Fracture Characteristics of Asphalt Concrete in Mixed-Loading Mode at Low-Temperature Based on Discrete-Element Method

Abstract

The facture failure of asphalt concrete at low temperature is one of the main deterioration modes for asphalt pavement. This study combines experimental tests and heterogeneous simulations to analyze the fracture properties, the internal tensile force, and the crack propagation of asphalt concrete in three fracture loading modes (mode I fracturing, mode II fracturing, and mixed mode I and II fracturing) and at four temperatures (−15°C, −6°C, °C, and 1°C). The fracture loading mode and temperature have significant effect on the fracture properties, the internal tensile force, and the crack propagation. Results show that (1) the fracture toughness in mixed mode I and II fracturing is the lowest, whereas the crack velocity in mode I fracturing is the fastest; (2) the crack path of asphalt concrete subjected to shear loading condition is more complex; (3) the propagation trend of the main cracks at −15°C and −6°C is similar, and passes through aggregates and mastics directly; (4) although the main crack at °C still passes through aggregate, it tends to cross the aggregate edge and passes through the aggregate/mastic interface; (5) deflection of the main crack occurs when the path of least resistance is around a relatively strong aggregate and passes along the aggregate/mastic interface at 1°C; and (6) the maximum internal tensile force and the number of failed contacts are consistent with the fracture toughness and the crack morphology, respectively.