The role of Al in C–S–H: NMR, XRD, and compositional results for precipitated samples

Sun, Guokuang; Young, J. F.; Kirkpatrick, R. James

doi:10.1016/j.cemconres.2005.03.002

Cited by 338 publications

(262 citation statements)

References 40 publications

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“…This is in agreement with Pardal et al [35], who prepared C-A-S-H from C-S-H and a hydrogarnet (C 3 AH 6 ) saturated solution and observed that the produced C-A-S-H maintained the tobermorite structure. The maximum Al/Si ratio they found in C-A-S-H was 0.19, which is in agreement with other studies, either experimental (e.g., [36]) or recently found in a Roman concrete immersed in seawater [18], in which a wide interlayer spacing, 11.49Å, for Al substituted tobermorite is reported in close agreement with our XRD results. However, the Al/Si ratio in all those studies was lower than the Al/Si found in the present study, which is within the range of 0.24-0.29.…”

Section: Discussionsupporting

confidence: 93%

Nature of C-(A)-S-H Phases Formed in the Reaction Bentonite/Portlandite

Fernández

Gonzalez

Ruiz

et al. 2014

Journal of Geochemistry

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Reactions between bentonite/montmorillonite and portlandite have been studied in the context of the engineered barriers of a purpose built repository for the deep geological disposal of spent fuel and high-level radioactive wastes. Portlandite was selected as the representative material of cement leaching in the early alkaline stage expected in a repository when conventional Ordinary Portland Cement (OPC) is used. Eight different batch experiments were performed for a reaction time near to two months, including bentonite or montmorillonite at montmorillonite/portlandite molar ratios of 2 : 1 and 3 : 1 under hydrothermal conditions. Temperatures of reactions were maintained constant at either 60 or 120°C. Calcium silicates hydrates with limited substitution of Al for Si (C-(A)-S-H phases with Al/Si <0.3) were formed with different structures and compositions as a function of the reaction conditions. Orthorhombic 11 Å-tobermorite-type phase was detected in experiments at 120°C while a more disordered monoclinic tobermorite formed at 60°C. These results are useful for the interpretation of experimental data in more complex experiments using concrete or cement pastes and bentonite, where C-(A)-S-H phases of variable compositions can precipitate, in addition to the characteristic cement hydrates and other secondary minerals carbonates.

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Section: Discussionsupporting

confidence: 93%

Nature of C-(A)-S-H Phases Formed in the Reaction Bentonite/Portlandite

Fernández

Gonzalez

Ruiz

et al. 2014

Journal of Geochemistry

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“…This band corresponds to the aluminium (IV) incorporated in bridging tetrahedra in the calcium aluminium silicate hydrate (Andersen et al, 2003;Sun et al, 2006). These results are consistent with the 29 Si MAS NMR data, where formation of calcium aluminium silicate hydrate type phases was identified after 1 d of curing, differing from the trends identified in sodium-carbonate-activated slag cement , where the distinctive peaks assigned to the strength-giving phase calcium aluminium silicate hydrate were only observed after 7 d of curing.…”

Section: Offprint Provided Courtesy Of Wwwicevirtuallibrarycomsupporting

confidence: 56%

Alkali-activated slag cements produced with a blended sodium carbonate/sodium silicate activator

Bernal

Nicolas

Deventer

et al. 2016

Advances in Cement Research

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An alkali-activated slag cement produced with a blend of sodium carbonate/sodium silicate activator was characterised. This binder hardened within 12 h and achieved a compressive strength of 20 MPa after 24 h of curing under ambient conditions, which is associated with the formation of an aluminium substituted calcium silicate hydrate as the main reaction product. Carbonates including pirssonite, vaterite, aragonite and calcite were identified along with the zeolites hydroxysodalite and analcime at early times of reaction. The partial substitution of sodium carbonate by sodium silicate reduces the concentration of carbonate ions in the pore solution, increasing the alkalinity of the system compared with a solely carbonate-activated paste, accelerating the kinetics of reaction and supplying additional silicate species to react with the calcium dissolving from the slag as the reaction proceeds. These results demonstrate that this blend of activators can be used effectively for the production of high-strength alkali-activated slag cements, with a microstructure comparable to what has been identified in aged sodium-carbonate-activated slag cements but without the extended setting time reaction usually identified when using this salt as an alkali activator.

