Unveiling the synergistic effect of in-situ generated calcium carbonate by CO2 mixing on the reaction of calcined clay

This study investigates the effect of in-situ generated calcium carbonate by CO2 mixing on the reaction of calcined clay and demonstrates that the in-situ generated calcium carbonate remarkably accelerates the reaction of calcined clay. The mechanism is revealed through the application of multiple techniques and thermodynamical modeling. The in-situ generated calcium carbonates are generally nano/micro-particles and provide the seeding effect for promoting the formation of reaction product. More importantly, it is found that in-situ generated calcium carbonates are highly reactive and could react with metakaolin from calcined clay to form carboaluminate, while prohibits the formation of stratlingite. Therefore, this study unveils the synergistic effect of in-situ generated calcium carbonate in promoting the reaction of calcined clay, indicating that CO2 mixing is a promising technique in promoting the performance of calcined clay based cementitious materials.