Abstract:Voids play an important role in the micro structure characteristics of asphalt mixtures, since moisture damage and aging will occur with the existing of water and air. In addition, voids are the weak points and defects in the mixture which are closely related to the force bearing performance and the damage process. A graded particle flow model of asphalt mixture was built up using discrete element method(DEM) package. The DEM fluid coupling analysis framework was used to calculate the parameters of each void such as volume and position. Finally the obtained voids distribution pattern was compared to actual results from CT scan and image analysis. It proves that the scheme employed in the paper is effective and reasonable.