Use of electric arc furnace oxidizing slag (EOS) and electric arc furnace reducing slag (ERS) powders in cement pastes for CO₂ sequestrations

This study investigated electric arc furnace oxidizing slag (EOS) and electric arc furnace reducing slag (ERS), byproducts of the steelmaking industry, as partial replacements for ordinary Portland cement (OPC) in a CO₂ curing environment. Carbonation depth, compressive strength, mercury intrusion porosimetry, X-ray diffraction, thermogravimetry, and microhardness analyses were performed, and the sequestered total CO₂ content was quantified on the cement pastes containing 30 % EOS (EOS-P) and 30 % ERS (ERS-P). EOS-P and ERS-P were more deeply carbonated than the OPC paste (OPC-P). CO₂ curing enhanced the compressive strengths of EOS-P and ERS-P, and its effect was pronounced for ERS-P. ERS-P cured with CO₂ for 6 days showed 2.38- and 1.20-times higher strength than normally cured ERS-P and OPC-P, respectively. The carbonation of ERS-P was associated with the inherent minerals (γ-C₂S and merwinite) in raw ERS. ERS-P sequestered 35.5 g of CO₂ per 50 mm cubic specimen, which was 1.16 and 1.14 times higher than EOS-P and OPC-P, respectively. The strength development under the CO₂ curing condition was more pronounced in ERS-P owing to the formation of CaCO₃ by carbonation.