Download - Asphaltic Concrete Mix Design

Asphaltic Concrete Mix DesignAsphaltic Concrete Mix Design

Seksyen Loji Dan KuariSeksyen Loji Dan Kuari

JKR Woksyop PersekutuanJKR Woksyop Persekutuan

KLKL

Construction Of Road in the 60’s by JKR

STILL Little PROBLEMS IN ROAD RESURFACING !

Is this JKR Works After 100 Years

Subgrade

Road StructureRoad Structure

Wearing Course

BinderCourse`

Roadbase

Sub-base

Cracking

CrackingCracking

Why cracking in asphalt surfacing undesirable?

1. It allows surface water to penetrate into the lower pavement layers, causing localised weakening of the pavement structure.

2. It reduces the dynamic modulus of the surfacing, making it less able to distribute imposed traffic loads.

PossiblePossible Causes of Cracking Causes of Cracking1. Excess fines in mixture.

2. Insufficient bitumen.

3. Insufficient compaction.

4. Improperly proportioned mixture.

5. Voids content too high.

6. Rolling when mixture too cold.

7. Overheating the bitumen.

8. Wet mixing time too long.

9. Improper joint preparation & construction.

10.Over Rolling - vibratory roller.

11.Too high amplitude - vibratory roller.

Rutting

RuttingRutting

Why rutting in asphalt surfacing undesirable?

1. It creates an irregular road profile, thus poor riding quality, dangerous to traffics.

2. It increases roughness, thus increases vehicle operating costs.

3. It allows surface water to accumulate, thus increases risk of skidding and aquaplaning, and water infiltration into pavement structure.

Possible Causes of RuttingPossible Causes of Rutting

1. Excess bitumen.

2. Excess fines in mixture.

3. Improperly proportioned mixture.

4. Excessive tack coat.

5. Excessive segregation.

Skidding

SkiddingSkidding

Does asphaltic concrete road surfacing lack the necessary macrotexture for skidding resistance at high speeds ?

Possible Causes of Smooth Possible Causes of Smooth Surface TextureSurface Texture

1. Excess fines in mixture.

2. Excess bitumen.

3. Over rolling.

4. Rolling when mixture too hot.

5. Excessive segregation.

6. Abrasion of aggregates by traffic.

Porous Asphalt

The solution ?

Stone Mastic Asphalt

Component Of AsphaltComponent Of Asphalt

AggregateAggregate FillerFiller BitumenBitumen

MECHANICAL PROPERTIES STANDARD REQUIREMENT

Crushing Value MS 30 < = 30Soundness AASHTO Test < = 12 %

Method T104Flakiness Index MS 30 < = 30Water Absorption MS 30 < = 2 %Polish Stone Value MS 30 > = 40( Wearing Course Only )

MARSHALL PROPERTIES WEARING BINDER

Stabilty > 500 kg > 450 kgFlow 2 mm - 4 mm 2 mm - 4 mmStiffness > 250 kg/mm > 225 kg/mmAir Void in Mix 3 - 5 Percent 3 - 7 PercentVoid in Aggregate Filled 75 - 85 Percent 65 - 80 PercentWith Bitumen

PHYSICAL PROPERTIES OF MIX AND MATERIALS

Bitumen Content 5.0 - 7.0 Percent ACW 14 Wearing5.5 - 6.5 Percent ACW 14 Binder4.0 - 6.0 Percent ACB 28 Binder

Density of Mix 2.33 mT per m3

SG Bitumen 80 - 100 1.022

Satu Ela Metal 0.667 mTSatu Ela Premix 0.625 mT

Satu mT Bitumen 20 mT PremixSatu litre Diesel 0.2 mT Premix 5 litre per mT Premix

MATERIALS STANDARD

JKR KUARI BUKIT PENGGORAK, KUANTAN

Aggregate - The Major Component Of Premix Production.

Basalt Granite

Coarse Aggregate TestingCoarse Aggregate Testing

1 Test Per Stockpile Per 2,500 Tons Of Asphaltic Concrete Produced;

* Aggregate Crushing Value.

* Sodium Sulphate Soundness.

* Flakiness Index.

* Water Absorption.

* Polished Stone Value (Wearing Course Only).

Limestones in wearing course?

Fine Aggregate TestingFine Aggregate Testing

1 test per stockpile per 2,500 tons of asphaltic concrete produced;

* Sodium Sulphate Soundness.

* Water Absorption.

Sand or quarry dust?

Fine aggregate: Natural sand, mining sand or quarry fines.

Cement or limestone?

Mineral filler: Rock dust, limestone dust, hydrated lime or hydraulic cement.

Anti-stripping agent: Ordinary Portland cement.

Material passing 75 um to bitumen ratio by weight 0.6 - 1.2.

Mineral Filler / Anti Stripping Agent

Bitumen grade: Penetration grade 80-100 (MS 124).

80-100 or 60-70 ?

Bitumen TestingBitumen Testing* Penetration.* Softening point.* Solubility in Trichloroethylene.* Ductility.* Flash point.* Retained penetration after thin film oven.* Loss on heating.

Test frequency: Not stated in JKR Guidelines or JKR/SPJ. Recommends one set of test per every bitumen delivery to the plant.

BITUMEN QUALITYBITUMEN QUALITY

PENETRATION TEST

penetrationvalue

in 0.1 mm

100 grammeneedle

bitumenat25

degreesCelsius

5 seconds

Mix Design

Mix Design RequirementsMix Design Requirements1. Grading of combined aggregates + filler -

Table 4.8 JKR/SPJ.

