Thermal transfer characteristics of asphalt mixtures containing hot poured steel slag through microwave heating

Hot poured steel slag (HPSS) was adopted as microwave absorber to replace partial limestone aggregate to prepare asphalt mixtures in this work. Thermal transfer characteristics of asphalt mixtures through microwave heating (MH) were discussed. Firstly, the MH capacity of HPSS with different particle sizes were studied. Then, the morphology and element percentage of HPSS were characterized with scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Subsequently, surface temperature, heating uniformity and thermal transfer characteristics were analyzed. The results show that HPSS has good microwave absorption capacity and the increment of HPSS in asphalt mixtures can increase the surface temperature. The surface temperature of asphalt mixtures with HPSS can be evidently influenced by microwave power due to the correlation between microwave energy and microwave power. Besides, the heating uniformity of asphalt mixtures decreases with the increase of HPSS content, which is mainly related to the spatial distribution and heat generating rate of HPSS. Finally, the thermal transfer characteristics of asphalt mixtures with HPSS are divided into three types according to thermal source intensity and thermal transfer efficiency. Overall, it can be used as functional asphalt mixtures to improve the sustainability of pavement because of the good microwave absorption performance of asphalt mixtures containing HPSS.