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

Abstract

Numerous studies have investigated the carbonation process of tricalcium silicate (C3S). 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-C3S and M-C3S. The findings indicated that both T-C3S and M-C3S exhibited a rapid carbonation reaction rate during the initial 12 h, which subsequently declined gradually. The carbonation products of T-C3S and M-C3S primarily consisted of calcite, with T-C3S also containing a proportion of aragonite calcium carbonate. The decomposition peak temperature of calcium carbonate weight loss increased with prolonged carbonation time for both C3S crystal forms. Prismatic or cubic morphology calcite formed in T-C3S and M-C3S 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-C3S. T-C3S exhibited superior compressive strength compared to M-C3S at all stages of carbonation. Additionally, a relationship was established between compressive strength, calcium carbonate content, and CO2 uptake. This study provided evidence that the crystal structure of C3S 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.