Deuel Associates, Inc.

GULF COAST TESTING LA BORA TORY INC. PINELLAS PARK, FL 33781

CONSTRUCTION MATERIALS ENGINEERING COUNCIL CERTIFIED

October II, 2019

Deuel & Associates, Inc. 565 South Hercules A venue Clearwater, Florida 33764

Attn: Mr. AI Carrier, PE

Subject: Report of Geotechnical Exploration Addendum No.1 Roadway Improvements Madeira Beach, Florida GCTL Project No. 25279

Dear Mr. Carrier:

Gulf Coast Testing Laboratory, Inc. (GCTL) has completed the requested evaluation for the use of

a revised pavement structure for the above-referenced project. Specifically, the use of a flexible

pavement structure with soil-cement base has been evaluated. In this regard, the recommendations for

a soil-cement based flexible pavement are presented in this Report of Geotechnical Exploration

Addendum No. I.

This report is intended to be utilized in direct conjunction with the initial Report of Geotechnical

Exploration (project No. 25279, dated June 3, 20 19) and presents a review of the project information

provided to us, a description of the site and subsurface conditions encountered as well as our pavement

recommendations.

5671 70th A VENUE NORTH PINELLAS PARK, FL 33781

CONSTRUCTION MATERIALS ENGINEERING COUNCIL CERTIFIED CERTIFICATE of AUTHORIZATION # 00002370

PHONE: (727) 544-4080 FAX: (727) 544-7532 Email: info(@gctlfl.com

Roadway Improvements, Madeira Beach, Florida GCTL Project No. 25279

October/!, 2019 Report ofGeoteclmical Exploration Addendum No. I

We appreciate this opportunity to provide our services to you and we look forward to serving as your

geotechnical consultant throughout this project. Should you have any questions in regard to the

information presented in this report, please do not hesitate to contact us at your earliest convenience.

Sincerely,

GULF COAST TESTING LABORATORY, INC.

Don R. Stites, P.E.

Digitally signed by Don R Stites Date: 2019.10.13 22:1 1:02 -04'00'

Principal Geotechnical Engineer Florida Registration No. 42290

II

Rick Davis President

TABLE OF CONTENTS

1.0 INTRODUCTION ..................................................................................................................... 1-1 1.1 PROJECT CHARACTERISTICS ............................................................................ 1-1

2.0 GENERALIZED SUBSURFACE CONDITIONS .............................................................. 2-1 2.1 SUB SURF ACE CONDITIONS ............................................................................... 2-1 2.1. I Existing Pavement Structure ..................................................................................... 2-1 2. I .2 Subgrade Soils ............................................................................................................ 2-2 2. I .3 Groundwater Conditions ............................................................................................ 2-2

3.0 EVALUATIONS AND DESIGN RECOMMENDATIONS .............................................. 3-1 3. I GENERAL ................................................................................................................. 3-1 3.2 SUBGRADE .............................................................................................................. 3-2 3.3 BASE .......................................................................................................................... 3-3 3.4 ASPHALTIC CONCRETE ....................................................................................... 3-4 3.5 PAVEMENT THICKNESS DESIGN ...................................................................... 3-4

4.0 CONSTRUCTION CONSIDERATIONS ............................................................................. 4-1 4.I FILL PLACEMENT AND SUBGRADE PREPARATION ................................. .4-I 4.2 GROUNDWATER CONTROL ............................................................................... 4-2

5.0 BASIS FOR RECOMMENDATIONS .................................................................................. 5-1

APPENDIX

SUGGESTED SPECIFICATIONS FOR SOIL-CEMENT BASE COURSE CONSTRUCTION


October II, 2019 Report ofGeoteclmical £tploration Addendum No. I

1.0 INTRODUCTION

1.1 PROJECT CHARACTERISTICS

l11e subject project is located along within Madeira Beach in Pinellas County, Florida. Specifically,

the subject property is expected to include Johns Pass Avenue, Lillian Drive, Crystal Drive, East

Parsley Drive, West Parsley Drive, !29th A venue East, 131 51 A venue East, Pelican Lane, Marguerite

Drive, Village Boulevard, and 1291h Avenue West. These roadways are were observed to consist of

existing asphaltic concrete surfaced roadway areas with concrete curbing. This addendum is

understood to consist of evaluating the subsurface conditions encountered with anticipation of utilizing

a flexible pavement structure with a soil-cement base. The finished grades of the pavement areas are

expected to generally coincide with the existing grade levels.

