Acceleration of Early Hydration in Belite-Rich Cement by Remelting Reaction

Abstract

Hydration activity of belite-rich cement, based on the heat evolution for up to -10d, was effectively improved by a remelting reaction of the constituent belite. The modified cement, termed “remelted belite cement, ” is mainly composed of belite in which the remelting reaction occurred for a large extent, and thus distinct from the conventional belite-rich cement. The liquid, exsolved by the reaction, contained a much higher concentration of alkalies than the host belite. The alkalies accelerated the hydration and the main heat evolution peak began -7h earlier during the initial stage up to -30h. The subsequent heat evolution between -30h and -10d was mainly increased by the presence of twin boundaries in the host β-phase belite; the boundaries on the crystal surface behaved like active centers for the reaction with water. The grindability was also improved by the remelting reaction, in agreement with a previous study.