The Characterization of Carbide Slag by Carbonation Curing and Its Enhancement Performance in Blended Cement Paste

Capturing CO2 and using solid waste effectively has become a focus of attention. During this study, carbide slag (CS), a calcium-rich waste, was treated through carbonation. The characteristics of CS and carbonated carbide slag (CCS) were examined, and their influence on blended cement paste performance was investigated. The results showed that Ca(OH)2 and CaCO3 were the main mineral composition in CS and CCS, respectively. The pH value of CS decreased with carbonation time, and the CS could absorb 618 g/kgCO2 using a carbonation treatment. The presence of CCS in blended cement pastes accelerated cement hydration. It was found that cement pastes with CS had a reduced compressive strength, whereas the incorporation of less than 10% CCS improved the compressive strength. Calcium monocarbonate was detected in the hydration product of blended cement paste with CCS because of the reaction of CaCO3 in CCS with aluminate. In summary, carbonated carbide slag, as a novel CO2-storage material, can enhance the performance of blended cement paste. This research promotes the application of CS as supplementary cementitious materials in cement-based materials.