1-1

Roadway Improvements, Madeira Beach. Florida GCTL Project No. 25279

October II, 2019 Report ofGeoteclmical &pi oration Addendum No. I

2.0 GENERALIZED SUBSURFACE CONDITIONS

2.1 SUBSURFACE CONDITIONS

2.1.1 Existing Pavement Structure

Based on these measured values, the average individual roadway pavement thicknesses have been

tabulated below.

Street Asphaltic Base Base Location Concrete Thickness Material

Thickness (Inch) (Inch)

Johns Pass Boulevard 2.5 6.6 Crushed Shell

Lillian Drive 2.0 8.0 Crushed Shell

Crystal Drive 1.8 6.4 Soil Cement

East Parsley Drive 2.5 4.7 Soil Cement/Crushed Concrete

West Parsley Drive 3.3 5.0 Soil Cement

1291h A venue East 1.4 6.9 Soil Cement

131 st A venue East 1.5 6.5 Soil Cement

Pelican Lane 2.2 4.0 Soil Cement

Marguerite Drive 2.5 6.0 Soil Cement

Village Boulevard 2.3 6.7 Soil Cement

1291h Avenue West 5.5 6.5 Crushed Shell

In this regard, based on our review, it is recommended the existing pavement section be considered as

follows:

Asphaltic Base Base Concrete Thickness Material Thickness (Inch)

(Inch) 2.2 6.1 Soil Cement

2-1


2.1.2 Subgrade Soils

October 11, 2019 Report of Geotechnical Exploration Addendum No. 1

Underlying the asphaltic concrete and pavement base materials, the subsurface materials encountered

generally consisted of a mixture of fine SAND (SP), slightly silty find SAND (SP-SM), silty SAND, and

marine shell fragments, with interbedded layers of SILT (ML) that extended to a depth of at least 5.2 feet

below the existing ground surface (soil boring termination). It is noted that the borings for DRI-13 and

DRI-16 encountered Peat at a depth range of 3.5 to 4.9 feet below the existing ground surface elevation.

2.1.3 Groundwater Conditions

As recorded during the time of our subsurface exploration the groundwater level was encountered at an

approximate depth range of 1.8 to 4.1 feet below the existing ground surfaces; the deeper groundwater

level measurements may have been artificially lower due to the silty material restricting groundwater

flow. It is estimated that the groundwater level will generally coincide with the adjacent intercostal

waterway. In this regard, it is estimated that the normal seasonal high groundwater level will be located

approximately one foot below the existing pavement surface elevations.

2-2

Roadway Improvements. Madeira Beach, Florida GCTL Project No. 25279

October II, 20I9 Report of Geotechnical Exploration Addendum No. I

3.0 EVALUATIONS AND DESIGN RECOMMENDATIONS

The following evaluations and recommendations have been developed on the basis of the previously

described project characteristics and subsurface conditions encountered during this exploration. The

subsurface data was evaluated utilizing correlations between the engineering performance

characteristics of similar subsurface conditions.

The following pavement recommendations presented in the following sections are considered

minimum for the site, soil and limited traffic conditions expected. The final pavement thickness

design should be determined by the project civil engineer using information obtained during the

subsurface exploration program and an analysis of anticipated traffic conditions.

3.1 GENERAL

Based on the results of the subsurface exploration, the near-surface soils encountered across the project

site consists of uncontrolled earthfill that predominately consists of very low permeable soils which

also have a shallow normal seasonal high groundwater level and a shallow aquitard ("confining")

layer. Structures constructed overlying this type of material tend to exhibit aesthetic and structural

distress, which was exhibited in the existing roadway structures.

Although the existing asphalt could be milled and repaved, it is believed this pavement would

experience similar distress in limited time durations. In this regard, in order to improve the existing

pavement, it is recommended that pavement reconstruction be performed. It is believed a semi

flexible pavement structure with a soil-cement base is considered the preferred pavement section for

the proposed roadway areas.

Soil-cement is a highly compacted mixture of soil/aggregate, cement, and water that is commonly

used as a pavement base for residential streets and commercial parking areas. The soil material in

soil-cement can be almost any combination of sand, silt, clay, gravel, or local granular materials,

such as slag, caliche, and limerock. In addition, a wide variety of waste materials including cinders

and fly ash can all be utilized as soil material. Old granular-base roads can also be reclaimed to

make great soil-cement.

3-1


In general, before construction

begins, laboratory tests establish the

cement content, compaction, and

water requirements of the soil

material to be used. During

construction, tests are made to

confirm that the requirements are

being attained. Soil-cement is

commonly mixed m a central

pugmill (see photograph). The

mixed soil-cement is then hauled to

October II, 2019 Report of Geotechnical Exploration Addendum No. I

the jobsite and spread on the prepared subgrade. the mixture is compacted to the specified dry

density and cured to prevent evaporation of water and assist in developing strength through cement

hydration.

