The Use of Steel Slags in Transport Infrastructures: A Critical Review

The increasing demand for the development and expansion of transport infrastructures requires alternative solutions that are economically and environmentally viable to provide the necessary raw materials. Transport infrastructures consume a large amount of natural aggregates; however, from a circular economy perspective, industrial by-products can effectively replace these materials. This avoids the environmental impacts associated with the extraction of natural raw materials and simultaneously provides a destination for the industrial by-products. For this purpose, it is important to evaluate if existing standards and technical requirements that were developed for natural aggregates are suitable for industrial by-products. This review study is focused on slags from steelmaking process in electric arc furnaces, which are generally of two types: oxidizing (black colored) and reducing (lighter colored), specifically addressing the requirements of these materials for the granular layers of transport infrastructures. The chemical composition of the slags is analyzed as well as its physical and mechanical characteristics, swelling behavior, and leachate content, discussing testing procedures and technical specifications.