Synergistic effect of CO2-mineralized steel slag and carbonation curing on cement paste

Cement-based materials have favorable capacity of solid waste and CO2 disposal. In this study, a synergistic CO2 treatment, including CO2 mineralization of steel slag admixture and carbonation curing of cement paste, was proposed. The influence of synergistic CO2 treatment on pozzolanic activity of steel slag, CO2 sequestration, and compressive strength of specimens were investigated. Results show that synergistic CO2 treatment cannot significantly increase the compressive strength but can improve the CO2 sequestration efficiently (up to 10.76 %), while a single CO2 treatment could only improve CO2 sequestration by 6.75 %. MIP, 29Si NMR, XRD-rietveld, and Raman spectroscopy were used to determine the effect of synergistc CO2 treatment on microstructure and mineral composition of samples. A barrier layer generated on the surface of steel slag particle was observed in SEM images. This barrier layer composed of carbonates reduces the early activity of CO2 mineralized steel slag.