This paper present some recent developments in using Finite Element Method (FEM) and the 3D microstructure of asphalt concrete reconstructed from x-ray tomography imaging to evaluete its performance. Asphalt concrete is modeled as a material composed of an effective solid and void. The stress concentration factor and its distribution are computed and correlated to the overall resistence of the mixtures agains rutting and fatigue, and the internal structural quantities. The corellation of the stress concentration factor with the field performance of the WesTrack mixed indicates that mixes with large stress concentration factors, as expected, may be more prone to rutting and fatigue cracking than those with smaller stress concentration factors