Study on the effective composition of steel slag for asphalt mixture induction heating purpose

Abstract Reuse steel slag as aggregate for induction heating has grown up to an important subject of asphalt pavement. However, how the composition and size of steel slag affect its induction heating efficiency still requires further study. This paper investigated steel slags’ induction heating efficiency by components, size and iron element proportion dependency analysis. Steel slags and powders of iron, Fe3O4, natural mineral as well as steel slags were employed to fabricate samples that simulate steel slags as various composition. Their corresponding heating efficiencies were acknowledged through infrared camera. Moreover, X Ray Fluorescence and Electron Probe Micro Analyzer are used to characterize the element compositions of the samples and elements distribution within steel slags. Results showed that, the effective components of steel slag’ induction heating were Fe3O4 and iron. Fe3O4 contributed the dominant part to steel slags’ induction heating efficiency at micron size (smaller than 75 μm). In addition, the size increase of steel slags showed negative effect on their induction heating efficiency, and steel slags of higher iron element proportion generally had higher heating efficiency. Alternatively, the induction heating mechanisms of Fe3O4 and iron are distinct. The dominant mechanism of iron is eddy current loss, while hysteresis loss and residual loss contribute the main part to Fe3O4’s induction heating. Through the superposition of the mechanisms, Fe3O4 consequently shows better induction heating efficiency than iron. This study provides laboratory foundation for selection and utilization of steel slags which is used as the heated material in further steel slag based asphalt mixture.