Manual for Supervision

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MANUALFOR

SUPERVISION AND TRAININGOF FIELD ENGINEERS FOR

ROAD MAINTENANCE


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Table of Contents

1. Introduction........................................................................................................................................1

1.1 Importance of Quality Control.....................................................................................................1

1.2 Works to be Supervised................................................................................................................1

1.2.1 Description of Works............................................................................................................1

1.2.2 Construction Procedures........................................................................................................2

2. Responsibilities of Supervising Engineer............................................................................................3

2.1 Summary of Duties of Supervising Engineer................................................................................3

2.1.1 Project Control Activities......................................................................................................32.1.2 General Responsibilities for Works by Contract and Force Account.....................................4

2.1.2.1 Contract Works..............................................................................................................4

2.1.2.2 Works by Force Account................................................................................................4

2.1.2.3 Project Documents.........................................................................................................4

2.1.3 Progress Reports and Records...............................................................................................5

2.1.3.1 Project Diary Records....................................................................................................5

2.1.3.2 Measurement Book.........................................................................................................6

2.1.3.3 Records of Sampling and Test Results...........................................................................6

2.1.3.4 Progress Charts and Records..........................................................................................7

2.1.3.5 Progress Reports............................................................................................................7

2.2 Project Management Control........................................................................................................7

2.2.1 Project Works Programming.................................................................................................7

2.2.2 Activities Flow Chart............................................................................................................8

2.2.2.1 Bar Chart.......................................................................................................................8

2.2.2.2 Resource Balancing........................................................................................................8

3. Materials and Workmanship............................................................................................................10

3.1 Properties of Soils......................................................................................................................10

3.1.1 Shear Strength.....................................................................................................................10

3.1.2 Compression and Consolidation..........................................................................................103.1.3 Permeability........................................................................................................................11

3.1.4 Plasticity.............................................................................................................................11

3.1.5 Volume Change...................................................................................................................12

3.1.6 Chemical Properties............................................................................................................12

3.1.7 Laboratory Tests for Soil Properties...................................................................................13

3.1.8 Rock Classification.............................................................................................................13

3.2 Compaction................................................................................................................................16

3.2.1 Fundamentals of Soil Compaction.......................................................................................16

3.2.2 Compaction Tests................................................................................................................17

3.2.2.1 General Description......................................................................................................17

T.A. for Institutional Support to the Department of State for Works, Communications & Insformation Final Report Phase II

DHV Consultants BV, The Netherlands September 1998

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3.2.2.2 Laboratory Compaction Tests......................................................................................17

3.2.2.3 Field Density Tests.......................................................................................................18

3.2.2.4 Problems Relating to Density Control..........................................................................18

3.2.2.5 Statistical Variations....................................................................................................193.2.3 Compaction Equipment.......................................................................................................19

3.2.3.1 Types of Compaction...................................................................................................19

3.2.3.2 Equipment Selection Summary.....................................................................................21

3.2.3.3 Proof Rolling................................................................................................................22

3.2.4 Compaction of Fill..............................................................................................................23

3.2.4.1 Sands and Gravels........................................................................................................23

3.2.4.2 Silt................................................................................................................................23

3.2.4.3 Clay..............................................................................................................................23

3.2.5 Asphalt Paving....................................................................................................................24

3.2.5.1 Types of Asphalt Paving..............................................................................................24

3.2.5.2 Bitumen Prime and Tack Coats....................................................................................243.2.5.3 Single Surface Treatment.............................................................................................26

3.2.5.4 Double Surface Treatment............................................................................................27

3.2.5.5 Bitumen Sand Seal.......................................................................................................27

3.2.5.6 Cold Mix Asphalt.........................................................................................................28

3.3 Maintenance of Paved Roads.....................................................................................................29

3.3.1 Patching of Potholes and Repair of Depressions..................................................................29

3.3.2 Repair of Surface Cracking.................................................................................................29

3.4 Maintenance of Unpaved Roads.................................................................................................30

3.4.1 Patching of Potholes and Repair of Depressions..................................................................30

3.4.2 Grading of Roads................................................................................................................30

3.5 Maintenance of Shoulders..........................................................................................................30

3.6 Maintenance of Roadside Drains and Culverts...........................................................................31

4. Site Control Requirements................................................................................................................32

4.1 Control of Construction Site and Equipment..............................................................................32

4.2 Safety Precautions for Handling Bitumen...................................................................................32

4.3 Sampling Procedures..................................................................................................................32

4.3.1 General Requirements.........................................................................................................32

4.3.2 Value of Test Results..........................................................................................................33

4.4 General Testing Requirements....................................................................................................35

4.4.1 Construction Stages.............................................................................................................35

4.4.1.1 Road Construction........................................................................................................35

4.4.1.2 Maintenance works.......................................................................................................35

4.4.1.3 Frequency of Quality Control Tests..............................................................................36

4.5 Storage and Handling of Materials.............................................................................................38



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4.5.1 General Requirements.........................................................................................................38

4.5.2 Supplying and Stockpiling Aggregates................................................................................39

4.5.3 Storage of Bituminous Materials.........................................................................................39

4.5.4 Materials Stacked by the Roadside......................................................................................39



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1. INTRODUCTION

1.1 Importance of Quality Control

Supervision of project works is carried out by means of inspection, measurement and testing,and these comprise the main methods for control of workmanship and quality and enforcementof specifications for road and bridge construction and maintenance works.

The purpose of quality control is to ensure that the works on completion fully meet theplanned and designed requirements and that the materials and workmanship are of a highenough standard to perform satisfactorily (and economically) for the intended life span.

Regular inspection and testing are the tools necessary to prevent unacceptable results causedby such factors as poor workmanship, changes in the sources of materials or poor qualitymaterials, unsuitable or inadequate equipment, and long exposure of the site works to adverseconditions.

These technical guidelines consider the important procedures to be followed. They explain therole of the supervising engineer, and describe how the value of inspection and testing dependsto a large extent on the nature of sample testing and application of test results.

1.2 Works to be Supervised

1.2.1 Description of Works

Works to be considered under these guidelines comprise the construction, betterment, andmaintenance of the road network of The Gambia. Supervision will provide for project sitecontrol covering:i. General Responsibilities

Works to be carried out in accordance with the project specifications. Supervision willinclude for checking:

Contract documents Works programme schedule Accuracy of setting out of project

Works for location, line and level Correct grades and crossfalls Correct dimensions and levels of various structures Suitability of plant and equipment Sources of materialControl will also provide for site organization and management of works to the extentrequired for the particular project, and measurement and certification of completed work.

ii. Materials Quality ControlQuality control is necessary to ensure that the materials proposed for use in the Works aresuitable and satisfactory and meet the specification requirements. The materials should beinspected and tested before incorporation into the Works.



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iii. Workmanship Quality ControlControl of workmanship and performance is necessary to ensure that the finished workmeets the design and specified construction standards. This will provide for inspection and

testing of all works carried out, including: Soil condition and bearing capacity for road and various structures Selection and uniformity of materials provided and mixed on site Thickness of pavement layers and foundations being laid Required compaction and density and related strength Bitumen temperature and rate of application

Concrete consistency and ultimate strength Acceptance of job mixesQuality control of workmanship will require continuous supervision throughout theexecution of the works.

1.2.2 Construction Procedures

Works to be supervised will be carried out either by Contract or Force Account depending onresources and capabilities, labour demands, and degree of specialization required for the

particular project.



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2. RESPONSIBILITIES OF SUPERVISING ENGINEER

2.1 Summary of Duties of Supervising Engineer

2.1.1 Project Control Activities

The duties of the Supervising Engineer in carrying out supervision and control of projectworks are outlined in detail below in table 2.1 which lists the project and control activities.