3.2 SUBGRADE

Following removal of the existing pavement structure, including asphaltic concrete and underlying

base material, it is recommended the exposed soils be proofrolled with a non-vibratory drum roller,

having a static weight on the order of four tons, under the direction of a Geotechnical Engineer in order

to confirm the ability of the soils to properly support the expected roadway development. The

pavement subgrade should be compacted to a minimum depth of six inches to a density of at least 92

percent of the Modified Proctor maximum dry density (ASTM 01557).

Any fill used to elevate the cleared pavement areas to subgrade elevation should consist of "clean"

well-graded to fine sands having less than five percent finer than the No. 200 sieve, unifonnly

compacted to a density of at least 92 percent of the soil Modified Proctor maximum dry density.

One layer of a Geogrid stabilization material (such as Tensar Geogrid SS20, TriAx TXI40, Mirafi

BXG120, or approved equivalent) is expected to significantly improve the pavement stability. In this

regard, one layer of geogrid is recommended to be placed overlying the compacted and approved

pavement subgrade. Stabilized sub grade is not recommended with the use of Geogrid.

3-2



The Geogrid material should be placed in accordance with the manufacturers' recommendations. In

general, it is recommended that the Geogrid be placed as follows:

• Unroll the Geogrid, pull taut and stake.

• Overlap all end sections of the Geogrid approximately 18 inches.

• Dump, spread and compact approximately 4 to 6 inches of base material. Rubber-tired

vehicles and track-mounted vehicles should not operate on the Geogrid material prior to

placement of the base material.

3.3 BASE

A soil cement base (see

photograph) should be

designed according to FOOT

or PCA modified short cut

design procedure. A strength

of 300 to 400 psi should be

achieved on laboratory cured

compressive

specimens molded

strength

from

samples taken from the base

material as it is placed; higher

compressive strengths should

be avoided in order to limit shrinkage cracking. Before paving, the soil cement base should be

checked for soundness should be firm and true to line and grade prior to paving. As a guideline for

pavement design, we recommend that the soil cement base materials be a minimum of eight inches

thick in heavily traveled drives.

It is noted that soil cement pavements tend to develop aesthetic disruptions along the pavement surface

due to shrinkage cracking of the cement treated base material. In order to effectively reduce reflection

cracking and improve the aesthetic quality of the improved roadways, it is recommended that a

geosynthetic material, such as Mirafi MPV500 or approved equivalent, be placed in accordance with

the manufacture's recommendations between the asphaltic concrete and the soil cement base.

3-3


October II, 2019 Report of Geotechnical £"pi oration Addendum No. 1

3.4 ASPHALTIC CONCRETE

The asphaltic concrete structural course should consist of at least 2~ inches ofType SP-9.5 or SP-12.5

asphaltic concrete material. Type SP-9.5 or SP-12.5 should be utilized because of their durability

qualities. The asphaltic concrete should meet standard FOOT material requirements and placement

procedures as outlined in the current FOOT Standard Specifications for Road and Bridge Construction.

3.5 PAVEMENT THICKNESS DESIGN

The following pavement designs are based upon the design methods described in the FOOT "Flexible

Pavement Design Manual for New Construction and Pavement Rehabilitation" (Document No. 625-

0 10-002-b, dated April 1, 1993 ). These designs present the recommended range of IS-kip-equivalent

single axle loads for the "light duty", "moderate duty", and "heavy duty" pavement sections presented.

Based on the pavement conditions observed and the subsurface conditions encountered, the

evaluations were performed using the following parameters:

• Design Reliability = 85% at an overall standard deviation of 0.45 • Initial Serviceability= 4.2; Terminal Serviceability= 2.0; • Modulus of Resiliency, Mr = 8700 psi • Structural Coefficient for Asphaltic Concrete = 0.44 • Structural Coefficient for Soil Cement= 0.15 • Structural Coefficient for Compacted Subgrade = 0.04

Pavement Pavement Structural 18Kip Duty Structural Section Number Equivalent

Single Axle Loads

2.2" TypeS 6.1" 6" 2.1 70,000 Asphaltic Soil Cement Compacted

Existing Concrete Subgrade

2W' Type SP 8" 6" 2.9 600,000 Asphaltic Soil Cement Compacted

Moderate Concrete Geogrid Subgrade

2W'Type SP 10" 6" 3.3 1,800,000 Asphaltic Soil Cement Compacted

Heavy Concrete Geogrid Subgrade

3-4

Roadway Improvements, Jyfadeira Beach, Florida GCTL Project No. 25279

October 11, 2019 Report of Geotechnical £"Cploration Addendum No. I

4.0 CONSTRUCTION CONSIDERATIONS

4.1 Fill Placement and Subgrade Considerations

The following are our recommendations for overall site preparation and mechanical densification work

for construction of the proposed development, based on the anticipated construction and our boring

results. These recommendations, along with the Suggested Specifications for Soil-Cement Base

Course Construction presented in the Appendix of this report, should be used as a guideline for the

project general specifications prepared by the Design Engineer.

