Water vapour sorption experiments on hardened cementitious materials. Part II: Essential tool for assessment of transport properties and for durability prediction

This paper forms the second part of a series. In this second part, transport properties are theoretically and experimentally studied on various hardened cementitious materials, in order to evaluate the influence of some parameters (degree of saturation, mix-composition, …). Water vapour and moisture diffusion coefficients, as well as liquid water or gas permeability, as a function of the degree of saturation can be assessed from water vapour sorption experiments along with a complementary test, a numerical model and/or analytical formulas. Here, the analysis focuses in particular on the meaning of the various coefficients obtained by different methods. The results point out that, owing to the complex phenomena that take place during drying–wetting processes and to their moisture history dependency, inadequacy can arise between the diffusion coefficients involved in the theoretical description and those actually measured. Moreover, the concept of intrinsic permeability, independent of the permeating fluid, does not seem relevant for cementitious materials when liquid water is regarded, except maybe for highly permeable ones.