CONSTITUTIVE MODELING OF UNSATURATED DRYING DEFORMABLE MATERIALS

Thermodynamics of open continua, when applied directly at the macrosco pic engineering scale, allows one to extend unambiguously the principa l concepts of continuum thermomechanics of solids to polyphasic porous materials, whose fluid constituents are subject to liquid-vapor phase change. This approach provides a consistent and relevant framework fo r the formulation of the constitutive equations of partially saturated deformable porous materials such as concrete. After recalling the gen eral theory, the modeling is specified for porous materials that are p artially saturated by a liquid water phase changing into its vapor pha se, the latter forming with the dry air an ideal mixture. The nonlinea r poroelasticity, as reference modeling, is then detailed. The theory is applied to the modeling of the drying shrinkage of concrete samples with isothermal sorption curves as only experimental data. The predic ted shrinkage is found to be in close agreement with the observed one for a range of humidity greater than 50%. The drying shrinkage of a wa ll is finally examined. The analysis includes the study of the tempera ture variations due to latent heat effects. These variations are shown to be negligible.