CO2-fixing steel slag on hydration characteristics of cement-based materials

In this paper, the effects of CO2-fixing steel slag powder on the hydration characteristics of cement-based materials are compared, including the early liquid phase ion concentration, hydration heat, chemically bound water and strength. After the steel slag powder is cured by CO2 form the cement kiln flue gas, the calcium-containing ore phase is transformed into calcium carbonate. Calcium carbonate has a nucleating effect, which promotes the early hydration process, increases the ionic concentration and pH value of the liquid phase. Moreover, residual bacteria also have a positive effect when using bacteria and steel slag for CO2 sequestration. The change of the steel slag powder to the liquid phase environment leads to a significant difference in the early hydration exotherm, and the hydration kinetic parameters also have a large change. Comparing with the untreated steel slag powder, the low-carbon clean cement-based materials prepared from the CO2-fixing steel slag powder have a higher degree of hydration reaction from the NG process to the I process and from the I process to the D process during hydration. It shows that the steel slag powder after CO2 fixation is beneficial to the early hydration process. The monitoring of long-term performance found that the low-carbon auxiliary cementitious material prepared by the synergistic CO2 fixation of bacteria and steel slag powder has greater application potential in cement-based materials.