I. Prior to grading operations, the existing pavement structure should be removed. The

exposed materials should be evaluated by GCTL to confirm that all unsuitable materials,

if any, have been removed and that the soils are capable of supporting the proposed

pavement structures. Proofrolling should be performed with a self-propelled non

vibratory drum roller having a static drum weight on the order of four tons. Careful

observations should be made during proofrolling to help identify any areas of soft yielding

soils that may require over-excavation and replacement. It is noted that non-vibratory

compaction is recommended in order to avoid "pumping" conditions due to groundwater.

2. It is recommended that the natural ground be compacted to a dry density of at least 92

percent of the Modified Proctor Test maximum dry density (ASTM D-1557) to a

minimum depth of six inches below stripped grade within the pavement areas.

3. Following satisfactory completion of the proofrolling and compaction operations, the

proposed pavement subgrade area may be brought up to finished subgrade levels, if

required. It is recommended that off-site fill consist of soils having no more than five

percent passing the No. 200 sieve, and be free of rubble, organics, clay, debris and other

unsuitable material. Fill should be tested and approved by GCTL prior to acquisition.

Approved sand fill should be placed in loose lifts not exceeding six inches in thickness.

The fill soils should be compacted to a dry density of at least 92 percent of the Modified

Proctor Test maximum dry density within the pavement areas.

4-1


October II , 2019 Report of Geotechnical Exploration Addendum No. I

4. Soil moisture content may need to be controlled in order to facilitate proper compaction.

If additional moisture is necessary to achieve the compaction objectives of imported fill,

then water should be applied in such a way that will not cause erosion or removal of the

subgrade soils. A moisture content within two percentage points of the optimum

indicated by the Modified Proctor Test (ASTM D-1557) is recommended prior to

compaction ofthe natural ground and fill.

5. A representative from GCTL should be retained to provide on-site observation of

earthwork and ground modification activities. It is important that GCTL be retained to

observe that the subsurface conditions are as we have discussed and reported herein, and

that foundation construction, ground modification and fill placement are in accordance

with our recommendations.

4.2 GROUNDWATER CONTROL

Groundwater was encountered at a depth range of 1.8 to 4.1 feet below the existing ground surface

elevations. Groundwater levels should be detennined immediately prior to excavations and

construction. It is estimated that the groundwater level will generally coincide with the adjacent

intercostal waterway. In this regard, it is estimated that the normal seasonal high groundwater level

will be located approximately one foot below the existing pavement surface elevations. Groundwater

is expected to be satisfactorily controlled with a sump pump system for near-surface pavement

construction.

Soils exposed in the bases of all satisfactory excavations should be protected against any detrimental

change in conditions, such as physical disturbance or rain water. Surface runoff water should be

drained away from the excavations and not be allowed to pond.

4-2



5.0 BASIS FOR RECOMMENDATIONS

Our professional services have been performed, our findings obtained, and our recommendations

prepared in accordance with generally accepted geotechnical engineering principles and practices.

This company is not responsible for the conclusions, opinions or recommendations made by others

based on these data.

The scope of the exploration was intended to evaluate soil conditions within the primary influence of

the existing pavement and does not include an evaluation of potential deep soil conditions such as

sinkholes and/or compressible subsurface soils. The analysis and recommendations submitted in this

report are based upon the data obtained from the soil borings performed at the locations indicated.

Regardless of the thoroughness of a geotechnical exploration, there is always a possibility that

conditions between borings will be different from those at specific boring locations and that conditions

will not be as anticipated by the designers or contractors. In addition, the construction process may

itself alter soil conditions.

If any subsoil variations become evident during the course of this project, a re-evaluation of the

recommendations contained in this report will be necessary after we have had an opportunity to

observe the characteristics of the conditions encountered. The applicability of the report should also

be reviewed in the event significant changes occur in the design, nature or location of the proposed

facility.

