Effects of Internal Structure on Anisotropic Creep Behavior of Asphalt Mixture Based on User-Defined Three-Dimensional Discrete Element Method

Abstract This study investigated the effects of internal structure on the anisotropic creep behavior of asphalt mixture based on user-defined three-dimensional (3-D) micromechanical discrete element method (DEM). A 3-D micromechanical discrete element asphalt mixture composed of coarse aggregates, asphalt mastic, and air voids was modeled by using DEM software called Particle Flow Code in Three Dimensions (PFC3D). Uniaxial creep tests performed on discrete element models of asphalt mixture were conducted by PFC3D. The effects of aggregate orientations, sphericity, and void orientations were investigated. It was indicated that the longer the projected lengths of aggregates were in the loading direction, the more significant the effect on the anisotropic creep behavior of asphalt mixture. The anisotropy effects on the creep behavior of the asphalt mixture became more obvious as the aggregate sphericity decreased. Moreover, applying the load in the long-axis direction of void orientation could result in relatively small creep strain. It is necessary to take into full consideration the effects of internal structures on the anisotropic creep behavior of asphalt mixtures during material design and field construction to improve the pavement performance.