Roller Compacted Concrete in UK

Experiences and Opportunities

ERMCO Representatives Meeting

Cascais, 7 June 2013

Steve Crompton, MBA, B.Eng, MICT

National Technical Director

Cemex UK

2

Contents

Background – Why RCC now?

What is RCC

– Production

– Installation

– QC

Applications

Pavement design

Additional benefits of RCC

Case studies and opportunities

3

The use of asphalt in UK infrastructure is

often deemed to be the only option to fulfil

the requirements of modern day contracts

Background

4

0

5

10

15

20

25

30

35

40

Background

Economic pressures driving ‘More for Less’

The UK Asphalt Market

5

BITUMEN 36%

AGGREGATES 29%

HAULAGE 11%

FUEL 9%

FC 8%

OVERHEADS 3%

OTHER VARIABLE COST

2%

ELECTRIC POWER 1% OTHER RAW

MATERIALS 1%

Background

6

BLS Inflation Indexes since Jan 1971

0

200

400

600

800

1,000

1,200

1,400

1,600

1,800

Jan

-71

Jan

-74

Jan

-77

Jan

-80

Jan

-83

Jan

-86

Jan

-89

Jan

-92

Jan

-95

Jan

-98

Jan

-01

Jan

-04

Jan

-07

Jan

-10

Pri

ce I

nd

ex (

Base Y

ear

= 1

971)

Paving Asphalt (CAGR=6.9%)

Cement (CAGR=4.3%)

Ready Mix Concrete (CAGR=4.7%)

Aggregate (CAGR=4.7%)

PPI-Commodities (CAGR=4.3%)

CPI (CAGR=4.4%)

(Data thru June 2011)

Paving Asphalt

All Other Indexes

BLS Inflation Indexes since Jan 1971BLS Inflation Indexes since Jan 1971

0

200

400

600

800

1,000

1,200

1,400

1,600

1,800

Jan

-71

Jan

-74

Jan

-77

Jan

-80

Jan

-83

Jan

-86

Jan

-89

Jan

-92

Jan

-95

Jan

-98

Jan

-01

Jan

-04

Jan

-07

Jan

-10

Pri

ce I

nd

ex (

Base Y

ear

= 1

971)

Paving Asphalt (CAGR=6.9%)

Cement (CAGR=4.3%)

Ready Mix Concrete (CAGR=4.7%)

Aggregate (CAGR=4.7%)

PPI-Commodities (CAGR=4.3%)

CPI (CAGR=4.4%)

(Data thru June 2011)

Paving Asphalt

All Other Indexes

-40%

-20%

0%

20%

40%

60%

80%

100%

120%

140%

ge

n-7

2

ge

n-7

5

ge

n-7

8

ge

n-8

1

ge

n-8

4

ge

n-8

7

ge

n-9

0

ge

n-9

3

ge

n-9

6

ge

n-9

9

ge

n-0

2

ge

n-0

5

ge

n-0

8

ge

n-1

1

An

nu

al

Infl

ati

on

Rate

(%

)

CPI (Avg=4.4%, St Dev =3.1%)

PPI-Commodities (Avg=4.3%, St Dev =5.6%)

Aggregate (Avg =4.8%, St Dev =3.4%)

Ready Mix Conc. (Avg =4.4%, St Dev =4.5%)

Cement (Avg=4.4%, St Dev =5.8%)

Paving Asphalt (Avg=8.4%, St Dev =20.9%)

Paving Asphalt’s 40-year historical rate is 2 to 4% higher than the general rate of inflation

(higher than concrete and cement’s and much more volatile)

Background

7

Background

So why the reliance on asphalt?

‘Time is Money’

+

‘Sticking Plaster’ approach to infrastructure maintenance

+

Tradition ?

8

Definition: “Roller Compacted Concrete is a no-slump concrete placed by an asphalt paver

and compacted by rollers”

Materials are same as concrete – well graded, angular aggregates, cement, and water – but

different mixture proportions. (Cement content around 300kg/m3)

Zero slump (consistency of damp aggregate)

No pavement formwork, consolidated with paver and vibratory rollers

No reinforcing steel

After curing, RCC properties and performance are similar to PQ concrete

What is RCC?

