Simulation of low-temperature brittle fracture of asphalt mixtures based on phase-field cohesive zone model

In this study, a phase-field cohesive zone model (CZM) was presented to simulate the low-temperature brittle fracture of asphalt mixture by finite element method (FEM). The phase-field CZM was applied directly to simulate low-temperature homogeneous fracture of asphalt mixtures. Furthermore, a combination method was proposed for the heterogeneous fracture analysis of asphalt mixtures at low temperature. In this method, the phase-field CZM and the conventional interface CZM are used to simulate the cohesive fracture within the fine aggregate matrix (FAM) and the adhesive fracture at the FAM-aggregate interface, respectively. Then, the applicability of the phase-field CZM to simulate mixed-mode fracture in asphalt mixtures was analyzed by the single-edge notch beam tests with different notch offsets. Furthermore, the cohesive fracture simulation of asphalt mixture based on phase-field CZM and interface CZM was compared. The results indicate that the nu-merical results based on the phase-field CZM in both homogeneous and heterogeneous fracture analysis are in good agreement with the experimental results. The softening curve of the interface CZM gradually converges to that of the phase-field CZM as the adhesive stiffness increases. Under the same traction-separation law, the crack path predicted by the combination method is similar to that of the pure CZM method. However, the combination method shows a more pronounced brittle behavior of the material. In addition, the combination method has higher computational efficiency and requires less computational memory. In summary, this study provides an effective method to simulate homogeneous and heterogeneous brittle fracture of asphalt mixture at low temperatures.