Factors influencing the hydration kinetics of ye'elimite; effect of free lime

Abstract

This study investigates factors influencing the hydration of ye'elimite, comparing stoichiometric ye'elimite-rich clinkers with and without free lime (Y-C and Y, respectively). Although the hydration sequences and products were similar, there were notable differences in their kinetics. Y-C exhibited rapid hydration upon contact with water, followed by a significant slowdown within minutes. Contrary, Y demonstrates a slower early hydration, but reached the main hydration period earlier and proceeded more rapidly thereafter. Solution analyses revealed higher initial calcium and aluminium concentrations for Y-C, while the sulfur concentration was reduced. This was attributed to the rapid dissolution of free lime, along with some ye'elimite, resulting in the instantaneous formation of ettringite and aluminium hydroxide. Consequently, the solution composition was altered, causing delayed onset of monosulfate formation and main hydration period. These findings contribute to understanding the hydraulic reactivity of ye'elimite and its potential implications for cement production processes.