ITEM CONTROL ACTIVITY DETAIL

1 Review of Contract/Projectdocuments

a. Contracts Notice to commence works

Conditions of Contract

Contract drawings/specificationsb. Projects (Force Account) Budget and Authority

Project drawings and specification Schedule of works

2 Review of ProjectOrganisation

Project Management and Personnel Delegation of Authority Liaison with Contractor and Project Manager

3 Review of workingProcedures

Staff assignments Methods of communication Testing procedures and facilities

Project reporting and monitoring Financial controls

4 Mobilisation and Setting outof Works

Inspection of drawings and site measurements Location of project office and mixing plantetc. Sources material supplies Suitability of plant and equipment

5 Site Supervision of ProjectWorks

Continuous inspection and checking ofworkmanship and performance Photographic records Visual checks for quality control

Field and laboratory tests (with necessaryfollow-up) Job instructions

Works problems and divergence fromcontract/project design

6 Measurement andCertification of Work

Weekly/Monthly measurement of quantity ofwork completed Work certificates and contract payments Variation orders

7 Project Reporting andMonitoring

Daily diary records Project performance and progress (including



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test results) Expenditure records and review of budgetagainst actual cost

Major activities and critical path analysis Contractor relationship

Project staff records and management facilities(Force account work)

8 Project Completion Financial Measurements Final inspection Completion certificate Clearing site Maintenance

Table 2-1. List of project control activities.

2.1.2 General Responsibilities for Works by Contract and Force Account

2.1.2.1 Contract WorksFor projects to be carried out on a contract basis, the Supervising Engineer shall work underthe control of a Project Manager and be responsible for inspecting and testing works carriedout by contract as described above and in accordance with the contract documents (including

plans and specifications) issued for the project.

2.1.2.2 Works by Force AccountFor projects to be carried out on a Force Account basis the level of control will depend on thesize and importance of the project. Major works will be under the control of a Project

Manager to whom the Supervising Engineer will be responsible. Minor works may however becontrolled directly by the Supervising Engineer, and responsibilities will include directinglabour and plant, setting out, providing works estimates and control costing sheets, preparingnecessary site working drawings, using standard specifications relevant to the work andarranging for appropriate material tests.

2.1.2.3 Project DocumentsThe Supervising Engineer will be required to undertake supervision of various types of

projects and the main types to be considered are shown at tables 2.2 and 2.3 below. Theproject documents to be used by the Supervising Engineer will vary according to the nature ofthe project and extent of the work to be carried out. Full lists of the documents required are

described below.

Project Works by ContractA full set of the contract documents will include:

General Conditions Part I General Conditions Part II Technical Specifications Bill of Quantities Bid Document Instruction to Bidders



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Project Works by Force AccountContract documents are not necessary. However full sets of project specifications are requiredtogether with all relevant data, described above. No relaxation should be permitted in the

standard of quality control and workmanship, and all specified tests should be followed.Progress report sheets should be completed, as-built drawings prepared, and expenditurerecords maintained. Site records should include full information on labour and plantmovements, and details should be kept of all materials supplied and used on site.

2.1.3 Progress Reports and Records

The Supervision Engineer will prepare and maintain the following project site reports: Project Diary

Measurement Book Sampling and Test Results

Project Drawings and As-Built Records Progress Charts and Records Progress ReportsThese records are considered in detail below:

2.1.3.1 Project Diary RecordsIt is a general requirement for the Supervising Engineer to keep a written diary recording dailyevents of the project construction works. For major works an extensive record is requiredincluding the events shown in the following list. For minor projects the detail will be limited tothe essential activities (marked ). number and classification of men and plant employed on the site and their location on

the work;

materials supplied to the Contractor and received by him and materials on hand;

delivery, installation and removal of Contractors plant and details of major plantbreakdowns and return to service;

location and description of operations carried out each day;

results of field tests on materials;

date and method of delivery of test samples to the laboratory;

dates of commencing and finishing various sections of the construction work;

dates of opening sections of the road to traffic;

details and dates of notification of authorised amendments to the drawings orspecifications;

details of any instructions or warnings given to, or important conversations held with theContractor of his representative;



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particulars of detours including their condition and the date of opening or closing;

weather conditions, including approximately rainfall and effect on the progress of the

work; Flood conditions are to be recorded where they affect drainage works;

particulars of any delays which occur on the work and the reasons for them;

remarks concerning any unusual features of the work or associated incidents;

dates of visits to the site by the Project Manager and important members of theContractors company;

instructions received from the Project Manager;

where similar material are drawn from different sources the locations of these materialsin the work to be recorded.

2.1.3.2 Measurement BookThis book is an important document and will be used for the preparation of contract paymentsand statements, and for the determination of project progress. It will be available on requesttot the Project Manager and to the Inspectorate Auditor for cross checking progress paymentsand project status. Measurement of works completed will be taken and recorded. Records ofthe receipt and issue of construction materials will be made to enable certification of thespecified amounts used on the works. The Measurement Book should record the followingitems (preferably in duplicate).

all measurements of completed work; quantities and types of materials; details of duly authorized deductions and extras; details of any work being carried out by the Contractor on an actual cost basis (day work),

with a reference to the authority for the work; details of the materials rejected or work condemned and disposal of rejected materials (this

information should also be recorded in the Supervising Engineers diary);

In recording in his measurement book details of work carried out by the Contractor on anactual cost basis (day work) the Supervising Engineer should separately show for each job: the number of men engaged, the hours worked by each and the classification and the rate of

pay for each; the amounts of materials used and their cost to the Contractor at the site of the works; the make, class and other relevant particulars of each plant item used and the time worked

by it; description and final measurement of the work completed;

2.1.3.3 Records of Sampling and Test ResultsIt is necessary to ensure that the sampling and testing procedures are in accordance with thespecification requirements, and (for minor projects) where specifications are limited or not

provided, that appropriate tests are carried out to meet the specifications. The Supervising



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Engineer will study the testing procedures called for, and develop field and laboratory testingschedules.

The results will be recorded in respect of: routine tests required special tests, including job design mixes Quality performance

Records will be kept of all cases of test failures, and to follow-up action taken.

2.1.3.4 Progress Charts and RecordsProgress records will be prepared and kept up-to-date by the Supervising Engineer to cover:i. Progress and performance data. This will include a record of progress and expenditure for

each major work activity, preferably maintained on a daily basis.

ii. Control information. This should include progress schedules, activities flow chart (criticalpath analysis for major works), and project expenditure control graphs drawn for plottingproject costs and progress. Provision should also be made for comparing actual againstplanned performance and expenditure.

iii. Project forecast. These will be needed to anticipate future expenditure and contract orproject requirements. They will take into account quality of work, delays due to defects ormodifications, and general contractor performance.

iv. Quality performance. This will be recorded to show the number of site inspections andtests carried out (in accordance with established schedules). Results will be comparedagainst specification, and action noted and followed up for all defects and failures.

2.1.3.5 Progress ReportsThe Supervising Engineer will prepare progress reports on a regular basis (usually monthly)for the Project Manager. The report will record all essential data referred to above, and be ofstandardised format in accordance with local requirements.

2.2 Project Management Control

Project management control is an important responsibility to be shared by the Project Managerand the Supervising Engineer, and will include planning and analysing project activities andrecording both physical and financial progress.

2.2.1 Project Works Programming

The following steps are necessary in the planning and control technique. Identification of project activities and preparation of activities flow chart. Allocation of priorities (critical activities) and preparation of bar-chart. Resource balancing.

It is to be noted that this process is similar to the basic steps required for critical pathscheduling but is easier to apply for management of rural projects.



