Structural Evaluation

8/12/2019 Structural Evaluation

1/12


2/12

RuttingSurface depression in the wheel path. Pavement uplift(shearing) may occur along the sides of the rut. Rutsare particularly evident after a rain when they are filledwith water.

Possible Causes: 1. Insufficient compaction of HMA layers during construction.2. Improper mix design or manufacture .


3/12

Corrugations A form of plastic movement typified by ripples(corrugation) or an abrupt wave (shoving) across thepavement surface. The distortion is perpendicular tothe traffic direction. Usually occurs at points where

traffic starts and stops (corrugation) or areas whereHMA abuts a rigid object (shoving).Possible Causes:

1. Usually caused by traffic action (starting and

stopping).2. Excessive moisture in the sub grade.


4/12

RavellingThe progressive disintegration of an HMA layer fromthe surface downward as a result of the dislodgementof aggregate particles.Possible Causes:

1. Loss of bond between aggregate particles and theasphalt binder.

2. Aggregate Segregation.3. Inadequate compaction during construction.


5/12

CrackingIt occurs due to the relative movement of pavementlayer materials, by the repeated application of heavywheel loads resulting in fatigue failure.Possible Causes:

1. Poor joint construction.2. A reflective crack from an underlying layer .


6/12

Patching An area of pavement that has been replaced with newmaterial to repair the existing pavement. A patch isconsidered a defect no matter how well it performs.Possible Causes:

1. Previous localized pavement deterioration that hasbeen removed and patched.

2. Utility cuts.


7/12

Pavement unevenness Important methods adopted to evaluate

surface conditions are1)Unevenness index2)Pavement serviceability index (PSI)3)Present serviceability rating(PSR)


8/12

Unevenness index

Unevenness of a road surface is a majordetriment to safety &efficiency of travel.

An equipment capable of integrating theunevenness of the pavement surface in(cm/km)length of road may be calledbump integrator.

The pavement unevenness is equated tothe riding quality by the given table


9/12

Unevenness index in

old pavements

Riding quality

Below 9595to11920to144

145to240 Above240

In New pavementBelow 120120to145

Above 145

ExcellentGoodFair

Poor(possibleresurfacing)Very poor(resurfacingrequired)

GoodFair (acceptable)

Poor(not acceptable)


10/12

Pavement serviceability index

This concept was introduced by American

Association of State HighwayOfficials(AASHO).

In this concept, the serviceability of thepavement is judged by a panel ofexperts ,by riding over the pavement.The experts are sensitive to theperception and wishes of the users.


11/12


12/12

Structural Evaluation

Deflection Method: A quality pavement elastically deformsunder wheel load application & there isan elastic rebound deflection of thedeformed pavement surface.

Structural Evaluation

Documents