Enhanced carbonation performance of rice husk ash blended cement-based composites through in-situ CO2 mixing

The carbon capture, utilization, and storage (CCUS) technology has garnered significant attention in achieving carbon neutrality including construction sector. This study investigates the hydration and carbonation mechanisms of cement-based samples subjected to early mineral carbonation in a CO₂-rich environment, especially by incorporating rice husk ash (RHA). The in-situ CO₂ mixing of cement samples was conducted under sealed conditions for 60 min at a CO₂ concentration of 10 vol%. The effects of various RHA addition ratios on the early-stage carbonation reaction were examined. The results demonstrated that increasing the RHA content enhanced CO₂ sequestration within the porous structure of RHA, facilitating the formation of various carbonates. This carbonate formation contributed to the improvements in initial strength development and CO₂ sequestration. Meanwhile, during the sealed curing period, a significant transformation of CaCO₃ into monocarboaluminate was observed. These findings suggest the potential for adopting RHA and in-situ CO₂ mixing as an environmentally sustainable and efficient strategy for CO₂ sequestration using cement-based materials.