Monte Carlo simulations of Ca–montmorillonite hydrates

Chávez-Páez, Martı́n; dePablo, L.; DePablo, Juan

doi:10.1063/1.1374536

Cited by 76 publications

(109 citation statements)

References 16 publications

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“…One explanation for reversible adsorption would be that the layered structure would not open up making intercalation negligible. This would be surprising and contrary to observations of a significant increase in Xray basal spacing on wetting Ca-montmorillonite [33,38]. There is, however, not universal agreement on this issue as some numerical simulations would indicate [39].These simulations, however, were focused on stability of Ca-montmorillonite at high temperatures and pressures.…”

Section: Mass Change Isothermscontrasting

confidence: 48%

Dimensional change and elastic behavior of layered silicates and Portland cement paste

Beaudoin

Raki

Alizadeh

et al. 2010

Cement and Concrete Composites

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/npsi/ctrl?lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?lang=fr Access and use of this website and the material on it are subject to the Terms and Conditions set forth at http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. For the publisher's version, please access the DOI link below./ Pour consulter la version de l'éditeur, utilisez le lien DOI ci-dessous.http://dx.doi.org/10. 1016/j.cemconcomp.2009.09.004 Cement and Concrete Composites, 31, 9, p. 34, 2009-09-01 Dimensional change and elastic behaviour of layered silicates and Portland cement paste Beaudoin, J. J.; Raki, L.; Alizadeh, R.; Mitchell, L. D. ABSTRACTThe role of water in hydrated Portland cement paste (hpc) is germane to understanding the nature of nanostructure -property relationships of the material. The irreversible dimensional changes of hpc and phase pure C-S-H that occur on wetting and drying are dissimilar to those observed for other silicate minerals of interest to cement science. This irreversibility in hpc is also observed for the modulus of elasticity parameter. Length change, mass change and modulus of elasticity isotherms (including drying-wetting cycles) were determined for specimens of hpc, Camontmorillonite and 1.4 nm tobermorite. Length change and modulus of elasticity versus mass loss curves were also obtained for phase pure C-S-H (C/S= 0.8,1.0 and 1.5). All the isotherms exhibit significant irreversible behaviour. Similarities and differences in the nature and character of the isotherms and the relevance of the C-S-H data are discussed. Inferences are made with respect to the nanostructural nature of hpc, its dimensional response in aqueous media and the correspondence in behaviour of synthetic C-S-H and that formed in hpc. It is apparent that hpc has unique characteristics that are responsible for stability.

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Section: Mass Change Isothermscontrasting

confidence: 48%

Dimensional change and elastic behavior of layered silicates and Portland cement paste

Beaudoin

Raki

Alizadeh

et al. 2010

Cement and Concrete Composites

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“…Sato et al, 1992) or modelled by molecular dynamic approaches (Tambach et al, 2004;Chavez-Paez et al, 2001). The number of water layers in the interlayer depends on the nature of the interlayer cations and on the compaction degree (Kozaki et al, 1998;Ferrage et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Porosities accessible to HTO and iodide on water-saturated compacted clay materials and relation with the forms of water: A low field proton NMR study

Montavon

Guo

Tournassat

et al. 2009

Geochimica et Cosmochimica Acta

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. Porosities accessible to HTO and iodide on water-saturated compacted clay materials and relation with the forms of water: A low field proton NMR study. Geochimica et Cosmochimica Acta, Elsevier, 2009, 73 (24) AbstractThe aim of the present work was to quantify accessible porosities for iodide and for a water tracer (HTO) on water-saturated compacted clay samples (illite, montmorillonite and MX-80 bentonite) and to relate these macroscopic values to the forms of water in these porosities (surface/bulk water, external/internal water). Low field proton NMR was used to characterize and quantify the forms of water. This enabled the three different populations (structural OH, external surface and internal surface water) to be differentiated on hydrated clays by considering the difference in proton mobility. An accurate description of the water forms within the different populations did not appear possible when water molecules of these populations were in contact because of the occurrence of rapid exchange reactions. For this 2 reason, it was not possible to use the low resolution NMR method to quantify external surface and bulk water in fully water-saturated compacted clay media at room temperature. This latter information could however be estimated when analyzing the samples at -25°C. At this temperature, a distinction based on the difference in mobility could be made since surface water remained in a semi-liquid state whereas bulk water froze. In parallel, accessible porosities for anions and HTO were determined by an isotopic dilution method using capillaries to confine the materials. HTO was shown to probe the whole pore volume (i.e. the space made of surface and bulk water). When the surface water volume was mainly composed of interlayer water (case of montmorillonite and bentonite), iodide was shown to be located in the pore space made of bulk water. When the interlayer water was not present (case of illite), the results showed that iodide could access a small fraction of the surface water volume localized at the external surface of the clay particles.

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“…A number of authors carried out simulations in the NP z T ensemble. [15][16][17][18][19][22][23][24][25]28,[31][32][33][34][35][36]42,46 This technique imposes the pressure normal to the clay layers (P z ) and allows the basal spacing (d001) to equilibrate at a given number of water molecules. An alternative approach is simulating swelling clay minerals in the grand-canonical (µVT) ensemble.…”

Section: Introductionmentioning

confidence: 99%

“…An alternative approach is simulating swelling clay minerals in the grand-canonical (µVT) ensemble. 3,[18][19][20][21][26][27][28] In this case, water molecules are inserted into or removed from the clay system under the condition of a fixed water chemical potential, which is related to the water vapor pressure. Hensen and Smit 29 combined the NP z T and the µVT approach and carried out simulations in the µP z T ensemble.…”

Section: Introductionmentioning

confidence: 99%

Molecular Simulations of Swelling Clay Minerals

2004

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We have carried out molecular simulations in the grand-canonical ensemble of water and cations in Wyoming and Arizona montmorillonite clay minerals, with varying relative humidity. Several water models and cations are used to investigate the swelling of these clays. We show how the water content depends on the type of clay, type of cation, the basal spacing, and the relative humidity. Related to the layering of water molecules in the interlayer space, the pressure normal to the clay sheets oscillates as a function of the basal spacing. Minima in corresponding free energy curves indicate the presence of dehydrated states and layered hydrates. The development of these stable states and the corresponding basal spacings are in agreement with experimental data. Density profiles show significantly different interlayer structures depending on the type of clay and models used. We show a relation between formation of two-layer hydrates and the position of the cations. The simulations with the MCY water model underestimate the spacings of two-and three-layer hydrates, whereas our simulations with the TIP4P model produce a better agreement. Therefore, we recommend the TIP4P model for simulating clay minerals. In addition, we report remarkable ordering of cations and water molecules in a one-layer Arizona montmorillonite hydrate.

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Monte Carlo simulations of Ca–montmorillonite hydrates

Cited by 76 publications

References 16 publications

Dimensional change and elastic behavior of layered silicates and Portland cement paste

Dimensional change and elastic behavior of layered silicates and Portland cement paste

Porosities accessible to HTO and iodide on water-saturated compacted clay materials and relation with the forms of water: A low field proton NMR study

Molecular Simulations of Swelling Clay Minerals

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