Micromechanical finite element modeling of asphalt concrete materials considering moisture presence

Asphalt Concrete (AC) is a composite material consisting of natural or recycled aggregates blended with petroleum-based binder. The majority of pavements in the U.S. include AC materials which are often exposed to the adverse effects of moisture. Moisture damage is one of the major factors that decrease the service life of pavements by causing and/or facilitating the development of several distresses. In this context, this study numerically investigates the effect of moisture presence on the micro, meso, and macroscale responses of AC materials. A Micromechanical modeling framework based on the Finite Element Method (FEM) was developed to examine the potential of moisture damage in AC materials. The microstructure of the material was characterized using the non-destructive X-ray Computed Tomography (CT) technique. Images obtained from X-ray CT scans were used to generate FEM-based micromechanical models. Preliminary analyses were performed to identify the Representative Volume Element (RVE) of the composite AC material. It was observed that relatively small window sizes, as low as 15 mm, were able to reasonably capture the bulk and shear moduli of the AC mixture. A hydro-micromechanical approach for studying moisture damage was followed. Moisture fields throughout the microstructure were generated in a mass diffusion procedure followed by mechanical loading with the properties of AC constituents evolving as a function of moisture state. Results obtained quantified the contribution of cohesive and adhesive damage on the overall mixture response to moisture presence