Increasing Microwave Heating Efficiency of Asphalt-Coated Aggregates Mixed with Modified Steel Slag Particles

Abstract

Microwave technology has been used in asphalt pavement for years, but microwave heating efficiency of asphalt mixtures needs to be improved. In this paper, steel slag particles were modified by a coprecipitation method for improving the Fe3O4 content on its surface, and then used to completely replace fine aggregates. The electromagnetic properties and microwave heating rates were tested to evaluate the microwave absorption efficiency of the modified steel slag asphalt mixture (MSAM). Also, temperature sensors were used to measure the temperatures of each layer in the mixture slab, for comparing with the data obtained in a numerical model. The results show that the surface temperatures of MSAM increase to 74°C, and the internal temperatures are 10–20°C higher than the surface ones after microwave heating for 120 s, which is 74.4% higher than the basalt asphalt mixture (BAM). The tested temperature distributions are in good agreement with those of simulation, suggesting that the study is very promising and is expected to promote the microwave heating technology in asphalt pavements.