Part 4 Unbound Pavement Materials

7/29/2019 Part 4 Unbound Pavement Materials

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Section 6 Part 04 General Specification

Rev. 0 1/10

TABLE OF CONTENTS

4.1 GENERAL ......................................................................................................................... 2

4.1.1 Scope ........................................................................................................................ 2

4.1.2 References ................................................................................................................ 2

4.1.3 Definitions .................................................................................................................. 3

4.1.4 Submittals .................................................................................................................. 3

4.1.5 Quality Assurance ..................................................................................................... 4

4.2 MATERIALS ...................................................................................................................... 4

4.2.1 Sources of Materials .................................................................................................. 4

4.2.2 Storage and Handling of Materials ............................................................................ 4

4.2.3 Inspection Testing and Control .................................................................................. 4

4.2.4 Fine Aggregate .......................................................................................................... 5

4.2.5 Coarse Aggregate ..................................................................................................... 5

4.2.6 Water ......................................................................................................................... 6

4.3 MAIN EQUIPMENT ........................................................................................................... 6

4.3.1 General ...................................................................................................................... 6

4.3.2 Paving Machines ....................................................................................................... 6

4.3.3 Central Mixers ........................................................................................................... 7

4.4 MIX DESIGNS ................................................................................................................... 7

4.5 SCREENING AND MIXING ............................................................................................... 7

4.6 SPREADING AND COMPACTION ................................................................................... 7

4.7 CORRECTIVE ACTION .................................................................................................... 8

4.8 PROTECTION OF SURFACE ........................................................................................... 9

4.9 TESTING ........................................................................................................................... 9

4.9.1 General ...................................................................................................................... 9

4.9.2 Compaction ............................................................................................................... 9

4.9.3 Gradation ................................................................................................................. 10

4.9.4 Thickness ................................................................................................................ 10

4.9.5 Evenness and Level ................................................................................................ 10


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PART 4 UNBOUND PAVEMENT MATERIALS

4.1 GENERAL

4.1.1 Scope

1. This Part includes materials, equipment and construction requirements forgranular base material (aggregate sub-base and road base courses).

2. Related Parts are:Part 1, GeneralPart 3, EarthworksPart 5, Asphalt Works

4.1.2 References

1. The following standards are referred to in this Part:

British Standards

BS 812, Testing aggregates

BS 1377, Methods of tests for soils for civil engineering purposesTest 1 Determination of the moisture contentTest 2 Determination of the liquid limit of soilsTest 3 Determination of the plastic limit of soilsTest 4 Determination of the plasticity index of soilsTest 6 Determination of the specific gravity of soilsTest 7 Determination of the particle size distributionTest 8 Determination of the organic matterTest 13 Determination of the dry density/moisture relationship (4.5 kg

rammer method)Test 15 Determination of the dry density of the soil on siteTest 16 Determination of the California bearing ratio.Test 16 Determination of the California bearing ratio.

BS 5930 Code for Practice for Site Investigations

ASTM

D 2607 Standard Classification of Peats, Mosses, Humus and RelatedProducts

D 2974 Standard Method of Test for Moisture, Ash and Organic Matter of

Peat MaterialsD 2975 Standard Method of Test for Sand Content of Peat MaterialsD 2976 Standard Method of Test for pH of Peat MaterialsD 2977 Standard Method of Test for Practical Size Range of Peat

Materials.

AASHTO

M 145 Classifications of Soils and Soil-Aggregate Mixtures for HighwayConstruction Purposes


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T 2 Sampling Stone, Slag, Gravel, Sand and Stone Block for Use asHighway Material

T 11 Amount of Material Finer than 0.075mm Sieve in AggregateT 27 Sieve Analysis of Fine and Coarse AggregatesT 86 Investigating and Sampling Soils and Rock for Engineering

Purposes

T 87 Dry Preparation of Disturbed Soil and Soil Aggregate Samples forTest.

