will continue to be used in this area. The materials would

be suitable for use in dry conditions where rainfall is

less than 250 mm/year.

NOTE:

Other pits of prior stream gravels are located 20 Ian east

of Hay, BalranaldYouga Station Pit, Finley Common Pit, 10uldene Station Pit and Yorks Pit (ref also Maps

34&39).

Granite outcrops occur at Tocumwal and Berigau.


SITE

Location. Frasers Pit 35km north of Dubbo.

Approx. Lat 3 10 59' south, Long 1480 38' east.

Climate. Temperate sub humid, rainfall 550mm per year. Water table is >5 metres below natural surface.



PROPERTIES

Silty sandy sub rounded sandstone gravel of low

plasticity. Typical grading and plasticity:

19 9.5 4.75 2.36 .425 .075

100 98 96 82 42 20

PI = 12 LS = approx. 2

Low hardness, low soundness

IL PL

24 12

SOUl·ce Rock: Weathered clayey sandstone gravel overlying sandstones of Jurassic Age.

Map number 35

USAGE

Suitable as a select subgrade, sub base and base course

layer in light to medium trafficked roads. AADT up to 4000. Use as a road base beneath spray sealed road

surface.

PERFORMANCE

This nahlrally variable material should be pushed up

by dozer in the pit to ensure mixing. Further mixing by

windrowing with grader to blend in sand and clay fractions.

Construction at 85% OMC. OMC 7% at MDD of 2.06

tonnes/m3• In-situ CBR of 50 at EMC. Compaction

with vibrating smooth drum roller.


Map number 35

SITE

Location. Narrandera, southern NSW. Lat 34 45 South,

Long 146 33 East.

Climate. Senti arid. Rainfall 350mm/yr.

Water tab le; unceltain, probably >6m.

Moisture Index Im = -20 (fi:om map).

Topography. Munumbidgee plains.

PROPERTIES

Clayey sandy gravel (prior stream gravel), generally fine

graded with some small rounded qualtz pebbles.

Grading is as follows:

19 9.5

100 100

4.75 2.36 .425

LL=22%, PL= 13%.

99 97 57

Fines to sand ratio 0.075/2.36 = 0. 3 1

.075

30 PI 19

Subgrade, typically silty clay, estimated CBR <5%.

USAGE

Suitable as select subgrade, sub base and base course layer in low and medium trafficked roads (up toAADT

2000, 40% CV S). Some addition of lime is needed to

improve suitability for higher traffic loadings.

PERFORMANCE

Satisfactory perfOlmance on low - medium trafficked roads. Control to prevent moisture entering the

pavement is required

Unsuitable as a wearing surface. Suitable as a sub base or base on sealed roads, unsuitable as a sealing

aggregate. At EMC, CBR 25%. When placing if PI is too

low it is difficult to compact without flooding the

material. If too wet it can become very slippery.

Shoulders should be spray sealed

Compaction at 80% OMC by means of vibrating

sheepsfoot, vibrating smooth and pneumatic tyred

roller. Typical OMC 7% at MDD of 2. 10 tonnes/m3.


SITE

Location. Attunga 20km north of Tamworth.

Approx. Lat 300 56' south, Long 1 500 50' east.

Climate. Temperate sub humid, rainfall 700mm per year.

Water tab le not known.



PROPERTIES

Moderately hard sound limestone of good shape and

durability.

1 9 9.5 4.75 2.36 .425 .075

95 70 45 35 28 20

P I = 0 - 8 LS = na

lL PL

na na

Source Rock: Sedimentary rocks of Devonian to

OrdovicianAge.

Map number 36

USAGE

Suitable as a select subgrade, sub base and base course

layer in low to medium trafficked roads (AADT up

to 5000).

PERFORMANCE

Suitability as a base depends upon sealing of surface to waterproof and prevent softening by moisture entry.

Construction at 90% OMC. OMC 7% at MDD of 2.10

tonnes/m3. Compaction with vibrating smooth drum roller.


Map number 36

SITE

Location. Combelton Grange and Hellhole quarries near

Nowra. Lat 340 53' South, Long 1500 36' East.

Climate. Temperate. Rainfall 1200nunlyr.

Water table; unceltain, probably <6m.

Moisture I ndex 1m = +20 (from map).

Topography. Undulating coastal strip.

PROPERTIES

Reddish brown medium strength and grey green weak

poorly graded sandstones.

Typical representative gradings are as follows:

19 9.5

CG 76 54 HH 100 76

4.75 2.36 .425 .075

46 41 33 9

54 41 29 8

LL= 19%, PL= 16%, LS= 2-3%

CG = Combelton Grange Quany 40nun

HH = Hellhole Quany 20nun

PI

NP NP

Hardness, medium. Average crushing value 36.

Subgrade, sandy silt, estimated CBR 5%+.

Source Rock. Sandstones of Permian Age from the

Nowra Sandstone and Wandrawandian silty sandstone

formations.

USAGE

Quarried product suitable as a crushed sub base and base course layer in low and medium trafficked roads.

Some addition of fines (approx 10%) is needed to

improve suitability as unsealed road wearing course.

PERFORMANCE

Satisfactory performance repOlted on low - medium trafficked roads up to 5 x 105ESAs. Control of drainage

required to minimise ingress of moisture to pavement.

Suitable as a sub base or base on sealed roads, generally unsuitable as a sealing aggregate. Average 4 day soaked CBR 50%+ (Values well in excess of this have

been reported).

Moisture should be added at the pit. Desirable MC at construction 75-85% of OMC.


SITE

Location. Tomerong and South Nowra near Nowra

Lat 34 53 South, Long 150 36 East.

Cl imate. Temperate. Rainfall 1 200mm/yr.

Water tab le; uncertain, probably <6111.

Moisture I ndex Im = +20 (from map).

Topography. Undulating coastal strip.

PROPERTIES

Dark grey fine grained relatively weak shale (siltstone)

from Tomerong and South Nowra Quarries, South of

Nowra.

Grading is as follows:

19 9.5 T40 76 54 T20 99 70 SN2 100 ro

4.75 2.36 .425 .075 PI 40 32 20 11 3

48 35 21 12 2

32 21 9 5 NP

Average LL = 1 9%, PL = 1 6%. LS = 2-3% T40 = TOl11erong 40mm, T20 = Tomerong 20mm,

SN2 = South Nowra 20ml11. Product PI x P075 = 24 to 33.

Hardness, mediul11. Av wet strength 75, Av dry strength

227 , Variation 67.

Map number 36

Subgrade, Black Fine sandy/silt, estimated CBR 5%.

Source Rock Siltstones of Penni an Age from the Berry

and Wandrawandian formations.

USAGE

Suitable as a crushed sub base and base course layer in

low and medium trafficked roads (up to 2000). Two stage

crushing produces a well graded material. Requires lime

stabilisation if used on major roads.

PERFORMANCE

Satisfactory performance on low - medium trafficked

roads. Control to prevent moisture entering the

pavement is essential. Modification with 2% hydrated

lime required for use as sub base only on heavier trafficked main roads.

Suitable as a sub base or base on sealed roads, unsuitable

as a sealing aggregate. Average 4 day soaked CBR 55%. (Values from 32% up to 1 30% have been reported.)

Unable to take added moisture on the road prior to

compaction, must be added at the pit.

Compaction by means of vibrating sheepsfoot, vibrating

smooth and pneumatic tyred roller. OMC 7% at MDD

of 2.08 t0l1l1eshn3• Moisture content at construction 90% of OMC.


Northern Territory

-10

1 -15 1

1

6 1 7 1 1 • 1

1

1 • -20

1 1 1

1 4: 1 • 1 1 1

1

1 1 -25

r ------- - ------ _

23 24 25 --I------+---t---f----30 125 130 135 140

LEGEND

@] Location Map • Soil sample

Map number 2

SITE

Location. Cullen, adjacent to the Stuart Highway 200km

south of Darwin. Lat 1 30 22' south, Long 1 3 10 1 3' east.

The local material is a granitic sand soil derived from

highly weathered medium grained granite.

PROPERTIES

The grading for granitic sand is as follows.

9.5 4.75 2.36 .425 .075

1 00 98 83 46 24

PI

5

LS 2

In the Northern TelTitory granitic soil derived from

medium grained granite (0. 6 - 2.0 mm) generally has a

high plasticity and large percentage passing 0.075 sieve.

USAGE

Considered unsuitable because of excessive fines,

breakdown under compaction and strength loss when wet of OMC.

,,,. I I

PERFORMANCE

r --- - -+ -I A R! A

Tests were done with cement added, which reduced

plasticity and improved strength and m o isture susceptibility.

Addition of 3% cement was sufficient to make base quality material.


SITE

Location. On the Stuart Highway near Wauchope,

I OOkm south of Tennant Creek. Lat 200 39' south, Long

1 340 l3' east.

The local material is a fine sand-clay mix (there are no

suitable hard rock/gravels closer than 501(111).

Topography is undulating, fine sandy silty soils with some granite and metamorphic outcrops nearby.

Climate. Semi-arid, 500mm per year rainfall with hot

climate. Water table is < 5metres below natural surface.


PROPERTIES

Ref Cullen Granitic Sand data sheet.

Source Rocl{ is an area of highly weathered Proterozoic

Granite to the south of Tennant Creek

Map number 15

USAGE

See Cullen Granitic Sand data sheet.

PERFORMANCE

See Cullen Granitic Sand data sheet.


Map number 15

SITE

Location. On the Stu31i Highway between chainages

1376 km and 1392 Ian. Lat 22° 01' south, Long 1 33° 25'

east.

The local material is a fine sand-clay mixed with local

material. (There are no suitable hard rock/gravels.)

Topography is undulating, fine sandy silty soils with some granite and metamorphic outcrops nearby.

Climate. Arid. 150mm per year. Water for construction

often unavailable. Water table is >5 metres below natural

surface.


PROPERTIES

The grading is as follows.

Sand Clay

Ch l376 km

Ch l392 km

PI x PP .425 < 200.

2.36 .425 .075 LS

100 75 22 1.5

100 68 16

\ fJ 8mv.wtlld "

\ ,WInN:,. ',::.

Source Rock is surficial deposits and deep weathering mantle of Permian period, generally more than

5m thick.

USAGE

Traffic light, AADT around 300 with 3% heavy vehicles.

PERFORMANCE

Sealed sand-clay roads in the Ti Tree area have given

good service over many years.

Unsealed sand-clay surfaces have given satisfactory performance for traffic up toAADT 50. However some

silty non-plastic mixes have been unsuitable for unsealed roads due to the rapid loss of material under traffic.

1 00 Pavement materials in road building - Guidelines for making better use of local materials

Queensland

-10 �---r---_

-20

-25

-30 135

3

1 � . . : • • 1 8 •

•

I I 25 :26 27 I I ,----

140 145 150

LEGEND


155

,ueensland

Map number 9

SITE

Location. Croydon is located on the foothills of the

GregOly Range bordering the plains of the south eastern Gulf Region approx 150 km east of Norman ton. Lat 1 80

1 2' south, Long 1420 15' east.

Topography. Undulating foothills.

Climate. Hot and Sub Humid, <10001lli11 per year.

Moisture Index 1m = O.

PROPERTIES

Typical grading and plasticity are:

1 9 9.5 4.75 2.36 .425 .075 LS PI

99 91 70 51 40 1 7 3 4

Product P I x PP 425 = 1 60.

ACY = 50.

Source Rock. Deep weathering mantle of early igneous

rocks (Middle Proterozoic) which occurred in the

Cretaceous Period. The general description is "Plateaux

with widespread laterite and bauxite development on

sandstone and siltstone parent rocks, clayey sand".

The ironstone gravel is formed from an accumulation of iron oxides capable of hardening to form ferricrete.

I R fA 1------I I

USAGE

Used on the Gulf Developmental Roads in the vicinity of Croydon. The deposit is variable and requires some

screening to bring within specification limits. Careful

selection in the pit is required because the quality

changes with horizons. Skill is required in wim1ing

suitable gravels. The stone is less sound and softer

than the NOlmanton Ironstone found further west.

PERFORMANCE

Suitable as a base on the low volume roads in this

locality. At a Standard Compaction of 1 00% the

unsoaked CBR is 182% and the 4 day soaked CBR value

is 1 09.


Queensland

SITE

Location. Normanton on the NOIman River, south

eastern Gulf Country. Lat 1 7040' south, Long 141004' east.

Topography. River flood plains.

Climate. Hot and Sub Humid, > 1 OOOmm per year.

Moisture Index 1m = +20 to +10.

PROPERTIES

Typical range of grading and plasticity are.

1 9 9.5 4.75 2.36 .425 .075 LS PI 80 55 40 30 12 5 0 0 99 90 70 55 30 20 4 8

Product PI x PP 425 = < 200.

ACY = 22.

Source Rock Surficial deposits and deep weathering mantles fonned in the Cretaceous period. Generally

more than 5m thiclc The general description is : "Plateaux with widespread laterite and bauxite

development on sandstone and siltstone parent rock,

clayey sand". The ironstone gravel is formed from an

accumulation of iron oxides capable of hardening to form ferricrete.

