The real structures of clinotobermorite and tobermorite 9 Å: OD character, polytypes, and structural relationships

Merlino, Stefano; Bonaccorsi, Elena; Armbruster, Thomas

doi:10.1127/0935-1221/2000/0012-0411

Cited by 102 publications

(114 citation statements)

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“…However, it appears unlikely that the primary sites for Ca-OH are at surfaces (where bond valences are unsatisfied), since this would imply that the Ca-OH content scales with the surface area of C-S-H; this does not agree with water adsorption [37,38] and recent small-angle neutron scattering (SANS) [39] studies showing that the greatest specific surface area in C-S-H occurs at low Ca/Si ratios (i.e., near 1), where charge balance [3,12] and INS [36] data show the lowest Ca-OH content. The evidence between interlayer and main layer Ca-OH sites is less clear, but the latter appears more likely since nearly all Ca-OH bonds in 1.4-nm tobermorite [2] and jennite [9] are from main layer Ca. Assuming this is true in C-S-H, the Ca-OH in the main layer can occur randomly (as in a solid solution) or in a more organized fashion as in jennite (at least in small regions); however, when the Ca-OH content is high (as in C-S-H gel), it would seem more likely that a jennite-like structure would eventually result due to a driving force to organize into a more (locally) ordered structure.…”

Section: Si-oh and Ca-oh In C-s-hmentioning

confidence: 99%

“…The reaction of C 3 S or b-C 2 S with about half their weight of water produces a hardened paste containing two products: C-S-H gel and Ca(OH) 2 …”

Section: Less-crystalline Phases: C-s-h(i) C-s-h(ii) and C-s-h Gelmentioning

confidence: 99%

“…The structure of 1.4-nm tobermorite, Ca 5 Si 6 O 16 (OH) 2 ·8H 2 O, which has only been recently solved by single crystal diffraction methods [2], has long been known to be based on a composite layer composed of a distorted central Ca-O sheet that is ribbed on either side with single § dreierketten [7,8], i.e., silicate chains that repeat at intervals of three silicate tetrahedra. Two of these tetrahedra, called paired tetrahedra, share two oxygen atoms with the central Ca-O sheet, while the third, called a bridging tetrahedron, shares only one ( Figure 1).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Solubility and structure of calcium silicate hydrate

Chen

Thomas

Taylor³

et al. 2004

Cement and Concrete Research

692

414

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C-S-H, the poorly crystalline calcium silicate hydrate formed in cement paste and aqueous suspension, is characterized by extensive disorder and structural variations at the nanometer scale. An analysis of new and published solubility data for C-S-H formed by different preparation methods and with a broad range of compositions illustrates a previously unrecognized family of solubility curves in the CaO-SiO 2 -H 2 O system at room temperature. As demonstrated by 29 Si magic-angle spinning (MAS) NMR data and by charge balance calculations, the observed differences in solubility arise from systematic variations in Ca/Si ratio, silicate structure, and Ca-OH content. Based on this evidence, the family of solubility curves are interpreted to represent a spectrum of metastable C-S-H phases whose structures range from purely tobermorite-like to largely jennite-like. These findings give an improved understanding of the structure of these phases and reconcile some of the discrepancies in the literature regarding the structure of C-S-H at high Ca/Si ratios.

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Section: Si-oh and Ca-oh In C-s-hmentioning

confidence: 99%

“…The reaction of C 3 S or b-C 2 S with about half their weight of water produces a hardened paste containing two products: C-S-H gel and Ca(OH) 2 …”

Section: Less-crystalline Phases: C-s-h(i) C-s-h(ii) and C-s-h Gelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Solubility and structure of calcium silicate hydrate

Chen

Thomas

Taylor³

et al. 2004

Cement and Concrete Research

692

414

View full text Add to dashboard Cite

show abstract

“…17 The initial-structure parameters for minerals in the sample were obtained from the literature: chrysotile (Falini et al), 18 (Merlino et al). 22 X-ray fluorescence analysis was performed on a Rigaku RIX-3100 spectrometer equipped with a Rh target, and operated at a tube voltage of 50 kV and a tube current of 80 mA. Na, Mg, Al, Si, P, K, Ca, Ti, Mn and Fe were measured using Kα lines.…”

Section: Methodsmentioning

confidence: 99%

Preparation and Evaluation of a Chrysotile Asbestos-containing Standard Material for Validating X-Ray Diffractometric Quantitation

et al. 2011

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A standard material containing chrysotile asbestos for the validation of x-ray diffractometric quantitation was developed using an asbestos-containing building material i.e., perlite board. The board as the base material was crushed, pulverized, and homogenized. The homogeneity of the powder of perlite board was estimated by analysis of variance. The diffraction intensity values of the crystalline phases and the concentrations of elements determined by x-ray diffractometry and x-ray fluorescence analysis were used for analysis of variance. There is no significant difference between the within-bottle variance and the between-bottle variance, indicating that the powdered perlite board was sufficiently homogenous. The concentration of chrysotile in the material was determined using two methods: an internal standard/x-ray diffractometry method and the x-ray diffractometry/Rietveld refinement. The concentration of chrysotile in the material was determined by an internal standard/x-ray diffractometry method and the material had a chrysotile concentration of 24.1 ± 0.2 mass%.

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“…Megaw et al (1956) were the first to investigate the crystal structure of tobermorite. Three structures of tobermorite phases have been reported according to their different basal spacing : (1) water-free 9 Å tobermorite (riversideite, Ca 5 Si 6 O 16 (OH) 2 ) (Merlino et al 1999(Merlino et al , 2000; (2) 11 Å tobermorite (Ca 5-x Si 6 O 17-2x (OH) 2x ·5H 2 O) (Merlino et al 1999(Merlino et al , 2001; and (3) 14 Å tobermorite (plombierite, Ca 5 Si 6 O 16 (OH) 2 ·7H 2 O) (Bonaccorsi et al 2005). Although Bonaccorsi et al (2005) refined the crystal structure of 14 Å tobermorite using synchrotron radiation X-ray diffraction (XRD), the detailed structural properties of water molecules in the interlayer remain unknown.…”

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Study of Water Molecules in Interlayer of 14 Å Tobermorite

Yoon

Monteiro

2013

ACT

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The molecular structure and dynamics of interlayer water of 14 Å tobermorite are investigated based on molecular dynamics (MD) simulations. Calculated structural parameters of the interlayer water configuration are in good agreement with current knowledge of the refined structure. The MD simulations provide detailed information on the position and mobility of the hydrogen and oxygen of interlayer water, as well as its self-diffusion coefficient, through the interlayer of 14 Å tobermorite. Comparison of the MD simulation results at 100 and 300 K demonstrates that water molecules in the interlayer maintain their structure but change their mobility. The dominant configuration and self-diffusion coefficient of interlayer water are obtained in this study.

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The real structures of clinotobermorite and tobermorite 9 Å: OD character, polytypes, and structural relationships

Cited by 102 publications

References 0 publications

Solubility and structure of calcium silicate hydrate

Solubility and structure of calcium silicate hydrate

Preparation and Evaluation of a Chrysotile Asbestos-containing Standard Material for Validating X-Ray Diffractometric Quantitation

Molecular Dynamics Study of Water Molecules in Interlayer of 14 Å Tobermorite

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