Influence of thermochemical high-temperature reconstruction on mechanical properties and activity of stainless steel slag

The stainless steel slag's low activity, primarily attributed to its high γ-C₂S and low C₃S content, impedes its effective utilization. This study employs a thermochemical high-temperature reconstruction method utilizing lime and bauxite as tempering agents to regulate the mineral phase. Through an array of tests and analytical techniques, including compressive strength test, activity index, XRD, SEM, and hydration heat analysis, the impact of Ca/Si ratio and sintering temperature on the mechanical properties and activity of reconstituted stainless steel slag mortar is examined. The findings indicate that at a Ca/Si ratio of 4.2 and a sintering temperature of 1290°C, the reconstructed slag demonstrates optimal mechanical properties and activity, yielding compressive strengths of 43.69 MPa and 62.58 MPa at 7 days and 28 days, respectively, with remarkable 28 day activity index of 143.49%. The proposed thermochemical high-temperature reconstruction method ingeniously employs high temperature to increase the content of C₃S while rapid cooling prevents the alteration of the C₂S crystalline structure. This innovation significantly enhances the mechanical properties and activity of the stainless steel slag, offering promising avenues to increase its utilization rate.