Map number 9

USAGE

Normanton Ironstone is used extensively in the Gulf

area at Karumba and 011 the Burke Developmental Roads. Due to the wet climate it is generally screened (even on

lower volume roads of AADT 1 00-200). The material

is variable and skill is required in winning good gravel

due to the changes between horizons.

PERFORMANCE

Suitable as a base on the low volume roads in this

locality. The stone appears to crush more than the

Croydon Ironstone found further to the east. At a

Standard Compaction of 100% the unsoaked CBR is

160% and the 4 day soaked CBR value is 71 %.


,ueensland

Map number 10

SITE

Location. Mareeba on the Atherton Tablelands

approximately 50 Ian west of Cairns. Lat 16° 59' south,

Long 145° 25' east.

Topography. High tablelands.

Climate. Hot and humid, rainfall up to 7000mm per

year. Moisture Index 1m = +20.

PROPERTIES

Typical range of grading and plasticity are:

19 9.5 4.75 2.36 .425 .075 LS 80 55 40 30 12 5 0 99 90 70 55 30 20 4

PI

o 8

Product P I x PP 425 = 45-60 (much less than 200).

ACV=37

Source Rock. The laterites occupy parts of the

tablelands and plateaux in western areas. Sourced from

colluvial deposits formed through gravity producing

deposits of angular stones on slopes and ridges. The

parent rock is underlying granite formed in the Permian

period.

The general area descliption is: "A complex of granites,

volcanic, sedimentary and metamorphic lithologies

comprising tablelands, plateaux and hilly uplands of the

coastal mountains and ranges".

USAGE

Has been used successfully on roads withAADT up to

3000 (Kennedy Highway) and in a wet climate.

PERFORMANCE

High quality pavement material is produced relatively

inexpensively by screening and blending with sand and

ctUsher dust. The material has good strength properties.

At a Standard Compaction of 1 00% the unsoaked CBR

is 1 1 7% and the 4 day soaked CBR value is 8 9%.


'ueensland

SITE

Location. This deposit isArea U weathered colluvium, located East of Kyuna. Lat 2 1 0 35' south, Long 1420 00' east. The colluvial deposit comprises clayey sands and

gravels produced from erosion of old duricrust surfaces.

Topography . Black Plains country.

Climate. Semi Arid. Rainfall 400mm per year.

Temperature hot.


PROPERTIES


19 9.5 4.75 2.36 .425 .075 LS PI

84 70 53 39 21 10 9 U.5

Product PI x PP 425 = 234.

Source Rock. The general description of the area is: "Stony black soil plains with widespread silcrete and fenicrete mesas and some minor alluvial and sandy tracts,

Area U is one of these minor sandy tracts of poor quality".

Map number 17

USAGE

Not used in its natural state. The gravel is variable and

suffers loss of strength when wet. When used on the

Landsborough Highway, it has been stabilised with

varying percentages of lime and cement.

PERFORMANCE

At a Standard Compaction of 100% the unsoaked CBR

is 48% and the soaked CBR value is 25%.


Queensland

Map number 17

SITE

Location. Lat 21 0 15' south, Long 1 4 3 0 00' east.

Coleraine siltstone is derived from a highly weathered

low strength siltstone. The stone is very soft and breaks

down during construction.

Topography. Undulating, near watershed ..

Climate. SemiArid. 500nul1 per year. Temperature hot.


PROPERTIES


19

85

9.5 4.75 2.36 .425

79 71 67 61 .075 LS% PI 19 1.6 NP

Source rock. Soft Cretaceolls siltstone. General description of the area is: "flat to gently undulating

black soil plains developed on sandstones, mudstones and alluvium".

USAGE

Good gravel, readily available and extensively used on the Landsborough Highway (McKinley to Cloncurry)

and on the Barldy Highway. The gravel is screened to

remove oversize and to rectify fines grading.

PERFORMANCE


is 36% and the 4 day soaked CBR value is 30%.

1 0 6 Pavement materials i n road building - Guidelines for making better use o f local materials

,ueensland

...

N D • An ...

SITE

Location. Near Julia Creek. Lat 200 40' south, Long 1 410 45' east. Comprising outcrops of Toolebuc

Limestone, the formation is calcareous siltstone with

thin beds oflimestone.

Topography. Plains country with northerly flowing

rivers towards the Gulf.

Climate. Semi Arid.<500mm per year. Temperature hot.

Moisture I ndex 1m = -30.

PROPERTIES


19

71 9.5 4.75 2.36 .425 56 44 37 26


ACV=43.

.075 LS% 19 5.5

PI

9.5

Map number 17

Source Rock Surficial deposits from deep weathering in the Cretaceous period, generally> 5m thick.

General description as for Coleraine siltstone.

USAGE

The stone is harder than the Silver Hills limestone but

breaks down under construction. The material has been used directly and also with 5% cement added in recent

times on the Flinders Highway. Has also been used

directly on secondaty roads such as Julia Creek - Kyuna.

The harder stone requires grid rolling to break up

oversize material.

PERFORMANCE


is 36% and the 4 day soaked CBR value is 30%.

Pavement materials in road building - Guidelines for making better use of local materials 1 07

,ueensland

Map number 17

SITE

Location. This deposit is SW of McKinlay and west of

Kyuna. Lat 210 16' south, Long 1410 1 7' east. The Jacobs Bore colluvial deposit comprises residual and

colluvial gravel covering a series of gentle slopes to

mica schist ridges. The deposit has a high percentage of qualtz.

Topography. Undulating.

Climate. SemiArid, hot. Rainfa1l 400mml year.

Moisture I ndex 1m = -40.

PROPERTIES


19

81

9.5 4.75 2.36 .425

57 53 48 37

.075 LS% 16 3.5


Soundness ACV = 2 7, High % of quartz.

PI 3

Pi N D I .k_ I

Source Rock. Sedimentary layers formed in the

Cretaceous period and subjected to metamorphosis. It

adjoins deep surficial deposits formed in that period

immediately to the east. General description of the area

is: "rugged parallel ranges and narrow lowlands

developed on metamorphic igneous rocks - minor

laterite areas".

USAGE

Good gravel, readily available and extensively used on

the Landsborough Highway (McKinley to Cloncurry)

and on the Barkly Highway. The gravel is screened to remove oversize and to rectify fines grading.

PERFORMANCE

At a Standard Compaction of 100% the 4 day soaked

CBR value is 60%.

1 0 8 Pavement materials i n road building - Guidelines for making better use o f local materials

,ueensland

SITE

, I , I

71- -_h '1 I .. / I

Location . T his deposit of Kyuna silcrete is south of Kyuna in KelTs Table Mountain. Lat 21 0 44' south, Long 1410 55' east. Silcrete is found on mesa caps. The

silcrete is a cemented sand like deposit produced by

groundwater movements.

Topography, foothills of the Tableland.

Climate. SemiAridAOOmm per year. Temperature Hot.

PROPERTIES


19

99 9.5 4.75 2.36 .425 66 40 25 13


.075 LS% 8 3

PI

Source Rock. The general description of the area is:

"Stony black soil plains with widespread silcrete and

ferricrete mesas and some minor alluvial and sandy tracts". Kyuna silcrete comes from a mesa.

Map number 17

USAGE

The stone is hard and a good quality fine crushed rock

pavement material can be manufactured from this source

for use on the Landsborough Highway.

PERFORMANCE

At a standard compaction of 100% the soaked CBR

value is 81 %. This is sufficient to meet specification as

a road base material.

Stone quality. TheACV is 26 (wet) and 22 (dlY).


Queensland

Map number 17

SITE

Location. Near Richmond. Lat 200 44' south,

Long 143008' east.

Consists of outcrops of Toolebuc Limestone. T he formation is calcareous siltstone with thin beds of

limestone.

Topography. Foothills of the Newcastle Ranges.

Climate. SemiArid, 500mm per year. Temperature hot.

Moisture Index Im = -30.

PROPERTIES


19

83 9.5 4.75 2.36 .425 69 52 43 31

Product PI x PP425= 582,

.075 LS%

25 8

PI

20

Source Rock Surficial deposits from deep weathering

in the Cretaceous period, generally> 5m thic1c

General description as for Coleraine siltstone.

USAGE

\ '1 "

...... U!t... //

.. ,J

,/,/"0 U E

:':':��'��.:�--- ... /--'- PI'!-/ f./ ",.-.�;,O! " ,"-- .,·t�·

,/ ",r� .. ···�;;:··l",-----,i�· _.,I! �� " I

w __ �:::r - .. ' ,rr -- __ 1'

The stone is very soft and breaks down during the

construction process. The material has been used on Richmond secondary roads where trafficAADT < 100.

PERFORMANCE

Difficult to improve the prope11ies of such a soft material. It was utilised on the Flinders Highway with 6% cement

added. At a Standard Compaction of 1 00% the

(unstabilised) un soaked CBR is 37% and the 4 day

soaked CBR value is 21 %,


Queensland

I '\ � i ': \ I.tr= ..... �� (;'I I ')

".��:,.(; . . J( .::

Map number 17

," --', (. I),"':"�'u;r�----" '-

��r;L A .� D . '"".� I I , � . ,.0' ···· .. ,:·;; ·

SITE

��.�,.-. .... ,;,�!::--��;.� '. , .

I < ... ---_ l!

Location. Landsborough Highway, between Winton and Longreach and Winton and Hughenden. Lat 220

23' south, Long 1430 02' east.

Climate. Arid! Semi arid. Rainfall between 250mm and 500 1111n/yr.

Water tab le >6metre below surface.

Moisture Index 1m = -50 (from map),

PROPERTIES

Soft, brown, fine grained poorly graded plastic

decomposed "sandstone". Grading as follows:

19 9.5 4,75 2.36 425

100 94 100 98

Product PI x P 425 = 560 - 600,

Subgrade, clays and black soil.

Subgrade test CBR 8% to 11%.

lnsitu Moisture Content 24%.

075

25 30

PI

6 12

LS

Source Rock Pits are located in the extremely to highly

weathered surface deposits of sandstone from the

Winton Formation.

USAGE

Low traffic 5 x 105 ESAs AADT.

Very soft poor quality material used only because of a lack of any other economic source material. Surface bitumen sealed. Won using small dozer and grid roller

to reduce oversize. Spread and compacted in 100 -150mm

layers with rubber tyred roller. Minimum pavement

thickness 200 mm.

PERFORMANCE

Perfo1l11ing satisfactorily only because of the aridity of

the area and the moisture content in the pavement remains well below OMC. Highly moisture sensitive.

Essential to keep water out of pavement. After rain,

seal edges vulnerable to damage by scour and rutting.

Shoulders are sealed to 0. 6m beyond carriageway.

Stabilisation with cement, lime, bitumen. The sandstone

tends to absorb bitumen in hot conditions. Best

performance with I metre wide bitumen emulsion

stabilised edge strips.

Pavement materials in road building - Guidelines for making better use of local materials 1 1 1

Queensland

Map number 18

SITE

Location. Near Durrandella on the Alpha to Tambo

Road, 150 Iml South west of Emerald.

Topography. High tablelands. Lat 240 07' south, Long

1460 35' east.

Climate. Edge of the SemiArid zone,

rainfall < 500nU11 per year.


Wate r tab le < 5 metres below natural surface.

PROPERTIES

Sand Clay mix. Typical range of grading and plasticity

providing satisfactory results are:

Site 4.75 2.36 .425

6

13

R = Ratio .075/.425.

96 99

97

.075 LS R 37 2 .38

62 4.5 .62

46 7.5 .47

.� D \ �

' )-�I: - -----�-;> I

I

"�" Ld� . "� ' "

('>;., .'. J

g ! �

i ( � 1.!::t • .Uo.\

Source Rock . Sand-clays derived from sediments formed in the Jurassic, Triassic and Permian periods.

USAGE

Initially the road has to be unsealed and has to have

sufficient binder to hold the sand together, but not so much as to become slippery or boggy when wet. A

suitable mix can be confirmed by two tests:

I . Ratio PP.075/PP.425 => 0.35

(Upper limit about 0. 7)

2. Linear Shrinkage to be between 2.0 & 4.5.

Kapitzke verified that these figures can be used widely

in North Queensland.

PERFORMANCE

In most cases on the Alpha - Tambo Road with the local

materials a 1 : 1 mix was satisfactory.

According to Kapitzke local materials which performed well on unsealed roads in the 1950's were sealed in the

1 9 60 's and performed well in the dry conditions

prevailing.

1 1 2 Pavement materials in road building - Guidelines for making better use of local materials

Queensland

SITE

Location. Leichardt and Barwon Highways and others

near Goondiwindi. Lat 280 33' south, Long 1500 18'

east.

Climate. Semi arid - temperate subhumid. Rainfall between 500-800mm/yr.

Water tab le >6 metres below surface.

Moisture I ndex 1m = -20 (from map).

PROPERTIES

White Rock is a low strength silicified kaolinitic material

with a variable range of properties. Grading is variable

around a typical range at 2 - 4 m in pit at Kilbronae as

follows:

75 37.5 19 9 .. 5 4.75 2.36 .425 .075 96 81 71 63 52 45 30 17

100 99 95 92 89 87 63 52

LL = 36 - 39% P I = 15 - 1 9 LS = 7.5 - 10%>

Product PI x P 425 = 830 - 1153>

Map number 28

Source R ock. Product of leaching iron and aluminium

from Tertiary and Cretaceous sedimentary rocks.

