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 cement pastes and concretes. First, the equilibrium moisture properties of the hardened materials are described by means of water vapour sorption isotherms, which illustrate the hysteretical behaviour of the materials. Experimental results of drying shrinkage versus relative humidity (RH) are also reported here. These experimental data are in good agreement with the numerical results provided by a thermodynamic modelling based on capillary stresses and hygromechanical couplings. In particular the linearity of the strains-RH curve over a wide range is pointed out in both cases. Isothermal drying process at RH = 50% has experimentally and numerically been studied. After identification of the intrinsic permeability of the materials from experimental weight losses, numerical moisture profiles were compared with gamma-ray attenuation measurements. The influence of the initial moisture state of the materials that results from self-desiccation in particular was pointed out on the evolution of the moisture profiles as a function of time. (C) 1999 Elsevier Science Ltd. All rights reserved.