Propagation Characteristics of Dispersion Cracks in Asphalt Concrete at Low Temperatures

Abstract

Asphalt concrete is a typical heterogeneous composite material at the mesoscale. Under the action of external load, its internal dispersion cracks interact with each other, thereby changing the crack propagation behavior, especially in low-temperature environments. In this context, this study developed a meso-structure model of asphalt concrete with randomly distributed dispersion cracks based on the Taylor medium model and the discrete element method. A virtual semicircular bending test was performed to obtain macro and micro parameter data, including stress–strain curves, data regarding the crack propagation process, and the crack-area stress field, to analyze the propagation characteristics of dispersion cracks with various crack density parameter values, f, in asphalt concrete. The results indicated that (1) the predictions based on the Taylor medium model exhibit a good correlation with the numerical simulation results, demonstrating the reliability of the simulation. Moreover, the interference between dispersion cracks hinders crack propagation, significantly enhancing the low-temperature crack resistance of asphalt concrete. This interference effect is most pronounced when f is set to 0.6. (2) Crack interference between dispersion cracks primarily occurs during the crack incubation stage, extending the incubation time of internal cracks in asphalt concrete and improving early crack resistance. (3) When f is less than or equal to 0.6, the predominant failure mode of asphalt concrete is tensile stress failure. However, when f exceeds 0.6, the fracture mode of asphalt concrete shifts from tensile fracture to shear fracture.