A through solution model for volume changes of cement hydration

Abstract

Changes of volume, temperature and bonding forces accompany every chemical reaction. Cement hydration leads to volume shrinkage during CSH formation and is influenced by a twofold phase transition. Dissociation of cement into pore solution leads to volume swelling while the followig crystallisation process produces volume shrinking. In the Through Solution (TS) — model presented here, the volume changes of cement reaction are described on the base of a consecutive reaction A - X- Z. The initial product A is considered as bulk volume of cement. X as a transition state product becomes the most important factor for the total reaction rate. The final product Z, as the volume of water bonded CS-phases, is regarded as the degree of hydration. The model has been shown to give adequate results for common cement reaction types.