Conll10n in SE QLD.

USAGE

Low traffic to medium traffic 5 x 105

ESAs.

Used in low to moderate rainfall areas.

Material for higher traffic roads require ripping and

stockpiling with a Cat D8 dozer. Material for low traffic roads can be won with a front end loader in the pit.

PERFORMANCE

Pelforms well in all locations utilised where better quality

alternatives are unavailable. Will not perfOim in high

traffic, high rainfall situations. Reworking of the material reduces strength and must be kept to a

minimum. Measures are required to keep water out of

pavement.

Mechanical stabilisation with up to 15% natural sand

added to improve grading and reduce PI.

Compaction at 100% Standard and 80% OMC. Up to CBR 96% achieved.

OMC range variable 1 1.5% to 16.6% depending on grading. At 100% OMC, CBR ranges from 24% to 37% unsoaked, 5% to15% soaked at MDD range 1.7 to 1 . 9

tOilles/m3.


Queensland

Map number 28

SITE

Location. Hornleigh and Mt. Wooroolin near Kingaroy. Lat 26° 32' south, Long 151 ° 50' east. Local material is a

fine grained laterite gravel.

Climate, Sub tropical with summer rainfall. Water table unknown.

Moisture Index -20.

Annual rainfal l 400- 600mm.

PROPERTIES

The materials from Hornleigh and Wooroolin were

respectively the best and the least satisfactory in terms

of properties.

Material

Hornleigh

Wooroolin

4.75 .425

80 55

95 85

. 075 PI 40 8-10

80 11-15

The moisture contents of the unsoaked samples were

near OMC. Unsoaked and soaked CBR values measured

at 95% modified compaction were:

Hornleigh 75-120% unsoaked, 26-30% soaked.

Wooroolin 50- 75% unsoaked, 45-65% soaked.

I I !

I I

Source Rock. Laterised basalts of Tertiary period.

USAGE

Low to medium trafficked roads in the Kingaroy area.

Best used in well drained situations as the fine grained

material is moisture sensitive.

PERFORMANCE

The lateritic gravel materials used at Kingaroy have

performed successfully on a number of roads in the

area. Care is required in construction as during

reworking and recompaction, fUliher breakdown of the

material and strength loss can result. When broken up, recompacted and CBR remeasured, there was a

significant drop in the unsoaked CBR values as follows:

Hornleigh 40-60% .

Wooroolin 35-45%.

Use of cLUshed 1 9mm aggregate screenings as a surface armouring has proven successful.


Queensland

SITE

Location. Coastal areas nmih of Brisbane. Approximate

Lat 27° 00' south, Long 153° 00' east. Local material is a

Silty-Sand or Loam.

Climate,Humid Sub tropical with summer rainfall.

Water table unknown.

Moisture I ndex + 100.

Annual rainfall 1200- 1 600mm.

PROPERTIES

Grading and compaction properties of this sandy material area is follows:

Sieve 4.75 .425 .075 PI

Loam 9 9 8 9 23 NP

The moisture content of the un soaked samples at Standard Compaction were near the OMC of 1 6%.

Maximum dry density 1 750 kg/m3.

Source Rock. Aeolian sand/silts overlying sandstones of Jurassic periods.

Map number 28

USAGE

As a select fill at best on low to medium trafficked roads.

PERFORMANCE

Must be used in well drained situations as the fine

grained material will become unstable in wet conditions.

Should be placed and compacted within 0 to -2% of

OMC. Compaction too far below OMC produces a

porous material, highly susceptible to water penetration.

Unsoaked CBR is 20%.


South Australia

I L. I 23 :

31

- - - - - - - - - - - - - -

24 25 •

130 135 140

LEGEND

-25 I I I I I I -30 I I I I I

-35


Map number 33

SITE

Location . Pimba near Woomera. Approximate

Lat 310 12' south, Long 1 360 49' east.

The material is a sandstone gravel locally known as Arcoona sandstone.

Climate, Arid.

Water table> 6111.

Moisture Index -50 (from map).

Annual rainfal l <200mm.

PROPERTIES

White and light brown arkosic sandstone gravel with

sandy clay of medium plasticity; some gypsum present.

100% passing 75mm sieve, no other grading data. LL =

30% max, PI = 10% max.

Sou rce Rock. Late Proterozoic (Precambrian)

sediments and in-situ surficial weathering product.

USAGE

Used as a base course on lightly trafficked roads in

Woomera and as a sub base on recent heavy

construction. The nahlral material has been used as a

base course on the Pimba-Eucolo Creek section of the Shlali Highway and on the Wirrappa - Roxby Downs

Highway.

PERFORMANCE

The material is ripped by dozer and pushed up in the

pit. The whole face is worked to approximately 3 meh'es

depth to ensure primary mixing of layers. Large stones and lack of PI in sections of the pit can cause problems during compaction if primary mixing is not carried out.

Basecourse quality crushed rock could be produced with appropriate equipment. The material would be

unsuitable as a sealing aggregate.

Some failures have occurred, mainly due to ingress of

water into the subgrade during wet periods. The 4 day

soaked CBR of <20% compares with the unsoaked value of l 60%.


________ --"'J,, ___ _

\ I N

• Y�h"

I II ' ' ' '\"

B I G H T

-J- ------- - - --- --

SITE

I I

Location . Multee Road pit 30km east of Ceduna. Lat 320

08' south, Long 1330 41 ' east.

Climate. Arid. Rainfa1l 300nUll/yr.

Water table > 6 metres below natural surface. Area not flood prone.

Moisture Index 1m = -35 (from map).

Topography. Flat to undulating limestone plateau.

PROPERTIES

Hard limestone conglomerate with clay binder. No data

on grading

Source Rock is surficial calcareous Aeolianite and calcrete, generally >5m thick overlying limestones of

Cretaceous Period and metamorphic strata.

Map number 32

USAGE

Suitable as select subgrade, sub base and base course. Light to medium traffic roads.

PERFORMANCE

Satisfactory performance reported under the light to

medium traffic conditions. Estimated that a CBR in the

range 30-50% was achieved.

Compaction was carried out on air dried material, no

water added, with a vibrating sheepsfoot roller, a

vibrating smooth drum and a pneumatic tyred roller.


Map number 33

SITE

Location. Eyre Highway, Yaninee to Kyancutta. Lat 320 57' south, Long 1 350 16' east.

Climate. SemiArid. Rainfall 330mmlyr.

Water tab le; uncertain, probably >6m.



PROPERTIES

Calcrete rubble material from Oswald's Pit, 3km east of

Yaninee. Grading is as follows:

37.5 1 3.2 4 .75 2.36 425 075

92 56 35 30 24 9.5

LL=20%, PL = 15%.

Product PI x P075 = 45.

Fines to sand ratio PP.075/PP 2.36 = 32.

Hardness, medium.

Los Angeles Abrasion 36-39.

P I

5

LS 2

Subgrade, Grey brown clayey sand

Subgrade test CBR 8%

Source Rock. Cemented windblown sands (calcreted Aeolianite) of the Bridgewater Formation of Pleistocene

age. Original source rocks probably the Nullarbor

limestones of Teliiary age.

USAGE

Traffic AADT 6 70 with 45% commercial vehicles

( Interstate haulage and local grain).

Calcrete rubble (crushed), pavement thickness 100 to

350mm. Extensively used as a base and wearing course for sealed and unsealed roads on the Eyre Peninsula.

PERFORMANCE

Satisfactory performance on low - medium trafficked

roads. Precise moisture control is essential to achieve compaction. Modification with 2% cement to prevent

early rutting.

Compaction by means of vibrating sheepsfoot, vibrating

smooth and pneumatic tyred roller. OMC 8% at MDD of 2.04 tonnes/m3. Moisture content at construction 90%

of OMC. Soaked CBR in the range 70% - 120%.


SITE

L oca tion. Loxton to Nuriootpa Road. Typical

Murraylands region. 17 km west of Loxton. Lat 340 2 7'

south, Long 1400 28' east.

Climate. Arid. Rainfall 260mm/yr.

Water tab le > 6 metres below natural surface. Area not flood prone.

Moisture Index 1m = -35 (from map ).

Topogl'aphy. Flat to undulating Mallee type country. Material is a soft rubbly limestone.

PROPERTIES

Grading for subgrade, rubble and screenings:

19

SG

RB 94 SC 92

9.5 4.75 2.36 97

76 60 46 76 61 46

.425 .075 85 46 36 15

25 10

SG = Subgrade, RB = Limestone rubble, SC = Screened limestone

PI x % .425 (rubble) = 6x36 >200.

and Screened limestone = 5 x 25 < 200.

LL% PL%

36 14 22 16

23 18

Source Rock is weathered rubbly limestone comprising

surficial deposits and deep weathered mantle of Cretaceous period. Generally > 5m thick.

Map number 34

USAGE

On local light to medium traffic roads (AADT 70).

Limestone pavement on sandy clay s ub grade. Formation 300-500mm above natural ground surface

level. 6 m sealed road full width with 1m gravel

shoulders. Pavement thickness nominally 150111lll.

PERFORMANCE

SatisfactOlY performance reported under the light traffic

conditions. The pavement material was placed and

compacted under "air dlY" conditions (MC approx 6%).

OMC limestone l O% and subgrade 1 6%. CBR in the range 30-50% achieved.

Rockbuster may be considered for in-situ processing

either after ripping in the pit or on the road. May be cement stabilised.

Compaction was carried out on air dried material, no

water added, with a maximum of twelve passes per

layer on 120 mm thick layers with a 5 tonne vibrating

sheepsfoot roller, a 4 tonne vibrating smooth mum. Final

rolling with a 3.5 tonne pneumatic tyred roller caITied

out to "tighten" the surface.

The pavement and sub grade remained dry as placed

except under the outer 0.5 m (the outer edges of the

seal).

Pavement materials in road building - G uidelines for making better use of local materials 1 2 1

Map number 37

SITE

Location. South Coast Road, Kangaroo Island, east of

Rocky River. Lat 35° 57' south, Long l 3 6° 44' east.

Climate. Cool Temperate (Dry Subhumid). Rainfall

between 485nun and 640nmliyr.

Water tab le > 1 metre below surface.

Moisture Index 1m = -20 (fi-om map).

Topography. Slightly undulating sand coastal.

PROPERTIES

Laterite material ii-om McGhee's Pit. Grading is as follows:

19 9.5 4.75 2 . . 3 6 .425 .075 95 66 41 31 26 8

L L = 20%, PL = 12%.

Product PI x Pm = 208.

Fines to sand ratio PP075/PP2.36 = 26.

Subgrade, yellow brown sandy clay:

9.5 4.75 2.36 425 075 PI

96 90 85 77 59 23

LL = 41 %, PL = 1 8%.

Sub grade test CBR 8% to 1 1 %.

In-situ MC 24%.

PI LS%

8 2

LS 9

I I I + -�--I

Source Rock. Lateritic gravels (above the 200m

contour) developed as a result of prolonged weathering

of Cambrian sediments in the Triassic period.

USAGE

TrafficAADT of200 per day (1987) with 10% conunercial

vehicles (tourist, grain & livestock).

Laterite gravels, pavement thickness 100 to 250mm.

Extensively used as a base and wearing course for sealed and unsealed roads on Kangaroo Island.

Deficiency in plastic fines and rounded nature of the

gravel can be a problem.

PERFORMANCE

Satisfactory performance on low trafficked roads. Lack

of plastic fines to bind the material and roundness of

particles can result in premature loss of shape of road.

Where sealed, excessive moisture at construction can

lead to premature failure by rutting.

Compaction by means of vibrating smooth and pneumatic tyred roller. OMC 4.5% at MDD of 2.33

tOlmes/m3. Moisture content at construction, 90% of OMC.


SITE

Location. Test site on Lameroo to Kulkami Road, 17 km from Lameroo. Lat 350 l3' south, Long 1400 20' east.

Climate. Arid to semi arid. Rainfall 350mm/yr.

Water tab le > 6 metres below natural surface. Area not

flood prone.

Moisture I ndex 1m = -30 (fi'om map).

Topography. Flat to undulating Mallee type countly.

PROPERTIES

Grading in roadbed:

2 .. 36 .425 .075 LL% PL% PI LS% SJ 97 94 32 32 13 19 7 SC 98 94 21 23 15 8 3

SG = Subgrade, SC = Sand Clay

Fine sandy clay has reduced PI due to addition of

fine sand.

Map number 38

Source Rock comprising surficial deposits and deep

weathered mantle of Carboniferous period. Generally > 5m thick.

USAGE

6 m sealed road full width including shoulders. Sand

clay pavement thickness nominally 150mm. Traffic

AADT 70.

PERFORMANCE

SatisfactOlY performance repOlied under the light traffic

conditions. The pavement material was placed and

compacted under "air dry" conditions. CBR in the range 30-50% achieved.


-40

-45

Tasmania

1 44 1 50

LEGEND

o Location Map • Soi l sample

Tasmania

Map number 40

SITE

Location. Round Hill near Burnie. Approximate

Lat 410 04' south, Long 1 450 54' east.

The material is a quartzitic sandstone and slate deposit.

Climate, Temperate with winter rainfall. Water table

variable.