T 88 Particle Size Analysis of SoilsT 89 Determining the Liquid Limit of SoilsT 90 Determining the Plastic Limit and Plasticity Index of SoilsT 93 Determining the Field Moisture Equivalent of SoilsT 96 Resistance to Abrasion of Small Size Coarse Aggregate by Use of

the Los Angeles Machine.T 100 Specific Gravity of SoilsT 104 Soundness of Aggregate by Use of Sodium Sulphate or Magnesium

SulphateT 143 Sampling and Testing Calcium Chloride for Roads and Structural

Applications.T 176 Plastic Fines in Graded Aggregates and Soils by Use of the Sand

Equivalent TestT 180 Moisture Density Relations of Soils using a 10 1b (4.54 kg)

Rammer and an 18 in (457 mm ) Drop.T 191 Density of Soil In-Place by the Sand-Cone MethodT 193 The California Bearing RatioT 204 Density of Soil In-Place by the Drive Cylinder MethodT 205 Density of Soil In-Place by the Rubber-Balloon MethodT 217 Determination of Moisture in Soils by Means of a Calcium Carbide

Gas Pressure Moisture tester.

4.1.3 Definitions

1. Optimum moisture content: the moisture content of soil at which a specificdegree of compaction will produce the maximum dry density whendetermined in accordance with AASHTO standard T180.

2. Maximum dry density: the dry density of soil obtained using a specificdegree of compaction at the optimum moisture content when determined inaccordance with AASHTO standard T180.

3. Sub-grade: the compacted existing ground or fill for 0.5m beneath formation.4. Formation: the completed earthworks level shaped in readiness to receive

the sub-base.5. Sub-base: the compacted fill material forming the layer between the

formation and the road base or base course.6. Road base: the compacted selected material forming the layer between the

sub-base and base course.7. Base course: the layer of bituminous material between the road base or sub-

base and the wearing course.

4.1.4 Submittals

The Contractor shall submit recent test results for the proposed sources ofmaterials for all quality requirements of the Contract.


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4.1.5 Quality Assurance

If requested the Contractor shall arrange for the Engineer to visit the source ofthe materials and jointly take samples for testing. The Contractor shall carry outtesting as directed by the Engineer.

4.2 MATERIALS

4.2.1 Sources of Materials

1. The Contractor shall notify the Engineer of the proposed sources ofmaterials.

2. The Engineer shall approve the sources before delivery of materials to thesite.

3. Where a proposed source of material is not approved, the Contractor shallpropose an alternative source of material.

4.2.2 Storage and Handling of Materials

1. Materials shall be so stored and handled as to assure the preservation oftheir quality and fitness for use in the works. Even after source approval hasbeen given materials may again be inspected and tested before use in thework.

2. Stored material shall be located so as to facilitate prompt inspection.3. All storage sites shall be restored to their original condition before

acceptance of the Works.4. Handling and stockpiling of aggregates shall at all times be such as to

eliminate segregation or contamination of the various sizes. Stockpiles shallbe kept flat, and the formation of high cone-shaped piles shall not be

permitted. When conveyor belts are used for stockpiling aggregates theEngineer may require the use of baffled chutes or perforated chimneys.

5. When trucks are used to construct stockpiles, the stockpiles shall beconstructed one layer at a time with trucks depositing their loads as close tothe previous load as possible. The use of tractors or loaders to push materialdeposited at one location to another location in the stockpile shall not beallowed during the construction of the stockpile and their use shall be limitedto leveling the deposited material only.

6. The Contractor shall take all necessary protection measures in the storage,handling and stockpiling of materials to prevent contamination of materialsby dust. The measures that the Contractor proposes to take shall be subjectto the approval of the Engineer.

4.2.3 Inspection Testing and Control

1. For verification of plant weights and measures, character of materials usedin the preparation of the mixes, testing and other quality controlrequirements, the Engineer shall at all times be provided access to allportions of the mixing plant, aggregate plant, storage yards, crushers andother facilities used for producing and processing the materials ofconstruction.


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2. The Engineer shall have authority to take samples and perform tests on anymaterial supplied to the site from any source whatsoever in order toestablish compliance and to accept or reject as He deems necessary.Samples shall also be taken from completed work to determine compliance.The frequency of all sampling and testing shall be as designated by theEngineer.

3. The Contractor shall provide suitable facilities at the quarry or plants to carryout all necessary tests on the raw materials and mixes.

4. The Contractor shall arrange for obtaining specimens of materials andsamples taken from stockpiles, including the provision of any necessaryequipment and plant. This work shall be performed in the presence of theEngineer if so directed by the Engineer.

5. Materials that are not in compliance shall be rejected and removedimmediately from the site of the works unless otherwise instructed by theEngineer.

