Investigation of the CaO-Al2O3-SiO2-CaSO4-CaCO3-H2O system at 25 degrees C by thermodynamic calculation

D Damidot, S J Barnett, F P Glasser, D E Macphee

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The phase diagram of the CaO-Al2O3-SiO2-CaSO4-CaCO3-H2O system relevant to cement has been calculated at 25degreesC and 1 bar pressure. It is composed of 331 stable phase assemblages in equilibrium with the aqueous phase and contains 30 invariant points with 15 solids. Thaumasite appears to be a stable phase with a wide stability domain. Compared to ettringite, thaumasite is stable to lower pH and generally demands higher sulphate concentrations to be stable.

Original languageEnglish
Pages (from-to)69-76
Number of pages8
JournalAdvances in Cement Research
Issue number2
Publication statusPublished - Apr 2004


  • thaumasite
  • NA2O
  • cement

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