Effect of High Temperature on the Expansion and Durability of SSRSC

Abstract

This study explores the potential of using stainless steel slag, an industrial by-product of the stainless steel refining process, as a substitute for cement in concrete to promote material reuse and ecological sustainability. The research involves preparing concrete a cylindrical specimen with varying levels of substitution, ranging from 0 to 20%, and curing them for different ages (1, 3, 7, 28, and 56 days) to evaluate the engineering durability of the resulting stainless steel reducing slag concrete (SSRSC). The study found that the compressive strength of the SSRSC at 28 days was 27.44 MPa, with a splitting strength ranging from 12.81 MPa to 15.34 MPa. As the substitution amount increased, the strength decreased, but there was a positive correlation between the compressive and splitting strength. The ultrasonic wave velocity growth also increased with each substitution amount, showing that the compactness and growth of the samples improved. The surface resistance of all the samples was lower than 20 kΩ-cm, indicating that the porosity and change in porosity caused by substitution were minimal. Regarding durability, the study found that high-temperature fire damage at 200 °C catalyzed the quality, compressive strength, and resistance, but the ultrasonic wave velocity decreased. After fire damage at 600 °C and 800 °C, the compressive strength of the samples decreased by 48–57% and 76–85%, respectively, indicating that higher temperatures have a greater effect on concrete and resistance to early aging. In terms of sulfate corrosion resistance, a higher substitution amount reduced the likelihood of spalling during the early stages of the cycle, and the cumulative weight after the fifth cycle was higher than that of the control group. The autoclave expansion test revealed that the later curing age of the sample, the greater the expansion and the amount of substitution. The porosity of the samples also increased with higher temperatures and substitution amounts.