Hydration and Hardening Characteristics of Anhydrite Binder Modified with Slag

Abstract:

The paper presents a study of the hydration and hardening process of anhydrite binder,the activating mechanism of sulfate salt typed activator,and the modifying effects of anhydrite with slag through the determination of hydration rate,temperaturerising and ion concentration in liquid phase of anhydrite in combination with the macroperformance measurements.The addition of sulfate salt promotes the solution of anhydrite,increases ion concentration and supersaturation degree in liquid phase,and accelerates the gypsum crystal nucleation and growth.The hydration of slag forms water rigid minerals such as ettringite and hydrated calcium silicate,and the strength and waterresistance of the anhydrite binder material are accordingly increased.Anhydrite hinder material activated by sulfate salt and modified with slag is characterized by higher strength,good water resistance and low shrinkage rate.The hydration and hardening experience five stages such as rapid dissolution,latency period,hydration accelerated period,domain hydration period and slow hydration period.The setting time of binder material depends on latency period,and the densification and strength development of the hardened anhydrite paste are mainly concentrated at the stage of hydration accelerated period and stable hydration period.