Modeling of Hollow Cylindrical Asphalt Mixture Specimens

The hollow cylindrical asphalt mixture specimens were modeled with discrete element method. The dynamic moduli of the samples were predicted. The microstructure of asphalt concrete specimen was captured from an X-ray tomography images. The asphalt concrete hollow cylindrical images were divided into aggregate, mastic and air voids domain. The particle size of the mastic was less than 2.36mm in this paper. Aggregate, mastic and air voids domain were identified from the density index of the X-ray computed tomography images. The coordinates of aggregate, mastic and air voids domain was defined by density index to develop two dimensional (2D) and three dimensional (3D) discrete element models (DEM). The dynamic modulus of the asphalt mixture was calculated from stress divided strain in each temperature and frequencies. The comparison of predicted and laboratory measurement dynamic modulus has been investigated in this paper. When compared with the dynamic modulus of 2D DEM and 3D DEM against the laboratory measurement, the average difference was 6.25% for 3D DEM; the average difference was 17.72% for 2D DEM; and the average difference of dynamic modulus was 22.19% when compared with 3D DEM and 2D DEM. It was found that 3D DEM had better predicted dynamic modulus comparing 2D DEM.