The recommendations provided are based in part on project information provided to us and they only

apply to the specific project and site discussed in this report. If the project information is incorrect or if

additional information is available, the correct or additional information should be conveyed to us for

review. Our recommendations may then be modified, if necessary. Experienced geotechnical

personnel should observe and document the construction procedures used and the conditions

encountered. Unanticipated conditions and inadequate procedures should be reported to the design

team. We recommend that the owner retain GCTL to provide this service based upon our familiarity

with the project, the subsurface conditions, and the intent of the recommendations and design.

5-1

APPENDIX

SUGGESTED SPECIFICATIONS

FOR SOIL-CEMENT BASE COURSE CONSTRUCTION

rmm PORTLAND CEMENT ASSOCIATION

suaaested Specifications lor Soil-Cement Base course construction

1.GEnERAL 1.1 Description. Soil-cement shall consist of soil, portland cement,

and water proportioned, mixed, placed, compacted, and cured in

accordance with these specifications; and shall conform to the lines,

grades, thicknesses, and typical cross-sections shown in the plans.

These suggested specifications cover construction of soil-cement

base course, also referred to in some areas as cement-treated based,

cement-treated aggregate base, full depth recycling of flexible pave

ments, cement-recycled asphalt and base, and other names.

These specifications are intended to serve as a guide to format and

content for normal soil -cement construction. Most projects have

special features or requirements that should be incorporated in the

project documents.

2. MATERIALS 2.1 Soil. "Soil• may consist of ( 1) any combination of gravel, stone,

sand, silt, and clay; (2) miscellaneous material such as caliche,

scoria, slag, sand-shell, cinders, and ash; (3) waste material from

aggregate production plants; (4) high-quality crushed stone and

gravel base course aggregates; or (5) old flexible pavements, includ

ing the bituminous surface and stone or gravel base course.

The soi l shall not contain roots, topsoil, or any material deleterious

to its reaction with cement. The soil as processed for construction

shall not contain material retained on a 2-in. (50-mm) sieve except

for bituminous surface recycling work, which can contain up to 5%

of the total mixed material retained on a 2-in (50-mm) sieve.

2.2 Portland Cement. Portland cement shall comply with the latest

specifications for portland cement (ASTM C 150, ASTM C 1157,

CSA A-23.5, or AASHTO M 85) or blended hydraulic cements (ASTM

C 595, ASTM C 1157, CSA A-362, or AASHTO M 240).

<Cl 2001 Portland Cement Association All rights reserved.

2.3 Water. Water shall be free from substances deleterious to the

hardening of the soil-cement.

2.4 Pozzolans. If used, pozzolans including fly ash, slag, and silica

fume shall comply with the appropriate specifications (ASTM C 618,

AASHTO M 295 for fly ash; ASTM C 989, AASHTO M 302 for

slag; ASTM C 1240 for silica fume; or CSA A-23.5 for all).

2.5 Curing Compounds. Curing compounds shall comply with the

latest specifications for emulsified asphalt (ASTM D 9773) or liquid

membrane-forming compounds for curing concrete (ASTM C 309).

2.6 Sand Blotter. Sand used for the prevention of pickup of curing

materials shall be clean, dry, and non-plastic.

3. EQUIPMEnT 3.1 Description. Soil-cement may be constructed with any machine

or combination of machines or equipment that will produce com

pleted soil-cement meeting the requirements for soil pulverization,

cement and water application, mixing, transporting, placing, com

pacting, finishing, and curing as provided in these specifications.

3.2 Mixing Methods. Mixing shall be accomplished in a central

mixing plant or in place, using single-shaft or multiple-shaft mixers.

Agricultural disks or motor graders are not acceptable mixing

equipment.

3.3 Cement Proportioning. The cement meter for central-plant

mixing and the cement spreader for in-place mixing shall be capa

ble of uniformly distributing the cement at the specified rate.

Cement may be added in a dry or a slurry form. If applied in slurry

form, the slurry mixer and truck shall be capable of completely

dispersing the cement in the water to produce a uniform slurry,

and shall continuously agitate the slurry once mixed.

IITiiiJ SOIL-CEMENT INFORMATION

3.4 Application of Water. Water may be applied through the mixer

or with water trucks equipped with pressure-spray bars.

3.5 Compaction. Soil-cement shall be compacted with one or a com

bination of the following: tamping or grid roller, pneumatic-tire roller,

steel-wheel roller, vibratory roller, or vibrating-plate compactor.

