Phase evolution and mechanical performance of an ettringite-based binder during hydrothermal aging
Nguyen, Hoang; Carvelli, Valter; Kunther, Wolfgang; Illikainen, Mirja; Kinnunen, Päivö (2021-02-24)
Nguyen, H., Carvelli, V., Kunther, W., Illikainen, M., & Kinnunen, P. (2021). Phase evolution and mechanical performance of an ettringite-based binder during hydrothermal aging. Cement and Concrete Research, 143, 106403. https://doi.org/10.1016/j.cemconres.2021.106403
© 2021 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
https://creativecommons.org/licenses/by-nc-nd/4.0/
https://urn.fi/URN:NBN:fi-fe202102245881
Tiivistelmä
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.
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