Clarifying the three stages of elasticity development during C3S hydration: Contributions of ion correlation forces and van der Waals interactions

Abstract

The elasticity development of cement-based materials is primarily attributed to the hydration of C3S. Indeed, it is directly linked to the evolution of driving forces, encompassing both the ion correlation forces and van der Waals interactions. However, clarifying and distinguishing their respective contributions at each stage is really challenging. In this paper, the elasticity development of C3S-CaCO3 pastes can be divided into three stages according to the dominant driving force. The onset of the second stage occurs within the induction period, while the onset of the third stage marks the transition from the induction period to the acceleration period. During the first stage, the van der Waals interactions serve as the dominant driving force, with the role of ion correlation forces between C3S particles being secondary. Moving to the second stages, the strengthening of ion correlation forces between CSH particles become increasingly important in enhancing elasticity. In the third stage, the elasticity development stems from the combined contributions of van der Waals interactions and ion correlation forces between CSH particles. It is noted that the contribution of ion correlation forces significantly outweighs that of van der Waals interactions, with the latter being influenced by the increase in solid volume fraction.