Kinetics of the hydration reactions in the cement paste with mechanochemically modified cement Si-29 magic-angle-spinning NMR study

A comparative Si-29 solid State NMR study of kinetics of the hydration reac tions in cement pastes based on rapid-hardening ordinary Portland cement (S H) and on the mechanochemically modified cement (MSH) is presented. The mec hanical activation of a cement/silica fume blend in a vibrating mill accele rates the hydration reactions by 15-20%, especially during the initial peri od of hardening. Variations in relative intensities of Si-29 resonances ass igned to the hydration products in SH/MSH blends suggest different structur es of hydrated SH nets. This can be correlated with a pronounced increase o f the MSH-cement binding capacity reported earlier. (C) 1999 Elsevier Scien ce Ltd. All rights reserved.