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“…Studies analysing laboratory-synthesised C-(A-)S-H specimens have identified that phasepurity decreases as the Al/Si and Ca/(Al+Si) molar ratios of the solid phase increase, suggesting that a 'soft' upper bound on the Al content of C-(A-)S-H exists in the composition range relevant to cementitious materials of Al/Si ≈ 0.2 [19][20][21]. The secondary phases formed in these systems are typically AFm (Al 2 O 3 -Fe 2 O 3 -mono) type phases such as strätlingite (C 2 ASH 8 ), katoite (C 3 AH 6 , which is the Si-free end member of the hydrogarnet series C 3 AS y H 6-2y , 0 ≤ y ≤ 3) and/or the 'third aluminate hydrate' (TAH) [19,21].…”

Section: Preprint Version Of Accepted Article Please Cite As: Rj Mmentioning

confidence: 99%

“…The secondary phases formed in these systems are typically AFm (Al 2 O 3 -Fe 2 O 3 -mono) type phases such as strätlingite (C 2 ASH 8 ), katoite (C 3 AH 6 , which is the Si-free end member of the hydrogarnet series C 3 AS y H 6-2y , 0 ≤ y ≤ 3) and/or the 'third aluminate hydrate' (TAH) [19,21].…”

Section: Preprint Version Of Accepted Article Please Cite As: Rj Mmentioning

confidence: 99%

Effect of temperature and aluminium on calcium (alumino)silicate hydrate chemistry under equilibrium conditions

Myers

L’Hôpital

Provis

et al. 2015

Cement and Concrete Research

312

130

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ReuseUnless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. KeywordsTemperature, Calcium-Silicate-Hydrate (C-S-H), Thermodynamic Calculations, Hydration Products, Blended Cement. AbstractThere exists limited information regarding the effect of temperature on the structure and solubility of calcium aluminosilicate hydrate (C-A-S-H). Here, calcium (alumino)silicate hydrate (C-(A-)S-H) is synthesised at Ca/Si = 1, Al/Si ≤ 0.15 and equilibrated at 7-80°C. These systems increase in phase-purity, long-range order, and degree of polymerisation of C-(A-)S-H chains at higher temperatures; the most highly polymerised, crystalline and crosslinked C-(A-)S-H product is formed at Al/Si = 0.1 and 80°C. Solubility products for C-(A-)S-H were calculated via determination of the solid-phase compositions and measurements of the concentrations of dissolved species in contact with the solid products, and show that the solubilities of C-(A-)S-H change slightly, within the experimental uncertainty, as a function of Al/Si ratio and temperature between 7°C and 80°C. These results are important in the development of thermodynamic models for C-(A-)S-H to enable accurate thermodynamic modelling of cement-based materials. IntroductionTemperatures experienced by cement and concrete based construction materials in service can vary greatly, due to heat evolution from cement hydration, variable ambient environmental conditions, steam curing, and other factors. understanding of the nature of C-S-H and other constituent phases in these systems at equilibrium [6][7][8][9] has meant that hydrated neat PC materials can be accurately described by thermodynamic modelling at temperatures from 5°C to above 80°C [10]. Extending this analysis to the CaO-Al 2 O 3 -SiO 2 -H 2 O system represents a major step toward applying this technique to hydrated PC blends with high replacement levels of supplementary cementitious materials, which are not fully described by existing thermodynamic models [11]. This will enable a much deeper understanding of the chemistry and phase composition, and hence durability, of these materials in service.The chemistry and structure of calcium (alumino)silicate hydrate (C-(A-)S-H) products at ambient conditions have been the subject of sustained research for more than half a...

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The role of Al in C–S–H: NMR, XRD, and compositional results for precipitated samples

Cited by 338 publications

References 40 publications

Nature of C-(A)-S-H Phases Formed in the Reaction Bentonite/Portlandite

Nature of C-(A)-S-H Phases Formed in the Reaction Bentonite/Portlandite

Alkali-activated slag cements produced with a blended sodium carbonate/sodium silicate activator

Effect of temperature and aluminium on calcium (alumino)silicate hydrate chemistry under equilibrium conditions

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