Benchmarking Falling Weight Deflectometer Deflection Bowl Parameters: Case Study for Indian Conditions and the Applications to Rehabilitation Design

Abstract

The paper presents the application of falling weight deflectometer (FWD) for the assessment of the structural capacity of a network of roads at district level by mechanistic-empirical technique and bench-marking of deflection bowl parameters to Indian conditions and demonstration of its application for the design of flexible pavement rehabilitation thicknesses. FWD and a road measurement and data acquisition system (ROMDAS) were used to collect the structural and functional condition data of in-service flexible pavements at network level. Homogeneous pavement sections were grouped based on the cumulative difference approach. The deflection bowl parameters were used to assess the structural condition of the pavements, based on the layer strength indices, i.e., base layer index (BLI), middle layer index (MLI), and lower layer index (LLI), which are developed for Indian conditions by relating the preceding indices with the measured performance. Back-calculated moduli values were used for the computation of the strains in the pavement layers. An attempt has been made to relate the structural condition indices with the critical strain values calculated (horizontal tensile strain at the bottom of bituminous layer and vertical compressive strain on top of the subgrade layer). The structural adequacy of pavement was assessed and the rehabilitation thickness was estimated using mechanistic-empirical design approach.