High-resolution solid-state 29Si NMR of polymorphs of Ca2SiO4

Grimmer, A.‐R.; Lampe, F. von; Mägi, Μ.; Lippmaa, É.

doi:10.1016/0008-8846(85)90120-6

Cited by 49 publications

(13 citation statements)

References 7 publications

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“…For the signals in the unreacted AODNS_80 slag [Fig. (a)], the resonance at −79.7 ppm is close to the signal reported for cuspidine at Q 1 site, the resonance at −73.5 ppm can represent γ‐C 2 S and the peak at −71.3 ppm can be associated with β‐C 2 S, at Q 0 sites . As the 29 Si NMR spectra for merwinite and bredigite, to the best of the authors’ knowledge, are not available in literature, analysis was performed on synthetic mineral phases obtained from Bodor et al .…”

Section: Resultssupporting

confidence: 65%

Alkali Activation of AOD Stainless Steel Slag Under Steam Curing Conditions

et al. 2015

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Crystalline argon oxygen decarburization slag, in powdery form, was investigated for its hydration potential by alkali activation and curing at 80°C. Na-silicate and K-silicate of the same modulus were used as activators. Isothermal calorimetry at 80°C indicated exothermic reactions in the slag pastes. When the slag mortars were cured under steam at 80°C appreciable gain in compressive strength was measured. This was attributed to C-S-H which was detected in TG, FTIR, and 29 Si NMR analyses. Upon hydration at 90 d, the amount of crystalline phases decreased, whereas the XRD amorphous content in the slag increased. Electron microscopy showed the formation of different morphologies of reaction products depending on the alkaline activator employed. Presence of reaction rims around the crystalline phases with a major presence of Ca, Si, and O in the reacted matrix was observed in elemental maps.

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Section: Resultssupporting

confidence: 65%

Alkali Activation of AOD Stainless Steel Slag Under Steam Curing Conditions

et al. 2015

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“…2 and agree well with published data. 11 There are two overlapping peaks (−69 and −71 ppm) in the sample calcined at 700°C for 1 h (␣Ј L -C 2 S), but it is not clear whether the −71 ppm peak can be assigned solely to ␣Ј L -C 2 S or if there is a contribution from ␤-C 2 S, which has a single sharp peak at −71 ppm. The sample calcined at 1400°C has one sharp peak at −73 ppm assigned to ␥-C 2 S. The weak peak at −71 ppm is attributed to coexisting ␤-C 2 S, although this polymorph is not detected by XRD.…”

Section: (1) Phase Developmentmentioning

confidence: 98%

Hydration Kinetics and Phase Stability of Dicalcium Silicate Synthesized by the Pechini Process

Hong

Young

1999

Journal of the American Ceramic Society

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Reactive dicalcium silicate (Ca 2 SiO 4 ) has been synthesized by the Pechini process, and hydration kinetics studied. With increasing calcination temperature, the amorphous product first crystallizes to ␣ L -phase and subsequently to the ␤-and ␥-phases. The specific surface area, ranging from 40 to 1 m 2 /g, strongly depends on the calcination temperature of 700°-1200°C for 1 h. Samples with a high surface area have a high water demand; a water/cement ratio >2.0 is required to produce formable pastes in some instances. Hydration kinetics are determined by XRD, 29 Si magic-angle spinning nuclear magnetic resonance (MAS NMR), and differential scanning calorimetry/thermogravimetry (DSG/TG). The hydration rate depends only on the surface area, not on the polymorph. Complete hydration occurs in as early as 7 d. Very little calcium hydroxide (Ca(OH) 2 ) is formed in the most reactive specimens (calcined at 700°and 800°C), which indicates the Ca/Si ratio in C-S-H gels is ∼2.0, but more Ca(OH) 2 forms from samples calcined at higher temperature. The silicate structure of the hydrated Ca 2 SiO 4 pastes is investigated using 29 Si MAS NMR spectroscopy and trimethylsilylation analysis.

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“…Q 1 represents chain end group tetrahedra, with typical chemical shift at around 279 ppm; Q 2 represents middle chain groups where both adjacent tetrahedra are occupied by silicon (shift at around 285 ppm) and Q 2 (1Al) represents middle chain groups where one of the adjacent tetrahedra is occupied by aluminium (which results in a down field shift of around 3 ppm, giving a typical value of 282 ppm); Q 3 represents branching sites and Q 4 crosslinking sites in a three-dimensional framework. Following previous studies, a peak at around 273?5 ppm was assigned to c-C 2 S. [7][8][9][10][11] The broad peak on Fig. 1b with a chemical shift of 275 ppm is due to unreacted glassy slag.…”

Section: X-ray Diffractionmentioning

confidence: 99%

Nature of C–S–H in 20 year old neat ordinary Portland cement and 10% Portland cement–90% ground granulated blast furnace slag pastes

Taylor

Richardson

Brydson

2007

Advances in Applied Ceramics

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The purpose of this study was to investigate the effects of age on calcium silicate hydrate (C-S-H) present in two cement pastes: one in which the C-S-H at a younger age had a high Ca/Si ratio and another that had a low ratio. The study involved characterising a 20 year old neat ordinary Portland cement (OPC) paste (high Ca/Si) and a blend of the OPC with 90% ground granulated blast furnace slag (GGBS; low Ca/Si); the results are compared with data on the same mixes at 14 months old. The morphology of the outer product (Op) C-S-H in the blend was essentially the same as at 14 months, whereas that in the neat OPC paste appeared to be finer. The mean aluminosilicate chain length of the C-S-H was considerably longer in both pastes than in similar systems at younger ages. The chemical composition of the C-S-H in both pastes was significantly different than at 14 months: in the neat OPC paste, the Ca/Si ratio of the outer product C-S-H had increased with age, whereas that of the inner product C-S-H had decreased; the Ca/Si ratio of Op C-S-H in the blended paste had decreased with age. An entirely tobermorite based nanostructural model can account for the data for the C-S-H in the blend, whereas the data for the neat paste require some jennite or calcium hydroxide based structure; the distribution of the TEM-EDX analyses favours the T/CH model.

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High-resolution solid-state 29Si NMR of polymorphs of Ca2SiO4

Cited by 49 publications

References 7 publications

Alkali Activation of AOD Stainless Steel Slag Under Steam Curing Conditions

Alkali Activation of AOD Stainless Steel Slag Under Steam Curing Conditions

Hydration Kinetics and Phase Stability of Dicalcium Silicate Synthesized by the Pechini Process

Nature of C–S–H in 20 year old neat ordinary Portland cement and 10% Portland cement–90% ground granulated blast furnace slag pastes

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