Moisture Index (1m) + 1 00 (from map).

Annual rainfall 1 200mm.

PROPERTIES

Grading and compaction propelties of the material were

in the following range:

Sieve

LS = 4 - 5%.

9.5 4 .75 2.36 .425

26 1 8 1 6 1 2

4 7 32 30 10

Dust ratio 0. 71 - 0. 69.

PI LL%

10 2 9

7 23

Source Rock: The Burnie quartzite and slate is an alteration of well bedded black slaty mudstone and quartzite of silt and sand grade of Precambrian age.

These are overlain by basalts of Teriary age.

I '7'"

USAGE

Used as a base course on the light to moderately

trafficked roads for over half a century with satisfactory

peformance.

PERFORMANCE

Widely available in the Round Hill area. Not a

particularly high grade construction material. The

gradings show an excessive amount of both oversize

and undersize material. Increased traffic loadings and

environmental pressures on the working of this source

have seen their continued use under threat.

The likely durability of the material is moderate at best.

Blending with other material such as the locally available basalt may improve grading and compaction properties.


SITE

Location. Pipers River Road east of Launceston between chainages 2 9 -40 km from Launceston. Lat 4 10 06' south,Long 1 470 05' east.

Climate. Temperate. Rainfall 760mmlyr.

Water table > 6 metres below natural surface. Area not

flood prone.

Moisture I ndex 1m = +40.

Topography. Undulating to hilly, drainage varies from good to fair.

PROPERTIES

Grading in roadbed:

19

QJ 94 9.5 4.75 2.36 .425 .075

QG = Quartz Gravel.

55 39 28 PI

4 is

Soil Suction Pf in a pit 460mm below centreline is 2. 7 .

Quartzite gravel o n silty clay and sandy clay sub grade

of low to intermediate plasticity.

Tasmania

Map number 40

Source Rock comprising Palaeozoic sedimentary

basement rocks.

USAGE

Traffic AADT is approximately 300 with about 15%

commercial vehicles including log trucks with very heavy loads to Georgetown timber mills.

The road is boxed construction, originally sealed to 5.5m

width with gravel shoulders.

PERFORMANCE

Truck loading was causing rutting and potholing and edge breaks. Benkelman Beam readings were 1.0 - 1.5mm

on good sections and 2 . 0-2.5mm on poor (cracked)

sections.

Sub grade moisture content was OMC + 2%. Pavement

moisture content was OMC -1 %, with little difference

between inner and outer wheel paths. Increased

pavement thickness and full width (7 .2m) construction

should improve perfOlmance.


-30

-35

-40

Victoria

, , , , , , •

f 311 , , ,

. '" - .. . ' \

., ""

, , , • • , 38 , ,

• •

140 145

LEGEND

o Location Map

• Soil sample

151

leloria

Map number 38

SITE

Location. Mt. Bolton on Sunraysia highway, near Waubra, City of Ballarat . Approximate Lat 37022' south, Long 143038' east.

The material is a granitic sand of colluvial origin.

Climate, TemperatelMediterranean with winter rainfall. Water table variable. Moisture Index -20 (from map). Annual rainfall 600- 800mm.

PROPERTIES

Grading and compaction properties of the material were in the range as follows:

Sieve 2.36 .425

75-90

.075 PI

30-50 18-25 4-8 (Est)

T he moisture contents of the unsoaked samples at standard compaction were near the OMC of 1 6%. Maximum dry density 1750 kg/m3•

8 ASS

--1------------'�_i·�"' _ __.I---I1q

Source Rock: Granite intlUsion of Devonian age. Thought to have undergone deep weathering in the Tertiary period.

USAGE

Used on light to moderately trafficked roads.

PERFORMANCE

Widely used where granite outcrops are available. Increased traffic loadings and environmental pressures on the working of these pits has seen a decline in their use.

Suitable as capping material over soft sub grades, as a sub-base, (formerly used on main arterial roads/ highways in wetter parts of the State) and as road base on low to medium traffic municipal roads. Suitable as a wearing surface only on lightly trafficked roads. Not suitable under heavy commercial vehicle loadings. Care must be taken to avoid material with excessive mica content.

The material is easy to work. Simply spread, water and compact at OMC and using smooth dlUm heavy roller. Will not normally respond to vibration. Avoid compaction of very thin layers as this can cause delamination.


SITE

Location. Pyramid Hill approximately 70km north of Bendigo and 19km east of the Loddon Valley Highway. Lat 360 03' south, Long 144007 ' east.

Climate. Mediterranean. Rainfall <400mm/yr.

Water table generally> 6 metres below natural surface except near irrigated propelties in the flood plain. Area not flood prone.

Moisture Index 1m = -20 to -30 (from map).

Topography. Flat to undulating countly.

PROPERTIES

Sandstone and granite. Grading in roadbed:

SI S2 G

19 65 80 98

9.5 57 68 72

4.75 2.36 .425 51 42 36 60 50 42 49 31 13

.075 PI 11 0-10 15 0-10 6 3

SI & S2 =Pat'illa sandstone. G = Fine crushed granite blended with Parilla sandstone.

Source Rock Standard pavement material is available from a quarry in the granite outcrop at Pyramid Hill but is too costly for use on most roads in North Central Victoria. No materials are available on the Loddon flood

plain except soft sandstone of the Mallee formation.

ietaria

Map number 38

USAGE

It is necessary to add fines to the granite fine crushed rock for workability and compaction. The granite provides a wearing course for unsealed roads particularly where the base layer is of soft Parilla sandstone.

The sandstone has a large percentage (approx 50%) passing the 2.36mm sieve and has about 20% oversize material.

The pit face is worked on a slope of 1 : 1.5 to ensure a good mix and has to be ripped down and across the face before dozing to a stockpile of material with a maximum size of 250mm. The oversize is fillther broken down on the road bed by grid rolling.

PERFORMANCE

The fine sand has been used successfully on all classes of road with pavement depths of 150nun (minor roads) and up to 425nun (heavy traffic).

Sandstone material is not very good for unsealed gravel roads where it has a short life due to early loss from the pavement. An armour coat of granite fine crushed rock (approx 25mm) will extend the life of unsealed pavements with reduced maintenance cost and provide a superior riding surface.

Pavement materials in road bui ld ing - Guidelines for making better use of local materials 1 3 1

Map number 38

SITE

Location. TertialY gravels from Kays Pit at Barkers Creek near Guildford. Lat 370 09' south, Long 1 4 40 10' east.

Climate. Meditenanean. Summer rainfa1l 400mmlyr. (N0l1h of Great Divide).

Water table > 6 metres below natural surface. Area not flood prone.

Moisture Index Irn = -20.


PROPERTIES

Tertiary gravel pits have a layer of surface gravel < 1m thick and a hard cap of approx 1 m under which there is a gravel deposit of up to 20m thiclmess. Stones are smooth water WOl11 and are in layers. Some sandy layers tend to be coarse and free.

USAGE

On the Midland Highway between Harcourt and Castlemaine. It is best to extract and mix the deposit full depth by dozing down an inclined face to a stockpile in the floor of the pit.

Material can be used unmodified with success on minor roads. Due to the relatively high clay content they are workable and compact easily. Removal of the clay by washing tends to render the gravel unworkable (bag of marbles effect). With too high a clay content the laboratOly four day soaked CBR value is poor, in the range of 20-30%.

PERFORMANCE

To achieve standard specification a mechanical stabilisation is required with addition of sandy loam. This produces a well graded material. (9% passing .075 and PI = 3 has been achieved). This material compacted well has performed satisfactorily. It is much more cost effective to use as won, unstabilised material in a dry environment.


Western Australia

-10

1 -15

6 •

-20 I I I

13 14: I I I

-25 I I

22 23: I I I -30 I

•

��_\-\ -35

115 120 125

LEGEND

@] Location Map

• Soil sample

130

Western Australia

Map number 00

SITE

Location. Cocos atoll, Indian Ocean. Lat 12°- 1 1' south, Long. 960 -50' east.

Climate. Tropical defined wet season. Rainfall 4 19mm1 yr. Evaporation 2, 1 OOmmlyr.

Water table approximately 2m below surface ..

Moisture Index 1m = -20 (fiom map).

Topography. Flat coral atoll approx 3m above sea level.

PROPERTIES

Grading in coral sand subgrade material ranges between the following:

4.75 2.36 425 075 PI is 70 65 46 9 NP -

83 81 40 3 NP -

90 87 55 12 NP

Grading in the coral rubble pavement ranges between the following:

19 9.5 4.75 2.36 425 075 PI is 80 64 48 36 18 10 NP 75 50 39 30 14 7 NP 90 70 56 42 20 1 1 NP

Note: Final row is grading after compaction.

96° 50'

Horsburgh Is 12'05' -------r�----�-----------------� Direclion Is

�omels

'i)

\ 'al

South Keeling li; Islands �_ ." ,\ �

Indian Ocean

Source Rock. Coral reef material which has become detached and decomposed.

USAGE

Airfield pavement material. Undisturbed coral sand subgrade with coral rubble pavement.

The sub grade was at 88%of MDD which was 1,760 kglm3.

The coral rubble pavement was compacted to 95% MDD with sheepsfoot rollers plus a heavy pneumatic tyred roller. After compaction the surface was filliher worked with smooth and rubber rollers and watered to produce a smooth surface. Sealing aggregate and concrete aggregate were produced from the coral material.

PERFORMANCE

The pavement has performed satisfactorily and has been progressively upgraded to take larger and more modern aircraft.

134 Pavement materia ls in road bui lding - Guidelines for making better use of local materials

Western Australia

SITE

Location. Cable Beach Road north of B roome Lat 1 7 ° 58' south, Long 1 22° 1 4' east. Material is Pindan sand (sand-clay)

Climate. Semi arid, hot. Rainfall 600mmlyr of which 85% occurs between December and May. Water table generally> 6 metres below natural surface.

Moisture Index hn = + 1 0 (from map).

Topography. Low - undulating relief.

PROPERTIES

A red brown clayey sand of low plasticity, soil properties and grading as follows:

2.36

1 00

100

425

8 1

82


075

1 9

1 5

PI

3

nil

Source Rock. Pindan Sand is a name commonly used to describe a characteristically red brown clayey sand occuring extensively throughout the Murchison, Pilbara and Kimberley of WA.

Map number 5

USAGE

Used on this lightly trafficked road as a base beneath bituminous seal. Forms the surface of many low traffic unsealed roads throughout north-western WA.

PERFORMANCE

Performance beneath seal is satisfactory in prevailing environment. In a dlY state the material is able to accept very heavy wheel loads but it rapidly deteriorates on wetting. During the monsoonal wet season serious shoulder scour is developed. Shoulders should be sealed, stabilised or protected with gravel sheeting.

Under modified compaction the OMC for this material varies between a high of 7 -8% at approx average MDD of 2,000 kg/m3.

Construction and compaction to 95% MDD at MC of 75-90% OMC. Dry back over several days prior to priming. An EMC of 35-45% OMC has been observed.

Compaction by two passes of smooth steel drum roller, followed by seven passes of a 30 tonne multi wheel self propelled rubber tyred roller. Finish off with one pass of smooth steel drum roller.

Pavement materials in road bui ld ing - Guidelines for making better use of local materials 1 3 5

Map number 6

SITE

Location. Great Northern Highway near Fitzroy Crossing. Lat 180 1 1' south, Long 125036' east.

Climate. Add. Rainfall 250nun/yr.

Water table >6 metres below surface.

Moisture Index 1m = -50 (fiom map).

Topography. Fitzroy River basin.

PROPERTIES

Locally known as limestone gravel or popcorn gravel. White to pale brown, fine to coarse grained sity gravel. Suggested grading for use in pavement:

1 9 9.5 4 .75 2. 36 .425 075

100 72 54 4 1 34 23 81 63 55 43 29

LL=23 -24%

Product PI x P425 = 374 - 5 16.

Product LS x P425 = 185 - 258.

Dust ratio = 0.62 - 0.68.

Calcium carbonate (CaC03) = 37-38%.

PI 1 1

13

LS 5

7

Source Rock. Scattered calcrete deposits typically 1-

2m thick beneath thin soil cover underlain by more clayey material. Mainly pedogenic (chemically altered soil) in origin, found in association with parent calcareous sedimentary rocks of Permian age.

USAGE

Good quality material used as base course on low to medium traffic roads in arid regions. To maintain correct plasticity, sh'ict depth control in the pit is required.

PERFORMANCE

Pelforms well due to the aridity of the area. Better quality, economically alternative material is lacking. The moisture content in the pavement must remain well below OMC. Fluffing of the base course and blistering of the seal can cause problems.

The material is cured typically 24 hours prior to compaction with finished base course dried back to 80%

OMC. Bore water used for pre-wetting and compaction.

Material tends to self-stabilise with time ( 1-2 years) producing gains in base course strength.

Special priming and sealing techniques are required.

1 36 Pavement materials in road building - Guidel ines for making better use of local materia ls

r

. 'Y1----- � . -�

SITE

Location. Hamelin to Denham Road south of Shark Bay. Lat 260 24' south, Long 1 1 4000' east.

Climate. Arid warm. RainfaIl 2 1 Omm/yr. Evaporation 2,700mmlyt:


Moisture Index 1m = -50 (f1-om map).