4. GDnSTRUGTIDn REQUIREMEnTS 4.1 General

4.1.1 Preparation of Subgrade. Before soil-cement processing begins,

the area to be paved shall be graded and shaped to lines and grades

as shown in the plans or as directed by the engineer. During this

process any unsuitable soil or material shall be removed and replaced

with acceptable material. The subgrade shall be firm and able to sup

port without yielding or subsequent settlement the construction

equipment and the compaction of the soil-cement hereinafter speci

fied. Soft or yielding subgrade shall be corrected and made stable

before construction proceeds.

4.1.2 Mixing and Placing. Soil-cement shall not be mixed or placed

when the soil aggregate or subgrade is frozen, or when the air tem

perature is below 40• °F (4 °(). Moisture in the soil at the time of

cement application shall not exceed the quantity that will permit a

uniform and intimate mixture of the soil and cement during mixing

operations, and shall be within 2% of the optimum moisture content

for the soil-cement mixture at start of compaction.

The operation of cement application, mixing, spreading, compacting

and finishing shall be continuous and completed within 4 hours from

the start of mixing. Any soil-cement mixture that has not been com

pacted and finished shall not be left undisturbed for longer that 30

minutes.

4.2 Central-Plant-Mixed Method

4.2.1 Mixing. Soil-cement shall be central-plant mixed in an

approved continuous-flow or batch-type pugmill, or rotary-drum

mixer. The plant shall be equipped with metering and feeding devices

that will add the soil, cement, and water into the mixer in the speci

fied quantities. If necessary, a screening device shall be used to

remove oversized material greater than 2 in (SO mm) from the raw

soil feed prior to mixing. Soil and cement shall be mixed sufficiently

to prevent cement balls from forming when water is added. The max

imum plasticity index of the soil shall be eight.

The mixing time shall be that which is required to secure an intimate,

uniform mixture of the soil, cement, and water.

Free access to the plant must be provided to the engineer at all times

for inspection of the plant's operation and for sampling the soil-cement

mixture and its components. If the actual quantities of the mix vary

more than 3% by weight of the specified quantities, the engineer may

require such changes in the plant operation as will provide the

required accuracy.

4.2.2 Handling. The soil-cement mixture shall be transported from the

mixing plant to the paving area in trucks or other equipment having

2

beds that are smooth, clean, and tight. Truck bed covers shall be pro

vided and used at the engineer's discretion to protect the soil-cement

during transport from moisture variations due to weather conditions.

Any soil-cement wet excessively by rain, whether during transport or

after it has been spread, will be subject to rejection.

The total elapsed time between the addition of water to the mixture

and the start of compaction shall be the minimum possible. Haul time

shall not exceed 30 minutes, and compaction shall start as soon as

possible after spreading. In no case shall the total elapsed time exceed

45 minutes between the addition of water to the soil and cement and

the start of compaction.

The contractor shall take all necessary precautions to avoid damage

to completed soil-cement by the equipment.

4.2.3 Placing. Immediately prior to placement of the soil-cement, the

receiving surface shall be in a moist condition. The mixture shall be

placed without segregation at a quantity per linear foot (meter) that

will produce a uniformly compacted layer conforming to the required

grade and cross section. The mixture shall be spread by one or more

approved spreading devices. Not more than 60 minutes shall elapse

between placement of soil-cement in adjacent lanes at any location

except at longitudinal and transverse construction joints.

4.3 Mixed-in-Place Method

4.3.1 Preparation. The surface of the soil to be processed into soil

cement shall be at an elevation so that, when mixed with cement and

water and recompacted to the required density, the final elevation

will be as shown in the plans or as directed by the engineer. The

material in place and surface conditions shall be approved by the

engineer before the next phase of construction is begun.

4.3.2 Scarifying. Before cement is applied, the soil to be processed

may be scarified to the full depth of mixing. Scarification and pre

pulverization are required for the following conditions:

(1) For cohesive soils with a plasticity index greater than 20, the soil

shall be damp at the time of scarifying to reduce dust and aid in pul

verization.

(2) For full depth recycling of flexible pavements where the bitumi

nous surface is incorporated into the mixture, the pulverization to

final specified gradation, as noted in Section 4.3.4, shall be accom

plished prior to cement application.

(3) For slurry application of cement, initial scarification shall be done

to provide a method to uniformly distribute the slurry over the soil

without excessive runoff or ponding.

4.3.3 Application of Cement. The specified quantity of cement shall

be applied uniformly in a manner that minimizes dust and is satisfac

tory to the engineer. If cement is applied as a slurry, the time from first

contact of cement with water to application on the soil shall not

exceed 60 minutes. The time from slurry placement on the soil to

start of mixing shall not exceed 30 minutes.

4.3.4 Mixing. Mixing shall begin as soon as possible after the cement

has been spread and shall continue until a uniform mixture is produced.

