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HIGHWAYENGINEERING

5-3 AGGREGATE FOR PORTLAND CEMENT CONCRETE PAVEMENT

5-4 MINERAL FILLER

5-5 BITUMINOUS MATERIALS

5-6 BITUMINOUS BINDERS


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5-3 AGGREGATE FOR PORTLAND CEMENT CONCRETE PAVEMENT

In order to obtain high quality concrete, road agencies have imposed almost withoutexception that all aggregates shall pass appropriate tests for strength, soundness, wear or thecombination of these three.

1. The presence of organic impurities in the aggregates intended for concreting road pavementmay cause slow or non-hardening of the concrete. Under ASSHTO T-21 standard test, theaggregate is treated with a mixture of sodium hydrochloride solution, and when the aggregate

turns dark, organic materials are said to be present in the aggregate.

2. The strength of fine aggregate is measured by the compression tests of sand-cement mortar.

3. Soundness of fine aggregate is measured by the resistance to deterioration under the action ofSodium or Magnesium Sulfate. The sodium sulfate test is five cycles. The maximum loss underASSHTO specification is 10%.

4. For Coarse aggregate the requirement consists of crushed stone, gravel, blast furnace, slag orapproved inert materials of similar characteristics or combination thereof having hard, strongdurable pieces free from adherent coatings.


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The Department of Public Works and Highways Standard Specifications

classify aggregate under item 703 and specifically provides that:

1. Aggregate shall consist of hard, durable particles or fragments of crushed stone,crush slug or crushed natural gravel. Material that breaks up when alternativelywetted and dried shall be discarded.

TABLE 5-2 MAXIMUM AMOUNT OF DELETERIOUS MATERIALS

PERMITTED IN COARSE AGGREGATE FOR CONCRETE

AASHTO M-80

MaterialsMaximum AllowablePercent by Weight

Pavements Bridge Deck

Chert (2.40 specific gravity) 3.00% 3.00%

Coal and Lignite 0.5 0.5

Clay Lumps 3 2

Material Passing No.200 Sieve 1 1

Sodium Sulfate Soundness 12 12

Magnesium Sulfate 18 18


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CHERT COAL LIGNITE

Aggregates soundness test before Aggregates soundness test after


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2. Coarse aggregates is the material retained on the 2.00 mm (No.10) sieve and shall have apercentage of water not more than 50 for sub-base and not more than 45 for base and surfacecourses as determined by ASSHTO designation test T-96.

3. Fine aggregate is the material passing the No. 10 sieve (2.00 mm) consisting of natural,crushed sand, and fine mineral particles. Thefraction passing the 0.075 mm (No. 200) sieve shouldnot be greater than 0.66 (2/3) of the fraction passing the 0.425 mm (No. 40) sieve.

4. For Base coarse, the fraction passing the 0.425 mm (No.40) sieve shall have a liquid limit of notmore than 25 and a Plastic Index (PI) not greater than 35, and Plastic Index not greater than 12.

5. For Surface coarse, the fraction passing the 0.425 mm (No.40) sieve shall have a liquid limit ofnot more than 35 and Plasticity Index not less than 4 nor exceed 9.

AASHTO Designation M-80+ Based on Standard Sizes of Coarse for Highway Construction AASHTO Designation M-43# Note more than 5% shall pass a No. 8 sieve

TABLE 5-3 SELECTED GRADING OF COARSE AGGREGATE FOR CONCRETE

Range in sizeSize + Percentage by Weight Passing L aboratory Sieves Having Square Openings

Number 2-1/2 2 1-1/2 1 3/4 1/2 3/8 No. 4

1-1/2 " to No. 4 7 - - - - 100 90-100 40-70 0-15#

3/4 " to No. 4 67 - - - 100 90-100 - 20-55 0-10#

1 " to No. 4 57 - - 100 90-100 - 25-60 - 0-10#

1-1/2 " to No. 4 467 - 100 95-100 - 35-70 - 10-30 0-5

2 " to No. 4 357 100 95-100 - 35-70 - 10-30 - 0-5

1-1/4 " - 3/4 " 4 - 100 90-100 20-55 0-15 - 0-5 -

2-1 Inch 3 100 90-100 35-70 0-15 - 0-5 - -


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Limerock base course

Coarse aggregates Fine aggregates
http://www.pavementinteractive.org/wp-content/uploads/2010/12/Base.jpg


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5-4 MINERAL FILLER

The strength of road pavement will increased in dust additives which dense the gradedmixture is added. It is called mineral filler that reduces the void contents in the mixture, this dustadditive is not the ordinary dust that is being found in our floor or tables.

