LAUSR

The effect of different configurations of normal contact stresses on the rutting performance of asphalt concrete overlays on a soft and stiff Crushed Aggregate Base (CAB) layer is investigated. A three-dimensional (3-D) finite element model of a pavement structure is generated. The effect of different types of simplified normal contact stresses and a realistic 3-D normal stress on the rutting performance is investigated. Since the failure mechanism of asphaltic materials at high temperature is mainly related to the flow of the material, the viscoelastic and viscoplastic constitutive relationships coupled with the hardening-relaxation mechanisms are utilized to represent the behavior of asphalt concrete layer. This constitutive relationship is part of the PANDA (Pavement Analysis using Nonlinear Damage Approach) model developed by the authors and their collaborators. As the result of simulation, the magnitude of the rut depth on the asphalt concrete layer is generally determined to be inversely proportional to the stiffness of the CAB layer, and the rut depth on the asphalt concrete layer under the realistic 3-D normal stress is about 1.5 times greater than the rut depth under uniformly distributed normal stress.