This study investigates the fracture behavior of asphalt concrete by modeling it as a multiphase material composed of aggregates and mastic. A series of two-dimensional finite element models was developed using a random aggregate generation and distribution algorithm to simulate the heterogeneous microstructure of asphalt mixtures. The generated specimens were analyzed in ABAQUS software, focusing on the evaluation of Mode I and Mode II stress intensity factors (SIFs) and stress distribution in single-edge notched beam (SENB) configurations. The simulation results demonstrate that the spatial distribution of aggregates plays a significant role in determining both the mode and magnitude of SIFs. While the Poisson ratios of the constituents had a negligible effect, their elastic moduli showed a considerable influence on fracture response. As the crack length increased, the stress field became more localized, indicating a shift from distributed elastic deformation to concentrated fracture. Additionally, regions with lower stiffness acted as stress amplifiers, guiding the crack path through weaker zones and intensifying local stress concentrations. These findings underscore the importance of accounting for microstructural heterogeneity in the fracture analysis and design of asphalt mixtures.
