Ambient Temperature Drying Shrinkage and Cracking in Metakaolin-Based Geopolymers

Authors

  • Carsten Kuenzel,

    1. Department of Civil and Environmental Engineering, Imperial College London, London, UK
    2. Centre for Advanced Structural Ceramics, Department of Materials, Imperial College London, London, UK
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  • Luc J. Vandeperre,

    1. Department of Civil and Environmental Engineering, Imperial College London, London, UK
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    • Member, The American Ceramic Society.
  • Shane Donatello,

    1. Eduardo Torroja Institute of Construction Science (CSIC), Madrid, Spain
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  • Aldo R. Boccaccini,

    1. Centre for Advanced Structural Ceramics, Department of Materials, Imperial College London, London, UK
    2. Institute of Biomaterials, University of Erlangen-Nuremberg, Erlangen, Germany
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    • Member, The American Ceramic Society.
  • Chris Cheeseman

    Corresponding author
    • Department of Civil and Environmental Engineering, Imperial College London, London, UK
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Author to whom correspondence should be addressed. e-mail: c.cheeseman@imperial.ac.uk

Abstract

Ambient temperature drying shrinkage in metakaolin-based geopolymer pastes exposed to low relative humidity environments has been investigated. The effect of varying the geopolymer composition (water content, Si:Al ratio, Na:Al ratio, and Na+ or K+ cations) on the sensitivity to ambient temperature drying shrinkage is reported. The definition of “structural” water as being the minimum water content required that prevents contractions in the gel structure, and thus drying shrinkage from occurring, is introduced. From the results presented, it is clear that the ionic charge density of cations, the total quantity of cations, and the relative quantities and stabilities of cation: AlO4 pairs in the paste are major factors affecting the sensitivity of pastes to ambient temperature drying shrinkage.

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