Comparative study of flexible pavement layers moduli backcalculation using approximate and static approach

Abstract

Pavement Backcalculation process is mathematically an indeed complex inverse problem that can be approached deterministically or probabilistically for the realistic estimation of pavement layer moduli using Non-destructive testing devices. Therefore, selection of appropriate backcalculation technique and thereby identifying the optimum value of pavement layer moduli is a daunting task in the current scenario. This study made an attempt in comparing two techniques namely radius of curvature method using ELMOD 6.0 program, and analytical method that adopts mathematical adaptive technique using Boussinesq’s formulae with Odemark’s consecutive three-layer system for estimating pavement layer moduli. Experimental investigations were carried out by using falling weight deflectometer (FWD) as per Indian standards on a selected two lane highway flexible pavement stretch of 20.00 km at an interval of 1.00 Km. The results of comparative analysis depict that bituminous layer moduli estimated from two techniques are in a mean variation of 32.29%. Whereas, the mean variation of granular and subgrade layer moduli at all the test locations is 27.16% and 5.61% respectively. This variation is due to various limiting factors of different methods, thereby layer moduli estimated from the approximate method provides quick solution considering non-linearity, transient behavior, does not require any seed values. Thus, this comparative study validates the applicability of approximate technique due to its simplicity and rapid calculation for structural evaluation of flexible pavement physical system.