The mixed material shall meet the following gradation conditions:

(1) For soils, 1 00% of the soil-cement mixture shall pass a 1-in.

(25-mm) sieve and a minimum of 80% shall pass a No. 4 (4.75-mm)

sieve, exclusive of any gravel or stone. Gravel or stone shall be no

more than 2-in. (50-mm) nominal maximum size.

(2) For full-depth recycling, the final mixture (bituminous

surface, granular base, and subgrade soil) shall be pulverized such

that 95% passes the 2-in. (50-mm) sieve and at least 55% passes the

No. 4 (4.75-mm) sieve. No more than 50% of the final mixed materi

al shall be made of the existing bituminous material unless approved

by the engineer and included in a mixture design. Additional material

may be added to the top or from the subgrade to improve the mixture

gradation, as long as this material was included in the mixture design.

The final pulverization test shall be made at the conclusion of mixing

operations. Mixing shall be continued until the product is uniform in

color, meets gradation requirements, and is at the required moisture

content throughout. The entire operation of cement spreading, water

application, and mixing shall result in a uniform soil, cement, and

water mixture for the full design depth and width.

4.4 Compaction. Soil-cement shall be uniformly compacted to a min

imum of 98% of maximum density based on a moving average of five

consecutive tests with no individual test below 96%. Field density of

compacted soil-cement can be determined by the 1) nuclear method

in the direct transmission mode (ASTM D 2922, MSHTO T 238); 2)

sand cone method (ASTM D 1556, AASHTO T 191 ); or rubber bal

loon method (ASTM D 2167 or MSHTO T 205). Optimum moisture

and maximum density shall be determined prior to start of construc

tion and also in the field during construction by a moisture density

test (ASTM D 558 or AASHTO T 134).

At the start of compaction whether central-plant mixed or mixed-in

place, the moisture content shall be within 2% of the specified optimum

moisture. No section shall be left undisturbed for longer than 30 minutes

during compaction operations. All compaction operations shall be com

pleted within 2 hours from the start of mixing.

4.5 Finishing. As compaction nears completion, the surface of the

soil-cement shall be shaped to the specified lines, grades, and cross

sections. If necessary or as required by the engineer, the surface shall

be lightly scarified or broom-dragged to remove imprints left by

equipment or to prevent compaction planes. Compaction shall then

be continued until uniform and adequate density is obtained. During

the finishing process the surface shall be kept moist by means of fog

type sprayers. Compaction and finishing shall be done in such a man

ner as to produce dense surface free of compaction planes, cracks,

ridges, or loose material. All finishing operations shall be completed

within 4 hours from start of mixing.

4.6 Curing. Finished portions of soil-cement that are traveled on by

equipment used in constructing an adjoining section shall be protect

ed in such a manner as to prevent equipment from marring or damag

ing completed work.

3

After completion of final finishing, the surface shall be cured by appli

cation of a bituminous or other approved sealing membrane, or by

being kept continuously moist for a period of 7 days with a fog-type

water spray that will not erode the surface of the soil-cement. If curing

material is used, it shall be applied as soon as possible, but not later

than 24 hours after completing finishing operations. The surface shall

be kept continuously moist prior to application of curing material.

For bituminous curing material, the soil-cement surface shall be

dense, free of all loose and extraneous materials, and shall contain

sufficient moisture to prevent excessive penetration of the bituminous

material. The bituminous material shall be uniformly applied to the

surface of the completed soil-cement. The exact rate and temperature

of application for complete coverage, without undue runoff, shall be

specified by the engineer.

Should it be necessary for construction equipment or other traffic to

use the bituminous-covered surface before the bituminous material

has dried sufficiently to prevent pickup, sufficient sand blotter cover

shall be applied before such use.

Sufficient protection from freezing shall be given the soil-cement for

at least 7 days after its construction or as approved by the engineer.

4.7 Construction Joints. At the end of each day's construction a

straight transverse construction joint shall be formed by cutting back

into the completed work to form a true vertical face.

Soil-cement for large, wide areas shall be built in a series of parallel

lanes of convenient length and width meeting approval of the engi

neer. Straight longitudinal joints shall be formed at the end of each

day's construction by cutting back into completed work to form a true

vertical face free of loose or shared material.

Special attention shall be given to joint construction to ensure a verti

cal joint, adequately mixed material, and compaction up against the

joint. On mixed-in-place construction using transverse shaft mixers, a

longitudinal joint constructed adjacent to partially hardened soil

cement built the preceding day may be formed by cutting back into

the previously constructed area during mixing operations. Guide

stakes shall be set for cement spreading and mixing.

