Effect of electric furnace steel slag powder on the strength of green low-carbon concrete with high-titanium blast furnace slag

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This study explores the application of electric furnace steel slag powder (EFSSP), fly ash (FA), and high-titanium heavy slag (HTHS) from Panzhihua City, China, in producing green low-carbon concrete. The properties of these waste materials were characterized, and the fluidity and hydration activity of the EFSSP-FA composite admixture in cement mortar were tested. Additionally, the strength of HTHSC mixed with EFSSP-FA composite admixture was evaluated at various curing times, and the microstructure of the concrete mortar layer was analyzed. The study shows that the 7-day activity indices of EFSSP and FA are 61 % and 51.96 %, respectively, with fluidity ratios of 92.53 % and 124.58 %. Mixing EFSSP and FA compensates for their individual limitations. At a 1:1 mass ratio, the composite admixture achieved a 69.89 % activity index and 114.46 % fluidity. The pozzolanic reaction within the composite admixture was evident, promoting the continuous formation of C-S-H in HTHSC, the compressive strength after curing periods of 520 days, 300 days, 180 days, and 90 days reached approximately 190 %, 170 %, 150 %, and 130 % of the 28-day strength, respectively. The XRD, SEM, TG, and DSC characterization results for the HTHSC mortar layer at different curing stages were consistent with the observed trends in compressive strength. Since the raw materials used for concrete preparation were industrial waste, this portion was excluded from carbon emissions calculations. The all-industrial waste HTHSC achieved approximately a 30 % reduction in carbon emissions, the carbon emissions per unit of strength at 520 days of curing were approximately 55 % of those at 28 days.