Topography. Coastal plain.

PROPERTIES

Clayey sand. Grading in roadbed ranges between the following:

19 9.5 4.75 2.36 425 075 PI LS

100 100 82 15 NP 0.5

Map number 20

Source Rock A red deselt clayey sand of aeolian origin. Although fine grained the material is not high in quartz and may be lateritic in origin. Located on deep surficial Quaternary limestone and sandstone deposits derived from the Cretaceous period. Generally greater than 5 metres thick.

USAGE

Traffic AADT of < 1 50 per day with 4% commercial vehicles.

Material used as a base course (locally called a "sand clay" although clay is not always present) . It appears to show a gain in strength over time, i.e. self-stabilising propelties.

PERFORMANCE

Good; seal intact except for some edge fretting. The unsealed shoulder has worn as expected. Conditions are very dry generally. Equilibrium Moisture Content is approximately 50% of modified OMC. Cores taken from the pavement showed "high strength".

Pavement materials in road bui lding - Guidelines for making better use of local materials 1 3 7

Western Australia

Map number 21

SITE

Location. Doolgunna Bypass north of Meek at han a on the Great Northern Highway. Lat 250 40' south, Long 1 190 11 ' east.

Climate. kid Watm. RainfaIl 209mm/yr.

Water table generally> 6 metres below natural surface.


Topography. Eastern slopes of the Robinson Ranges.

PROPERTIES

Grading in roadbed ranges between the following:

9.5 4.75 2.36 425 075 PI LS% 'if! 79 62 42 14 6 2 97 97 77 55 25 11 5

Product PI x P 425 = 252 - 624.

Source Rock. Surficial deep weathering produced laterites and clays over basement. Peak Hill nearby is of ancient Proterozoic sedimentary rocks which underwent metamorphic and volcanic change.

USAGE

TrafficAADT of 154 per day (1987) with 24% commercial vehicles.

PERFORMANCE

The material performed satisfactorily in the dry conditions. It is necessary to prevent water from ingressing the pavement base and sub-base during wet periods as softening and weakening of the pavement will result.

1 3 8 Pavement materials in road bui ld ing - Guidelines for making better use o f local materials

Western Australia

SITE

Location. Great Northern Highway between Mt Magnet (Lat 280 04' south, Long 1 1705 1' east) and Meekatharra (Lat 26035' south, Long 1 18030' east). Material is Coffee Rock.

Climate. Arid warm. Rainfa1l 200mm/yr.

Water table generally> 6 metres below natural surface.

Moisture Index 1m = -50 (fi:om map).

Topography. Low - undulating relief.

PROPERTIES

Coffee Rock is a silt/clay stone with pronounced cleavage. Grading in roadbed ranges between the following:

19 9.5 4.75 2.36 425 075 PI 98 94 89 85 52 18 18 87 59 40 32 16 5 NP

Product PI x P425 = 0 - 468.

is 9

The material is suitable as a base course in the local environmental circumstances.

Map number 21

Source Rock Ancient weathering product. Significant deposits of this material occur throughout the old weathered peneplain of inland WA.

USAGE

Performs satisfactorily as a thin sheeting on unsealed roads and as a sub base or base course under low -medium h·affic sealed roads.

PERFORMANCE

The Coffee Rock was extracted from pits by dozer and self elevating scraper. Material is spread by graders. Size reduction (if required) can be achieved by grid rolling.

Under modified compaction the OMC for this material varies between a high of 23% at an MDD 0[ 2048 kg/m3

and 9% at a MDD of 17 12 kg/m3.

Compaction by smooth steel drum and multi wheel self propelled rubber tyred rollers between 15-35 tonnes.


Map number 29

SITE

Location. Gingin Bypass approximately 7010n n0l1h of Perth on the Brand Highway. Lat 3 1 ° 2 1 ' south, Long 1 15° 55' east.

Climate. Subhumid warm. Rainfall 685mmlyr.



Topography. Slightly undulating sand coastal plain.

PROPERTIES

Lateritic gravel. Material from Moollabeenee Pit, Grading in roadbed ranges between the following:

9. 5 4. 75 2.36 425 68 53 46 2 1 82 70 62 29


Dust ratio 0.29 to 0.45.

075 6 13

PI LS% o 0. 6 10 4

Source Rock. Located on deep surficial limestone and sandstone deposits of Jurassic and Cretaceous periods.

USAGE

Traffic AADT of 1 ,700 per day ( 1987) with 13% conunercial vehicles.

Laterite gravels, pavement thickness 100 to 250nun .

PERFORMANCE

Satisfactory performance provided moisture is not allowed to penetrate the base. Excessive moisture at construction can lead to premature failure by rutting.


SITE

Location. MelTedin to Narembeen Road 33km from Merredin.

Lat 31 037' south, Long 1 1 80 32' east. Laterite gravel on clay subgrade.

Climate. Semi-arid. Rainfall 350nmvyr.

Water table generally> 6 metres below natural surface. Area not flood prone.

Moisture Index 1m = -25 (fi"ommap).

Topography. Flat to undulating countty.

PROPERTIES

Laterite Gravel; grading in roadbed:

19 9.5 4.75 2.36 S 96 L 99 92 67 49

S = Subgrade (LS = 10),

L= Laterite (LS =4).

Product PI x Pm = 256.

425 78 32

075 45 14

lL PL 36 15 23 15

Map number 29

Source Rock. Surficial deep weathering produced laterites and clays over acid intrusive rock (granite or diorite) basement of Proterozoic origin.

USAGE

Sealed road 6m wide with laterite gravel pavement, comprising 75mm to 150mm thickness.

Some sections have been boxed with clay shoulders others have full width pavement. Traffic AADT = 50.

PERFORMANCE

At Merredin the section with clayey soil shoulders has performed as well as comparable sections with gravel shoulders. Compaction was carried out air dry in 120nU11 Iayers. Rolling comprised 12 passes of 5 tOlU1e vibrating sheepsfoot, 4.5 tonne vibrating smooth drum and 3.5 tonne pneumatic tyred rollers. OMC subgrade = 15%, Standard DD = 1,824 kg/m3. OMC laterite = 6%, MDD = 2,384 kg/m3.

After compaction the MC of Clay soil subgrade was 35-60% Standard OMC. 83-97% Standard MDD. The Equilibrium Moisture Content appears to be about 70% for sub grade (higher than as built) and 80% for pavement (decrease after construction). A section of old road with 1 OOnun thickness of gravel behaved similarly to the test sites.

Pavement materia ls in road building - Guidel ines for making better use of local materia ls 1 4 1

stern

Map number 29

SITE

Location. WA Indian Ocean coastal belt ranging from Geraldton to Augusta. Lat 280 46' south, Long 1 14037' east to Lat 3401 9' south, Long 1 15009' east.

Climate. Mediterranean. Rainfall about 1200mm/yr.

Water table <6 metres below surface.


Topography. Flat to undulating coastal plains.

PROPERTIES

Pale yellow to brown, fine to coarse grained subrounded sand shelly calcarenite. Tamala limestone. Suggested grading for use in pavement sub-base:

75 1 00

19 60 80

4.75 2 . .36 425 20 40

Calcium carbonate (CaC03) = >60%.

Los Angeles Abrasion = 20-60%.

075 PI NP NP

Source Rock Deposits of these cemented coastal dune sands are 15 m thick comprising sand surface underlain by massive calcarenite beneath which lies a thick calcified sand horizon. Pleistocene in age.

CI�lll'f'lI;>O�

\---_._------------ \

USAGE

Tamala limestone provides an excellent sub-base for low and medium trafficked roads. Used extensively as a sub-base along the coastal belt from Perth toAugusta. Perth sand provides a good sub grade. Stabilisation with bitumen has been used to produce base course quality material for traffic> I 06 ESAs.

PERFORMANCE

Highly porous material of high strength, capable of recementing with time.The moisture infiltration must be prevented to reduce permeability inversion between pavement layers.

The material is readily available. It is ripped by dozer and then crushed beneath the dozer tracks to produce a suitable grading. It is easily worked during construction and requires no curing. Watering takes place during compaction.

Material tends to self-stabilise with time, producing gains in base course strength.

Special priming and sealing teclmiques are required.

1 42 Pavement materials in road building - Guidel ines for making better use of local materia ls

Wester

SITE

Location. South Coast Highway near Ravensthorpe, west of Esperance. Lat 33 055' south, Long 120002' east.

Climate. Subhumid warm. Rainfall 4 19mm/yr. Evaporation 2, 100nmllyr.

Water table unknown but probably> 6m below surface.

Moisture Index 1m = -20 (fi-om map).


PROPERTIES

Lateritic type material from Carlingup Road Pit. Grading in roadbed ranges between the following:

19 9.5 4.75 2.36 425 075 PI 1.S 96 79 48 29 22 11 NP <I 98 80 50 34 24 13 3 1.2

Product PI x PP425 = 64.

Dust ratio = 0.50.

Map number 30

Source Rock. Duricrust material has low aluminium and iron oxide contents but has the physical appearance of laterite. Located on Archaean granitic rocks and near the boundary of metamorphic sedimentary rocks.

USAGE

Traffic AADT of <ISO per day with 4% commercial vehicles.

Material used as a base course (occasionally called a "sand clay" locally although clay is not always present). It appears to show a gain in strength over time, i.e. selfstabilising properties.

PERFORMANCE

This pavement material has performed satisfactorily under local traffic and moisture conditions.

Pavement materials in road building - Guidelines for making better use of local materia ls 1 43

144 Pavement materials in road building - Guidel ines for making better use of loca l materials

Al.I Introduction A1.1.2 Terminology

A1.1.l General

This appendix presents a brief inh'oduction to pavement

design for lightly trafficked roads. For more detailed

pavement design information the reader is advised to

consult Austroads' Guide to the Structural Design 0/

Road Pavements (Austroads 1992), and in particular

for local roads the recently released Guide to the Design

a/ New Pavements/or Light TrafJic, APRG Report No.

21 (APRG 1998). Other useful reference are the

Unsealed Roads Mallual (ARRB 1993) and Sealed

Local Roads Manual (ARRB 1995) .

The layers of materials which make up a road pavement

stlUcture are shown in Figure A. l .

Property boundary Abutting property

In full width constlUction, shoulder and base material

are the same. There are variations with full width

constlUction and "boxed" cross sections. In arid and

semi-arid areas where pavement materials are

impermeable and subgrade strength is high at

equilibrium conditions (EMC), there may be a single

pavement base layer of 150 mm (or two layers of the

same material) and no sub-base layer.

Kerb

��l ��r_-;;;==�=::::=:::P=o:=�=�

n=iC t=��::a�=� =�� :::�

d=ic=

bY=J

F:==:ti=_\�N�;rt] .... ;

e

�/;"

o

�

otpath r.

/" ;p'� � � ��

Property boundary Abutting property

#'� Natural surface or batter

Verge Shoulder Shoulder 1------HRoadway or Carriagewav-+----- I

I .. , ---- Pavement ---j--

surface or batter

'--Roadside-�I-' --------- Formation ---t--------I .. Roadside->-1+--------------- Road Reserve -----l-----------I

Surface Courses Road surface ----''-'==-''==-7::::;::====�==== Wearing course Pavement Intermediate course structure Base Trimmed or prepared surface

In situ natural material or selected compacted fill Figure A 1. 1 Commonly used road terms

(Source: Dickinson 1984)

Sub-base i Subgrade

Pavement materials in road bui lding - Guidel ines for making better use of local materials 14 5

On an unsealed road it is common for the base course

to be constructed full width (no separately boxed

shoulders) and the wearing surface is effective across

the whole pavement width.

Al.l.3 Light traffic

As the use of local materials for pavements is mainly

applied to low volume roads in rural areas, this appendix

provides general information applicable to the design

of flexible pavements with design traffic in the range of

103 to 5 X 105 Equivalent Standard Axles (ESAs).

Al.I.4 Pavement strength

The California Bearing Ratio (CBR) test as described in

Chapter 3, does not measure any fundamental property

of the soil but gives an indirect measure of soil strength

and has proven useful in empirical design. The design

method is empirical because it is based on observations

of past performance to assess acceptable pavement

layer thicknesses given the CBR value of the pavement

subgrade and base materials at projected h'affic loadings.

As the traffic loading increases, the required minimum

total thickness increases. Higher quality materials are

required near the pavement slllface, with material having

a CBR value of 80% or better being required for at least

the top 100 nun of the pavement on busy roads. Beneath

this base layer, the lower strength requirements for sub

base layers permit the use of materials which, for various

reasons, would not be suitable for use in the base. In

general, a much wider choice of test propeliy limits can

be permitted, provided the material, when compacted,

has the required strength over the range of likely "in

service" moisture contents. Typically, material with a

CBR value in excess of 30% is used in the upper sub

base, and material with a CBR value in excess of 15% is

used where a lower sub-base is walTanted.

A1.2 Pavement design thickness

AI.2.I Pavement function

The function of the pavement structure is to support a

surface which has an acceptable riding quality. The

design process aims to provide a pavement which will

maintain its structural integrity, in order to provide a

good quality riding surface, over its design life. A

cOlTectly designed pavement should be able to serve

out its design life, with only a small chance of structural

failure occurring, without requiring any form of

rehabilitation.

