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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