Innovative Approach to Characterizing Damage Evolution in Asphalt Concrete during Fatigue Tests

Abstract

Fatigue cracking, either top-down or bottom-up, is one of the major distresses in asphalt pavements. One of the significant challenges in predicting the fatigue cracking behavior of asphalt concrete is that such behavior, unlike that of elastic materials, depends on external conditions, such as temperature and loading rate within the nondamage or damage domain. The application of the viscoelastic continuum damage (VECD) approach or its further development, the viscoelastoplastic continuum damage (VEPCD) approach, requires extensive material testing of the viscoelastic properties (i.e., creep compliance or relaxation), uniaxial or multiscale fatigue tests, and computations, which may hinder the implementation of this fundamental approach for the characterization of fatigue for asphalt concrete. This study develops a new approach, based on a derivative of Poisson’s ratio, to characterize the integrity and material damage of asphalt concrete. Fatigue tests are conducted for two mixes at different load levels and temperatures. It is found that a unique relationship exists between the dynamic modulus and strain ratio. Mastercurves are constructed to determine the damage evolution in asphalt concrete during fatigue tests, which provides the basis for developing constitutive models to predict the fatigue life of asphalt pavement.