Data Requirements from Falling Weight Deflectometer Tests for Accurate Backcalculation of Dynamic Modulus Master Curve of Asphalt Pavements

Abstract

Dynamic modulus (|E*|) master curve is a fundamental material property for an asphalt pavement. It is also a key input to DARWin-METM, a pavement design and analysis software that can predict progression of distresses. Backcalculation of |E*| master curve of an in-service pavement using Falling Weight Deflectometer (FWD) data can lead to more accurate estimation of its remaining service life (with the aid of DARWin-METM). However, backcalculation of the entire |E*| master curve, including the time-temperature superposition shift factor coefficients, requires more data than the surface deflection time-histories of a single FWD drop. This paper presents a novel |E*| backcalculation algorithm that is based on a genetic optimization methodology and a layered viscoelastic forward solution. The main objective of this work was to estimate a set of temperatures where FWD tests should be conducted, in order to maximize the portion of the |E*| master curve that can be accurately backcalculated. The results indicate that there exists a range of temperatures (of FWD testing) at which the FWD response leads to better inverse solutions. CE Database subject headings: Asphalt Pavements, Dynamic Modulus, Relaxation Modulus, Backcalculation, Viscoelasticity, Falling Weight Deflectometer, Nondestructive tests, Temperature effects, Optimization.