Dust additive is classified into:

1. Finely Powdered Limestone2. Slag3. Hydrated Lime4. Portland Cement5. Trap Rock Dust

6. Fly Ash

The DPWH Standard Specifications relative to mineral filler states that:

Mineral filler shall consist of finely divided mineral matter such as rock dust, slagdust, hydrated lime, hydraulic cement, fly ash or other suitable mineral matter. It shall be freefrom organic impurities and at the time of use shall be sufficiently dry to flow freely and shall beessentially free from agglomerations

AASHTO M-17 provides that:Percentage passing by weight shall be as follows:

No. 30(0.66 mm) sieve 50No. 50(0.30 mm) sieve 95-100No. 200(0.075 mm) sieve 70-100

AASHTO further stipulates that all minerals other than hydrated lime or Portland

cement, the Plastic Index (PI) value shall be 4 or less.


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Finely powdered limestone Slag Hydrated lime

Mineral filler Portland cement

Fly ashTrap rock dust


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Bituminous material or Asphalt in short, is a viscous liquid used asbinders for aggregates in road construction. At normal temperature, asphalt iseither slightly thicker than water or hard but brittle material that breaks a hammerblow when cold.

1. Bituminous material is in liquid form when mixed or combined withaggregates. This liquid form maybe produced either by heating the hard

asphalt, by dissolving in solvent or by emulsifying in water however, there arebituminous liquid materials available and ready for use.

2. The action of asphalt binder depends on its type and the aggregate it iscombined with. The purpose of the asphalt binder is to resist the abrasive forcetrue heavy traffic.

3. If road pavement is the open type, consisting entirely of coarse particles andasphalt, heavy binder is needed requiring more asphalts. On the other hand, ifthe aggregates in the pavement contains fine particles, cohesion will bedeveloped by surface tension in the thin asphalt film surrounding the fineparticles. Hence, less viscous asphalt is required.

5-5 BITUMINOUS MATERIALS


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+ F=9/5C+32

$ Temp. of the emulsified asphalt in the pugmill mixtureIi Rapid curing RC grades are not recommended for hot pugmill mixing

** Max. Temp. asphalt cement and cutback asphalt shall be below that at which fogging occurs.

TABLE 5-4 SUGGESTED SPRAYING AND MIXING TEMP. (C)

FOR BITUMINOUS MATERIALS AND ROAD TARS*+

Type and Grade of Asphalt

Pugmill Temperature + Spraying Temperature**

Dense Grade Open Grade Road Surface

Mixes Mixes Mixes Temp.

Asphalt Cement

AC-2.5 115-140 80-120 - 130+

AC-5 120-145 80-120 - 140+

AC-10 120-155 80-120 - 140+

AC-20 130-165 80-120 - 145+

AC-40 130-170 80-120 - 150+

AR-1000 105-135 80-120 - 135+

AR--2000 135-165 80-120 - 140+

AR-4000 135-165 80-120 - 145+

AR-8000 135-165 80-120 - 145+

AR-16000 150-175 80-120 -

200-300 pen 115-150 80-120 - 130+

120-150 120-155 80-120 - 130+

85-100 120-165 80-120 - 140+

60-70 130-170 80-120 - 145+

40-50 130-175 80-120 - 150+

Cutback Asphalt (RC, SC)

30 (MC Only) MC. 30+

70 20+ 50+

250 50-80ii 40+ 75+

600 75-100ii 55+ 95+

3000 80-150ii 110+

Emulsified Asphalt

RS-1, CRS-1 20-60

RS-2, CRS-2 50-80

MS-1, MS-2, CMS-2 10-70$ 20-70

MS-2h, CMS-2h 10-70$ 20-70

SS-1, CSS-1 10-70$ 20-70

SS-1h, CSS-1h 10-70$ 20-70

Road Tars

RT1-2-3 15-55 15-55

RT5-6 27-65 27-65

RT7-8-9 65-105 65-105 65-105

RT1-0-11-12 80-120 80-120 80-120


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5-6 BITUMINOUS BINDERS

Asphalt cement is used as binder for almost all high types of bituminous pavement.

Asphalt cement is a semi solid hydrocarbon retained after the fuel and the lubricating oils areremoved from the petroleum. The 60-70 penetrations is the hardest type .

penetration refers to the consistencies of asphalt cement as described underAASHTO-T49. it is the distance that the standard needle penetrates a sample under knownconditions of loading time and temperature. Recently, the procedure used in grading asphaltcement is the Viscosity Test rather then the Penetration Test.

Cutback or Liquid Asphalt

1. Liquid asphalt is a petroleum product consisting of asphalt cement with a liquid distillate(diesel, kerosene or gasoline). The less viscous asphalt contains diluents as little as 15%.

2. The use of cutback is being frowned for two reasons:

a. It is a usable fuel.b. It is an air pollutant.

