Acceleration of early hydration in belite-rich cement by remelting reaction

Hydration activity of belite-rich cement, based on the heat evolution for u p to similar to 10 d, was effectively improved by a remelting reaction of t he 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 concentrati on of alkalies than the host belite. The alkalies accelerated the hydration and the main heat evolution peak began similar to 7 h earlier during the i nitial stage up to similar to 30 h. The subsequent heat evolution between s imilar to 30 h and similar to 10 d was mainly increased by the presence of twin boundaries in the host beta-phase belite; the boundaries on the crysta l surface behaved like active centers for the reaction with water. The grin dability was also improved by the remelting reaction, in agreement with a p revious study.