Physical and Chemical Aspects of the Nucleation of Cement-Based Materials

Pavel Demo, Alexey Sveshnikov, Šárka Hošková, David Ladman, Petra Tichá

Abstract


A theoretical model of the nucleation of portlandite is proposed, and the critical size of a portlandite cluster and the energy barrier of nucleation are determined. The steady state nucleation rate and the time lag of the nucleation of portlandite are estimated for a pure solution of Ca(OH)2 in water. Possible connections with the corresponding properties for cement paste are discussed. A new method is developed for experimentally determining the concentration of Ca2+ ions during the initial stage of hydration of a cement paste. The time dependence of Ca2+ ions is measured for various water-to-cement ratio values. The results are discussed from the point of view of existing models of the induction period.

Keywords


cement paste; induction period; calcium concentration; nucleation rate; time lag

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ISSN 1210-2709 (Print)
ISSN 1805-2363 (Online)
Published by the Czech Technical University in Prague