Research on Electromagnetic and Rheological Performance of Microwave-Sensitive Emulsified Asphalt Containing SiC and Fe3O4

The limited microwave-heating performance caused by moisture and ordinary aggregates limits the application efficiency of emulsified asphalt in rapid pavement repair engineering. Silicon carbide (SiC) and ferrosoferric oxide (Fe₃O₄) were introduced as modifiers to prepare the microwave-sensitive emulsified asphalt used in this work. The electromagnetic properties, microwave heating properties, microstructural evolution law, and rheological performance of emulsified asphalt or its evaporation residue were studied. The results show that modification through SiC and Fe₃O₄ can produce a pronounced synergistic effect and can significantly enhance both the electromagnetic and high temperature rheological properties. Coupling polarization enhancement with magnetic responsiveness increases the dielectric constant and loss peaks compared with single doped samples. This compensates for the weak magnetic response or insufficient stiffness of single doped systems and leads to a maximum early-stage microwave heating rate increase of 176.2%. The rheological performance of the compound doped system is also markedly improved. The R (3.2 kPa) of the 2% SiC + 3% Fe₃O₄ group sample increased by 59.7% and the <i>J_nr</i> (3.2 kPa) decreased by 68.9% compared to the control group. The rigid and elastic complementarity of the two modifiers effectively suppresses irreversible deformation at high temperatures. Moreover, the modifiers accelerate the microstructural transition of the asphalt from a particulate state to a continuous phase under microwave exposure. Adjusting the compound doping ratio of SiC and Fe₃O₄ allows the system to be tailored for either high temperature stability or rapid heating, providing technical support for its application in microwave-assisted pavement repair field.