9

RCC is a blend of asphalt & concrete Paving technologies

Hot-Mix Asphalt Pavement Conventional Concrete Pavement

Shared construction characteristics

Similar aggregate gradation

Similar placement and compaction

Shared materials characteristics

Same materials (different proportions)

Similar curing requirements

What is RCC?

10

• Mid size applications

• 100 to 150 tons/hr

• Not all plants have mixers

• Fixed locations

• Capacity reduced due to low

water content of mixture

• High-volume applications

• Excellent mixing efficiency for dry

materials

• Consistent mix properties

• 250 to 600+ tons/hr

• Mobile, erected on site

• Lower mobilization costs

Central Mix Continuous Flow Pugmill

Production

11

Standard paver (80% to 85% initial density)

Widely available

High-production (4 to 6 m/min)

Lift thickness up to 150mm

May require multiple lift paving

– Impossible to pave adjacent lanes

Increased roll down to achieve density (grade control problems)

Easier to fix segregated areas before compaction

• High density screed

• High initial density (> 90%)

• Smoother surface with higher initial density

• Less roll down from to achieve density

• High production (4 to 6 m/min)

• Lift thickness up to 250mm

• Adjacent lanes easily paved

Standard Paver High Density Paver

Installation

12

Initial: 10 - 12 ton static & vibratory roller

– Thinner lifts may allow smaller roller

Establish roll pattern (check density a lot!)

Adjust based on moisture content (visual observation and lab measurements to confirm)

Compact to 98% of maximum wet density

Adjust moisture content if needed – impacts smoothness

Finer mixes achieve density easier

• Final: Combination, dual steel or rubber tired

• Maximum weight - 6 ton

• Remove roller marks

• NO MORE ROLLING!

Initial Compaction Finish Rolling

Compaction

13

Density tested with nuclear gauge in direct transmission mode

Test density behind paver and after roller to establish rolling patterns to achieve density

Continuously check density until comfortable

Achieve 98% of maximum wet density

Nuclear gauge gives general moisture fluctuation indication

• Cubes prepared with vibratory hammer

• 3 to 4 cubes per set

• Strength timing depends on traffic opening (1, 3, 7, 28 days)

• Cores can be obtained where density is not being achieved

Compressive Strength Moisture & Density

Quality Control

14

• Applied at same rate or slightly higher than conventional concrete

• Ensure uniformity with application process

• Apply as soon as possible behind roller operation

• Ensures durable surface

Curing Saw Cut & Fill Joints

• More aesthetically pleasing

• Early entry saw very effective, shortly following placement

• Recommend sawing within 2 - 6 hours to avoid uncontrolled cracking

• Depth: 1” to 1.5”

• Spacing: Maximum 36 times thickness, Max 6m

Finishing Touches

15

The Difference?

16

The ‘Time’ Issue

17

Industrial

Dockyard

Container storage

Airfield refuelling areas

Roads ?

Applications

18

HBM

(Flexible Composite)

Asphalt

(Fully Flexible)

Pavement Design

19

RCC does theoretically fit into to the HBM ‘family’ of materials

But.... the compressive strength of RCC is much higher (C32/40 +)

Therefore no design option is available for RCC in this methodology

Pavement Design

20

Pavement Design

Still a requirement for 100 to 180mm of asphalt overlay

21

Surface Course

Capping

Subgrade

CBGM

Sub-base

RCC

Potential option

Asphalt surface course to achieve:

Skid resistance and noise

reduction

Would require formal RCC

specification which in turn would

allow inclusion in design charts

Pavement Design

22

Benefits of RCC

23

Pavement Cost Analysis

24

$0,64

$0,5

Nom Disc Rate=8%

$0,34

$0,03

$0,50

$0,04

$0,19

$0,05

$0,46

$1.65

$0,4 $0,4

$0,9 $0,9

0 5 6 10 13 15 16 18 24 25 28 30 34 35 38 40 45 50

Rehabilitation – Activities based on Proper Maintenance Cycles for asphalt pavements. Current year costs are inflated at 4%, Rehab costs also include other

Incidental Costs (striping, mob, etc) - 40% of material costs, Traffic Control - 5% of material cost, and Engineering & Inspection - 5% of material cost

