Effect of CO2 curing on the resistance of calcium sulfoaluminate cement paste to elevated temperature

This study investigates the effect of CO2 curing on the resistance to elevated temperatures of calcium sulfoaluminate (CSA) cement paste. Water and CO2-cured CSA cement paste specimens were exposed to elevated temperatures of 150 degrees C, 300 degrees C, 500 degrees C, and 800 degrees C to evaluate their physicochemical and mechanical properties. The results demonstrate that CO2 infiltration alters the hydration mechanism of CSA cement, consequently enhancing its physical properties and thermal stability. Exposure to elevated temperatures induces changes in color and the formation of cracks in cement paste samples, with water-cured samples exhibiting more prominent cracks compared to CO2-cured samples. CO2-cured samples demonstrate less of a reduction in the compressive strength at high temperatures compared to water-cured samples, an outcome attributed to the enhanced stability and uniform pore size distribution. In conclusion, the CO2 curing process transforms ettringite and monosulfate into thermally stable calcium carbonate, which significantly enhances the thermal stability of the cement paste.