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

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, {sup 29}Si 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*.
Authors:
 [1] ;  [2] ; ;  [3] ;  [4] ;  [5] ; ;  [1] ;  [6] ;  [3]
  1. Andra — Scientific Division, 1-7 Rue Jean Monnet, Parc de la Croix Blanche, 92298 Chatenay-Malabry Cedex (France)
  2. (France)
  3. BRGM, 3 Avenue Claude Guillemin, 45060 Orléans Cedex 2 (France)
  4. CNRS, CEMHTI, UPR 3079, 45071 Orléans (France)
  5. Empa, Laboratory for Concrete & Construction Chemistry, Überlandstrasse 129, 8600 Dübendorf (Switzerland)
  6. Université de Poitiers-CNRS, UMR7285 IC2MP, Equipe HydrASA, Poitiers 86022 (France)
Publication Date:
OSTI Identifier:
22475512
Resource Type:
Journal Article
Resource Relation:
Journal Name: Cement and Concrete Research; Journal Volume: 73; Other Information: Copyright (c) 2015 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CRYSTAL STRUCTURE; CRYSTALS; ELECTRON MICROPROBE ANALYSIS; GLYCOLS; HYDRATES; HYDRATION; LAYERS; MAGNESIUM; MAGNESIUM OXIDES; MAGNESIUM SILICATES; NANOSTRUCTURES; NMR SPECTRA; SILICA; SILICON; SILICON 29; SYNTHESIS; TEMPERATURE RANGE 0273-0400 K; THERMAL GRAVIMETRIC ANALYSIS; TRANSMISSION ELECTRON MICROSCOPY; X-RAY DIFFRACTION