Performance of low-energy steel slag powders as supplementary cementitious materials

•The steel slag powders were produced using a low-energy grinding program.•The proposed powders acted as fillers and/or SCMs in the cement matrix.•The powders’ physical properties strongly influenced their performance as SCMs.•The low-energy steel slag powders can increase the eco-efficiency of the matrix. This study evaluated low-energy basic oxygen furnace slag (BOFS) powders as supplementary cementitious materials (SCMs). The powders were produced from residual BOFS fines generated in different stages of a steel slag aggregates processing plant. The results indicated that the performances of the proposed mortars were more influenced by the BOFS powders' physical properties than their chemical and mineralogical compositions. The BOFS powders acted as fillers and/or SCMs, increasing the eco-efficiency of the cement-based composites regarding their mechanichal performances. This study demonstrates the feasibility of using waste from steel slag aggregates processing plants as a low-energy alternative to replacing conventional SCMs.