Simulation of Asphalt Materials Using a Finite Element Micromechanical Model with Damage Mechanics

This work presents a theoretical/numerical study of the micromechanical behavior of asphalt concrete. Asphalt is a heterogeneous material composed of aggregates, binder cement and air voids. The load carrying behavior of such a material is strongly related to the local load transfer between aggregate particles, and this is taken as the microstructural response. Numerical simulation of this material behavior was accomplished by developing a special finite element model which incorporated the mechanical loadcarrying response between the aggregates. The finite element scheme incorporated a network of special frame elements each with a stiffness matrix developed from an approximate elasticity solution of the stress and displacement field in a cementation layer between particle pairs. A damage mechanics approach was then incorporated within this solution, and this led to the construction of a softening model capable of predicting typical global inelastic behavior found in asphalt materials. This theory was then implemented within the ABAQUS FEA code to conduct simulations of particular laboratory specimens. A series of model simulations of indirect tension tests (IDT) were conducted to investigate the effect of variation of specimen microstructure on the sample response. Simulation results of the overall sample behavior compared favorably with experimental results. Additional comparisons were made of the evolving damage behavior within the IDT samples, and numerical results gave reasonable predictions. TRB 2003 Annual Meeting CD-ROM Paper revised from original submittal. Sadd, Dai, Parameswaran, Shukla 3