Characterization and identification of equilibrium and transfer moisture properties for ordinary and high-performance cementitious materials

In this paper some aspects of equilibrium and transfer moisture properties of high-performance materials are presented and compared with ordinary ceme nt pastes and concretes. First, the equilibrium moisture properties of the hardened materials are described by means of water vapour sorption isotherm s, which illustrate the hysteretical behaviour of the materials. Experiment al results of drying shrinkage versus relative humidity (RH) are also repor ted here. These experimental data are in good agreement with the numerical results provided by a thermodynamic modelling based on capillary stresses a nd hygromechanical couplings. In particular the linearity of the strains-RH curve over a wide range is pointed out in both cases. Isothermal drying pr ocess at RH = 50% has experimentally and numerically been studied. After id entification of the intrinsic permeability of the materials from experiment al weight losses, numerical moisture profiles were compared with gamma-ray attenuation measurements. The influence of the initial moisture state of th e materials that results from self-desiccation in particular was pointed ou t on the evolution of the moisture profiles as a function of time. (C) 1999 Elsevier Science Ltd. All rights reserved.