Carbonated waste paste calcined clay cement with enhanced CO2 mineralization and early strength

Modern concrete offers a significant potential for carbon capture, utilization and storage due to their alkaline nature. Herein, we combine the CO₂ mineralization in the waste cement paste (WCP) with calcined clay cement to develop a novel low-carbon cement—carbonated waste paste calcined clay cement (CWPC³). Our results suggest that 1 kg WCP efficiently mineralizes ∼0.27 kg CO₂ within 2 h, and together produces amorphous silica-alumina gel. This carbonated WCP promotes early hydration and strength development due to its high pozzolanic reactivity. Compared with conventional limestone calcined clay cement (LC³), CWPC³ has higher early strength and lower embodied carbon. Our work provides a synchronized solution to treat WCP while reducing embodied carbon in construction materials.