Effect of Particle Size Distribution on Hydration Kinetics

Abstract

ABSTRACTA general method has been developed for determining the effects of particle size distribution (PSD) on the kinetics of hydration. Given the PSD and the kinetic rate for particles having a single size, expressions can be derived for the variation of the total degree of hydration with time. The method was applied to PSD and kinetic functions typical of cement systems that account for reaction, diffusion and expansion of spherical hydrate layers. The PSD was found to critically affect the kinetics. A key feature of the theory follows with time those particles that have become totally hydrated, so-called “dead” particles. This produces a dead-particle hydration curve having approximately the same shape and location as the overall hydration curve. It can be represented analytically in all cases and gives a measure of the disguise provided by the distribution.