Recent advances in research on steel slag for asphalt pavements: A review

Steel slag (SS), as a by-product of the steelmaking process , often fails to receive sufficient attention in terms of its potential application value. In some early-industrialized developed countries , the reutilization rate of SS is relatively high. However, in certain developing countries, such as China, SS is commonly regarded as solid waste and is directly stockpiled, resulting in a relatively low utilization rate. This not only leads to a waste of land resources but also poses potential environmental risks due to the leaching of heavy metal ions from the SS. This review summarizes the latest research findings on the application of SS in asphalt pavements construction, revealing that steel slag asphalt mixture (SSAM) have demonstrated superior interfacial properties and skeleton structural compared to traditional asphalt mixtures. These factors contribute significantly to the outstanding pavement performance of SSAM, such as deformation resistance , fatigue resistance , skid resistance and thermal performance. However, challenges such as volume expansion remain major obstacles to the large-scale application of SS in asphalt pavement construction. Furthermore, this review provides an overview of the environmental impacts of SSAM, including carbon dioxide emissions, volatile organic compounds (VOCs) emissions, and heavy metal leaching. Additionally, by summarizing existing research, it has been found that when the SS content in SSAM falls within the range of 50 %-75 %, the various properties of SSAM achieve a relatively ideal balance. This review not only synthesizes the latest findings in this field but also offers valuable insights for the broader application of SS in sustainable infrastructure, contributing to both environmental sustainability and economic efficiency.