Comparison of Structural Performance of Low Volume Roads in Kerala Using Falling Weight Deflectometer

The study aims to evaluate the structural adequacy of Low-Volume Roads (LVRs) in Kerala using the Falling Weight Deflectometer (FWD). The analysis of pavement deflection data involves a back-calculation process, where pavement layer moduli are derived from deflection values obtained via FWD. This process utilizes specialized software and customized programming. Specifically, the KGPBACK software package is adopted for back-calculation, and a Python program is employed to perform back-calculation using the BISAR (Bitumen Stress Analysis in Roads) method in MATLAB. For this study, LVRs with a surface type of Open Graded Premix Carpet (OGPC) and Bituminous Concrete of thickness 40 mm (BC-40) are selected. These roads are constructed directly above a granular layer and have a thin bituminous surface layer. Estimating the remaining life of LVRs involves evaluating their current condition and predicting future performance under anticipated traffic loads and environmental conditions. The remaining life in the base year has been estimated in accordance with IRC: 115-2014 and IRC: 37-2018, based on the rebound deflection obtained using FWD. The selected LVRs for the study are found to be safe against fatigue and rutting criteria. The back-calculated moduli using KGPBACK and the BISAR method reveal that pavement layer moduli can be accurately simulated by both methods. Furthermore, the BISAR method can be adopted as an alternative to KGPBACK software. The validated moduli values also provide a good model fit when comparing the deflection values.