Comparative Study of Asphalt Pavement Responses under FWD and Moving Vehicular Loading

Abstract

This study aimed to compare pavement responses caused by impulsive dynamic loading and moving vehicular loading using mechanistic pavement analysis. Finite-element (FE) models were developed to simulate falling weight deflectometer (FWD) loading with axisymmetric FE models and to simulate moving vehicular loading with three-dimensional (3D) FE models. Two flexible pavement structures with different asphalt layer thicknesses and temperature profiles were considered in the analysis. The FE models simulated dynamic impulse loading during FWD testing and moving tire loading patterns with 3D tire-pavement contact stresses. It was found that the pulse durations of compressive stresses in the asphalt layer were significantly affected by speed and pavement depth in what can be described as an exponential relationship. However, pulse duration was found to be pavement-dependent, and the quantitative relationship between pulse duration and speed and depth could only be developed for each individual pavement structure. The equivalent speed of FWD loading to moving loading varies depending on the type of response, asphalt layer thickness, and temperature. The usual assumption of FWD loading as representative of truck loading at typical highway speeds was only valid for pulse durations of compressive stresses. FWD loading caused greater pavement responses than moving tire loading at the highway speed under the same loading magnitude as the asphalt layer thickness decreased or the temperature increased. The study results emphasized the importance of using moving tire loading in mechanistic analysis of pavement responses.