Abstract：High-quality recycling of aggregates is one of the important tasks in the recycling of waste concrete, and cracking at the aggregate-mortar interface under microwave action is key to improving the quality of recycled aggregates.To further investigate the cracking behavior at the concrete aggregate interface under microwave action and analyze the influence of initial defects on the law of crack propagation at the concrete interface, an electromagnetic-thermal-mechanical multi-field coupled phase field model was established. This model simulates the dynamic distribution of the electromagnetic field, temperature field, and stress field in concrete under microwave action, and reveals the influence of key factors such as microwave power, heating time, and the position and angle of initial defects on crack propagation at the concrete interface. The reliability of the phase field model was verified by comparing with the results of microwave heating tests.The results show that the presence of initial defects can change the propagation path of interface cracks and has a dual-path influence on the material crushing effect: on the one hand, it significantly alters the distribution characteristics of the electromagnetic field inside the test block, inducing changes in the local temperature field; on the other hand, it forms a stress concentration effect at the crack tip, which changes the overall stress distribution. This not only affects the area of interface cracking but also increases the overall crack propagation rate and the damage area.The research results provide important theoretical support for the optimization of engineering applications of microwave-assisted concrete crushing technology.
2025, Vol. 46 