Nominal Expenditures by Pavement Type Total Cost Net Present Value

M $

M $

In this example Asphalt is 26% more expensive than RCC throughout the life

cycle of the road

year

Asphalt – Rehab: Crack / cape sealing in years 6, 13, 16, 24, 34, 38

Microsurfacing in years 10, 28

Major rehab in year 18 (2” OLAY + PDR)

Major Rehab in year 45 (Full Replace)

PCC – Rehab: Patch & diamond grind at years 25, 35, 2” AC Overlay at yr 45

26 %

Life Cycle Cost Analysis

25

Cost Issues

Cementitious options now cheaper to build

Reduced maintenance

Longer life

Lower whole life cost

More traffic per £ invested

On going fuel and environmental savings

26

Added Benefit Reducing Fuel Use

Many world wide studies show fuel savings for rigid pavement construction

• 6% Eupave • 2.4% NRC, Canada • 6.7% NRT, Sweden • 3.1% NRI, Japan • 1.1% TRL, UK • 5.8% University of Texas, USA

27

Added Benefit – Rolling Resistance

28

The Noise Issue

94

96

98

100

102

104

106

0 5 10OB

SI S

ou

nd

Level

(d

BA

)

Pavement Age

Asphalt Surface –

ARFC / OGFC

95

97

99

101

103

105

0 5 10OB

SI S

ou

nd

Level

(d

BA

)

Pavement Age

Concrete Surface -

NGCS

29

Advances in Noise Reduction

An innovative, diamond saw-cut surface designed to provide a consistent profile absent of positive or upward

texture

• A uniform land profile design with a predominantly negative texture

• A hybrid texture that resembles a combination of diamond grinding (called flush grind) and longitudinal

grinding

• Can be done as a single step or a 2 step process

• Visit www.ngcs.info for 25 additional references on the pavement surface type

• Could compete with HRA in terms of noise

30

Further Benefits - Lighting

US studies have suggested that up to 30% saving in artificial lighting cost can be

achieved by using a light coloured surface

31

CASE STUDIES

32

Druids Heath Bus Terminus

Asphalt RCC

CBR 15 15

Subbase 150mm 150mm

Pavement 260mm 200mm

Overall 410mm 350mm

•Repeated heavy loading of parked buses

•Oil spillage

•Disruption to public transport, congestion if re-routing employed

•Options were asphalt or RCC

33

Druids Heath Bus Terminus

34

• Transverse joints cut every 4 – 5 metres

• Cut using dry blade to one third of the depth

• Filled with bitumen emulsion prior to rolling

Druids Heath Bus Terminus

35

Druids Heath Bus Terminus

36

Impetus Waste Transfer

PAV 2 RCC

CBR 10 10

Subbase 150mm 150mm

Pavement 400mm 400mm

Overall 550mm 550mm

Program 16 weeks 6 weeks

• Large storage area for compost waste

• Difficult ground conditions

• Time pressure on program

• No asphalt design option

37

Impetus Waste Transfer

38

Impetus Waste Transfer

39

Impetus Waste Transfer

40

Current Applications in UK

• Lorry & Trailer Parking

• Container Storage & Handling

• Materials Storage & Handling

• Composting Hardstandings

• Waste Recycling Sites

• Heavy Industrial Access Roads

• Farm Roads

• Port Pavements

• Fuel Resistant Applications

41

Future Applications in UK

HIGHWAYS

Highway Agency & Local Authorities

Under consideration, with induced

cracking and surface course

for bus lanes, motorway widening and as

an alternative to

fully flexible pavements

AIRFIELDS

May require surface course

Ideal for Taxi Ways & Airplane Stands

NEW BUILD HOUSING

Composite solutions under consideration

42

Summary

• RCC is not a new product

• Economics are driving contractors to seek ‘more (and more) for less’

• The challenge is to improve understanding and knowledge of RCC

• Specifications and design charts need to include RCC as an option

• RCC has all the attributes of concrete, with the installation speed of asphalt

• Concrete paving is becoming a viable economic and sustainable option in many

applications

43

Conclusions

Lower initial cost

Lower lifetime cost

Less maintenance

Lower Fuel usage

Lower CO2 emissions from road traffic

Economic benefits through lower fuel use

More road miles per £ invested

Predictable cost inflation

A better way to build pavements!

44

Thank You