Micromechanical Simulation of Asphalt Samples Using a Finite Element Network Model

The micromechanical load transfer and failure of asphalt concrete samples are simulated using a finite element network model. 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. The model incorporates a network of special frame elements with a stiffness matrix developed to predict the load transfer between cemented particle pairs. The stiffness matrix was initially created from an approximate elasticity solution of the stress field in a cementation layer between particles. Continuum damage mechanics was then incorporated within this solution, leading to the construction of a micro-damage model capable of predicting typical global inelastic behavior found in asphalt materials. The finite element micro-model was first used on samples generated from image analysis of actual asphalt material. Using this scheme, simulation models of an indirect tension and a compression sample were generated from surface photographic data of actual laboratory specimens. Simulation results compared favorably with experimental data collected on these samples. An additional series of simulations were also conducted on numerically generated samples with systematic variation of particular microstructure. These results provide comparisons of the effects of microstructure on the overall macro-response on asphalt samples.