Three-Dimensional Discrete Element Modeling of Crack Development in Epoxy Asphalt Concrete

Cracking in epoxy asphalt concrete (EAC) used for a steel bridge wearing course has always been a major cause of structural and functional deterioration of this material, particularly in cold climate. Therefore, it is important to understand the complex fracture behavior of this heterogeneous mixture, which is composed of irregularly shaped and randomly distributed aggregates surrounded by asphalt mastics. A three-dimensional (3D) fracture model independent of laboratory, based on the discrete element method (DEM), is reconstructed using a randomly generating algorithm to investigate the fracture behavior. A bilinear cohesive-softening model is implemented into the DEM framework to simulate the crack initiation and propagation in EAC. Several experimental tests are performed to obtain input parameters of materials for numerical models. The simulation results of a single-edge notched beam test agree well with experimental results and accurately capture the stress distribution and development of fracture zone. The modeling technique herein provides insight into the progressive cracking process; 3D visualization of crack trajectories also demonstrates the influence of heterogeneity on crack path. The 3D user-defined microstructural DEM fracture model is capable of giving a realistic cracking process of quasi-brittle materials such as EAC and can help us better understand various fracture mechanisms through numerical simulations.