Numerical study on the internal heating mechanism of asphalt mixtures under microwave thermal induction

WU Wenliang; PENG Junlin; LI Zhi

doi:10.16186/j.cnki.1673-9787.2023110060

Abstract：Objectives In engineering applications,microwave thermal induction techniques are typically evaluated based on surface temperature measurements,while the mechanism of microwave-induced heating within the structure remains unclear.Methods To investigate this mechanism,COMSOL-based finite ele-ment simulation was employed.The overall electromagnetic parameters of asphalt mixtures were derived from those of individual materials,and an electromagnetic-thermal coupled finite element analysis was con-ducted.This approach enabled the analysis of the internal electric field intensity distribution within cubic specimens,from which the mechanism of internal temperature rise induced by microwaves was inferred.The simulation results were further validated by examining the surface temperature variations of asphalt specimens under different microwave induction durations.Additionally,the study clarified the internal tem-perature distribution patterns and uniformity of asphalt mixtures with different gradations under microwave induction.Results The microwave-absorbing performance of various aggregates can be evaluated by their en-ergy dissipation capabilities.Among them,diabase exhibited superior microwave absorption compared to other aggregates.The numerical simulations showed that when subjected to microwave induction for 200 sec-onds,diabase-based asphalt mixtures across different gradations reached an average internal temperature exceeding 80 °C,meeting the thermal requirements for healing microcracks.Conclusions Asphalt mixtures with diabase as the aggregate skeleton can be efficiently heated to above 80 °C within 200 seconds under microwave induction,satisfying the conditions necessary for internal crack healing.This indicates a high po-tential for applying microwave-induced healing technology to prevent the development of functional dis-tresses such as potholes and raveling in asphalt pavements.