Effect of temperature and superplasticizer on hydration of C3S and carbonation products of C-S-H

This study investigated the effect of different C3S hydration temperatures and the addition of superplasticizer on the microstructure of C-S-H and the polymorphy of subsequent carbonation products. Various analytical methods, including XRD, TG, 29Si NMR, and SEM, were employed. The results showed that increasing the hydration temperature elevated the polymerization degree of C-S-H and altered its morphology. This change consequently influenced the polymorphy of carbonation products, primarily calcium carbonates (calcite, aragonite, and vaterite) generated in the subsequent carbonation process. The amount of aragonite and vaterite increased from 5.20 % to 13.39 % as the hydration temperature rose from 20 degree celsius to 85 degree celsius. The addition of naphthalene sulfonate gormaldehyde condensate (NSF) also elevated the polymerization degree of C-S-H and increased the amount of aragonite and vaterite by 4.8-7.35 %. Hydration temperature and NSF are found to be responsible for the different morphology of C-S-H and its carbonation products. Fiber-like C-S-H gels formed at high temperatures are more likely to produce aragonite and vaterite, while foil-like C-S-H gels formed at normal or low temperatures are more likely to generate calcite during carbonation.