A thermodynamic approach to the hydration of sulphate-resisting Portland cement

Waste Management
Barbara Lothenbach, Erich Wieland

Abstract

A thermodynamic approach is used to model changes in the hydrate assemblage and the composition of the pore solution during the hydration of calcite-free and calcite-containing sulphate-resisting Portland cement CEM I 52.5 N HTS. Modelling is based on thermodynamic data for the hydration products and calculated hydration rates for the individual clinker phases, which are used as time-dependent input parameters. Model predictions compare well with the composition of the hydrate assemblage as observed by TGA and semi-quantitative XRD and with the experimentally determined compositions of the pore solutions. The calculations show that in the presence of small amounts of calcite typically associated with Portland cement, C-S-H, portlandite, ettringite and calcium monocarbonate are the main hydration products. In the absence of calcite in the cement, however, siliceous hydrogarnet instead of calcium monocarbonate is observed to precipitate. The use of a higher water-to-cement ratio for the preparation of a calcite-containing cement paste has a minor effect on the composition of the hydrate assemblage, while it significantly changes the composition of the pore solution. In particular, lower pH value and higher Ca concentrations appea...Continue Reading

References

Apr 25, 2006·Journal of Colloid and Interface Science·J TitsM H Bradbury

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Citations

Mar 2, 2012·Environmental Science & Technology·Laure AimozSergey V Churakov
Apr 4, 2006·Waste Management·A M ScheideggerR Dähn
Feb 27, 2018·Dalton Transactions : an International Journal of Inorganic Chemistry·H RojoJ Tits
Nov 21, 2009·Environmental Science & Technology·Peter MandalievErich Wieland
Feb 21, 2008·Environmental Science & Technology·Erich WielandRainer Dähn
Apr 7, 2007·Environmental Science & Technology·M VespaA M Scheidegger

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