Evaluation of Fatigue Cracking in Asphalt Mixtures Based on Surface Energy

Abstract

Fatigue cracking in an asphalt mixture is a process whereby microcracks in the asphalt–aggregate interface propagate into extensive interconnected cracks under repeated loads. The fatigue performance of asphalt is influenced by the load as well as the intrinsic nature of the asphalt–aggregate system. This study used the surface energy concept of asphalt and aggregate systems to characterize the fatigue behavior of asphalt mixtures. The surface energy of asphalt and aggregate at different temperatures were measured using Wilhelmy plate method and contact angle meter, respectively. By using dissipated pseudostrain energy of nonlinear viscoelastic material and micromechanics cracking model, the effect of surface energy on fatigue life of the asphalt mixtures was analyzed. Laboratory test indicated that the surface energy of the asphalt generally decreased with an increase of temperature. Compared with AH70 grade asphalt, the surface energy of styrene-butadiene-styrene block copolymer (SBS)-modified asphalt was less sensitive to temperature. Using SBS asphalt and basalt improved fatigue life of asphalt mixtures because of improved adhesion.