For a given traffic of known volume and load, a

pavement's ability to perform is dependent on three

main factors:

• pavement materials performance (CBR at in-situ

condition);

• the presence of excess moisture which adversely

affects most materials - maintaining design

Equilibrium Moisture Content (EMC); and

• subgrade support stiffness (design CBR at EMC).

At the design stage the issue of material performance is

met by the selection of appropriate quality materials

for the varying roles that they play in the pavement

structure. It is of considerable importance that during

construction the assumptions made about material

quality during the design process are satisfied. The

materials lIIust be stl'Ol1g enough to transfer the load to

subgrade and stiff enough to do so without serious

rutting of the top layel:

Most pavements contain measures to control the ingress

of water into the pavement structure. The provision of

a surface seal, sealed shoulders, side drains, and if

necessary, sub-surface drainage (or moisture balTiers)

will reduce the influence of water on pavement

pelformance.

The remaining factor, subgrade support, is in many

respects beyond the control of either the designer or

constructor, and is therefore the primary factor

influencing the pavement thickness design. The

designer has to assign a CBR value to the subgrade.

This may be evaluated by field and/or laboratory testing

and/or experience.

In order to decide on minimum thickness of various

layers, the designer has to know:

• design CBR of subgrade at Equilibrium Moisture

Content;

• design traffic; and

• design CBR of pavement layers at Equilibrium

Moisture Content.


Figure A 1.2 illustrates the flexible pavement design

system for granular pavements with thin bituminous

surfacing.

Al.2.2 Granular pavements with thin bituminous surfacing

There are three design charts presented inAPRG Report

No. 2 1 (APRG 1998). They differ in the level of confidence

provided to the designer that the pavement will outlast

the design traffic - i.e. that the levels of surface rutting

and roughness will remain within acceptable limits for

the period that the pavement is subjected to the design

traffic. Detailed guidance in the selection of a design

chart for a specific design situation is provided inAPRG

Report No. 2 1. The chalis indicate, for a given level of

design h'affic (ESAs) and a given design subgrade CBR,

the following:

• the minimum thickness of cover required over the

subgrade; and

• for each granular material placed on the sub grade,

the minimum thickness of cover required over it

(determined from the CBR value of the material).

On major roads, for at least 100 mm of the uppelmost

pavement layer, material with a CBR greater than 80% is

required. The actual base thickness will depend on the

quality and strength (CBR value) of the sub-base(s)

used. Where only one material is used, thickness will

be decided from the design CBR value of the subgrade.

A lower CBR value for the top 100 mm (commonly 60%

but in some cases as low as 30%) is suitable for low

traffic roads in semi arid areas and where moisture

ingress can be controlled.

A1.2.3 Pavements for unsealed roads

Pavement design curves for unsealed roads are based

on a probability level of 80% (ie. 20% risk of

rehabilitation of the pavement being required before

the end of the design life). The thicknesses given by

these curves accord reasonably well with the fully

developed thicknesses employed in practice for

unsealed roads and their use is recommended for the

pavement thickness design of unsealed roads.

Because unsealed roads can be periodically reshaped,

and regravelled, these 80% probability curves would

Pavement design for light traffic

Assessment of Prediction of design subgrade design traffic

1 Optional

modification of design traffic for

level of performance

+

Determination of basic pavement

thickness

Consideration Selection of of available ----+ tentative pavement materials

r---.L...----, Assessment of

CSR of each pavement material

pavement structure

Cover for each

pavement material

• ad'qua,e? �

YES

Ensure minimum base thickness

satisfied

Adoption of pavement design

Modification of pavement

structure to increase cover

Figure A 1.2: Flexible pavement design system for granular pavements with thin

bituminous surfacing

(Source: Adapted from Austroads 1992).

Pavement materials in road building - Guidel ines for making better use of local materia ls 1 47

provide a reasonable estimate of the full thickness of

pavement for unsealed roads, taking into account h·affic

loads, sub grade soil strength and moisture conditions.

A1.2,4 Design eBR for subgrade

The purpose of sub grade evaluation is to estimate the

SUppOlt that the subgrade will provide to the pavement

during the life of the pavement. The support provided

will be heavily dependent on the material type, its

moisture content and degree of compaction.

For all pavement design procedures, the subgrade

sh·ength is characterised by its Design CBR. Appropriate

soil characterisation may be effected by Dynamic Cone

Penetrometer (DCP), undisturbed sampling for

laboratory CBR testing (unsoaked or 4-day soaked),

disturbed sampling for laboratory remoulded CBR

testing (unsoaked or 4-day soaked), field moisture

content, particle size distribution and Atterberg Limits.

For the low traffic situation in general, it is likely that

knowledge of the soil types in a specific region, coupled

with knowledge of their previous performance as

subgrades, may provide considerable assistance in

estimating a Design CBR for a specific project.

A1.2.5 Design charts

The following chart fromAPRG RepOlt No. 2 1 (Figure

AI.3) would be appropriate in most cases for

construction of unsealed and temporary rural roads

carrying light traffic where site conditions are well

understood.

For sealed roads carrying light to moderate traffic, it

may be more appropriate to use Figure A lA, which

gives a slightly thicker pavement.

A1.2.6 Estimating Design Traffic

The "Design Traffic" is an estimate of the cumulative

number of "Equivalent Standard Axles" (ESAs) expected

over the "Design Period" in the most heavily trafficked

lane.

In essence, the damage caused to a flexible pavement

by a single passage of a load on an axle-group is

expressed in terms of the number of passages of a

reference axle load - termed the "Standard Axle" -

required to produce the same damage. The Standard

Axle is a single axle with dual tyres transmitting a load

of 80 kN to the pavement. Other axle load types (dual

axle, tri-axle) are convelted to an equivalent measure of

standard axles known as Equivalent Standard Axles

(ESAs). Tables inAPRG Report No. 21 (APRG 1998)

provide representative values of average ESAs per

commercial vehicle for each road type. This information

is presented as a guide only and may require appropriate

modification in light of actual traffic information which

the designer may have available.

The larger contribution to pavement distress is made

by environmental influences in the low traffic situations.

A1.2.7 Selection of material type

Guidance on appropriate properties of natural materials

when used in road pavements is provided in these

Guidelines and also in the NAASRA publication

Pavement Materials Part 2, Natural Gravel, Sand

Clay, and Soft Fissile Rock (NAASRA 1980).

Several material types may be suitable for the particular

case, and the designer will have to make the final

selection after consideration of availability of materials,

local construction and maintenance practice, equipment,

environmental conditions (rainfall, temperature, depth

to groundwater table) and available funding, together

with a risk assessment of each pavement and surfacing

option for the conditions expected during the

pavement's conshuction and service life. Selection may

often involve compromise between conflicting

requirements.

Reference should be made to Austroads' Pavement

Design Guide (Austroads 1992) and APRG Report

No. 2 1 (APRG 1998) to provide further guidance.

Bituminous surfacings are discussed in NAASRA's

Guide to the Selection oj Bituminous SUI/acings Jor

Sprayed Work (NAASRA 1989), which is in the course

of revision.

A1.2.8 Pavement design example

Following is a simple pavement thickness design

example for a granular pavement with a spray seaL

148 Pavement materials in road bui ld ing - Guidelines for making better use of local materials

Pavement design for light traffic

Thickness of cover (mm)

Thickness

o .. ·1 MINIMUM BASE THICKNE

'SS

100

200

300

400

500

. .. :

-

r 'Subgrade with CBR<3 r should be designed as per r subgrades with CBR=3 � but with the initial subgrade I- layer stabilised to a depth I- of 100 - 150 mm

2 3 4 5 6789 4 10

---

. -

I -

-

C�R3b '--CBR20 =� 19��1� CBR9

CBR7 CBR5 - -CBR4_ I--

-CBR3' - r-

2 3 4 5 6789 5 10 2

Traffic: ESAs

Figure A1.3

Design chart for granular pavements with thin bituminious surfacing (80% confidence)

(Source: from APRG No. 2 1, APRG 1998).

o MINIMUM BASE

'TH

'ICKN

'ESS

100 CBR30 CBR20 CBR15-CBR12

200 CBR9 r--f- I- CBR7 1--1- -- -r-- - -r--

of cover 300 I-- - CBR5 r-I- -

(mm)

400

500 i--- 'Subgrade with CBR<3 := should be designed as per f- subgrades with CBR=3 I- but with the initial subgrade f- layer stabilised to a depth I- of 100 - 150 mm

2 3 4 5 6789 4 10

---:- CBR4 _ -

2

CBR3'

3 4 5 6789 105

Traffic: ESAs

Figure A1.4

--

2

-I--

r-

3 4 5 x 105

Design chart for granular pavements with thin bituminous surfacing (90% confidence)

(Source: from APRG No. 2 1, APRG 1998)

Pavement materials in road building - Guidel ines for making better use of local materials 1 4 9

Design parameters

Use design chart with

Design traffic

90% confidence limit

2 x 105 ESAs

Design subgrade CBR 4%

Available materials: crushed rock CBR 80%

quarry rubble CBR 40%

pit rubble CBRIO%

Design process

Figure AlA shows that for traffic life of 2 x 105 ESAs the

total thickness of pavement required over a design

subgrade of CBR 4% is 350 mm.

The maximum thickness of the lowest quality material,

the pit rubble, may be found by considering it as a

subgrade with a CBR of 10%. From the chart

(FigureAIA), for traffic of 2 x 105 ESAs and CBR 10%,

the overlying thickness of material required is 200 nun.

Therefore the maximum thickness of the pit rubble (sub

base) layer is 350 - 200 = 150 nm1.

The top 200 mm remains to be designed and may be

found by considering it as a subgrade with a CBR of

40%. From the chart (Figure A lA), for traffic of 2 x

105 ESAs and CBR 40%, the overlying thickness of

material required is 100 mm. Therefore the maximum

thickness of the quarry rubble (base) layer is 200 - 100

= 100 mm

The crushed rock (CBR 80%) is suitable for the

remaining 100 mm of pavement.

The final pavement configuration is therefore:

Base course: 100 nun crushed rock CBR 80%

Upper sub-base: 100 nun quarry rubble CBR 40%

Lower sub-base: ISO mm pit rubble CBR 10%

Total pavement thickness

= ( 100 + 100 + 150) = 350 11U11.

1 50 Pavement materials in road bui ld ing - Guidelines for making better use of local materials

A2. 1 Introduction

This appendix serves to remind the practitioner that in

order to gain the maximum benefit from the available

local road pavement materials and pavement design,

sound construction techniques must be employed in

the construction of a new pavement and associated

works.

In carrying out construction, all operations must be in

accordance with the applicable safety laws and

regulations. All personnel must be given appropriate

training so as to be aware of their responsibilities. Road

users and adjoining land holders must be able to pass

safely through or around the road works, including any

side tracks.

More comprehensive advice on the construction of new

pavements can be found in various publications,

including the Sealed Local Roads Manual (ARRB

1995) and the Unsealed Roads Manual (ARRB 1993),

which detail the construction sequence to be followed

and the various techniques and procedures to be used

in maximising pavement strength and ride ability over

time. For example, as a general rule, a deficiency in

either density or thickness can lead to a significant

decrease in performance of a pavement.

The sequence of construction is generally as follows:

Preparation

• service relocations where appropriate, particularly

in urban areas

• clearing and site preparation

• establishing borrow pits

Drainage provisions

• surface drainage

• culvert construction

• subsoil drainage

Earthwori{s

• setting out

• construction of and compaction of earthworks

Pavement construction

• subgrade preparation

• pavement construction (sub-base and base)

• pavement surfacing

Site clean up.

Some aspects with particular relevance to non-standard

materials and lightly trafficked roads are discussed

below.

A2.2 Treatment of local pavement

materials

A2.2.1 General

As has been discussed earlier in these Guidelines in

Chapter 2; "standard granular material will be tolerant

of mishandling and will perform well in most

circumstances" (Metcalf 197 8). While wet-mixed fine

crushed rock delivered to an urban road can be placed

and the required density achieved in a matter of hours,

this is obviously not so for most roads in the more

remote, semi arid and arid areas. When dealing with

marginal or non-standard materials there are three key

factors to consider: materials, drainage and quality of

construction.

Pavement materials in road bui ld ing - G uidel ines for making better use of local materials 1 5 1

Unlike "standard granular materials" used on major

roads, the local pavement materials tend to be much

more difficult to handle and are less tolerant of

mishandling. They require the careful selection of

watering and compaction plant in order to produce the

optimum result for that material. Often the fmther away

from "standard" properties that a local material displays,

the greater the care that is required to shape, compact

and prepare a tight, dense and smooth surface in

preparation for a seal. It has been argued that

specifications should be tailored to each particular

combination of site and material (if specified or known)

so that a contractor would be forewarned of any

additional effort required.

A2.2.2 Winning materials

An operating plan will be needed. This plan should

detail the extent of the extraction work, both in area and

volume, and identify at which time and for how long,

sub-sections of the pit area are to be progressively

worked over the expected life of the pit. Details of

progressive rehabilitationlrevegetation should also be

provided in the plan.

Most natural materials are variable, and so mixing and

blending to obtain a homogeneous mixture will usually

be required. In the pit it is important to doze downwards

through the entire depth of the face, and then move

material parallel to the face to ensure thorough mixing.

