Effects of Fluoride and Sulphate Mineralizers on the Properties of Reconstructed Steel Slag

Abstract Improving the cementitious activity and volume stability of steel slag by thermal reconstruction is an innovative method for efficient utilization of steel slag. In this study, different amounts of CaF 2 and CaSO 4 were added to steel slag as a mineralizer based on the determining admixtures needed for the reconstruction reaction, and the effects of CaF 2 and CaSO 4 on the cementitious activity and volume stability of the reconstructed steel slag were investigated. The results show that when the CaF 2 content is increased to 5 wt%, the cementitious activity index of the reconstructed steel slag gradually increases to 92%, which is 12% higher than the first level technical requirement specified by the national standards, and the free CaO ( f - CaO) and MgO ( f -MgO) contents gradually decrease to 0.35 and 0.13 wt%, respectively. With increasing CaSO 4 content, the cementitious activity index first increases and then decreases, while the contents of f -CaO and f -MgO show the opposite trend. When the CaSO 4 content is 2 wt%, the activity index is 105%,which is 25%higher than the first level technical requirement specified by the national standards, and the f -CaO and f -MgO contents reach minima of 0.44 and 0.35 wt%, respectively.