Distribution of Water in Synthetic Calcium Silicate Hydrates.
Understanding calcium silicate hydrates (CSHs) is of paramount importance for understanding the behavior of cement materials because they control most of the properties of these man-made materials. The atomic scale water content and structure have a major influence on their properties, as is analogous with clay minerals, and we should assess these. Here, we used a multiple analytical approach to quantify water distribution in CSH samples and to determine the relative proportions of water sorbed on external and internal (interlayer) surfaces. Water vapor isotherms were used to explain the water distribution in the CSH microstructure. As with many layered compounds, CSHs have external and internal (interlayer) surfaces displaying multilayer adsorption of water molecules on external surfaces owing to the hydrophilic surfaces. Interlayer water was also quantified from water vapor isotherm, X-ray diffraction (XRD), and thermal gravimetric analyses (TGA) data, displaying nonreversible swelling/shrinkage behavior in response to drying/rewetting cycles. From this quantification and balance of water distribution, we were able to explain most of the widely dispersed data already published according to the various relative humidity (RH) conditions and measurement techniques. Stoichiometric formulas were proposed for the different CSH samples analyzed (0.6 < Ca/Si < 1.6), considering the interlayer water contribution.
UMR CNRS 7285 IC2MP, Université de Poitiers , Equipe HydrASA, rue Albert Turpain, Bat B8, 86022 Poitiers, France.|Environment and Process Division, BRGM , 3, avenue Claude Guillemin, F-45060 Orléans Cedex 2, France.|Andra , 1/7 rue Jean Monnet, Parc de la Croix Blanche, 92298 Châtenay-Malabry Cedex, France.
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Roosz
Environment and Process Division, BRGM , 3, avenue Claude Guillemin, F-45060 Orléans Cedex 2, France.
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Gaboreau
Environment and Process Division, BRGM , 3, avenue Claude Guillemin, F-45060 Orléans Cedex 2, France.
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Grangeon
UMR CNRS 7285 IC2MP, Université de Poitiers , Equipe HydrASA, rue Albert Turpain, Bat B8, 86022 Poitiers, France.
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Prêt
CNRS-CEMHTI UPR 3079 , 1D Avenue de la Recherche Scientifique, 45071 Orléans Cedex 2, France.
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Montouillout
Environment and Process Division, BRGM , 3, avenue Claude Guillemin, F-45060 Orléans Cedex 2, France.
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Maubec
CNRS-CEMHTI UPR 3079 , 1D Avenue de la Recherche Scientifique, 45071 Orléans Cedex 2, France.
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Ory
Environment and Process Division, BRGM , 3, avenue Claude Guillemin, F-45060 Orléans Cedex 2, France.
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Blanc
UMR CNRS 7285 IC2MP, Université de Poitiers , Equipe HydrASA, rue Albert Turpain, Bat B8, 86022 Poitiers, France.
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Vieillard
Andra , 1/7 rue Jean Monnet, Parc de la Croix Blanche, 92298 Châtenay-Malabry Cedex, France.
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Henocq