If placed unsorted on the road formation, mixing by

windrowing and backblading with a grader will be

required.

A2.2.3 Drainage

When considering any form of road construction, a most

important factor is controlling the ingress of moisture

into the pavement. Drainage is effected by constructing

the pavement to an acceptable camber, at least 2% on

sealed and from 4% to 6% on unsealed roads, with side

drainage and culverts placed to conduct the water away

as quickly as possible. Local pavement materials are

generally much more susceptible to moisture effects

than "standard" materials as they are often less durable;

e.g. shales may decompose quite rapidly under alternate

wetting and drying cycles.

Drainage is fmther assisted by good "housekeeping" in

the following:

• shoulder maintenance - maintain crossfall and

prevent a buildup of "whip-off' chips or grass which

ponds water near the edge of seal;

• pavement maintenance - regulate depressions, ruts

and areas where water ponds on the seal and to

prevent water lying in unattended potholes for

lengthy periods. This is important if the top layer of

the pavement under the seal is relatively fine grained

(such as a granitic sand); and

• side drains and culvelts - keep clean and maintain

periodically.

A2.2.4 Compaction

Careful control of moisture during placement and

compaction coupled with local knowledge of the material

properties will also ensure the best possible compactive

effott is imposed. There are no universal specifications

or methods. This will be locality/material specific, based

on knowledge gained from experience with similar

materials. Often placing materials dlY of optimum is the

best approach so that equilibrium conditions are reached

quickly. However, dry placement of subgrade and

pavement requires heavy rollers in order to achieve an

acceptable density. With earthworks, it is usual to do

the work at a time when the in-situ material in the pit is

close to the desired EMC for the road formation.

DIY compaction is sometimes necessary when building

roads in remote arid or semi mid areas. All materials can

be placed dry but compact with differing results. The

better graded materials and clayey materials give a better

result. Mudstone appears to break down to an optimum

grading for mechanical interlock. Bulldust prone

sections can be treated by overlaying with clay.

Generally, the higher clay content materials give the

best results when compacted dry. In all cases of dry

compaction, traffic should be kept off or to an absolute

minimum to avoid surface damage and abrasion, until

moisture (or rain) is available.

Dry compaction of pavement materials, however, may

not always be appropriate or give the best result. Poorly


graded materials require more compactive effort than a

"standard" well-graded material to produce a strong

dense pavement. If silts are a significant component of

the fines, then compaction will be difficult. If the larger

size gravel components are weak, then they will crush

and break down under heavy compaction. Hence the

combination of rollers and amount of water added is

critical to each site. When water is used, care must be

taken to not wet up sub-base or sub grade layers, so

that shrinkage after sealing is avoided. In many

instances a diy-back period after preparation for sealing

is customary for particular materials.

The source of water used must also be assessed. In arid

areas particularly, bore water used may be highly saline

and this can cause swelling by crystallisation and

deformation of the pavement material. The presence of

salts in the pavement may also reduce adhesion of the

surface causing bituminous seals to blister, detach and

strip off. Further comments from practitioners on

construction techniques are included in the fifty

Material Data Sheets for individual sites in Chapter 7 .

When working on moisture sensitive subgrades and

using local pavement materials, success depends on

carrying out bitumen surfacing when the base layer is

near Equilibrium Moisture Content (EMC) and then

waterproofing to preserve condition. This

waterproofing could include sealing shoulders, using

rubberised binders or geotextile reinforced seal. If there

is a location along the job where the Ground Water

Table (GWT) is near the subgrade level, such as near a

creek crossing, then different materials which are less

sensitive to higher levels of moisture may have to be

used at that location.

In tropical climates where rainfall is seasonal and where

roads are located on heavy clay soils, a plastic membrane

has been placed across the entire road structure

(including batter slopes) at subgrade level, to combat

seasonal swelling and shrinking, with some success

(Hornsby 1 994).

A2.2.5 Preparation for sealing

Local pavement matelials won from a pit may often have

large lumps which must be broken down by rolling on

the road bed or graded to one side before preparation.


Even so there may remain oversize gravel cobbles of

40 mm size or more, in the base material mah"ix. During

final grading in preparation for sealing these can catch

under the grader blade and tear the prepared surface. It

may be necessary with some materials to carry out a

light "cut to waste" in the final stage of preparation. As

a final preparation check, the Clegg Hammer could be

usefully employed. This device is described elsewhere

in Chapter 3.

Layer thickness is very important when 'topping off'

with a light skilming of fine grained material (granitic

sand, sand clay etc.) to armour a less resistant base. If

a large windrow is spread on the surface to make a thin

layer, a "compaction plane" can form causing de

bonding with the layer below. Flaking of plate size pieces

of the bituminous seal might then occur shortly after

sealing.

A2.3 Environmental effects

For roads subject to low traffic volumes, relatively more

pavement distress is attributable to environmental

effects than is the case for higher volume situations.

The main environmental factors affecting pavement

performance are moisture and tempera hire.

Moisture

The moisture regime associated with a pavement has a

major influence on its performance. The stiffness,

strength and susceptibility to permanent deformation

of unbound materials and subgrades is heavil y

dependent on the moisture content of the materials.

Factors influencing the moisture regime within a

pavement include:

• climate and evaporation pattern of the locality;

• permeability of the wearing surface, shoulders and

adjacent surfaces and drains;

• depth to the water table;

• movement of ground water;

• relative permeabilities of the subgrade and pavement

layers; and

• pavement type (boxed or full width).

Pavement materials in road bui ld ing - Guidelines for making better use of local materia ls 1 53

These effects are often more significant in lower traffic

volume situations where wheel loadings often occur

close to the seal edge (or kerb) - the critical area of the

pavement in respect of moisture effects.

Non-standard local pavement materials are commonly

less stiff (have lower CBR or Resilient Moduli) than

standard granular materials. In addition, both stiffness

and strength are usually more sensitive to moisture

content.

Pavement constructed on expansive subgrades may

experience ongoing movement, with seasonal moisture

changes causing loss of shape and reduction in the

ride quality. In some cases this may become sufficiently

severe to require reconstruction or reshaping in a

relatively short period. These effects may be reduced

by one or more of the following:

• moisture barriers to reduce the movement of moisture

under the pavement;

• undertaking construction when subgrade moisture

content is close to EMC, the long term in-service

value;

• restricting the planting of trees and shrubs, and

watering of plantations close to the pavement;

• stabilising the subgrade with lime to reduce its

expansivity; and

• sealing the shoulders to reduce the movement of

moisture into the pavement.

Temperature

For lightly trafficked pavements the oxidation of

bitumen can cause rapid deterioration of the seal.

Bitumen oxidises on exposure to air, becoming brittle.

This process is accelerated by high temperatures and

ultra-violet radiation (from sunlight). Brittleness leads

to cracking of smface seals and ravelling of both surface

seals and asphaltic surfaces. Trafficking has a beneficial

effect by closing micro-cracks in bitumen films and

surface voids in asphalt, hence constraining oxygen

flow. In low traffic volume situations, this beneficial

effect is reduced, leading to earlier onset of the above

mentioned distresses. To counter this, the use of an

appropriate bitumen grade and aggregate spread rates,

or asphalt mixes which have lower voids and higher

bitumen contents at construction are reconunended.

Guidance may be found in NAASRA ( 1984 ano 1 989)

and Oliver ( 1 995). L

A2,4 Selection of plant

The various types of plant used in road construction

include scrapers, dozers, loaders, excavators, graders,

rollers, trucks and compactors, and where processing

is required, screening and crushing plant.

Scraper

Larger scrapers, Cat 623 equivalent and upwards will

win most materials on a horizontal surface except for

the hardest mudrocks and cart economically up to 2km.

The scraper is also a capable rubber tyred roller and

with one grader can make up the most cost efficient

road construction plant.

Dozer

Capable of ripping, pushing, stockpiling and mixing all

materials along a horizontal smface. Cat D6 or equivalent

and upwards is the best size for the harder materials.

When ripping a single tyne parallel shank ripper

assembly is best. With softer materials use of a dozer

may be "overkill". Dozers must be "floated" to move

from location to location, and this will incur lost time

and extra costs.

Loader

The rubber tyred fi'Ont-end loader can win most matelials

except for the hard mudrocks where it becomes inefficient

and suffers heavy wear and tear. Tyres particularly can

suffer excessive wear on harder materials. The size and

capacity of front-end loaders should be matched to the

trucks they are working with (e.g. consider truck side

heights). They will normally have trouble wilming and

loading at the same time.

Excavator

Excavators are becoming more popular. The bacldlOe

excavator can win most materials except for the hard

rocks. An excavator can operate on the cut face or

veltical surfaces fi'om above or below. It is not generally

suited to mixing materials. It is best when winning and

loading at the same time, excavators and trucks can

produce better than scrapers in some operations.


Grader

Specialised plant excellent as a mixer/spreader, h'immer,

shaper and drain cutter. Efficient in soft materials to

depths of 0.5 m.

The scraper/grader combination can be an extremely

efficient road building unit without any other plant.

Ensure that scrapers do not travel the road network on

their own tyres; for example, a scraper could heavily

overload a rural pavement causing significant damage

and may cause the collapse of drainage structures.

Rollers and other compaction plant

Compaction equipment must be suited to the pavement

material and the moisture condition. The grid roller, the

smooth drum vibrator and the rubber tyred roller are the

units most commonly used. Small plate compactors

and hand held air ranuners can also be useful in restricted

areas such as backfilling over culverts.

Trucks

The carting operation, except for very short hauls (less

than 2 km) will employ trucks of various type and size.

Rear tipping body trucks with dogs and semi tippers

are often used. In some areas with longer haul distances

semi tippers and road trains may be used. The rigid

body tipper truck may, however, be used more easily on

other works, such as aggregate spreading and

maintenance.

. . ;. --' "; - , -

G rader/loader

Dozer

Selection of appropriate plant for the job is vital

-' Yf \;-' . . I . -i;



1 5 5

1 56 Pavement materials in road bui lding - Guidelines for making better use of local materials

Appendix 3

A3.1 The Thornthwaite Moisture Index

In extremely wet regions, water drains through the soil

almost continuously and there is little change in overall

moisture content with season. Moisture contents under

the pavement are similar to those in the exposed soil.

The dry category corresponds to arid or semi-arid

conditions and seasonal moisture changes are small. In

general, the moisture content of the soil is governed by

the average humidity of the atmosphere. Where the

climate is intermediate between wet and dry seasonal

changes of moisture content in the exposed soil in the

shoulders will affect conditions under the pavement

edges causing swelling and shrinkage. This is a

relatively common problem around Australia including

in the more populated areas, for example in patis of

metropolitan Adelaide and Melbourne.

The Thornthwaite climate classification system for

describing climates, devised in 1 9 3 1 by C. W.

Thornthwaite, divides climate into groups according to

vegetation characteristics. Vegetation type is determined

by precipitation effectiveness (PIE, where P is the total

monthly precipitation and E is the total monthly

evaporation). The sum of the monthly PIE values gives

the PIE index which is used to defme humidity provinces.

In 194 8 the system was modified to incorporate a

moisture index (Thornthwaite Moisture Index) which

relates the water demand by plants to the available

precipitation, by means of an index of potential

evapotranspiration, calculated from measurements of

air temperature and day length. In arid regions the

moisture index ( 1m) can be negative because

precipitation is less than potential evapotranspiration.

(Concise Oxford Dictionary of Eatih Sciences, 1991).

The overall availability of moisture during the year can

thus be assessed using the Thornthwaite Moisture

Index, which can be determined directly by substitution

of known climatic data into the equation below or from

the graphical plot of the data as shown in Figure A3 . 1.

The Moisture Index (I) is determined by substitution of

the relevant data into the following equation:

where:

D = drainage;

1 = 100 D - 60 d

Ep

d = moisture deficit; and

Ep = potential evapotranspiration.

D, d and Ep are determined from climatic data, i.e.

basically fi'om records of hours of sunshine and rainfall.

A3.2 Soil suction and subgrade strength

The prediction of the Equilibrium Moisture Content is

of concern mainly in areas where rainfall greater than

650 mm per annum occurs or where the soil suction (PF)

is less than about 3. In drier areas, the pF is generally

greater than three and a high sub grade strength value

usually occurs. The main concern in drier areas would

appear to be the moisture changes in soils with high

sluink-swell properties.

Pavement materials in road bui ld ing - Guidelines for making better use of local materials 1 57

/ \

, \

\ )

, - ) \

\ \

\

I \ ) ' - -50 _ / \

/ - ) \

a 0 +100M \9+20

Figure A3. 1: Climate map of Australia based on the Thornthwaite Moisture Index

(Source: Richards et al. 1983)

A common measure of suction is the pF scale in which

pF is defined as:

pF = 10g)O h

where h is the magnihlde of suction in cm of water, a

positive value.

When the moishlre content of the soil is governed by

climate, the precipitation and evapotranspiration (based

on rainfall and hours of sunshine) are the dominant

factors. The equilibrium soil moishlre conditions under

the central region of the pavement can be predicted

from the Thornthwaite Index versus Suction graph

shown in FigureA3.2.

