Anisotropic Viscoplastic Continuum Damage Model for Asphalt Mixes

Permanent deformation is one of the most significant distresses that causes severe damage in asphalt concrete (AC) pavements. It is caused by high traffic loads associated with high field temperatures. It is believed that permanent deformation develops at a small rate and accelerates with the initiation of microcracks in asphalt pavements. An anisotropic viscoplastic continuum damage model is developed to describe the permanent deformation of asphalt pavements. The model is based on Perzyna's formulation with Drucker-Prager yield function modified to account for the material inherent anisotropy. The material anisotropy parameter is measured through microstructural analysis of two-dimensional sections of asphalt mixes. Furthermore, a damage parameter is included in the model in order to quantify the nucleation of microcracks that develop to macrocracks at later stages. The model's parameters are all determined from strength and static creep tests.