6. Where defects in the materials or the completed work have been corrected,the Contractor shall not proceed with subsequent work until approval hasbeen given by the Engineer.

7. Materials which require drying before performing any of the designated testsshall be dried out at temperatures not greater than 100 C.

4.2.4 Fine Aggregate

1. Fine aggregate (passing the 4.75mm sieve) shall consist of natural sandand/or crushed mineral aggregate and shall be of such gradation that whencombined with other required aggregate fraction in proper proportions, theresultant mixture will meet the designated gradation. The parent rock of thecrushed mineral aggregate shall be Gabbro in accordance with Group 4 ofBS 812 or similar.

2. The fine aggregate shall be clean and free from organic matter, clay-balls

and other extraneous or detrimental materials.3. The ratio of fine aggregates passing the 0.075mm sieve shall not exceed

66% of the portion passing the 0.425mm sieve.4. The material passing the 0.425mm sieve shall have a maximum liquid limit

of 25% and the plasticity index shall not exceed 6%.5. Where the source of fine aggregate does not meet the above requirements,

the Contractor may, with the Engineer's approval, add fine aggregate andfiller to correct the gradation or to change the characteristics of the materialpassing the 0.425mm sieve so as to meet the requirements. Such additionalmaterial shall be added in a manner which ensures a completelyhomogeneous material.

4.2.5 Coarse Aggregate

1. Coarse aggregate (retained on the 0.425mm sieve) shall consist of crushedstone, crushed gravel with 50% by weight with fractured faces and shall beof such gradation that when combined with other required aggregatefractions in proper proportion, the resultant mixture will meet the designatedgradation. The parent rock of the crushed stone shall be Gabbro inaccordance with Group 4 of BS 812 or similar.

2. The flakiness index of the aggregate shall not exceed 35 % when tested inaccordance with BS 812.


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3. The percentage of wear of coarse aggregate shall not exceed 40 % whentested for resistance to abrasion in accordance with AASHTO T96.

4. The coarse aggregate shall be hard and durable and free from organicmatter, clay and other extraneous or detrimental materials.

5. Coarse aggregate shall be subject to the sodium sulphate soundness losstest in accordance with AASHTO T104. The maximum allowable sodium

sulphate soundness loss shall be 18 %.6. The total loss factor when tested in accordance with the 10 minute

immersed rotational test shall not exceed 20%. The test shall be carried outin accordance with one of the following appropriate standards: BS, ASTM orAASHTO.

4.2.6 Water

Sea and brackish or saline water shall not be used in the mixing, spreading andcompacting operations for granular base.

4.3 MAIN EQUIPMENT

4.3.1 General

1. Unless otherwise stipulated herein the provisions of Section 6, Part 3(Earthworks), in respect of the main machinery and tools used in earthworksconstruction, shall be adhered to, subject to the modifications and additionsin this clause.

2. The Contractor shall not be allowed to use any equipment or plant beforeobtaining the approval of the Engineer, and the Contractor shall undertakesound technical methods in operation and to engage skilled and trainedoperators, mechanics and labor to carry out the works.

3. The Engineer shall have the right to stop the use of any equipment or plant

which be deems to be inferior to the quality required and to instruct theremoval of such equipment and to have it replaced by suitable equipment orto alter the method of operation at any time he so desires.

4. The Contractor shall immediately comply with such instructions withoutbeing entitled to any indemnities or extensions as a result of suchinstructions.

5. The Engineer shall have the right to expel any operators, mechanics or laborand to instruct suitable replacement thereof at any time be deems suchaction is necessary.

4.3.2 Paving Machines

1. Paving machines shall be self-propelled and shall be capable of spreadingthe sub-base and base materials in one operation so as to make it ready forcompaction with minimum shaping.

2. The paving machines shall be provided with a screed that strikes off anddistributes the material to the required width and level.

3. The width of each spread shall not be less than a traffic lane wide.4. The screed shall be adjustable to the required width being laid.5. Screed action includes any practical motion that produces a finished surface

texture of uniform appearance.


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4.3.3 Central Mixers

1. A central mixing plant shall be either of an approved drum or pugmill typewith a moisture control system so that the material may be spread withoutfurther mixing or processing.

2. Means shall be provided for regulating the flow of material to the mixer. The

various feeds shall be calibrated to allow adjustments to the mix design tobe carried out.