The usefulness of the Thornthwaite Index is in its

relationship to soil suction and hence soil strength, or

more correctly stiffness. The information has enabled

zones of equilibrium suction to be established for

Australia. The dish'ibution of these soil suction contours

is shown in Figure A3.3. The contours represent the

Equilibrium Moisture Content achieved in a subgrade

beneath a sealed surface having good drainage

conditions.

Clearly, because of the soil suction effects, the strength

of fine grained subgrades in arid and semi arid areas

can be much greater than for similar materials in more

humid areas. The danger for road pavements in semi

arid and arid areas is that when occasional unseasonally

wet periods occur, the subgrade strengths not only

experience swelling but also a commensurate decrease

in strength and a much greater risk of pavement failure.

The expense incuned however, in assuming the weakest

soil condition and (over) designing and constructing a

thick pavement structure is not really cost effective in

arid and semi arid areas, when cyclical climatic conditions

bringing greater moisture may be 10 or more years apart.


The Thornthwaite Moisture Index

7

6

5 Moisture

soil suction - 4 pF units

3

2

_ heav� clay � I'-..

---r--... r--t--

sand --I-------l- I---pumice soils

o -60 -50 -40 -30 -20 - 1 0 o 1 0

Thornthwaite Moisture Index

-----r--

20 30 40 50 60

Figure A3.2: Relationship between equilibrium suction and Thornthwaite Moisture Index (Source: NAASRA 1972)

• Al ice Spri�gs I

I I , - - - - - - - - - - - - - - - - ,

Regions of pF 1-:-:,:,:-:-:,:-:1 2 to 3

� 3 to 4

c=J > 4

o

�Ob,rt

Figure A3.3: Map showing zones of uniform equilibrium suction (Source: NAASRA 1972)


References:

NAASRA (1972), Prediction of Soil Moisture Conditions

for Pavement Design. NAASRA Materials Engineering

Committee, ad hoc Subcommittee on moisture Conditions

in Sub grades ( 1972), Proceedings of the 7th ARRB

Conference, Adelaide 1974.

Oxford University Press ( 199 1), Concise Oxford

Dictionmy of Earth Sciences. Oxford University Press,

Oxford UK.

Richards, B.G., Peter, P. and Emerson, WW ( 1983), The

effects of vegetation on the swelling and shrinking of

soils inAustralia. Geotechnique, Vol 33, No 2, pp 127

- 139. Institution of Civil Engineers, London.


ERA PERIOD EPOCH

Recent

Quaternary Pleistocene

Pliocene

Cainozoic Miocene

Oligocene

Tertiary Eocene

Paleocene

Cretaceous

Jurrassic Mesozoic Triassic

Permian

Carboniferous

Devonian Palaeozoic Silurian

Ordovician

Cambrian

Proterozoic

Archaen Pre Cambrian

Age of the Earth?

Pavement materials in road bui ld ing - Guidelines for making better use of local materials

APPROXIMATE AGE YEARS

x 106

0. 1 ( 10,000)

3

12

25

37

56

65

130

180

230

270

350

400

450

500

600

2600

3600

5000

1 6 1

1 62 Pavement materials in road bui ld ing - Guidelines for making better use of local materia ls

MATERIALS DATA SHEET

LOCATION

LOCAL NAMES

DESCRIPTION

SOURCE ROCK and UNIFIED CLASSIFICATION

USAGE Subgrade

Sub-base

Base

Surfacing

Stabilisation

PERFORMANCE CHARACTERISTICS

S I EVE (mm) 37.5 26.5 1 9 SPEC =

PI x % PASSING .425 mm sieve =

PI x % PASSING .075 mm sieve =

STRENGTH

9.5 4.75 2.36 .425 .075 LL %

CBR % Soaked CBR % Unsoaked

ACV / LAA (%) TEXAS CLASS

CONSTRUCTION DETAILS

Please complete and return to ARRB Transport Research Limited

Pavement materials in road bui lding - Gu idelines for making better use of local materials

PI LS %

1 63

1 64 Pavement materials in road bui ld ing - Guidelines for making better use of local materials

Atterberg Limits

Base

Black Cotton Soil

Boulders

California Bearing Ratio (CBR)

Clay

Clay Fraction

Cobbles

Cohesive Soil

Cohesionless or Non-cohesive Soils

Colluvial

Compaction

Dry Density (DD)

Dry Density / Moisture Conh'ol relationship

Equilibrium Moisture Content (EMC)

Geotextile

Grading

Gravel

Collective name for Liquid Limit and Plastic Limit tests. Originally proposed by A. Atterberg for determining soil states.

That part of the construction resting upon and through which the load is transmitted to the sub-base, subgrade or suppOlting soil.

A brown or black clay soil in which volume changes, swelling or shrinkage are particularly marked.

Rock pieces more than 200 mm in size.

The value given to an ad-hoc penetration test where the value 100% applies to a standard sample of good quality crushed material. Over 50 years the CBR empirical method of pavement design has evolved. (See Chapter 3.)

The finest soil fraction. Comprising colloidally fine, complex silicates fOlmed by the natural decomposition of igneous rocks.

That fraction of a soil composed of pmticles smaller in size than 0.002 mm .

This is the fraction that generally impmts plasticity to a soil and in appropriate quantities helps bind the material together. Too much clay can lead to unacceptable swelling and shrinkage in response to moisture.

Rock pieces being the coarsest soil fraction, between 60 mm and 200 mm .

Soil containing sufficient clay or silt particles to impart significant plasticity and cohesion.

Soils such as sands and gravels, which consist of rounded or angular (non-flaky) palticles and which do not exhibit plasticity or cohesion.

Weathered material transported by gravity.

The process whereby the soil particles are constrained, by rolling or other means, to pack more closely together, thus increasing the dry density of the soil.

The mass of the dry material after drying to constant mass at 105 degrees Celsius, contained in unit volume of moist material.

The relationship between dry density and moisture content of a soil when a given amount of compaction is applied.

The moisture content at any point in a soil after moisture movements have stabilised in a constructed pavement.

A synthetic polymer fabric used as a filter or strengthening medium over soft soils. Also used on surface spray seals for enhancing strength and as a crack inhibitor. Usually supplied in rolls up to 5 metres wide and several metres in length. Various grades and classes are available.

See Pmticle Size Distribution.

Rock pieces of ilTegular shape and size occurring in natural deposits with or without fine material. May be rounded by the effects of water action.

Pavement materials in road bui ld ing - Guidelines for making better use of local materials 1 65

Gravel Fraction

Lateritic

Linear Shrinkage (LS)

Liquid Limit (LL)

Los Angeles Abrasion (LAA)

Mechanically Stabilised Soil

Modified (or heavy) Compaction

Moisture Content(MC)

Optimum Moisture Content (OMC)

Particle Size Dish'ibution (or Grading)

Pavement

Pavement, Flexible

Pavement, Rigid

Plastic Limit (PL)

Plasticity Index (PI)

Plasticity Modulus (PM)

Plasticity Product (PP)

That coarse fraction of a soil composed of particles between 2.0 mm and 60 mm.

Soils and rocks containing iron oxides as a major constituent in concentrated form, remaining behind when more soluble products have been leached away.

The percentage decrease in volume of the fine fraction of a soil when it is dried after having been moulded in a wet condition, approximately at the LL. 1t gives some indication of the volume change that is likely to occur in a soil when moisture content changes.

The moisture content, expressed as a percentage, at which the wet soil fines pass from a plastic to a liquid condition.

A test on coarse aggregates to measure strength/resistance to abrasion. Road base specifications will limit the value to a certain limit, e.g. <35%. Aggregate Cmshing Value (ACV) is a similar test.

A soil which has had its propetties modified by addition of another soil fraction to improve the grading and compactability.

Laboratory compaction of a soil sample using a heavy 4.5 kg hanuner to compact soil in a 150 nm1 diameter mould. NOtmally used for main road pavements with high traffic loads.

The loss in mass, expressed as a percentage of the dty material, when a soil is dried to constant mass at 105 degrees Celsius.

That moisture content at which a specified amount of compaction will produce the maximum dty density.

The spread of soil sizes (fractions) in a soil sample from gravel to sand to silt/clay as measured by passing the sample tlu'ough a nest of standard sieves. NOllnally displayed in a table or graphically as a grading curve.

Those layers of soil material above the subgrade, which when compacted act as a load bearing and erosion resistant surfacing for trafficking.

A pavement constructed of granular materials which when compacted together behave in a visco elastic manner and which flex under traffic. May be surfaced with gravel, a bituminous seal or asphaltic concrete.

A pavement constructed of cemented materials such that it acts as stiff slab. Such pavement types include heavily cement stabilised aggregate sub-bases or bases, lean mix concrete and concrete.

The moisture content at which the damp soil fines pass from a plastic to a solid condition, i.e. when the soil ceases to behave as a plastic material.

LL - PL, an indication of the clay content of soils; the larger the PI, the larger the clay content.

A measure of PI x % passing the 0.425 111111 sieve, useful in determining the compaction properties of a soil, e.g for natural gravels < 90 is normally recommended.

A measure of PI x % passing the 0.075 mm sieve, that is useful in limiting the degree of fines in a soil mix, e.g <45 is normally recommended for crushed base material and <60 for natural gavels.

1 66 Pavement materials in road bui lding - Guideli nes for making better use of local materials

Residual Soils

Rock

Sand Fraction

Silt

Silt Fraction

Soil

Soil Moisture Suction

Standard Compaction

Sub-base

Subgrade

Subsoil

Thornthwaite Moisture Index (lm)

Topsoil

Glossary

These are the weathered remains of rocks that have undergone no transportation. They are normally sandy or gravelly, with high concentrations of oxides resulting from a leaching process, e.g. laterites.

Hard rigid coherent deposit forming part of the earth's crust, which may be of igneous (granite, basalt), sedimentmy (sandstone, limestone, siltstone) or metamorphic (slate, hornfels) origin and which normally requires blasting. Soft, more easily excavatable materials such as clays, shales and sands which geologically are rocks will be termed soil in an engineering classification.

That portion in a soil mass that will pass between the sieve sizes of 2.0 mm and 0.075 mm. In geological terms a sand is between 2.0 and 0.06 mm; the 0.075 mm sieve is the nearest standard sieve to this value.

Mineral patticles deposited as sediment in water and of such a size that all will pass the 0.075 mm sieve. Individual patticles are indistiguishable to the naked eye.

That portion of the soil mass that lies between the sizes of 0.06 mm (0.075 mm) and 0.002 mm.

A mixture of inorganic mineral patticles together with some water and air, which may be further described as sands, gravels, silts and clays.

The suction forces which generate the cohesion in fine grained soils below the Liquid Limit.

LaboratOty compaction of a soil sample using a standard 2.5 kg hammer to compact soil in a 1 OOmm diameter mould. Tends to be used on more lightly trafficked roads and earthworks.

That layer of the soil structure that lies above the subgrade and below the base or base course.

The foundation level of a pavement. May be natural or constructed. This layer directly receives the load from the pavement.

The soil layer beneath the soil or pavement surface and above bedrock.

A moisture index which relates water demand by plants to available precipitation, by means of an index of potential evapotranspiration, calculated from measurements of air temperature and day length. In humid regions the index is positive and in arid regions it is negative.

The loose often organic top layer of soil that can support vegetation.

Unified Soil Classification System (USC) An internationally accepted system for classifying and describing soils for engineering purposes.

Water table The horizon in the soil at which the pore water is at atmospheric pressure. The level in a soil below which saturation occurs by moving or static groundwater. Moisture effects on pavement materials where the water table is less than 6-7 metres below surface can be significant.

Pavement materials in road building - Guidel ines for making better use of local materials 1 67

1 68 Pavement materials in road bui ld ing - Guideli nes for making better use of local materia ls

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Pavement materials in road bui ld ing - Guideli nes for making better use of local materials 173

174 Pavement materials in road bui lding - Guidelines for making better use of local materials

PAVEMENT MATERIALS IN ROAD B UILDING Guidelines for making better use of local materials

RESPONSE FORM

Please comment in the space below on ways in which the Guidelines may be improved

for practitioners.

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Position ________________________________ _

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arOb Transport Research

Thank you for your interest and comments

Please fax to George Giummarra

ARRB Transport Research Ltd

500 Burwood Highway

Vermont South

VIC 3 133 FAX' (03) 9887 8104

PAVEMENT MATERIALS IN ROAD B UILDING Guidelines for making better use of local materials

RESPONSE FORM

Please com ment in the space below on ways in which the Guidel ines may be improved

for practitioners.

Supplement Questionnaire please tick Yes Some No

• Subject matter - covered satisfactorily 0 0 0 • Text - adequate yet concise 0 0 0 • Meaning - clear and unambiguous 0 0 0 • Arrangement - orderly and logical 0 0 0 • Usefulness - likely to help in future 0 0 0 • Introduction - helpful background 0 0 0 • Data sheets 0 0 0

Specific comments:

Name ________________________________ __

Position ________________________________ _

Organisation ____________________________ _

Add ress ________________________________ _

arOb Tra nsport Resea rch

Thank you for your interest and comments

Please fax to George Giummarra

ARRB Transport Research Ltd

500 Burwood Highway

Vermont South

VIC 3 133 FAX- (03) 9887 8104

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