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Water sorption isotherms and hysteresis of cement paste at moderately high temperature, up to 80 °C

Lookup NU author(s): Dr Jiayi Wang, Dr Colin DavieORCiD, Dr Enrico Masoero

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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).

Abstract

© 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.

Publication metadata

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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