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2.2.2 Activities Flow Chart

An activities flow chart will be drawn up to identify all major (and critical) activities. A typical

flow chart is illustrated in figure 2.1 below.

Mobilisation Site prep.

Figure 2-1 Activities Flow Chart (Example)

The flow chart will be developed to the extent necessary to include all important workactivities, and the construction activities summarised above may require further detailingwithin the framework of the chart

2.2.2.1 Bar ChartPlanning and control by means of the bar-chart process produces results which are easilyapplied and understood at all levels of management. All work activities, identified by means ofthe activities flow chart, are given work precedence and priority, and are listed in the form of a

bar-chart which record activity, priority, quantity and time. Construction progress can be

monitored using the bar-chart to plot both planned and actual process.

2.2.2.2 Resource BalancingMore precise control may be necessary to ensure that the project expenditure is withinreasonable limits, and that progress is maintained at an acceptable level. For this purpose thefollowing two types of graphs are used.



Project Staff

Contractor

Set out

and

Peg site

Clear site

Construction:

(Subdivided)

Earthworks

Roads

Drainage

etc.

Tidy site

and

remove camp

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3. MATERIALS AND WORKMANSHIP

3.1 Properties of Soils

The important soil properties are: Shear strength Compression and consolidation Permeability Plasticity

Volume change Chemical properties

Each of these is discussed below.

3.1.1 Shear Strength

Shear strength is the property that enables material to remain in equilibrium when its surface isnot level. All solids exhibit this property to some extent. Shear strength is the major structural

property of soils. It is the property that determines the bearing capacity of a footing, the angleat which a cut or fill slope can resist slides, the pressure against a retaining wall. In mostcases, except for embankments, shear strength tests will be made on undisturbed samples.Tests are conducted in a drained and undrained condition depending on the conditiondeveloped in the field.

The shear strength of a soil is the result (sum) of internal friction between the particles andcohesion. Most fine-grained soils, primarily clay (and to a lesser extent, silts), develop most oftheir shear strength from cohesion. Granular materials, and clean sands in particular, developstrength from friction between adjacent particles.

Shear strength can be measured in the laboratory by direct shear tests and by triaxial sheartests. The shear strength of cohesive soils may be determined by the unconfined compressiontest (AASHTO T 208) and in the field by the vane shear test (AASHTO T 223).

3.1.2 Compression and Consolidation

The term compression is usually used to denote the total change in height of a soil mass due to

applied loads. Observations show that when a load is applied to soil, the volume decreases.Since the individual soil grains are for all practical purposes incrompessible, the change involume must be due to a decrease in the volume of the voids. If the soil is dry, the voids arefilled with air, and the volume change will depend on the rearrangement of the particles, whichcan be both shear strength-dependent and structure-dependent. If the soil is saturated, thevoids are filled with incompressible water, and the water must flow out of the soil mass beforethe soil grains can rearrange themselves. In soils of low permeability, this process requires atime interval for completion; hence, the movement occurs slowly.

The term consolidation is the time lag associated with the volume change under an appliedload. The application of a stress to any material will cause a corresponding movement. For



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common construction materials such as steel or wood, the movement occurs simultaneouslywith the application of stress. In contrast, fine-grained soils will usually exhibit a measurabletime lag between the application of a stress and the resulting movement. It is most noticeable

in saturated or nearly saturated soils of low permeability. Both properties are determined inconsolidation tests (AASHTO T 216) usually performed on undisturbed samples.Interpretation of the test results depends on the thickness and presence of layers of sand orother drainage layers which can act as escape channels for the water being forced out of thecompressible layer.

Consolidation and compression coefficients are used to predict the amount of settlement forbuilding foundations, bridge piers, high fills or embankments. Excessive settlement often canbe avoided by keeping the soil loads less than the weight of the overburden to be removed inorder to build the foundation. In some cases pre-loading of the foundation area will in advanceof construction will provide sufficient pre-consolidation to adequately minimize differential

and total settlement after construction is completed.

3.1.3 Permeability

Permeability is the property of a soil which permits water to flow through its pores anddepends on size and number of soil pores and relative water levels. Coarse-grained soils have arelatively high coefficient of permeability and fine-grained (silts and clays) have a lowcoefficient. Small volumes of fine grained materials can significantly reduce the permeability ofotherwise permeable coarse-grained materials. Permeability must be known in order tocompute the quantity of water that will flow through a given soil layer. It is used in problemsdealing with drainage; e.g. subsurface drains for highways or airfields or in de-watering areas

under construction. Permeability of a soil varies with such factors as void ratio, grain size anddistribution, degree of saturation, and obviously with the amount of compaction.

It is imperative that the foundation engineer or pavement designer knows where the permeableand impermeable layers are at a given site, including potential seepage layers which will beencountered in cuts and in foundation excavations. In a great many cases, it is not only

practical but necessary to modify the seepage paths and water table by temporarily orpermanently interrupting the natural flow channels at a site, by lowering the water table.

3.1.4 Plasticity

One of the distinguishing properties of cohesive soils is their ability to undergo large strainswithout rupture. This property is termed plasticity, and it is unique to fine grained soils usuallyreferred to as clays. However, grain size by itself cannot be used to differentiate between

plastic and non-plastic fine grained soils.

For any particular plastic soil, the amount of plasticity is a function of the water content. If aclayey material is uniformly mixed with sufficient water, the result is a fluid-like material whichwill deform freely under very low levels of stress. The water content at which measurableshear strength becomes apparent is called the liquid limit. As the water content decreases,shear strength will develop to the point where very small strains will cause fracture. The

plastic limit is the water content at which a 3 mm (1/8 inch) diameter thread may be rolled



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without crumbling. The difference in water content between the liquid limit and the plasticlimit is called the plasticity index (PI).

The principal application of such limits is in the classification of soils to identify the plasticityof the clay fractions.

3.1.5 Volume Change

Frequently, volume changes occur due to deformations in soil masses without any apparentapplication or removal of external loads. They may be caused by at least two different

phenomena. For example, the lowering of the ground water table in an area would result inincreased soil stresses which in turn are effective in producing a volume change withincompressible layers below the original ground water level. This can lead to the settlement offills or structures at or near the surface.

In other instances, volume changes may be the result of what is known as shrinkage or swellphenomena. Shrinkage and swelling are more pronounced in the fine grained soils, especiallyclays and most particularly clays of a particular mineralogical composition: e.g. -bentonite.This volume change or potential swell pressure can be measured for specific soils byconsolidation tests, and by the CBR test. It is also calculated from data obtained in theshrinkage-limit test (AASHTO T 92) where volumetric change = (FME - S)R. The volumechanges due to expansive clays can cause considerable damage to road pavements and

building sites unless precautions are taken to prevent the ingress of water and change inmoisture content.

Design steps for moisture control under pavement include: Identification of soil type and probability of water entry to subgrade, including

determination of Field Moisture Equivalent (FME) by AASHTO test T 93. Design pavement cross section to minimize water entry. Where subgrade is impermeable, the provision of permeable subbase as sub drainage layer.

Provision of adequate side drains.

3.1.6 Chemical Properties

Little information is available to the engineer on the influence of the soil chemical propertieson its physical properties, and tests are necessarily limited therefore.

The following properties are identified in these guidelines:i. Sodium/magnesium sulphates

Sulphate concentrations to be less than 1% in soils for cement/lime stabilisation. Soluble sulphate salts in water or soils will attack and damage Portland cementconcrete. Where this occurs a sulphate resisting cement must be used.

ii. pH value (Acidity-alkalinity) For cement/lime stabilised soils the pH value should be a minimum of 7. The pH value will also indicate the amount of organic matter present in a soil.



