Carbonation of Pure Minerals in Portland Cement: Evolution in Products as a Function of Water-to-solid Ratio

• Published in: Journal of Wuhan University of Technology. Materials science edition Vol. 39; no. 5; pp. 1214 - 1222
• Main Authors: Xiong, Kun, Shang, Xiaopeng, Li, Hongyan, Wang, Dan
• Format: Journal Article
• Language: English
• Published: Wuhan Wuhan University of Technology 01.10.2024
• Subjects: Cementitious Materials; Chemistry and Materials Science; Materials Science; portland cement; calcium carbonate; accelerated carbonation; water-to-solid ratio
• ISSN: 1000-2413; 1993-0437
• DOI: 10.1007/s11595-024-2988-1

Minerals in Portland cement including tricalcium silicate (C 3 S), β -dicalcium silicate ( β -C 2 S), tricalcium aluminate (C 3 A), and tetracalcium ferroaluminate (C 4 AF), show a significantly different activity and product evolution for CO 2 curing at various water-to-solid ratios. These pure minerals were synthesized and subject to CO 2 curing in this study to make an in-depth understanding for the carbonation properties of cement-based materials. Results showed that the optimum water-to-solid ratios of C 3 S, β -C 2 S, C 3 A and C 4 AF were 0.25, 0.15, 0.30 and 0.40 for carbonation, corresponding to 2 h carbonation degree of 38.5%. 38.5%, 24.2%, and 21.9%, respectively. The produced calcite during β -C 2 S carbonation decreased as the water-to-solid ratio increased, with an increase in content of metastable CaCO 3 of vaterite and aragonite. The thermodynamic stability of CaCO 3 produced during carbonation was C 3 A>C 4 AF>β-C 2 S>C 3 S. The carbonation degree of Portland cement was predicted based on the results of pure minerals and the composition of cement, and the error of predicted production of CaCO 3 was only 1.1%, which provides a potential method to predict carbonation properties of systems with a complex mineral composition.