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Article Dans Une Revue Cement and Concrete Research Année : 2023

Mechanisms and kinetics of C-S-H nucleation approaching the spinodal line: Insights into the role of organics additives

Résumé

Wet chemistry C-S-H precipitation experiments were performed under controlled conditions of solution supersaturation in the presence and absence of gluconate and three hexitol molecules. Characterization of the precipitates with SAXS and cryo-TEM experiments confirmed the presence of a multi-step nucleation pathway. Induction times for the formation of the amorphous C-S-H spheroids were determined from light transmittance. Analysis of those data with the classical nucleation theory revealed a significant increase of the kinetic prefactor in the same order as the complexation constants of calcium and silicate with each of the organics. Finally, two distinct precipitation regimes of the C-S-H amorphous precursor were identified: i) a nucleation regime at low saturation indexes (SI) and ii) a spinodal nucleation regime at high SI where the free energy barrier to the phase transition is found to be of the order of the kinetic energy or less.

Dates et versions

hal-04229656 , version 1 (05-10-2023)

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Christophe Labbez, Lina Bouzouaid, Alexander E.S. van Driessche, Wai Li Ling, Juan Carlos Martinez, et al.. Mechanisms and kinetics of C-S-H nucleation approaching the spinodal line: Insights into the role of organics additives. Cement and Concrete Research, 2023, 173, pp.107299. ⟨10.1016/j.cemconres.2023.107299⟩. ⟨hal-04229656⟩
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