Micromechanics-based Analysis of Effect of Internal Structure on Creep Anisotropy of Asphalt Concrete

Abstract

In order to investigate the effect of internal structure on creep anisotropy of asphalt concrete (AC), a three-dimensional (3D) micromechanical model was developed using discrete element method. The digital AC specimen composed of coarse aggregates, asphalt mastic and air voids was generated. The corresponding micromechanical models among the interactions of microscale components of digital AC specimen were assigned. The microscale viscoelastic parameters were obtained from laboratory dynamic shear test. Simulation of uniaxial creep tests were conducted on a number of cubic digital AC specimens with different aggregate orientations and sphericity. It was observed that the longer projected length of aggregates in loading direction, the smaller the creep strain is. The creep strain of AC was much smaller in the major axis direction of aggregate orientation as compared with the minor one. The creep anisotropy of AC became obvious with decreasing aggregate sphericity, especially when projected length of aggregates varied greatly in different directions.