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Crystal structure of magnesium silicate hydrates (M-S-H): The relation with 2:1 Mg–Si phyllosilicates

Abstract : Two magnesium silicate hydrates (M-S-H) with structural magnesium/silicon ratios of 0.57 ± 0.08 and 1.07 ± 0.13 were synthesized at room temperature, with one year of synthesis duration. Their structure was clarified by considering results from X-ray diffraction, TEM, 29Si MAS NMR spectroscopy, TGA, and EPMA. A modeling approach appropriate to defective minerals was used because usual XRD refinement techniques cannot be used in the case of turbostratic samples, where coherency between successive layers is lost. M-S-H with Mg/Si ratio of ~ 0.6 appears to be structurally close to nanocrystalline turbostratic 2:1 Mg–Si phyllosilicates. The increase of the Mg/Si ratio from 0.6 to 1.2 occurs by increasing the occurrence of defects in the silicate plan. The layer-to-layer distance evolves from 9.46 Å to 14 Å under air-dried and ethylene glycol conditions, respectively. Crystallites have a mean size of 1.5 nm in the ab plane, and 2.4 nm along c*.
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https://hal-brgm.archives-ouvertes.fr/hal-01356812
Contributeur : Anne-Marie Pouget <>
Soumis le : vendredi 26 août 2016 - 15:36:03
Dernière modification le : mardi 31 mars 2020 - 16:25:15

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Cédric Roosz, Sylvain Grangeon, Philippe Blanc, Valérie Montouillout, Barbara Lothenbach, et al.. Crystal structure of magnesium silicate hydrates (M-S-H): The relation with 2:1 Mg–Si phyllosilicates. Cement and Concrete Research, Elsevier, 2015, 73, pp.228-237. ⟨10.1016/j.cemconres.2015.03.014⟩. ⟨hal-01356812⟩

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