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

• Main Authors: Pavel Demo, Alexey Sveshnikov, Šárka Hošková, David Ladman, Petra Tichá
• Format: Article
• Language: English
• Published: CTU Central Library 2012-01-01
• Series: Acta Polytechnica
• Subjects: cement paste; induction period; calcium concentration; nucleation rate; time lag
• Online Access: https://ojs.cvut.cz/ojs/index.php/ap/article/view/1668

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.