Abstract:In order to evaluate the anti fatigue property of hard asphalt mixture, a series of four point bending fatigue tests were conducted to make a comparison between hard asphalt mixture SAC25 30# and polymer modified asphalt mixture SAC16 SBS. Both strain control mode and stress control mode were considered to make an overall evaluation of anti fatigue properties at different temperatures, and the accumulated dissipated energy Wf was used to analyze the energy variation trends of two mixtures. Besides, the effects of visco elastic parameters and stiffness difference on the dissipated energy were discovered and the ultimate strain and stress were introduced to correct the parameter of accumulated dissipated energy. The result indicates that hard asphalt mixture has a better anti fatigue performance under stress control mode at 20℃ and 5℃, but they are worse than SBS modified asphalt mixtures under strain mode at different temperatures due to their lower ductility. If WfR adopted, WfR of hard asphalt mixtures is lower with the growing fatigue life at 20℃, but WfR curve lies above that of modified asphalt mixture at 5℃, which indicates anti fatigue properties of hard asphalt mixtures have an obvious trend of decrease as temperature goes down. This indicator can be used as a reference to evaluate the fatigue performance of hard asphalt mixture.