Utilization of iron tailings as aggregates in paving asphalt mixture: A sustainable and eco-friendly solution for mining waste

Iron tailings are a type of solid waste yielded during the beneficiation process of iron mine. Its effective utilization has been of great concern in scientific community. The objective of this study is to systematically evaluate the feasibility of iron tailings as aggregates in paving asphalt mixture and investigate the methods of performance enhancement to improve its applicability in pavement engineering. To this end, a suite of tests and analyses was carried out on iron tailings and asphalt mixtures containing iron tailings. Results showed that the conventional physical properties of iron tailings can meet specification requirements. The weak adhesion of iron tailings to asphalt was due to acidic chemical compositions, but the adhesion gap between it and natural aggregates can be narrowed by utilizing high-viscosity asphalt. In terms of pavement performances, the asphalt mixtures with iron tailings coarse aggregates possessed a satisfactory high-temperature performance, but its low-temperature performance and moisture stability were poor relatively. By means of using limestone as fine aggregate or applying modified asphalt with superior properties, various key performances can reach the technical requirements for application in pavement. Moreover, the pavement performances of asphalt mix containing iron tailings can be further enhanced through adding hydrated lime or silane coupling agent and the comprehensive level surpassed conventional modified asphalt mixture that has been applied maturely in actual pavement project at present. Additionally, it is noteworthy that the recycling of iron tailings in asphalt pavement will also create huge benefits in the aspect of economy, environment and society.