Putting Cement to Sleep with Sucrose and Waking it up with Ca(OH)<sub>2</sub>

Abstract

In this work, the effects of sucrose on setting time, heat of hydration and hydration products were studied, and the corresponding hydration process and regulation mechanism were discussed. With the adsorption test of sucrose on Ca (OH)2 suspensions, the “wake up” mechanism of Ca (OH)2 on sucrose-retarded cement was discussed. The results indicate that sucrose is used as retarder to increase the dormant period by adsorption to the cement surface, but there exists a critical amount of sucrose. And the XRD patterns indicate that sucrose can accelerate the reaction of C3A and the formation of AFt, but restraint the hydration of C3S. Ca (OH)2 that was used as accelerator in this paper can adsorb the sucrose up to 6.2mg sucrose/g Ca (OH)2. The combined-use of sucrose and Ca (OH)2 does not change the shape of the heat rate curves significantly. And the dormant period of sucrose-retarded cement can be decreased with the doses of Ca (OH)2 increasing, because of its high surface and preferential adsorption of sucrose.