SENSITIVITY ANALYSIS OF MOISTURE TRANSPORT MODELS IN THE FRAMEWORK OF A RELIABILITY APPROACH

International RILEM Conference on Materials, Systems and Structures in Civil Engineering - Conference segment on Moisture in Materials and Structures, Lyngby, DANEMARK, 22-/08/2016 - 24/08/2016The durability of concrete is linked to the water content, its spatial and time evolution, since aggressive agents pass through the liquid or gas phase. Thus, predicting the service lifetime of reinforced concrete structures requires reliable moisture transport models. Numerous modeling tools have been developed in order to predict moisture profiles in cementitious materials, in function of the environmental conditions, the characteristics of the porous media, etc. The models can include the following mechanisms: the advection and diffusion of water in gaseous and liquid phases, as well as the thermodynamic equilibrium through the water vapor sorption isotherm. This study proposes to perform, in the framework of a reliability approach, a sensitivity analysis for two modeling tools: a multiphasic model or a simplified version based on the Richards' equation. The originality of this study is partly reached taking into account the variability of input data. The two models are applied in case of drying of two mature concretes (one high performance concrete and one ordinary concrete), i.e. mass loss kinetics and moisture profiles are simulated. The objective is to identify the most relevant mechanisms and influencing input data (mean value and standard deviation). The results of the sensitivity analysis points out the importance to define a relevant water vapor desorption isotherm and, to a lesser extent, the liquid-water permeability, as a function of saturation