Fatigue life modelling of asphalt pavements under multiple-axle loadings

Abstract

The fatigue damage caused by multiple-axle configurations is a key issue for pavement design. The standard fatigue test consists of the application of a continuous sinusoidal signal on a specimen, which enables the fatigue life to be described as a function of the strain level. For more complex loading signals, additional parameters were found to have an influence on the fatigue life of bituminous mixtures. In the French design method, the effect of multiple-axle loadings is simplified and taken into account via load equivalency factors using Miner's Law. In this article, we present a method for the computation of the fatigue life of bituminous mixtures under multiple-axle configurations that couples a structural approach and a material-based approach. The structural approach consists of a parametric study of real loading signals that enables the computation of the independent shape parameters characterising a loading signal. An experimental plan whose variables are the independent shape parameters was then defined and the synthetic loading signals constructed (material-based approach). The results of the laboratory fatigue tests enabled the computation of a multi-linear fatigue model that writes the fatigue life as a function of the independent shape parameters characterising the loading signal.