3. Cutback or liquid asphalt is classified into:a. Slow curing (SC) road soil.b. Medium curing (MC) cutback asphalt.c. Rapid curing (RC) cutback asphalt.

Cutback or Liquid Asphalt


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Emulsified Asphalt

Emulsified asphalt is a kind of mixture wherein the minute globules of asphaltdisperses in water. Asphalt content ranges from 55% - 70% by weight. Emulsion couldbe applied or mixed at normal temperature, because when the water contentevaporates, the asphalt remains. It has the following characteristics.

1. Emulsified asphalt is excellent wit wet aggregate because the water medium carriesthe asphalt into a superior contact with the particle surfaces.

2. Emulsified asphalt is an alternate to cutback asphalt for energy and environmentalobjectives. It is an effective material in coating electropositive aggregate such aslimestone but tend to strip from aggregates with high content of silica for having strongelectronegative surface charges.

3. The Cationic Emulsion is very effective on high siliceous aggregates but may strip

from high alkaline that carry strong positive surface changes.

4. Rejuvenating Agent is an emulsified petroleum resin sprayed over the surface of anold asphalt road that changes to asphaltenes causing the binder to harden and cracks.The rejuvenating agent sprayed over the pavement and softening the binder. Too muchapplication however, produces a slick pavement surface.


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Cationic Emulsion Emulsified asphalt


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Oxidized Asphalt and Road Tar

Oxidized asphalt is suitable only for roofing and similar application. Highway used ofoxidized asphalt is limited to water proofing of structures and filling joints of concrete pavement.

Road tar is by-product of the distillation process of coal. Tars are produced from

gashouse coal tar, cook oven tars and water gas tar.The AASHTO classification of coal tars includes RT-1 to RT-12 and RTCB-6.RT-1 is suitable for application as tack of Prime Coat at normal temperature.

The DPWH Specifications Classify Bituminous Tack Under Item 302 which provides

that:

1. Bituminous materials shall be either Rapid Curing Cut Back or Emulsified asphalt.

2. Tack Coat shall be applied only to dry surfaces or slightly moist. No tack coat shall be appliedwhen the weather is either foggy or rainy.

3. Immediately prior to the application of Tack Coat, the road surfaces lightly sprayed with water, but

not to be saturated.

4. The rate of application of either the Rapid Curing, Cut Back or Emulsified asphalt is within therange of 0.2 to 0.7 liter per square meter. Any excess of this specified quantity should be blotted

by sand or removed.

5. Tack Coat shall be sprayed not only as far I advance on the surface course as will permit I to dryand tacky condition. Traffic shall be kept off the Tack Coat until after fully dried.


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Oxidized asphalt

Tack Coat


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Bitumen-Rubber mixture

The bitumen rubber mixture for road pavementwas experimented in Holland in the year 1929. It was adopted inthe United States in 1947 and later, in European countries. Theassessments of the road states:

1. Very little improvement gained as far as coefficient of frictionon newly laid pavement but expect higher advantages after sixmonths. The analysis of the Bureau of Public Roads states that:

An appraisal of the real economic value of the additionof rubber to asphalt must wait on further observation of the

behavior of experimental pavements under the influence ofage, weather and traffic.

2. According to the report, powdered rubber foams added tobitumen has improved the stability of some but not all.


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Epoxy Resin as Binders

Epoxy binders are produced in a clear, dark, rigid and flexible form forapplication to either concrete or asphalt pavement. Hardening can be attained by mixingthe resin and the catalyst hardener prior to application. The result is called thermosetting.

Meaning, it will not soften under the influence of heat or the action of solvent like water orpetroleum products. The high cost of resin has restricted its use to bridge surfacing andother special non-skid seal coating surface only.

1. Test of consistency is subdivided into:

a. Kinematics Viscosity test AASHTO T-202b. SAYBOLT-FURAL TEST AASHTO T-72c. Engler specific gravity test AASHTO T-54d. The float test AASHTO T-50e. Penetration test AASHTO T-49f. Softening point test AASHTO T-53

2. Test for durability AASHTO T-523. Test for solubility AASHTO T-444. Distillation test AASHTO T-78

5. Thin film oven test AASHTO-1796. Flashpoint AASHTO T-48%797. Test for homogeneity of petroleum asphalt AASHTO T-1028. Special test for emulsion asphalt AASHTO T-59

a. Test for demulsibility d. Cement mixing testb. Test for settlement e. Particle charge and PH Test

c. Sieve test f. Miscibility and freezing test

Test for Bituminous Binders


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KinematicsViscosity tester

Engler specificgravity tester

Thin film oven test Flashpoint tester

Particle charge and PH Tester

Cement mixing testerSieve tester

Softening point tester Distillation tester

The float testerPenetration tester

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