PAVEMENT EVALUATION TECHNIQUESNON DESTRUCTIVE TESTS&DESTRUCTIVE TESTS

NON DESTRUCTIVE TESTSFALLING WEIGHT DEFLECTOMETER ( FWD)BENKELMAN BEAM REBOUND DEFLECTIONPLATE LOAD TESTWAVE PROPAGATION TESTS

FALLING WEIGHT DEFLECTOMETER ( FWD)In falling weight deflectometer (FWD) test an impulsive load is appliedIt corresponds to the effect of loading due to standard axle on in-service pavement. The instantaneous deflections of the road surface is measured at a number of points at different distances radially outward from the centre of the falling weight. Thus, the shape of deflection bowl is obtained.

Data used to calculate the stiffness related parameters of pavement structure.The elastic moduli of individual layers in a multi-layer system can be calculated based on surface deflectionsHelpful in Overlay design

Back calulation to find E value

PLATE LOAD TEST

WAVE PROPAGATION METHODSGround Penetration RadarsSpectral Analysis of Surface Waves (SASW) Ultra Sonic Surface Wave (USW) MethodsUsed to determine pavement thickness as well as to determine linear elastic modulus of pavement layersThese methods operate by measuring surface seismic waves generated by an impulsive source

Advantages: This is a test method that can take the place of lab testing of cores or cylinders. Test can be made within hours of construction.

Limitations: These measurement systems must occupy a particular location to be tested and remain stationary during the measurement process, with set and measurement time proportional to the number of receivers used. Therefore, road and bridge closures would be necessary for surveying existing pavements.

DESTRUCTIVE TESTSTraditional test method to determine physical pavement properties Tests are conducted in test pits, samples are obtained from core borings, and laboratory tests are conducted on the samplesThese tests have the advantage of examining actual in-service materials

DisadvantagesDestructive tests are expensive, particularly considering the amount of testing necessary for a network-level surveyMost properties determined by destructive testing change very little between surveysDestructive testing can also have a significant impact on traffic.