Effect of Different Kinds of Zinc (II) on Early Hydration of Calcium Aluminate Cement

Abstract

The early hydration of calcium aluminate cement (CAC) with different kinds of zinc (II), such as ZnSO₄·7H₂O, ZnO, Zn(NO₃)₂·6H₂O and ZnCl₂, was analyzed. Changes in consistency, setting time, hydration heat flow, hydration heat amount, ion concentration in solution, and hydration products were found upon the addition of different Zn²⁺. The water consumption of standard consistency of CAC is decreased with different Zn²⁺. Zn²⁺ can delay the initial hydration of CAC. The induction period of cement with Zn²⁺ is longer than that of CAC, especially the reaction time of the acceleration period is extended. Zn²⁺ can promote hydration hydrate of CAC at 24 h. The characteristic diffraction peaks of CA and CA₂ in CAC with different Zn²⁺ are significantly reduced. It can inhibit the formation of CAH₁₀ and promote the formation C₃AH₆ and AH₃ in hydration products at 24 h.

Keywords

zinc / calcium aluminate cement / ion concentration / hydration