Aluminum-27 solid state NMR spectroscopic studies of chloride binding in Portland cement and blends

J. A. Chudek, G. Hunter, M. R. Jones, S. N. Scrimgeour, P. C. Hewlett, A. B. Kudryavtsev

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    20 Citations (Scopus)

    Abstract

    Alumina-rich pozzolanic and latent hydraulic binders such as pulverized fuel ash, metakaolin, and ground granulated blast furnace slag, together with silica fume, are frequently added to Portland cement concrete to improve performance and to retard chloride ingress and thereby inhibit chloride-induced corrosion of the carbon steel reinforcement. 27Al{1H} MAS and CP/MAS NMR spectroscopies have been used to follow both the hydration processes of the cement blends and the interactions of chloride ion with the hydrated aluminum species. The spectra of the hydrated aluminate phases were interpretable on the basis that the AFt (Aluminate Ferrite tri-) phase ettringite, C6AS̄3H32 (3CaO·Al2O3·3CaSO4·32H2O, or C3A·3CaSO4·32H2O), and the AFm (Aluminate Ferrite mono-) phases calcium mono-sulphoaluminate, C4AS̄H12 (3CaO·Al2O3·CaSO4·12H2O, or C3A·CaSO4·12H2O), and the lamellar tetracalcium aluminate hydrate, C4AH13 (3CaO·Al2O3·Ca(OH)2·12H2O, or C3A·Ca(OH)2·xH2O) were present as the only hydrated species containing octahedrally-coordinated aluminum. In all cases, only the AFm phase Friedel's salt (3CaO·Al2O3·CaCl2·10H2O, or C3A·CaCl2·10H2O) could be identified as the major chloroaluminate phase produced by the interactions of the cement pastes with chloride ion.

    Original languageEnglish
    Pages (from-to)4275-4288
    Number of pages14
    JournalJournal of Materials Science
    Volume35
    Issue number17
    DOIs
    Publication statusPublished - 1 Sep 2000

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