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3.1.7 Laboratory Tests for Soil Properties

The following basic laboratory tests are given at table 3.1 and are carried out to determine soil

and aggregate properties and the suitability of soil for use as a road pavement material.

Item Test Description AASHTOTest

1 Sampling Stone, Gravel,Sand, Stone Block for use asHighway Materials

Methods of sampling for investigation andapproval of sources of supply for allmaterials

T 2

2 Particle size analysis of Soils Distribution of Particle sizes in soil T 88

3 Sieve Analysis of fine/coarseparticles

Particle size distribution of fine and coarseaggregates

T 27

4 Material finer than 0.075

mm

Determination of amount of material finer

than 0.075 mm (in combination with sieveanalysis above)

T 11

5 Clay Lumps and FriableParticles in Aggregate

Approximate determination of clay and softparticles in natural aggregates

T 112

6 Specific gravity of soils Ratio of equal volume weight of soil towater (< 4.75mm)

T 100

7 Atterberg Limits Liquid limitPlastic limit/Plasticity Index

T 89T 90

8 California Bearing Ratio(CBR)

Punching shear test for ratio of Laboratorycompacted soil (soaked) or in-situ soil to astandard broken stone layer

T 193

9 Test for Expansive clay Determination of swelling and shrinkage ofclay soils (Based on Atterberg limits)

T 258

10 Moisture-Density Test Standard laboratory compaction test on soilpassing 19 mm using 2.5 kg rammer with30.5 cm drop to determine maximumdensity and optimum moisture content

T 99

11 Moisture-Density Test As above test but using 4.54 kg. Rammerwith 45.7 cm drop

T 180

Notes: These tests are applicable to materials comprising subgrade, subbase and base coarse.

Table 3-1. Laboratory tests for soil properties.

3.1.8 Rock Classification

Rock quality classifications are typically based on the results of compressive strength tests,and/or the condition of core samples. Some rocks tend to degrade (igneous and metamorphic)or disintegrate (slake) rapidly upon exposure to the weather. Qualities of hardness, durabilityand the potential for slaking should be rated from laboratory tests, which will include:

Sulphate Soundness test (resistance to disintegration) Los Angeles Abrasion test for hardness

Repeated wetting and drying Slaking - durability test



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Weathering processes usually produce a reduction in rock hardness, and increase porosity anddiscolouration. The rock structure is of considerable assistance for identification purposes anda general classification relating to road construction materials is given in table 3.2 below.



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Classification Example of sourcematerial

Properties

Origin For Aggregate

Igneous Rock Intrusive(Coarse grained)

GabbroGranite, Diorite

Hard primary rock ofhigh strength inoriginal state

Decompose byweathering to hard/softrocks and soils-whichare a common sourceof road aggregate

Extrusive(Fine grained)

Basalt, Rhyolite,Obsidian, diabase

SedimentaryRock

Calcareous Limestone, Dolomite Cemented detritalmaterial derived fromweathered rock.Properties depend onnature of parent rock

Vary in compositionand condition somebeing hard, but othertoo soft for use aspavement material.Soft material usually

found near surface ofdeposit

Siliceous Shale, sandstone,chert, conglomerateBreccia

Metamorphicrock

Foliated Gneiss, Schist, Slate From sedimentary andigneous rockssubjected tothermal/dynamicpressures, and possiblychemical influences.Usually very hard, butmay show foliation,

cleavage, or closejoints

Often used as roadaggregate. The veryhard rock such asquartzite (derived fromsandstones) requiresspecial crushing withgrid rollers and impactbreakers to reduce to a

well graded aggregate

Non-foliated Quartzite, Marble,Serpentinite

Table 3-2. Rock classification related to road construction.

In addition to the properties given in table 3.2, it is important to remember that rocks may beaffected in different ways by the breaking and crushing process, and some types will present

better shape for road construction purposes. In general rock aggregates for constructionshould have a hardness of 5 - 7 (Mohs scale) as materials with hardness exceeding 7 maycause excessive damage and wear to the crushers. Impurities may also be a problem andshould be identified.

A summary of engineering properties of rock with particular reference to suitability for roadconstruction is given in the table 3.3.



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Type of rock Mechanicalstrength

Durability Chemicalstability

Surfacecharacter

Presence ofundesirableimpurities

Crushedshape

GraniteSyeniteDiorite

good good good good possible good

Felsite good good questionable fair possible fair BasaltDiabaseGabbro

good good good good seldom fair

Peridotite good fair questionable good possible good

LimestoneDolomite

good fair good good possible good

Sandstone fair fair good good seldom good

Chert good poor poor fair likely poor Conglome-rateBreccia

fair fair good good seldom fair

Gneiss Schist good good good good seldom good to poor

Quartize good good good good seldom fair

Marble fair good good good possible goodSerpentinite fair fair good fair to good possible fair

Amphibolite good good good good seldom fair Slate good good good good seldom poor

Reference Compendium 2 of Transport Research Board National Academy of Sciences.

Table 3-3. Engineering properties of rock (summary).

3.2 Compaction

3.2.1 Fundamentals of Soil Compaction

The strength and stability of a road pavement depend mainly on good compaction of thepavement foundation. The soil of compacted subgrade and subbase, and the compacted layerof base coarse material, must remain stable and without deformation under repeated wheelloads. The most important factor determining compaction results are: Type of material or soil

Water (moisture) content during compaction Nature and amount of compactive effort

These factors are inter-related. Thus a highly plastic clay soil will compact best at a relativelyhigh water content (using pneumatic wheel loader) whereas a granular soil such as sand orgravel will compact well and to a much higher density than clay at a relatively low watercontent (with a vibratory roller).

Where conditions are favourable, the compaction of dry materials is applied in practice forcrushed rock, sand and gravel, and rock fill. Vibratory compaction in particular can producehigh densities for dry sand layer (with silt content < 20 %).



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In general the difficulty to compact soil at water contents between the dry and water saturatedstate depends on the capillary forces, which create cohesion. Cohesion increases with adecrease in particle size.

Clay and other clay mixtures develop considerable cohesion, and consequently require mucheffort to compact. The higher the cohesion the greater the compaction needed. Thus theircompactability depends to a large extent on the water content, and therefore on weatherconditions. Due to their cohesion they must be compacted in lower lifts or thinner layers.

Coarse grained materials with little or no cohesion such as rock fill, sand and gravel are easierto compact than fine grained soils, and with vibration can be compacted in thick layers. Theyare also the best fill materials with respect to bearing capacity. A comparatively low silt or claycontent (5 - 10 %) is sufficient to make the material so impermeable that compaction must bemade at optimum moisture content, which should be the cased for most road base materials.

3.2.2 Compaction Tests

3.2.2.1 General DescriptionStandardised compaction tests are carried out to determine optimum water (moisture) contentand the corresponding maximum dry density (ed max.).

ed fieldDegree of Compaction =

ed max.

Note: ed max. = maximum dry density obtained by laboratory compaction

In general maximum dry density and optimum moisture content obtained for a givencompactive effort are primarily influenced by the soil type. It will be impossible to reach a highdensity if the sub soil is loose or elastic - as for instance a clay with a high water content. Insuch a case this layer must be consolidated (e.g. lime stabilisation) or filled in compactedlayers to obtain the required degree of compaction.

3.2.2.2 Laboratory Compaction TestsThe methods to determine optimum water content and the corresponding maximum drydensity are included in AASHTO test procedures T 99 and T 180 and are sometimes referred

to as Standard Proctor or Modified Proctor tests.

