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Methods of Pavement Design

Four Groups:

1. Group A2. Group B3. Group C

4. Group D

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Group A:

Empirical Methods using no soilstrength tests (Basic properties of soils

are involved)

• U.S. Highway Engineers Group IndexMethod

• Civil Aeronautic Administration, USAMethod

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Group B:Empirical Methods using soil strength(CBR Test is generally performed)

• CBR Method• North Dakota Cone Method• U.S. Navy and Flexible Pavement Committee

Method• Canadian Department of Transport Method

• Markwick Method for Rigid Pavement• Overseas Road Note-31• AASHTO Design Guide

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Group C:Methods based partly on theory and partly onexperience(Fundamental stress strain properties of subgradesoi ls and sometimes the base material aredetermined by shear or bearing test)

• Westergaard’s Method ( based on Plate Load Test)• Shear Strength Method• Golder’s Method• Kansas Highway Department Method• V. R. Smith Method

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Group D:Wholly Theoretical Method(These are based on mathematicalanalysis of the stresses and strains

throughout the pavement and subgradeand the true stress straincharacteristics of the variousmaterials)

• Burmster’s Analysis and DesignMethod

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PAVEMENT DESIGN BY

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Important Aspects:

• CBR > 80% for Base Material• If CBR > 30% for subgrade, then Sub-base

is not required• If subgrade has CBR < 4%, then use

Capping Layer • There are two types of Surface Dressings

1. Single Surface Dressing2. Double Surface Dressing

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Single &DoubleSurface

Dressing

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ROAD NOTE-31 Important Aspects:

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• Parent fines are the fines developedduring crushing of rocks. These areusually 5 mm or less in size. These should

be used to fill the voids of aggregates.• Macadam developed the design procedure

for the construction of pavements.

• Particle size is 37.5 mm or 50 mm in DryBound Macadam and Water BoundMacadam.

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• In Dry Bound Macadam, vibrations areused to fill the parent fines into the voids ofgravels.

• In Water Bound Macadam, water is usedto fill the parent fines into the voids ofgravels. This technique gives better resultsnormally to fill the voids. But if the

subgrade is clayey then water will reduceits strength.

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Pavement Components NomenclatureRoad Note-31

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ROAD NOTE-31-DESIGN STEPS

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DETAILED DESIGNFLOW CHART

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ROAD NOTE-31CHART-1

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ROAD NOTE-31CHART-7

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ROAD NOTE-31CHART-8