The Development of a Microstructural-Based Continuum Model for Hot Mix Asphalt

Permanent deformation is one of the primary distresses in hot mix asphalt (HMA). It is influenced by the properties of the mix constituents including microstructural features such as aggregate directional distribution (anisotropy), and damage. Conventional continuum constitutive models do not explicitly consider the influence of microstructure distribution on the macroscopic response. The main objective of this paper is to develop an elasto-visco-plastic continuum model that accounts for aggregate directional distribution and damage. This is accomplished by modifying the Drucker-Prager yield function to account for these microstructural features. This yield function is incorporated into Perzyna's viscoplastic flow function. The model is implemented in finite element (FE) using an implicit numerical integration algorithm. FE analysis is conducted to study the influence of key factors such as anisotropy and damage on the model response. In addition, the FE model is used to simulate the response of HMA to compressive and extension triaxial tests at different loading rates and confining pressures, and the numerical results are compared to experimental measurements.