Thermal stability of C-S-H phases and applicability of Richardson and Groves’ and Richardson C-(A)-S-H(I) models to synthetic C-S-H

Elena Tajuelo Rodriguez, Krassimir Garbev, Daniela Merz, Leon Black, Ian G. Richardson

Research output: Contribution to journalArticlepeer-review

211 Scopus citations

Abstract

Synthetic C-S-H samples prepared with bulk C/S ratios from 0.75 to 1.5 were analyzed by coupled TG/DSC/FTIR and in-situ XRD while heating, in order to correlate observed weight loss curves with the kinetics of evolved gases, and to investigate the transformations C-S-H → β-wollastonite → α-wollastonite. The temperature of the transformation to β-wollastonite increased with increasing C/S. The temperature for the transformation from β- to α-wollastonite meanwhile decreased with increasing C/S; indicating that excess CaO stabilized the α-polymorph. The transformation C-S-H → β-wollastonite was accompanied by the formation of α′LC2S for C/S > 1. In the case of C-S-H with C/S = 1.5, both β-C2S and rankinite were formed and then decomposed before the transformation to β-wollastonite and α′LC2S. C-S-H with low C/S was found to be more stable upon heating. The chemical structural models of Richardson and Groves’ and Richardson C-A-S-H(I) were used to obtain the structural-chemical formulae.

Original languageEnglish
Pages (from-to)45-56
Number of pages12
JournalCement and Concrete Research
Volume93
DOIs
StatePublished - Mar 1 2017
Externally publishedYes

Funding

Thanks are due to the European Commission for funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement 264448.

FundersFunder number
Seventh Framework Programme264448
European Commission
Seventh Framework Programme

    Keywords

    • A. Calorimetry
    • B. Calcium silicate hydrate (C-S-H)
    • B. Spectroscopy
    • B. Thermal analysis
    • B. X-ray diffraction

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