27Al and29Si magic angle spinning nuclear magnetic resonance spectroscopy of Al-substituted tobermorites

Komarneni, Sridhar; Roy, Rustum; Roy, Della M.; Fyfe, C. A.; Kennedy, Gordon J.; Bothner‐By, Aksel A.; Dadok, Josef; Chesnick, A. Scott

doi:10.1007/bf00552416

Cited by 129 publications

(105 citation statements)

References 15 publications

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“…In some of the spectra, the Q 2 peak has a shoulder near -83 ppm. This shoulder has been observed by a number of investigators [3,4,19,31,[64][65][66][67], but its assignment is still uncertain. It is generally assumed that the shoulder is produced by a subset of the Q 2 Si, and it is likely to represent at least some of those present as bridging tetrahedra [4,67].…”

Section: Ca Concentration Versus Ca/si Of the Solidmentioning

confidence: 89%

Solubility and structure of calcium silicate hydrate

Chen

Thomas

Taylor³

et al. 2004

Cement and Concrete Research

739

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: Ca Concentration Versus Ca/si Of the Solidmentioning

confidence: 89%

Solubility and structure of calcium silicate hydrate

Chen

Thomas

Taylor³

et al. 2004

Cement and Concrete Research

739

414

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“…18, 19 Komarneni et al further illustrated that Al [4] primarily entered Q 2 and Q 3 silicate chain sites. 4,17 Subsequently, others suggested that Al [5] and Al [6] also occurred in tobermorite.…”

Section: 13mentioning

confidence: 99%

“…metakaolinite, 8,11 kaolinite, 1 zeolite, 6 newsprint recycling residue 12 and y ash [14][15][16][17] ) and the optimization of its ion exchange performance. 4 It has also been reported that aluminum could inuence the formation of tobermorite to form Al-substituted tobermorite, in which Al substitution occurred at the Q 2 or Q 3 sites (the symbol Q represents one SiO 4 tetrahedron and the superscript indicates the number of other Q units to which it is bonded), 7 as illustrated in Fig. 1.…”

Section: 13mentioning

confidence: 99%

“…[3][4][5][6] Tobermorite is formed below 180 C and undergoes a phase transition path: CaO + SiO 2 / C-S-H gel / tobermorite. 7,8 It always appears within the rst 60 min, and its growth is completed within 5 h. 9 Three types of tobermorite exist, namely 14Å, 11Å and 9Å tobermorite, with their names relating to the d-spacing of (002) in their X-ray diffraction patterns, which depends on the number of water molecules per formula unit.…”

Section: Introductionmentioning

confidence: 99%

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Microstructure and characterization of aluminum-incorporated calcium silicate hydrates (C–S–H) under hydrothermal conditions

Zhao

2018

RSC Adv.

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The phase assembly and microstructure of the aluminum-incorporated CaO-SiO 2 -H 2 O system, which is technologically important in autoclaved building materials, catalysis and waste management, were investigated using XRD, SEM, FTIR and NMR depending on aluminum addition, reaction temperature and curing time. The content of each phase was obtained using the MAUD program based on the Rietveld refinement. The results revealed that the formation of the tobermorite phase was promoted at Al/(Al + Si) # 0.03, and subsequently retarded by higher aluminum addition, which was corroborated by the presence of more low polymerized and cross-linked (alumino)silicate chains. The phase purity decreased with increasing aluminum addition. Aluminum changed the morphology of tobermorite from plate-like to lath-like and fibrous. About a quarter of the (alumino)silicate chains in the C-S-H structure were linked though a^Si-O-Al^configuration, and this proportion was almost independent of aluminum addition. Furthermore, only Al[4] substituted for silicon in the aluminum incorporated C-S-H, while Al [6] just exited in the hydrogarnet phase. This work is beneficial for understanding the implication on microproperties of by-products or admixtures containing aluminum in concrete.

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“…'Normal' tobermorite with few interlayer tetrahedral linkages loses water at about 300 ~ with a reduction in apparent layer thickness to about 9.5/~ from 11.3A (along Z). In contrast, 'anomalous' tobermorite, which has numerous interlayer linkages, does not collapse significantly (E1-Hemaly et al, 1977;Mitsuda and Taylor, 1978;Komarneni and Roy, 1983) et al (1977) found that anomalous tobermorite may be more readily synthesized in the presence of alkali and A13 + cations. These substituted forms, especially involving Na++A13+ substitutions, exhibit more pronounced cation exchange characteristics and greater selectivity of Cs over Na or Ca from various dilute salt solutions (Komarneni andRoy, 1983, 1985).…”

Section: Introductionmentioning

confidence: 99%

Comparison of Cation Exchange in Ganophyllite and [Na + Al]-Substituted Tobermorite: Crystal-Chemical Implications

Komarneni

Guggenheim

1988

Mineral. mag.

Self Cite

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Ganophyllite and [Na + +At 3 +]-substituted tobermorite exhibited similar cation exchange properties and, in particular, selective cesium exchange. [Na + +A13+]-substituted tobermorite and ganophyllite showed a selective Cs exchange of 10.77 and 8.71 meq/100 g from 0.02N NaC1 and of 11.08 and 9.04 meq/100 g from 0.02N CaC12, respectively. The [Na + +A13+]-substituted tobermorite is structurally similar to ganophyllite: both are roughly analogous to 2:1 layer silicates, both have cross-linking tetrahedra across the interlayer region, and both have exchangeable cations located in zeolite-like sites in the interlayer region. The similarities in cation exchange properties imply that the residual charge configuration of the analogue 2 : 1 layer must be approximately equivalent also.

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27Al and29Si magic angle spinning nuclear magnetic resonance spectroscopy of Al-substituted tobermorites

Cited by 129 publications

References 15 publications

Solubility and structure of calcium silicate hydrate

Solubility and structure of calcium silicate hydrate

Microstructure and characterization of aluminum-incorporated calcium silicate hydrates (C–S–H) under hydrothermal conditions

Comparison of Cation Exchange in Ganophyllite and [Na + Al]-Substituted Tobermorite: Crystal-Chemical Implications

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