2. Bitumen content - Table 4.9 JKR/SPJ.

3. Marshall method of mix design - Clause 4.2.4.3 JKR/SPJ.

4. Test parameters of Marshall specimens - Table 4.10 JKR/SPJ.

5. Establish design aggregate grading and bitumen content with tolerances in Table 4.11 JKR/SPJ.


Table 4.8 JKR/SPJ.





Table 4.8 - Gradation Limits For Asphaltic Table 4.8 - Gradation Limits For Asphaltic

ConcreteConcrete

B.S. Sieve Size, mm % Passing By Weight20 100-10014 80-9510 68-90 5 52-723.35 45-621.18 30-450.425 17-300.150 7-160.075 4-10

SPECIFICATION

0

10

20

30

40

50

60

70

80

90

100

0.010 0.100 1.000 10.000 100.000

Sieve Size mm

% P

assi

ng


Table 4.8 JKR/SPJ.






Table 4.8 JKR/SPJ.





Table 4.9 - Design Bitumen ContentsTable 4.9 - Design Bitumen Contents

Class of Mix Normal Range of Design Bitumen Content by Weight of Mix

ACW 20 - WC 5.0 - 7.0 %

ACB 20 - BC 4.5 - 6.0 %

ACB 28 - BC 4.0 - 6.0 %

Clause 4.2.4.3 Asphaltic Concrete Mix Clause 4.2.4.3 Asphaltic Concrete Mix DesignDesign

1. Prepare specimens for standard stability and flow tests as per AASHTO T 245 using 75 blows/face.

2. Determine bulk specific gravity of specimens as per AASHTO T 166.

3. Determine stability and flow values as per AASHTO T 245.

4. Voids analysis; VMA, VFB, VIM.

Mix Design MethodMix Design Method

MS 535

Specification for asphaltic concrete for road pavement and airfield runway by the Marshall test method.

Asphalt Institute MS-2

Mix design methods for asphalt concrete.


Table 4.8 JKR/SPJ.





Table 4.10 - Test Parameters For Table 4.10 - Test Parameters For Asphaltic ConcreteAsphaltic Concrete

Parameter WC BC

Stability S > 500 kg > 450 kg

Flow F > 2.0 mm > 2.0 mm

Stiffness S/F >250 kg/mm >225 kg/mm

Air voids in mix 3.0 - 5.0 % 3.0 - 7.0 %

VFB 75 - 85 % 65 - 80 %


Table 4.8 JKR/SPJ.





Table 4.11 - Tolerances For Asphaltic Table 4.11 - Tolerances For Asphaltic

Concrete MixesConcrete Mixes Parameter Permissible Variation

% by weight of total mix•Bitumen content. +/- 0.2 %•Fractions of combined aggregate passing 5.0 mm and larger sieves. +/- 5.0 %•Fractions of combined aggregate passing 3.35 mm and 1.18 mm sieves. +/- 4.0 %•Fractions of combined aggregate passing 425 µm and 150 µm sieves. +/- 3.0 %•Fraction of combined aggregate passing 75 µm sieve. +/- 2.0 %

Trial LayTrial LayA minimum of 10 tons of each mix shall be placed in trial areas to demonstrate to the satisfaction of S.O. that the mixing, laying and compacting equipment conforms to the requirements of the specification, and that the proposed mixes are satisfactory. 1. Rollers.2. Paver.3. Trial site.4. Tests on premix sample :

Binder content & aggregate grading.Theoretical maximum specific gravity.Prepare Marshall specimens.Specific gravity, volumetric properties, Marshall stability and flow of Marshall specimens.

Trial Lay - ContinueTrial Lay - Continue5. Record temperatures of premix on lorry, at plant and site.6. Record laying temperatures.7. Record laying thickness.8. Check texture of paved surface.9. Record rolling temperatures.10. Record rolling pattern.11. Check texture and condition of compacted surface.12. Record compacted thickness and density from core samples.13. Check consistency in production.14. Check at least one longitudinal joint.

Temperature Of Bitumen < 177 C (350 F)

Aggregate Stockpile

Each aggregate shall be stored in a separate stockpile. Stockpiles of sand and other fine aggregates shall be kept dry using waterproof covers or other means.

Aggregate Grading TestAggregate Grading Test

Batch plant - 1 test per hot bin per day of production.

Drum mix plant - 1 test per cold bin per day of production.

Temperature < 163 C (325 F)

Sampling of premix

Sampling of PremixSampling of Premix

Sample quantity:> 20 mm (eg. ACB28) - minimum 24 kg.< 20 mm (eg. ACW20) - minimum 16 kg.

Sampling from lorry:> 20 mm - take 4 increments.< 20 mm - take 3 increments.One increment approx. 7 kg (use size 2 square-mouth shovel).Scoop 100 mm below surface.

Testing of PremixTesting of Premix

1 test per 200 tons of asphaltic concrete produced;

* Bitumen content & grading.

* Maximum specific gravity.

* Preparation of Marshall specimens.

* Bulk specific gravity of Marshall specimens.

* Volumetric properties (VMA, VFB, VIM).

* Marshall stability & flow.

Density and Thickness RequirementDensity and Thickness Requirement

1. Required compacted density;

Wearing Course : 98 - 100% Marshall density

Binder Course : 95 - 100% Marshall density

2. The average thickness over any 100 metre length shall be not less than the required thickness. The minimum thickness at any point shall be not less than the required thickness minus 5 mm.

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