Recent advances in the reuse of steel slags and future perspectives as binder and aggregate for alkali-activated materials

•The recovery rate for steel slag varies from 20 to 98%, depending on the country.•A state-of-the-art on the reuse of steel slag is presented.•Emphasis was given to the potential and challenges in construction materials.•Steel slag may be suitable as an alternative binder and aggregates for AAM.•LCA is important to assess the environmental impact.•The effect of SS on the durability properties of AAM needs to be addressed. Steel slag (SS) is a secondary material from the production of steelmaking with little commercial value. It has several possible applications as raw material for different industrial process. However, small amounts are reused in some countries, where this material continues to be a burden to the steel industry. This paper presents the recent advances in the utilisation of SS in activities other than steelmaking. The main focus is the potential use of SS as binder and aggregates in cement-based materials, notably in alkali-activated materials (AAM). The latter are alternative construction materials to Portland cement (PC) and sometimes with lower environmental impact. The paper also discusses technical and commercial challenges of employing SS as raw material, e.g. legislation barriers and need for thorough treatment processing. The findings indicate that SS is a well-established material in some applications, such as agriculture and road construction. The potential use of SS as cementitious material and aggregates for concrete is highly promoted in the literature. However, the major obstacles are the variable chemical composition of SS, expansion issues, and worse fresh properties when employed as aggregates. Those issues are detrimental to mechanical strength and durability. The use of SS as binder or aggregate for AAM is still incipient albeit promising. Studies on SS-based AAM present an improved interfacial transition zone, but still, low SS reactivity as a binder. The lack of durability studies and life-cycle assessment clearly shows the demand for further investigation. Overall, a great research opportunity is the employment of SS both as binder and aggregates in AAM.