PREDICTION OF WATER VAPOUR SORPTION ISOTHERMS AND MICROSTRUCTURE OF HARDENED PORTLAND CEMENT PASTES

Author(s): James M. de Burgh, Stephen J. Foster and Hamid R. Valipour
Book Title: RILEM International Symposium on Concrete Modelling - CONMOD 2014
Editor: Kefei Li, Peiyu Yan and Rongwei Yang
ISBN: 978-2-35158-139-1
e-ISBN: 978-2-35158-140-7
Publisher: RILEM Publications SARL
Publication year: 2015
Pages: 265-272
Total Pages: 8
Language: English

Abstract: Water vapour sorption isotherms (WVSIs) of cementitious materials offer a direct reflection of the physical microstructure through its interaction with moisture. They have long been the subject of close study, providing strong evidence behind much of our understanding of hardened cement paste (HCP) microstructure. Moreover, the ability to both understand and predict adsorption and desorption behaviour is essential in the application of performancebased approaches to durability analysis. Practical approaches for predicting the sorption behaviour of concrete and HCP have been the subject of renewed study in recent years. In this paper, a new physically based model for predicting the water vapour adsorption isotherm of arbitrary hardened Portland cement pastes is presented. The model is based on well established thermodynamic principles, applied to a microstructure which evolves with hydration. Calibration is performed using an extensive data set, and close agreement is achieved with both calibration data and independent data sets. The method uses closed form differentiable equations, and allows for the rational consideration of temperature effects – making the model suitable for use in multi-physics hygro-thermal analyses.

Online publication: 2015
Publication Type: full_text
Public price (Euros): 0.00