In the Standard Proctor test a 2.5 kg rammer is used to compact the soil sample held in a 10.2cm diameter mould. Maximum stone size is limited to 19 mm and larger stone must be sievedout. The sample is dried and mixed with varying proportions of water to determine maximumdensity.

A modified compaction test has been introduced to meet increased demands on compactionstandard mainly for higher quality sub-base and base coarse work. For the Modified Proctortest a 4.5 kg rammer is used.



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With the larger compaction energy used for the Modified Proctor test, the maximum drydensity is 5 - 10 % higher than that obtained with Standard Proctor (5 % for granularmaterials and up to 10 % for cohesive soils). The optimum water content is normally 3 - 8 %

lower at the Modified Proctor.

It is essential therefore to know and to indicate which laboratory compaction is to be used forany compaction control test. As previously stated, soil type is of prime importance.

3.2.2.3 Field Density TestsDensity tests in common use for site quality control include: sand replacement method (sand cone density test) - T 191

Water-balloon method - T 205 Tube sampling - BS 1377

i. Sand replacement methodThis is the most popular method for measuring the volume of the hole, and determining thedegree of compaction. Testing is limited to soil/aggregate particles not exceeding 50 mm insieve size. In the sand replacement method a hole is excavated by hand in the compactedfill, normally with a diameter of about 200 mm and a depth of about 150 mm. The weightand water content is determined by drying the sample in an oven at 1100 C. the volume ofthe hole is then measured by filling it with calibrated dry sand, usually from a special sandcone cylinder. With knowledge of the material weight and the volume of the hole, the drydensity (ed) of the compacted fill can be calculated. The degree of compaction (P) is thendetermined by the formula given at section 3.2.2.1.The density control based on the sandreplacement method requires time for drying of samples and density values are available the

day after testing.

ii. Water Balloon MethodAn alternative method is to determine the volume of the excavated hole by means of thewater balloon apparatus, which gives faster results, and is just as accurate.

iii. Tube SamplingFor fine grained soils, especially clay, tube sampling is used to take up samples for densitytests. A tube is driven down into the compacted soil and then removed with its soil content.This procedure is much faster that the sand replacement method.

3.2.2.4 Problems Relating to Density ControlUsing conventional test methods it is not possible to make quick and reliable decisions in thefield about the state of compaction of the earth subgrade, road subbase or base coarse. Evenwith a field laboratory available it may take hours to obtain the maximum dry density of a soilsample, and comparison with laboratory compaction tests is often difficult. The compactiontest results can be meaningful only if the material checked in the field closely resembles thesample tested in the laboratory.

For these reasons there are often wide discrepancies between the field and the laboratory testsfor maximum dry density, and new methods are under consideration.



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With the sand replacement method for instance, in order to reduce the time required in thelaboratory for drying the samples, the soil may dried over an open fire, or dried by pouringalcohol over the sample and igniting. Such techniques work best for coarse materials and are

relatively unreliable for fine grained soils.

3.2.2.5 Statistical VariationsField density measurements always show deviations, reflecting errors in the testing procedure,variations in soil properties, water content, etc. Standard deviations in the range of 2.0 to 4.0

per cent are common. At least three of four test values are necessary to obtain a safe densityvalue calculated as the average of the individual values. Statistical analysis of the valuesobtained at compaction tests are therefore more and more commonly used.

To be 95 per cent sure that no values below the specified level are obtained, the average valueof density test, with a standard deviation of for example 3.0 %, must lie 5.0 % over the

specified level. In practice it is usually too expensive to keep such a high density level, and soseparate low values now and then have to be corrected through an additional number of roller

passes. Corrections in the water content may also be necessary. One way to consider theunavoidable statistical deviations in density tests is to specify a minimum average density testover a longer period, for example 95 % Modified Proctor. This rule is completed with aspecification that no single density value below, say 92 % is permitted.

3.2.3 Compaction Equipment

The effectiveness of compaction varies with the type of compaction equipment. Major typesare smooth steel wheeled rollers, pneumatic tyred rollers, sheepfoot rollers, and vibrating

rollers or compactors.

For compacting granular soils, vibrating rollers usually give best results. Smooth wheeledrollers are sometimes used, and pneumatic tyred rollers will give good results if the granularmaterial contains some fines. For cohesive soils the kneading action privided by sheepfoot and

pneumatic tyred rollers works will. Silty soils may also be compacted efficiently with mosttypes of rollers. Smooth wheeled rollers are most used for finishing a compacted surface.

3.2.3.1 Types of CompactionCompaction is applied in one of four special ways:i. By static weight

ii. Vibrationiii. Impactiv. Kneading Action

ad. i. Static weight compactorsThese are either smooth steel wheel rollers of tandem or 3-wheel variety or pneumatic tyredrollers in a variety of sizes and weights with compaction dependent on tyre size.Roller weight - tandems : 8 - 10 ton

3-wheel : 10 - 14 ton

Smooth Steel Wheel Rollers



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Rather slow running, speed and not safe for use near edges of high steep sided fills. They arenot generally satisfactory for earthworks and other roller types are preferred. Most effectiveon soils of granular nature where crushing effect of the static weight is best. However loose

sand may be a problem to the heavier roller. Not so effective on granular-plastic (clay) andcohesive soils, where the rollers have a ploughing effect forming rolling waves and sponginess.Preference therefore for steel wheel rollers to be used for compacting coarse gravel, granularsubbase, crushed aggregates and rock-soil layers. Steel wheel rollers are also used forcompacting and finishing asphalt surfacing, but care should be taken to avoid cracking of thesurface, or crushing of the aggregate.

Pneumatic Tyred RollersChoice of self propelled or drawn rollers, with large or small tyres. They are ballasted to giverequired tyre surface pressure. Suitable for both sandy and cohesive soils with reasonably highmoisture content. Type pressure to be controlled. Small tyre rollers generally have two tandem

axles. They provide same unit surface pressure as large tyre units with less overall weight onmaterial being compacted and are most effective for roadworks. (Note that tyre inflation

pressure and contact pressure are not necessarily synonomous and may vary according to tyresize and wheel load). Small tyre rollers are most effective for granular type soils and can also

be used for general compaction purposes with maximum depth of compaction 15 cm. Theyhave poor flotation in loose material however, and the self propelled units tend to slip in wetsoil.

In general these rollers provide a more uniform compaction effect than steel wheel rollers andare becoming more popular for asphalt surfacing work as they do not produce compactioncracks and can be operated at higher speed than steel wheel roller. In addition bituminous

layers which are compacted with a rubber tyre roller are more completely sealed to keep outdirt and moisture. The large tyre pneumatic rollers in the range of 15 tonnes are generallytowed and will work on all types of soil. They can handle higher lifts with deeper penetration,

but require a greater number of passes to get complete coverage.

For the compaction of cohesive soils, well graded material, and dense graded aggregate, tyreinflation pressure should be within the range of 5 - 6.5 kg/cm2 (70 - 90 lbs/m2) For thecompaction of non-cohesive soils, including uniform sand and gravels, the tyre inflation

pressure should be between 2 - 5 kg/cm2 (30 - 70 lbs/in2).

ad. ii. Vibration Compactors

These are vibratory steel or rubber tyred rollers (excluding vibratory plates). They can be selfpropelled or towed. Compaction effect is influenced by the following parameters:

Static weight Number of vibrating drums Frequency and amplitude Roller speed Ratio between frame and drum weight Drum diameter and drive

The major influences for determining the compaction effect can be calculated as the combinedeffect of resonance frequency on the soil (amplitude magnification) and the effect of increasing



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frequency (vibration intensity). For best results this should be adjusted to match the actual soilresonant frequency.

