Influence of tartaric acid on early hydration and mortar performance of Portland cement-calcium aluminate cement-anhydrite binder.

The influence of tartaric acid on early hydration and mortar performance of Portland cement-calcium aluminate cement-anhydrite ternary binder is investigated in the presence of polycarboxylate-based superplasticizer. Tartaric acid delays the ettringite (AFt) formation and suppresses the early hydration of silicate. Good mortar fluidity is obtained only above a critical tartaric acid dosage that can inhibit AFt formation completely. However, the silicate hydration will be suppressed significantly at the same time, resulting in poor early strength. Tartaric acid delays the AFt formation mainly by the mechanism of poisoning nuclei growth. AFt amount is another factor that suppresses the early hydration of silicate. In the ternary binder system with higher CAC and C S ¯ content, less tartaric acid can suppress the early hydration of silicate completely until AFt transforms into monosulfoaluminate (AFm) to unlock it. [ABSTRACT FROM AUTHOR]