Unveiling the carbonation behavior of T-C3S and M-C3S: A comparative investigation

Numerous studies have investigated the carbonation process of tricalcium silicate (C ₃S). However, research on the carbonation of its different crystal forms remains relatively limited. This study explored the effects of accelerated carbonation on the performance and microstructure of T-C ₃S and M-C ₃S. The findings indicated that both T-C ₃S and M-C ₃S exhibited a rapid carbonation reaction rate during the initial 12 h, which subsequently declined gradually. The carbonation products of T-C ₃S and M-C ₃S primarily consisted of calcite, with T-C ₃S also containing a proportion of aragonite calcium carbonate. The decomposition peak temperature of calcium carbonate weight loss increased with prolonged carbonation time for both C ₃S crystal forms. Prismatic or cubic morphology calcite formed in T-C ₃S and M-C ₃S during the initial carbonation stages, leading to a denser microstructure. As the carbonation duration increased, the particle size of calcite also grew, displaying a more irregular morphology. Furthermore, needle-like or rod-like aragonite calcium carbonate was observed in T-C ₃S. T-C ₃S exhibited superior compressive strength compared to M-C ₃S at all stages of carbonation. Additionally, a relationship was established between compressive strength, calcium carbonate content, and CO ₂ uptake. This study provided evidence that the crystal structure of C ₃S not only influenced the rate of the carbonation reaction but also impacted the type and morphology of calcium carbonate products and the development of compressive strength.