4.8 Traffic. Completed portions of soil-cement can be opened imme

diately to low-speed local traffic and to construction equipment pro

vided the curing material or moist curing operations are not impaired,

and provided the soil-cement is sufficiently stable to withstand mar

ring or permanent deformation. The section can be opened up to all

traffic after the soil-cement has received a curing compound or subse

quent surface, and is sufficiently stable to withstand marring or per

manent deformation. If continuous moist curing is employed in lieu of

a curing compound, the soil-cement can be opened to all traffic after

the 7-day moist curing period, provided the soil-cement has hardened

sufficiently to prevent marring or permanent deformation.

4.9 Surfacing. Subsequent pavement layers (asphalt, chip-seal, or

concrete) can be placed any time after finishing, as long as the soil

cement is sufficiently stable to support the required construction

equipment without marring or permanent distortion of the surface.

I1Iilfl PORTLAND CEMENT ASSOCIATION

4.10 Maintenance. The contractor shall maintain the soil-cement in

good condition until all work is completed and accepted. Such main

tenance shall be done by the contractor at his own expense.

Maintenance shall include immediate repairs of any defects that may

occur. If it is necessary to replace any soil-cement, the replacement

shall be for the full depth, with vertical cuts, using either soil-cement

or concrete. No skin patches will be permitted.

5.1nSPEGTIDn AnD TESTinG 5.1 Description. The engineer, with the assistance and cooperation of

the contractor, shall make such inspections and tests as deemed neces

sary to ensure the conformance of the work to the contract documents.

These inspections and tests may include, but shall not be limited to, (1)

the taking of test samples of the soil-cement and its individual compo

nents at all stages of processing and after completion and (2) the close

observation of the operation of all equipment used on the work. Only

those materials, machines, and methods meeting the requirements of

the contract documents shall be approved by the engineer.

All testing of soil-cement or its individual components, unless otherwise

provided specifically in the contract documents, shall be in accordance

with the latest applicable ASTM, AASHTO, or CSA specifications in

effect as of the date of advertisement for bids on the project.

&. MEASUREMEnT AnD PAYMEnT 6.1 Measurement. This work will be measured (1) in square yards

(square meters) of completed and accepted soil-cement base course as

determined by the specified lines, grades, and cross sections shown on

the plans and (2) in tons (tonnes) or cwt of cement incorporated into

the soil-cement base course in accordance with the instructions of the

engineer.

6.2 Payment. This work will be paid for at the contract unit price per

square yard (square meter) of soil-cement base course and at the con

tract unit price per ton (tonne) or cwt of cement furnished, multiplied

by the quantities obtained in accordance with Section 6.1. Such pay

ment shall constitute full reimbursement for all work necessary to

complete the soil-cement, including watering, curing, inspection and

testing assistance, and all other incidental operations.

-------------------------------------------------1--------! I

KEYWORDS: compacting, curing, density, finishes, inspection, joints,

maintenance, measurement, soils, soil-cement, specifications, subgrades.

ABSTRACT: Specifies materials to use and construction methods needed

to produce soil-cement base courses. A resume of preparation; pulveriza

tion; cement application, mixing and spreading (mixed-in-place and cen

tral-plant-mixed methods); comapction; finishing; curing; jointing; main

tenance; measurements; and basis of payment for a soil-cement base

course.

REFERENCE: Suggested Specifications for Soil-Cement Base Course (SoilCement, Cement-Treated Base, Cement-Treated-Aggregate Base), 15008.11, Portland Cement Association, 2001.

CAUTION: Avoid prolonged contact between unhardened (wet) cement or cement-treated mixtures and skin surfaces. To prevent such contact, it is advisable to wear protective clothing. Skin areas that have been exposed to wet cement or cement-treated mixtures, either directly or indirectly or through saturated clothing, should be thoroughly washed with water.

This publication is based on the facts, tests, and authorities stated herein. It is intended for the use of professional personnel competent to evaluate the significance and limitations of the reported findings and who will accept responsibility for the application of the material it contains. The Portland Cement Association disclaims any and all responsibility for application of the stated principles or for the accuracy of any of the sources other than work performed or information developed by the Association.

I1IiilJ PORTLAND CEMENT ASSOCIATION

5420 Old Orchard Road Skokie, Illinois 60077-1 083 847.966.6200 www.portcement.org

An organization of cement companies to improve and extend the uses of portland cement and concrete through market development, engineering, research, education, and public affairs work.

18008.12

Deuel Associates, Inc.

Documents

Transcript of Deuel Associates, Inc.