Numerical Determination of Moisture Diffusivity in Concrete

Abstract

Accurate modelling of moisture diffusion is essential, as it dominates the drying process in concrete and governs the development of shrinkage strains that affect the short- and long-term deformation and cracking behaviour of structural elements. Key models available in the literature use porosity as the main parameter to predict the diffusivity of the material. Although physically sound, this approach is difficult to apply in practice, as the in-situ determination of concrete porosity is challenging. To address this, the present study uses readily available quantities (namely w/c ratio and concrete maturity) as primary material modelling parameters and investigates the effects of pore relative humidity and ambient temperature on the diffusivity properties of concrete using inverse numerical analysis and available experimental data. As a result, a diffusion modelling approach that can be readily used in practical applications is proposed and verified through finite element analyses. The results show that numerical predictions are in good agreement with experimental data. Specifically, the model is capable of capturing the effects of w/c ratio, concrete maturity and thermal conditions on the evolution of the moisture profile within drying concrete elements. The model can be used to determine drying shrinkage strains with a high degree of accuracy, thereby allowing for a more realistic assessment of crack evolution in drying concrete elements and its effects on overall structural performance.