The characterization and mechanism of carbonated steel slag and its products under low CO2 pressure

Steel slag can be applied as a promising carbon fixing material. This paper mainly explored the characterization and carbonation mechanism of steel slag and its products at relatively low CO2 pressure. The experimental conditions were pure CO2 gas, 0.02 MPa CO2 pressure and 24 h carbonation time. The carbonation reaction degree of samples was evaluated by numerical carbonation rate. The phase composition and microstructure of samples were analyzed by XRD, FTIR, TG and SEM. The mechanical properties of carbonated steel slag bricks were evaluated by flexural strength. The results show that the average flexural strength of carbonated steel slag bricks (CSSB) reaches 15.9 MPa, and the carbonation rate reaches 33.9 %, which has a good carbonation degree. Low pressure and short time operation methods were adopted in this research, which provides ideas for reducing cost and simplifying carbon dioxide storage process in steel slag carbonation industry. [Display omitted] •The characterization and mechanism of CSS and CSSB were explored at low CO2 pressure.•The average flexural strength was used to evaluate the mechanical properties of CSSB.•Two methods were applied to calculate and compare the carbon fixation of samples.