4.4 MIX DESIGNS

1. Aggregate sub-base and base courses shall consist of crushed mineral aggregatesor natural mineral aggregates of the designated gradation and thickness.

2. The maximum dry density and the optimum moisture content of the material shallbe ascertained as per the test procedure given in AASHTO standard T180and thisshall be used to assess the degree of compaction of the mix after rolling.

3. The pavement layer designated as sub-base may be substituted by any of thematerials designated to be laid on it subject to the approval of the Engineer.

4. The particle size shall be determined by the washing and sieving method of BS812 : part 103.

5. Fine and coarse aggregates for sub base shall be a combined gradation of materialthat meets the requirements of the specification for density and other properties.

6. Fine and coarse aggregates for road base shall be a combined gradation ofmaterial that conforms to the gradation of Class 1 or 2 as follows :

Percent PassingBS Sieve (mm) Class 1 Class 2

63 - -50 100 -

37.5 70-100 -25 55-85 100

20 50-80 90-10010 40-70 50-855 30-60 35-65

2.36 20-50 25-500.425 10-30 15-300.075 5-15 5-15

4.5 SCREENING AND MIXING

1. Screening shall be required for the materials used in sub base and road base toensure that the designated gradation is attained.

2. Screens shall be of the size and number required to remove oversize aggregateand, if necessary, to separate the materials into two or more fractions so that theymay be combined to meet the required gradation.

3. A central mixing plant shall be used for the mixing of materials.4. Mixing of separate materials on the roadway by motor grader will not be permitted.

4.6 SPREADING AND COMPACTION

1. Before commencing the construction of the sub base and road base, writtenapproval for the Engineer must be obtained that the sub-grade is in compliance.


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2. The optimum moisture content of the material shall be noted from the mix designand the actual moisture content determined at the plant after mixing.

3. If the natural moisture content is less than the optimum moisture content, thenecessary amount of water must be added to obtain the optimum content.

4. Allowance shall be made for the quantity of moisture which may be lost byevaporation in the process of raking, leveling and compacting, depending on

atmospheric temperature.5. The compacted layer shall have moisture content within +/- 2 % of the optimum

moisture content.6. The moisture content shall be uniform in all parts of the section where the work is

being carried out and in the various depths of the layer thickness.7. Road base and Sub base may be laid by either a paving machine with a spreader

box or end tipped from trucks and spread by grader.8. Compaction shall start immediately the material has been laid and as per the

approved rolling pattern.9. Work on the sub-base and road base courses shall not be permitted during rainy

weather.10. Material shall be spread to a thickness that would result in layers not more than

150 mm thick after compaction. Where the finished compacted thickness exceeds150 mm placing shall be executed in composite layers each layer not exceeding150 mm in compacted thickness as directed by the Engineer.

11. The course shall not be rolled when the underlying material is soft or yielding orwhen the rolling causes a wave-like motion in this course.

12. When the rolling develops irregularities, the irregular surface shall be loosened,then refilled with the same kind of material as used in constructing the course andagain rolled.

13. Along places inaccessible to rollers, the sub-base or road base course materialshall be tamped thoroughly with suitable mechanical tampers to achieve therequired density and finish.

14. Rolling must continue until a relative density of not less than 100 % of the

maximum dry density has been obtained as determined by the moisture-densityrelationship in AASHTO standard T180.

15. Care shall be taken so that layers already compacted under the layer beingexecuted do not get damaged, or that the formation is not damaged.

16. This aspect must be given special attention in places where rolling equipmentmakes turns to change direction.

17. Any such damage resulting in mixing the various layers constituting the differentsub-grades and road base courses shall be carefully made good by the Contractorat his own expense and to the satisfaction of the Engineer.

4.7 CORRECTIVE ACTION

1. Any material that fails to meet test requirements shall either be reworked orremoved and replaced and then retested to check for compliance.

2. Any soft spots, irregularities or depressions that develop in the surface of the sub-base or road base, shall either be corrected by loosening the surface of such areasand adding further material, or by removing the material in such areas andreplacing with further approved material.

3. In the event of heave occurring during compaction, caused either by excessivebuild-up of pore water pressure or the groundwater table being sufficiently high toaffect construction techniques, either of the following procedures shall be adoptedsubject to the approval of the Engineer:


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a. sufficient time shall be allowed to elapse enabling the excess pore water todissipate before further construction or compaction is carried out

b. the affected material shall be removed, and approved alternative constructionlayers substituted.