The self propelled vibratory rollers with two pneumatic drive wheels have become verypopular. Units of 6 - 10 tonnes are generally used for road construction work, with half theweight on the vibrating drum. Vibratory rollers provide the best results on non-cohesivegranular soils where they are superior to other types of rollers in achieving maximum density(at optimum moisture content). They are also best for compacting aggregates of relatively softstone (limestone).

Silt and silty clays can also be compacted to an extent provided water content is maintained ata level close to optimum moisture content. Drainage control is important therefore. Claymaterials with high plasticity should be avoided.

ad. iii. Compaction by ImpactCompaction is achieved mainly by the use of hand pneumatic tampers. Vibratory platecompactors are used for small work and in confined area such as trenches. The tamping action(impact) produces large pressure forces and compaction efficiency is good on almost all typesof soil including clay. These units have low frequency and high amplitude and produce aminimal vibratory effect. Most familiar however are the air powered tampers, and othercompactors which use a self contained petrol engine, giving a jumping up and down effect.

ad. iv. Sheepsfoot RollersFor cohesive soils including clays and silty clays, the proper compaction equipment to providethe necessary kneading action are rollers of the sheepsfoot type, including grid rollers.

Sheepsfoot rollers range in size from 2 - 20 tonnes. The average unit is about 2 metres wide,with a ballasted drum to increase the load, which is covered with protubing feet or lugs up to30 cm long of various shapes, including round, square, elliptical. The sheepsfoot rollers canhandle loose lifts up to 25 cm with compaction effected mainly through the protruding feet.They should not be used for compacting granular materials particularly stone bases or gradedaggregates, as this will cause segregation.

3.2.3.2 Equipment Selection SummaryEach of the various types of compactors has its own special application. Advantages areshown for pneumatic tyred and vibratory rollers, but static rollers are still widely used,especially for asphalt paving work.

The compaction ability of the vibratory rollers depends on the type of vibrator and type of soilto be worked, and these rollers with high frequency can be advantageously used for gravel andsand (non-cohesive materials). Also, vibratory rollers with directed vibrations limit the amountof loosening of the top layer of the compacted material.

The heavy towed rollers with lower frequencies and greater amplitudes provide impactvelocity and are will suited for the compaction of all cohesive materials and well graded soils.



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Pneumatic tyred rollers are more efficient than steel wheel rollers for many applications butcare should be taken in the selection as the compaction effect is dependent upon the size of thecontact area, wheel load, and tyre pressure.

It is to be noted that soils with too high a water content cannot be compacted with any type ofcompaction equipment. As a general guide for the Engineer the following table 3.4 gives a

basis for the selection of compaction equipment. Full scale field trials should be carried outunder actual site conditions before the final choice is made for any large scale project.

Suitable types of rollers

Materials to becompacted

selfpropelledvibrating

towedvibrating

towedrubbertyred

selfpropelled

rubbertyred

selfpropelled

smoothwheel

sheepsfoottowed

Medium/Heavy clay No Yes Yes No No Yes

Uniformly gradedgranular soils

Yes No No No Yes No

Well graded granularsoils

Yes Yes Yes Yes Yes No

Gravel/sand/clay mix Yes Yes Yes Yes Yes Yesblock stone/coral base Yes No No Yes No

crusher-runbase/macadam

Yes Yes No Yes Yes No

crushed stone wearingcoarse not more than 7.5cm thick on well rolledbase

Yes No No Yes Yes No

asphalt wearing coarse No No No Yes Yes No

sealed road surface No No No Yes Yes NoTable 3-4. Selection of compaction equipment.

3.2.3.3 Proof RollingProof or test rolling is carried out as a visual quality control test. It is most often used aftersubgrade compaction and before placing of base course aggregate. It is also used on naturalsubgrade in cut areas to determine the need for compaction. It is especially useful for naturallywet soils where areas of low soil density or excessive moisture are found. For dry soils, thesubgrade may show sufficient strength under proof rolling but still prove unstable when wet,and there is a danger therefore that proof rolling will give a false indication of firmness. When

proof rolling is carried out it is usually together with soil density testing. The supervising

engineer must use considerable engineering judgement when making a decision therefore andthe following problem conditions should be checked: Over size rock may be contained in the fill Wrong type of compaction equipment used Insufficient number of rolling passes Lift or layer thickness excessive Moisture content too low or too high

Heavy pneumatic rollers (up to 14 tonnes) with large tyres are usually used for proof rolling,but small tyred pneumatic rollers may also be used if the ballast is properly calculated. In



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general however it is considered that a maximum wheel load up to 5 tonnes should be used,and with pneumatic tyres inflated to a pressure not exceeding 0.7 kg/cm2 (10 lbs/in2).

3.2.4 Compaction of Fill

3.2.4.1 Sands and GravelsThe compaction properties of sands and gravels depend on the amount of fines contained.Free draining sand and gravel (containing less than 5 - 10 % of fines) will reach a higherdensity and can also be compacted in thicker layers when they are water saturated than at thelower natural water contents. For higher demands on the density and quality of the fill, watershould be added. Such a fill can be flooded with water to guarantee water saturation. In caseof a free-draining fill, rain does not stop the work, which is often the case with non free-draining soils. Very wet, free-draining fills are both de-watered and compacted when vibrated.

If sand or gravel contains a certain amount of fines (> 10 - 15 %), the soil is no longer free-drained and will become elastic and springy when the water content is high and it is bestcompacted at optimum moisture content.

With uniformly graded sand or gravel, it is difficult to obtain a high degree of compactionclose to the surface of the fill. Down to a depth of 10 - 15 cm, the compaction achieved withmedium or heavy vibratory or static rollers is lower than at greater depths, because of thelower shear strength of this type of soil. Compaction is best and most efficiently carried outwith vibratory roller followed by a smooth wheel roller, and high compaction densities can beobtained with light vibratory compactors in layer depths up to 25 cm. When smooth wheel or

pneumatic tyred rollers are used, compaction depth will be limited to 10 -15 cm.

3.2.4.2 SiltSilts are fine grained non-plastic soils. They have variable compactoin properties depending onthe proportion of fine sand and clay content and range between non-cohesive and cohesiveclay like material. During compaction, silts are very dependent on the water content - whichshould be kept close to the optimum, and at this level they are comparatively easy to compact.Silty sands have low cohesion and can be compacted in thick layers up to 1 m. when usingheave (towed) vibrator rollers (10 - 15 ton drum module weight).Silty soils with a certain amount of clay have considerable cohesion however, and will havesimilar compaction properties to clay soils. They are compacted with vibratory rollers, andalso with pneumatic tyred or smooth wheel roller.

3.2.4.3 ClayClay soils are plastic and compaction characteristics are highly dependent on the watercontent. when the water content is low, the clay becomes hard and firm. Above the optimummoisture content, the consistency of the clay soil becomes more and more plastic as the watercontent is increased. To obtain the specified density, the water content should not diverge toomuch from the optimum water content and the main problem in clay compaction is very oftento adjust the water content to the optimum.

The addition of water to a dry clay material by using water tanks, harrows, pulvimixers (soilstabilizers), etc. is time consuming and expensive. Water infiltration in the borrow pit is



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another alternative. When a grader is used to mix the water into the soil, layer depth shouldnot be more than 20 cms.

Drying a wet clay soil is sometimes difficult and can only be carried out during dry weatherconditions. Good results can be obtained by draining the soil in its natural state or by piling thematerial for drying. Layers of wet clay soils can be processed with harrows and sheepsfootrollers.

