Does enhanced hydration have impact on autogenous deformation of internally cued mortar?

摘要

To better understand the impact of internal curing water on autogenous deformation of cementitious materials, three cements, with different fineness, were made from the same batch of clinker. Setting time, internal relative humidity (IRH), autogenous deformation of plain and internally cured mortars with the cements were investigated. Isothermal calorimetry was used to reveal the hydration process of cement in mortar. The results reveal that, enhanced hydration has less influence on autogenous deformation. Internal curing water induces the hydraulic pressure in paste pores and thereby expansion of mortar when abundant one is introduced into cementitious materials, by maintaining the high saturation degree of pores accompanying generation of hydration products at the acceleration period of cement hydration. No expansion of cementitious materials would be observed if it is insufficient. However, the expanding of mortar would turn into shrinking when low efficient internal curing aggregate is used. This attributes to that internal curing water could not compensate the water reacted with cement and thus hydraulic pressure decreases. This happens when hydration heat release rate approaches its peak. Theoretically, enhanced hydration could cause the permanent expansion in mortar. However, it begins in the steady stage of cement hydration, which implies few impact of it on autogenous deformation of internally cured mortar. (C) 2019 Elsevier Ltd. All rights reserved.