Characterization of LTPP Pavements using Falling Weight Deflectometer

In this paper, the characteristics of the falling weight deflectometer (FWD) deflection were studied using a simplified deflection model in the form of Y = K1 exp (-X/K2) + Y0. The exponential curve was found to have the desired characteristics which match the FWD deflection bowls. In the equation, Y is the FWD deflection in microns and X is the radial distance in millimetres. The coefficients K1 and K2 of the model describe the structural characteristics of the pavements. The deflection model has been adopted in assessing the structural characteristics of road pavements in several City and Shire Councils in Southeast Queensland (SEQ). FWD deflection data used in the study are obtained from the 65 long term pavement performance (SEQ-LTPP) sites located within the region. The results indicate that the coefficient K1 and K2 are unique for each of the LTPP section selected in the study. The study suggests that the coefficient K1 is closely related to FWD deflection D0 and K2 is dictated by the strength of the pavement layers. The simplified deflection model developed in the study can be used to delineate the pavements with cement stabilised and natural gravel bases and pavements with poor subgrade.