4. For correction of low density or incorrect level, the top 75 mm shall be scarified,reshaped with material added or removed as necessary and re-compacted to the

designated requirement. The area treated shall not be less than 30 meters longand 2 meters wide or such area determined by the Engineer as necessary to attaincompliance.

5. Where the surface of the sub-base is covered in a very thin smooth skin composedof fine particles cemented together acting as a barrier to the prime coat the top75mm shall be scarified , reshaped, watered if necessary, and re-compacted priorto the application of prime coat.

6. The Contractor shall carry out additional testing if required by the Engineer toensure that the standard of compaction is satisfactory through the full depth of thelayer.

4.8 PROTECTION OF SURFACE

1. The Contractor shall protect the sub-base or road base course so that it shall bemaintained sound during work progress, after its completion and before receivingthe bituminous layers or before laying the surface overlay thereon.

2. Any damage caused to the layer if exposed to traffic or natural conditions resultingin damage to its surface shall be made good at the expense of the Contractor andto the satisfaction of the Engineer.

3. The Engineer has the right to stop all hauling over completed or partially completedsub-base and base courses when in his opinion such hauling is causing damage.

4. Following the completion of the sub-base or road base courses the Contractor shallperform all maintenance work necessary to keep the course in a condition forpriming.

4.9 TESTING

4.9.1 General

1. All testing shall be carried out in accordance with AASHTO T96, AASHTOT104 and the relevant Parts of BS 1377 or ASTM Standard Methods of test.

2. Prior to proceeding with the mixing of material individual stockpiles shall betested for compliance to the requirements of clause 4.2.

3. At any stage in the mixing, transportation, spreading or compactionprocess, the Engineer may instruct that these tests are carried out.

4. Before the application of any prime coat or any other paving course, the

aggregate sub-base and road base shall have been tested for compliancewith the requirements of this clause on testing and approved by theEngineer.

4.9.2 Compaction

1. The sub base or road base shall be compacted and tested for acceptancein accordance with AASHTO standard T180 and BS 1377 to attain aminimum density of 100 % of the maximum dry density of the material. Two


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tests every 500 m2 shall be carried out unless otherwise directed by theEngineer.

2. Wherever the degree of compaction is found to be less than required, thearea of sub-base or road base involved shall be satisfactorily corrected.

4.9.3 Gradation

1. The gradation of the placed material shall be checked by taking samplesfrom an area 0.5 m by 0.5 m from the full depth of the layer for every 1000m3 of laid material. The gradation shall be tested in accordance with BS812: Part 103.

2. The Engineer may also instruct that the gradation of material shall bechecked by taking samples from the mixing plant. The gradation shall betested in accordance with BS 812: Part 103.

3. Wherever the gradation is found to be outside the designated limits, thearea of sub-base or road base involved shall be scarified, removed orotherwise reworked as directed by the Engineer to provide a gradation incompliance.

4.9.4 Thickness

1. The thickness of the material shall be derived from checking the level bydipping from string lines stretched across the roadway between pins orkerbs. Unless agreed otherwise with the Engineer dipping shall be carriedout at intervals of not less than 10m.

2. The thickness of the material shall be derived at the location where thematerial is removed from the roadway for gradation analysis.

3. Wherever the thickness of compacted aggregate sub-base or road base isfound to vary from the thickness specified in the project drawings orspecification by more than 10 % the area involved shall be satisfactorily

corrected to provide the required thickness constructed to the designatedgrade level.

4.9.5 Evenness and Level

1. The final surfaces of the sub-base or road base shall be tested by means ofa 4 meter long straight edge and no rises or depressions in excess of 10mm shall appear in the surface.

2. The finished surface shall also be checked by dips or spot levels and shallbe constructed to the designated grade levels to within plus Zero mm andminus 20 mm.

3. Where these requirements are not met, the Contractor shall determine the

full extent of the area which is out of tolerance and shall make good thesurface of the course by scarifying to a minimum depth of 75 mm or 4 timesthe maximum particle size, whichever is the greater, reshaping by adding orremoving material as necessary, adding water if necessary and re-compacting.

END OF PART

Part 4 Unbound Pavement Materials

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