Analytical Model for the Alite (C3S) Dissolution Topography

Abstract

The surface topography that develops during the dissolution of alite (or C3S) has never been considered as an important aspect of the hydration of portland cement. Like many other minerals, alite dissolution results in the formation of etch pits. In this study, a simple model with a handful of parameters is proposed to explore the kinetic consequences of pitting on the dissolution of alite. The first consequence is an accelerating period during which the reactive surface, that is, the pit, expands. This new feature, to the authors’ opinion never reported previously for alite, is supported by experimental data. The mechanisms leading to the activation of the initial dissolution centers and to the growth of pits could be hindered by some inhibitory species such as aluminum ions or organic molecules. The model indicates that only a few assumptions about the formation of pits in the presence of these species are necessary to introduce an initial period of low dissolution prior to the accelerating phase. Such a low early reactivity is similar to the so‐called dormant period observed during portland cement hydration. The implications of this new model in cement hydration could go beyond this article and shed light on still unresolved fundamental questions on hydration behavior.