In general however clay fill with high plasticity should be avoided due to high compressibility,low shear strength, and difficulties with moisture content-density control. For compaction of asuitable clay fill the layers to be compacted should not exceed 15 cm. and the moisture contentshould be kept to within 2 % of the optimum valuees. When wet clays have to be used asembankment fills, alternate layers of clay and gravel/sand can be used to obtain a more rapidreduction of the water content and to produce a more stable fill.

Rollers for compaction include the sheepsfoot roller for initial compaction, followed bypneumatic tyred or smooth wheeled rollers preferably after light grading. The compactiveeffect of traffic over the embankment fill is also of value. Vibratory rollers may be used,

provided that have a high static weight (static linear load > 30 kg/cm). It is to be notedhowever that vibratory compaction of wet cohesive fill material with high ground water levelmay cause the water table to rise thereby increasing plasticity of the material.

3.2.5 Asphalt Paving

3.2.5.1 Types of Asphalt Paving

The types of asphalt paving to be used for surfacing the roads will here be limited to thefollowing range with final selection dependent on traffic levels and availabilty of materials. Single bituminous surface treatment (single sealing) Double bituminous surface treatment (double sealing) Bitumen sand seal

Asphalt cold mix surface layer

3.2.5.2 Bitumen Prime and Tack CoatsA bitumen priming coat is a low viscosity binder which is applied to a prepared and compactedunsealed aggregate base, prior to laying an asphalt surface layer course. The purpose of the

prime coat is to penetrate into the base course (5 mm) and to bind any surface dust or fine

material, thus ensuring a good bond with the surface layer. It should be applied at least 2 daysbefore surfacing commences and will provide a waterproof membrane to protect the basecourse. If covered with fine aggregate to provide a temporary running surface, the surfacelayer can be delayed for several weeks.

A bitumen tack coat is a very thin layer of a rapid setting binder which is sprayed over anexisting sealed pavement surface before application of the asphalt surface overlay. The binder

provides a bond between the existing surface and the new overlay.

Types of BitumenThe types of bitumen to be used are listed in table 3.5 below and are here further explained.



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Bitumen DesignationType of paving Straight

Run80 -100

Emulsion

CRS1 orCRS2

Rapid

curingRC 250

Rapid

curingRC 800

Medium

CuringMC 70

Medium

CuringMC 250

Medium

CuringMC 800

Tack Coat * * *Prime Coat * * * * *

Single/Doublesurface treatment

* *

Bitumen SandSeal

* * * *

Asphalt ColdMix

* * * *

Table 3-5. Types of bitumen.

For the bitumen primer low viscosity cutbacks are preferred usually of the medium curing

type. The denser the texture of the surface the lower the viscosity of the primer required togive adequate penetration. When straight run bitumen is to be cut back, 60/70 or 80/100

penetration bitumen may be used cut back with kerosene in the proportions 8 parts keroseneto 10 parts bitumen.

For the tack coat a rapid setting bitumen cut back or emulsion should be used. When straightrun bitumen (60/70 or 80/100 penetration) is to be cut back, the proportion should be 25-30

parts of kerosene to 100 parts bitumen.

Application RatesBitumen primer: Spraying rate will depend on porosity of the base coarse layer.

Low porosity layer (dense graded surface)from 0.5 l/m2 - 1.1 l/m2

High porosity layer (deficient in fine aggregate)from 0.8 l/m2 - 1.4 l/m2

Tack coat: Spraying rate will depend on condition and type of pavement surface asshown below:

Spray Rate (litres/square meter)

Type of binder New Surface Old weatheredsurface

Cut Back 0.15 0.15 - 0.35

Emulsion 0.20 0.20 - 0.50

Preparation of surface For surface priming

For preparation of an unsealed granular base layer, attention should be given to degree ofcompaction and to surface texture and shape. Defects due to insufficient compaction



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density, surface tolerances, and depressions should be corrected. The surface should thenbe swept to remove loose stones and dirt.

For laying tack coat

For preparation of a sealed pavement in readiness for surface overlay treatment the surfaceshould be inspected and defects such as potholes, edge breaks and depressions correctedwell in advance. The surface should be cleaned (by sweeping) of any loose or foreignmaterial with particular attention to removal of any shoulder material deposited on the

pavement. Any utility covers or manholes should be marked and recorded for later raising.

Application of Prime and Tack CoatsThe prime and tack coats should be applied by Bitumen distribution/sprayer in single sprayingoperations. For small areas, or where a mechanical sprayer is not available, application by handspraying or brushing may be necessary.

Quality Control The quality of the cut back bitumen or emulsion should be checked and certified A daily record of surfacing operations should be maintained, including measurement of

application rates achieved, and inspection of the treated surface to ensure proper anduniform coverage.

3.2.5.3 Single Surface TreatmentDescription: Used as a reseal over an existing pavement, or as first stage treatment over

reconstructed section of pavement.Aggregate: Single size screened and washed size 19 or 12 mm.Bitumen: Straight run 80 - 100 penetration or emulsion CRS 1 or CRS 2

Adhesion: Cutter oil (5 % kerosene) may be usedApplication Rates:

19 mm 12 mm Unit of measurement

Aggregate 50 - 65 65 - 80 m2 / m3

Binder 2.4 - 1.8 1.9 - 1.6 l / m2

85 - 100 Temperature range 1350 - 1760

Note: For bitumen emulsion increase rate by 50 %.

Normal Tests for Quality Control:Tests Limits

Los Angeles Abrasion 30% - 35% Maximum Sieve Analysis Retained on 4.75 mm sieve 90 minimum ALD and Shape

Aggregate PassingSieve mm

Minimum ALDmm

19 10

12 6

9 5

6 -

Temperature Control 10% of specified temperature



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3.2.5.4 Double Surface TreatmentDescription: New surface seal to compacted base course or reconstructed section of

pavement.Aggregate: Single size screened and washed:

Size 1st coat 19mm 12mm2nd coat 9mm 6mm

Bitumen: Straight run 80 - 100 penetrationAlternatively Emulsion CRS 1 or CRS 2

Adhesion: Cutter oil (5% kerosene) may be usedApplication rates:

19 mm 12 mm 9 mm 6 mm Unit of measurement

Aggregate 50 - 65 65 - 85 100 - 125 200 - 250 m2 / m3

Binder 85 - 100 2.4 - 1.8 1.9 - 1.6 1.2 - 1.0 1.0 - 0.8 l / m2Note: For bitumen emulsion increase rate by 50%

Normal tests for Quality Control:Test Limits

Los Angeles Abrasion 30 - 35 % Maximum Sieve Analysis Retained on 4.75mm sieve 90% minimum ALD and Shape See table in section 3.2.5.3 Temperature Control 10% of specified temperture3.2.5.5 Bitumen Sand Seal

Description: Short term reseal to an existing sealed pavement or to a reconstructedsection of pavement. Also used as temporary seal for pavement repair.

Aggregate: All passing 9.5 mm.Range mainly 2.38 mm - 2.75 mmRetained on 0.075 mm sieve - 90%

Bitumen: Straight run 80 - 100 penetrationEmulsion CRS 1 - CRS 2Rapid Curing RC 250

Application Rates:

Surface Bitumen (l / m2) Aggregate (kg / m2)

Unpaved 0.6 - 1.5 5 - 8

Paved 0.5 - 1.0 5 - 8

Normal tests for Quality Control:Test Limits

Sand Equivalent 50 % Minimum Sieve Analysis Temperature Control 1240C - 1620C



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3.2.5.6 Cold Mix AsphaltDescription: Cold mix for use on roads with low to medium traffic. To include:

Patching and minor repairs

Shape correction Edge widening Overlays

Thickness: Average compacted thickness from 2 - 5 cm in accordance withrequirements.

