Physical and chemical aspects of the nucleation of cement-based materials

0391378 - FZÚ 2014 RIV CZ eng J - Journal Article
Demo, Pavel - Sveshnikov, Alexey - Hošková, Š. - Ladman, D. - Tichá, P.
Physical and chemical aspects of the nucleation of cement-based materials.
Acta Polytechnica. Roč. 52, č. 6 (2012), s. 15-21. ISSN 1210-2709. E-ISSN 1805-2363
Institutional research plan: CEZ:AV0Z10100521
Keywords : cement paste * induction period * calcium concentration * nucleation rate * time lag
Subject RIV: BJ - Thermodynamics

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.
Permanent Link: http://hdl.handle.net/11104/0220433