Thermodynamic properties of Portland cement hydrates in the system CaO-Al2O3-SiO2-CaSO4-CaCO3-H2O

Thomas Matschei, Barbara Lothenbach, Fredrik P. Glasser

Research output: Contribution to journalLiterature review

343 Citations (Scopus)

Abstract

A database is presented for commonly-encountered cement substances including C-S-H, Ca(OH)(2), selected AFm, AR and hydrogarnet compositions as well as solid solutions. The AFm compositions include stratlingite. The data were obtained for the most part from experiment and many of the predicted reactions were confirmed by focussed experiments. The temperature-dependence of the thermodynamic data for the above phases, determined partly from experiment and partly from thermodynamic estimations, are also tabulated in the range 1 degrees C to 99 degrees C. Relative to previous databases, sulfate AFm is shown to have a definite range of stability range at 25 degrees C thus removing long-standing doubts about its stability in non-nal hydrated cement pastes. Carbonate is shown to interact strongly with stabilisation of AFm across a broad range of temperatures and, at low temperatures, to substitute into AFt. The new database enables the ultimate hydrate mineralogy to be calculated from chemistry: most solid assemblages, the persistence of C-S-H apart, correspond closely to equilibrium. This realisation means that hydrate assemblages can be controlled. The development of a thennodynamic approach also enables a fresh look at how mineralogical changes occur in response to environmentally-conditioned reactions; several papers showing applications are cited. (C) 2007 Elsevier Ltd. All rights reserved.

Original languageEnglish
Pages (from-to)1379-1410
Number of pages32
JournalCement and Concrete Research
Volume37
Issue number10
DOIs
Publication statusPublished - Oct 2007

Keywords

  • thermodynamics
  • thermodynamic data
  • AFm
  • AFt
  • hydrogamet
  • ettringite
  • stratlingite
  • phase relations
  • C-S-H
  • delayed ettringite formation
  • waste stabilization systems
  • aqueous solubility diagrams
  • oxide-silica-water
  • solid-solution
  • CAO-AL2O3-CASO4-H2O system
  • calcium-carbonate
  • blended cements
  • part I

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