Hydration kinetics of Portland cement shifting from silicate to aluminate dominance based on multi-mineral reactions and interactions

Abstract

A theoretical model for cement hydration was proposed to study multi-mineral reactive transport processes under various mineral compositions and determine the effect of multi-mineral reactions and interactions on cement hydration kinetics shifting from silicate to aluminate dominance. The reaction rates of each mineral dissolution, product precipitation, ionic diffusion, and adsorption were calculated individually through the degrees of undersaturation and supersaturation associated with the ionic concentration, all of which were coupled in the modified Poisson–Nernst–Planck equation. The hydration heat flow was then theoretically calculated by the superposition of the reaction rates of silicate and aluminate phases, which was derived from the calculated ionic concentration. The model was validated by comparison with experimental data obtained under various conditions, showing consistency. The combined effect of multi-mineral reactions and interactions on hydration kinetics was investigated using the model, and the results indicated that (1) faster dissolution of gypsum or a higher ratio of tricalcium aluminate to tricalcium silicate leads to a larger time interval between silicate and aluminate peaks; (2) faster precipitation of calcium silicate hydrate results in a more significant difference between silicate and aluminate peaks; and (3) the sulfate ion retards cement hydration kinetics shifting from silicate to aluminate dominance.

Keywords

• Portland cement
• Kinetics shift
• Interaction
• Mineral composition