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Lookup NU author(s): Dr Jiayi Wang, Dr Colin DavieORCiD, Dr Enrico Masoero
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
© 2022 The Authors. The constitutive models of concrete often consider water desorption isotherms to be near-equilibrium and significantly affected by moderately high temperature, 40–80°C, typically through microstructural changes. However literature data suggest that adsorption, not desorption, is near-equilibrium and moderate temperatures do not cause microstructural changes. This work supports the latter theory, through dynamic vapor sorption experiments on cement paste at 20–80°C. Samples were pre-conditioned at 60% relative humidity and 20°C, and isotherms were measured for several humidity ranges and testing rates. The results, corroborated by classical DFT simulations, indicate that adsorption is near-equilibrium and mostly unaffected by temperature, whereas desorption is out-of-equilibrium due to the ink-bottle effect at high humidity, and interlayer water at low humidity. Starting from the second cycle, desorption at higher temperatures features a shift of the cavitation pressure and overall a smaller hysteresis. A conceptual model of pore-specific temperature-dependent hysteresis is proposed to qualitatively explain the results.
Author(s): Wang J, Yio MHN, Zhou T, Wong HS, Davie CT, Masoero E
Publication type: Article
Publication status: Published
Journal: Cement and Concrete Research
Year: 2023
Volume: 165
Print publication date: 01/03/2023
Online publication date: 27/12/2022
Acceptance date: 21/12/2022
Date deposited: 27/06/2023
ISSN (print): 0008-8846
ISSN (electronic): 1873-3948
Publisher: Elsevier Ltd
URL: https://doi.org/10.1016/j.cemconres.2022.107076
DOI: 10.1016/j.cemconres.2022.107076
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