Influence of Calcium Carbonate Flour on Hydration, Strength, and Rheology of fast setting CSA based mortars

Calcium Sulfoaluminate cements (CSA) are a more sustainable alternative to Portland Cement (PC). On top of that, they can outperform PC in mortars application. The addition of calcium carbonate to such a system is beneficial as it improves workability, accelerates the setting time, and stabilizes the ettringite in the hardened mortar. In this paper, we are investigating the influence of fine calcium carbonate flour on CSA‐C$‐based mortars. The hydration course was traced by the means of isothermal microcalorimetry. It was observed that with the addition of fine calcium carbonates the heat release due to the hydration of CSA started earlier and resulted in the higher hydration peak. Higher hydration degree was able to partially compensate for additional water used to maintain workability. The rheological properties were measured with the rotational viscometer. The results were compared to the mortars of the same composition where fine calcium carbonate was replaced with the ground quartz sand of similar particle size distribution. Surprisingly, no differences in rheology and mechanical parameters between these flours were found.