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The low activity of stainless steel slag (SSS), primarily attributed to its high γ-C2S and low C3S content, impedes its effective utilisation. A thermochemical high-temperature reconstruction method using lime and bauxite as tempering agents to regulate the mineral phase was investigated in this work. Through an array of tests and analytical techniques, including compressive strength tests, activity index evaluation, X-ray diffraction, scanning electron microscopy and hydration heat analysis, the impacts of the calcium/silicon mass (CSM) ratio and the sintering temperature on the mechanical properties and activity of reconstituted SSS mortar were examined. It was found that, at a CSM ratio of 4.2 and a sintering temperature of 1290°C, the reconstructed slag demonstrated 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 alteration of the C2S crystalline structure. This innovation significantly enhanced the mechanical properties and activity of the SSS, offering promising avenues to increase its utilisation rate. [ABSTRACT FROM AUTHOR]

In this paper, addressing issues of the steel slag cementing, such as low activity and poor stability problem, calcium, aluminum and other components were introduced to reconstruct the steel slag with adding different proportions of MnO2 and analyzed using XRD, EDS, heat of hydration and activity index. And the study focuses on the effect of MnO2 doping on mineral formation and mechanical properties of reconstructed steel slag. The results show that at high temperatures, the doping of MnO2 can improve the ease of burning of reconstituted steel slag, and the effect of increasing the doping is significant. The incorporation of MnO2 promotes the formation of C4AF minerals, reduces the content of MgO, and has little influence on the formation of C2S. Mn3+ is easy to replace Fe3+ in C4AF to form solid solution. MnO2 can obviously promote the hydration of reconstructed steel slag, which shows that the acceleration period is advanced and the induction period is shortened. The gelling activity index increased firstly and then decreased with the increase of MnO2 dosage. When the dosage was 2.0%,the gelling activity was the best, the 90d compressive strength was 104.95 MPa, and the activity index was about 100%. [ABSTRACT FROM AUTHOR]

In this paper, a new method of basic oxygen furnace (BOF) slag component modification with a regulator was studied. The main mineral was designed as C4AF, C2S and C3S in modified BOF slag, and the batching method, mineral compositions, hydration rate, activation index and capability of resisting sulfate corrode also were studied. XRD, BEI and EDS were used to characterize the mineral formation, and SEM was used to study the morphology of hydration products. The results show that most inert phase in BOF slag can be converted into active minerals of C4AF and C2S through reasonable batching calculation and the amount of regulating agent. The formation of C4AF and C2S in modified BOF slag is better, and a small amount of MgO is embedded in the white intermediate phase, but C3S is not detected. With the increase in the CaO/SiO2 ratio in raw materials, the CaO/SiO2 ratio of calcium silicate minerals in modified BOF slag increases, the contents of f-CaO are less than 1.0%, and the activity index improves. Compared with the BOF slag, the activity index and exothermic rate of modified BOF slag improved obviously, and the activity index of 90 days is close to 100%. With the increase in modified BOF slag B cement, the flexural strength decrease; however, the capability of resisting sulfate corrode is improved due to the constant formation of a short rod-like shape ettringite in Na2SO4 solution and the improvement of the structure densification of the hydration products. [ABSTRACT FROM AUTHOR]