Aggregates: Two classes of mix are provided.Coarse grade maximum 20 mm nominal sizeFine grade maximum 9.5 mm nominal size

% by Weight Passing

Sieve Size mm 10 mm 19 mm

CoarseGrade

20 - 100

12.7 100 30 - 1009.5 85 - 100 0 - 55

4.75 20 - 45 0 - 100.075 0 - 5 0 - 2

Fine Grade 9.5 1004.75 90 - 1002.36 80 - 1000.6 25 - 100

0.075 0 - 11

Bitumen for Cold MixTwo main types of liquefied Bitumen are available for cold mix:i. Cut back bitumen available in three grades depending on the type and amount of solvent

used to make the bitumen liquid: Rapid Curing (RC) - blended with solvent such as naphtha or petrol.

Medium Curing (MC) - blended with kerosene or mineral turpentine. Slow Curing (SC) - with addition of flux oil, such as industrial diesel oil.

ii. Bitumen Emulsion - The bitumen is liquefied by mixing with one or more emulsifying andstabilising agents. The emulsion is classified as anionic (alkaline emulsifier) or cationic(acidic emulsifier). Cationic emulsions perform better under wet weather conditions and

can be used with a wider range of aggregates.

Grades of bitumen to use (see also table in section 3.2.5.2)Cut back bitumen - MC 70, MC 250, MC 800Bitumen Emulsion - CRS 1 and CRS 2

Rate of spread: Dependent on nature of work and layer thickness, and to be determined bytrials tests. Limits to be followed:MC 800 = 75 - 90 l/m3 aggregate



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CRS 2 = 125 - 145 l/m3 aggregate

Mixing Plant: For major works, a purpose built cold mix plant. For minor works, concrete

or paddle mixer minimum capacity 200 litres.

Spreading: For major works, mechanical paver. For minor works, carried out manuallyusing hand tools.

Note: Surface overlay work by mix-in-place methods to be used where no paver is available.Mix materials to be laid on primed surface of road and spread with grader

blade in thin layers to required thickness and cross section.

Compaction: Patching and minor works by vibrating tamper or pedestrian roller. Surfaceoverlay by smooth steel wheeled roller.

Blinding: A light blinding of the compacted surface is recommended with sand orcrusher dust.

Testing: Standard AASHTO test methods to be followed. A full list as below: Sampling of Bituminous Material - T 40 - to meet spec. req. Los Angeles Abrasion - T 96 - 40 % maximum Sieve Analysis of Fine & Coarse Aggregate - T 27 Unit weight of aggregate - T 19 Sand Equivalent - T 176 Rate of Spread - Field Control Measurement

3.3 Maintenance of Paved Roads

3.3.1 Patching of Potholes and Repair of Depressions

The Contractor will make sure that the pothole patching is done according to the requirementsgiven in the Technical Specifications or as to the directions of the Engineer.i. Excavate pothole or depression down to firm base with square cut sides and remove all

loose material. If found necessary also remove defective subgrade material.ii. Replace where necessary with approved subgrade material and compact with mechanical

rammer. Apply light tack coat of hot bitumen or cold emulsion with handspray to base and

sides.iii.Place base course aggregate in 10 cm layers (depending on depth) and hand tamp. Build thebase course up to within 5 cm of the pavement surface.

iv. Apply tack coat to base course aggregate and lay the prepared cold mix asphalt to acompacted thickness of 5 cm to bring to level slightly above surface.

v. Finish with final compaction using vibrator roller.

3.3.2 Repair of Surface Cracking

To repair isolated and minor non-structural cracking the following method shall be adopted bythe Contractor:



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i. Sweep and clean pavement surface and apply bitumen binder over dry surface using eithermechanical sprayer or handspray at approximately ratre of 1.5 liters/sq.m. (double for

bitumen emulsion).

ii. Cover binder with sealing aggregate or coarse sand spread at approximately rate of:For single size aggregate = 70 sq.m/cu.mFor coarse sand = 10 sq.m/cu.m

iii. Compact with 6 - 8 tons tandem roller or use pedestrian roller for small areas.iv. Where isolated cracking in the pavement is too wide to bge sealed with BURAS, the

altenative method shall be to seal each crack indiviually:

before sealing, the wide cracks shall be raked out to remove all dirt and debris. Bitumen cut-back or emulsionshall then be poured by can into each crack until thecrack is full.

Fine aggregate shall be added and sand shall be applied to the surface as a blotter for excessbitumen immediately after pouring.

3.4 Maintenance of Unpaved Roads

3.4.1 Patching of Potholes and Repair of Depressions

Deep potholes ( > 20 cms ), soft spots and depressions shall be repaired by hand in accordancewith the Engineers instruction and to the following method. The potholes or depressions shall

be cut back and boxed down to subgrade level. The subgrade shall be properly compacted andthe holes refilled with subbase material Class A as specified which shall be laid and tamped in10 cm layers. The top surface shall be laid with gravel as specified to a depth of 10 cm andcompacted by maintenance roller. Small areas may be compacted with mechanical rammer

according to the Engineers approval.

3.4.2 Grading of Roads

The grading of roads shall carried out according to the method described in the TechnicalSpecifications and to the Engineers approval. Grading shall preferably be carried out when the gravel surface is damp or after rain. If

grading is carried out during dry weather a water tanker should be made available to workwith the grader and spray the surface

For routine maintenance after heavy rain priority shall be given to grading out surfacescour and filling in wheel ruts.

Grading shall provide for a surface camber or crossfall of between 4% - 6%. High ridges of gravel which form at the road edges shall be graded into the middle of he

road and where necessary raked by hand to remove all oversize stone.The section of road to be graded shall be limited to the length which can be fully completed inone days work. Where traffic is heavy the length of road for grading shall be limited to a

practical length to minimise obstruction to traffic.

3.5 Maintenance of Shoulders

The shoulders shall be cut and reshaped by Motor Grader of Tractor using available materialon site. The shoulders shall be cut flush with the road edge and provided with crossfall of 5% -6% towards the side drain in accordance with the Engineers approval.



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Final trimming shall be carried out by hand labour and all surplus material includingvegetation, shrubs and other debris shall be removed from site in accordance with theinstructions of the Engineer.

3.6 Maintenance of Roadside Drains and Culverts

The maintenance of drains and culverts will be done according to the method described below.Roadside drainsi. All vegetation, sediment and other debris shall be removed from the drains and catchpits

and transported from site.ii. Earth drains shall be cut and trimmed to the required profile and grades necessary in

accordance with the Drawings and to the approval of the Engineer.iii. Lined drains in damaged or deteriorated condition shall be repaired with new mortared

stonework to the required profile as shown on the Drawings and to the approval of the

Engineer. Where so required new concrete foundations shall be provided. Back filling shallbe placed and compacted using selected material as directed by the Engineer.

Culverts, including Head and Wing Wallsi. All vegetation, sediment and other debris shall be removed from the culvert and from the

channel adjacent to the inlet and outlet of the culvert, and transported from site.ii. The culvert pipes, head and wing walls shall be inspected and any damage recorded and

reported to the Engineer.In accordance with instructions from the Engineer the Contractor shall carry out minor repairworks to the culverts, including mortar grouting to broken joints, and replacing damagedsections of mortared stonework or concrete to head and wing walls. Repair works to damaged

culvert pipes shall include all work which can be effectively carried out within the culvert pipe,without excessive excavation.



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4. SITE CONTROL REQUIREMENTS

4.1 Control of Construction Site and Equipment

The Supervising Engineer shall inspect the site and equipment provided for use on the projectsite, and shall verify registration and log records to ensure that they meet requirements for thework and are in accordance with the site schedule. Where any item of the equipment is founddefective or unsuitable he will request