Phase evolution and mechanical performance of an ettringite-based binder during hydrothermal aging

Hoang Nguyen*, Valter Carvelli, Wolfgang Kunther, Mirja Illikainen, Paivo Kinnunen

*Corresponding author for this work

    Research output: Contribution to journalJournal articleResearchpeer-review

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    Abstract

    Little is known about the performance of ettringite-based binders in hydrothermal conditions. This investigation aims to gain insights into the phase evolution and corresponding mechanical performance of an ettringite-based binder considering crystallization pressure caused by late-reaction products. Additionally, the role of fiber reinforcement on the strength retention of the binder was investigated. When aged at an elevated temperature under water-saturated conditions, hard-burned MgO hydrated to form brucite. The precipitation and growth of the brucite crystals led to a crystallization pressure of approximately 200 MPa calculated using thermodynamic modelling. Damage was observed after 4 months of aging with cracks in the microstructure and eventually a failure at the macro scale. Ettringite remained stable at 60 ◦C due to the water-saturated conditions. Polypropylene fiber delayed crack propagation and thus reduced the damage caused by crystallization pressure. The fiber improved the flexural performance of composite attaining deflection-hardening behavior regardless of aging conditions.
    Original languageEnglish
    Article number106403
    JournalCement and Concrete Research
    Volume143
    Number of pages15
    ISSN0008-8846
    DOIs
    Publication statusPublished - 2021

    Keywords

    • Degradation (C)
    • Ettringite (D)
    • Mechanical properties (C)
    • MgO (D)
    • Thermodynamic calculations (B)
    • Crystallization pressure

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