State of Water in Hydrating Tricalcium Silicate Pastes: The Effect of a Cellulose Ether

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• 作者：Stefano Del Buffa ; Emiliano Fratini ; Francesca Ridi ; Antonio Faraone ; Piero Baglioni
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：April 14, 2016
• 年：2016
• 卷：120
• 期：14
• 页码：7612-7620
• 全文大小：478K
• 年卷期：0
• ISSN：1932-7455

文摘

Time-dependent quasi-elastic neutron scattering (QENS) and differential scanning calorimetry (DSC) were applied to study water dynamics and hydration kinetic of the hydration reaction of tricalcium silicate in the presence of a methyl hydroxyethyl cellulose (MHEC) additive. The translational dynamics of the water confined in the developing hydrated calcium silicate matrix was probed at the molecular scale by QENS during the first 4 days, while the evolution of the matrix porosity and the hydration kinetics were determined up to 28 days of hydration by differential scanning calorimetry. The application of the boundary nucleation and growth model consistently improved the hydration kinetics picture, usually obtained from the application of the classical Avrami-Erove’ev model, allowing the evaluation of the individual contributions of nucleation and growth over the entire hydration process. In the presence of the cellulose ether the nature of the nucleation process is strongly modified, approaching a “spatially random” hydration mechanism. The water contained in the nanometric porosity of the hydrated calcium silicate matrix, which is fundamental for the efficiency of the hydration process, results increased when MHEC is added, leading to a delay of the onset of the hydration process and the enhancement of the efficiency of the reaction.