Improving the Electromagnetic Properties of Bitumen Using SiC-Fe3O4 Composites

Abstract

It is important to further improve the microwave absorption capacity of bitumen to promote the application of microwave heating in pavement maintenance. SiC-Fe3O4 composites were prepared as microwave-enhanced materials based on the impedance matching theory and the limitation of traditional single-phase microwave absorber. A network analyzer was used to measure the electromagnetic parameters. The rheological properties were evaluated and the morphological characteristics of SiC-Fe3O4 composites were studied. The process of microwave-heating of bituminous concrete was simulated and the heating rate and heat distribution were analyzed intensively. The results showed that the reflection loss of bitumen containing SiC-Fe3O4 composites reached −21.82 dB (the microwave reflectivity was only 1%), which is 13.4 dB lower than that of the bitumen containing SiC. The average heating rate of the bituminous concrete containing optimum SiC-Fe3O4 composites was 0.322°C/s, which is 1.88 times of that of pure bituminous concrete, and higher than that of bituminous concrete containing either SiC or Fe3O4. SiC-Fe3O4 composites improved the thermal conductivity of bituminous concrete, as well. The rheological properties of bitumen did not decline. The microstructure of SiC-Fe3O4 composites contributed to microwave absorption. It can be concluded that the bitumen containing SiC-Fe3O4 composites has stronger microwave-absorption ability compared with the bitumen containing a single-phase absorber. The bituminous concrete with composites had a greater microwave heating effect, and the optimum mass ratio of SiC to Fe3O4 was 1∶2.