Richardson, IG (2014) Model structures for C-(A)-S-H(I). Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials, 70 (6). 903 - 923 (21). ISSN 2052-5206
Abstract
C-(A)-S-H(I) is a calcium silicate hydrate that is studied extensively as a model for the main binding phase in concrete. It is a structurally imperfect form of 14 Å tobermorite that has variable composition and length of (alumino)silicate anions. New structural-chemical formulae are presented for single and double-chain tobermorite-based phases and equations are provided that can be used to calculate a number of useful quantities from 29Si NMR data. It is shown that there are no interlayer calcium ions when the silicate chains are of infinite length and that one is added for each tetrahedral 'bridging' site that is vacant. Preparations that have Ca/Si greater than about 1.4 include an intermixed Ca-rich phase. It is not possible to generate a structural model for a dimer that is crystal-chemically consistent with known calcium silicate hydrates if the starting structure is an orthotobermorite, i.e. of the type that has been used in all previous studies. Crystal-chemically plausible models are developed that are based instead on clinotobermorite. A number of models that represent different mean chain lengths are developed using crystal-chemical and geometrical reasoning. The models account for experimental observations, including variations in Ca/Si, H2O/Si, (alumino)silicate anion structure and layer spacing.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2014, International Union of Crystallography. Reproduced in accordance with the publisher's self-archiving policy. |
Keywords: | Cement-based concrete; binding phase; tobermorite |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Civil Engineering (Leeds) > Institute for Resilient Infrastructure (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 24 Feb 2015 11:59 |
Last Modified: | 24 Feb 2015 11:59 |
Published Version: | http://dx.doi.org/10.1107/S2052520614021982 |
Status: | Published |
Publisher: | International Union of Crystallography |
Refereed: | Yes |
Identification Number: | 10.1107/S2052520614021982 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:83022 |