The nonlinear humidity distribution occurs due to moisture diffusion when the concrete is exposed to an ambient air. These nonlinear humidity distribution induces shrinkage cracks on surfaces of concrete. Because this cracks largely affect on durability and serviceability of concrete structures, moisture diffusion in concrete must be investigated.
The purpose of this thesis is to propose the model of moisture diffusion coefficient that determines moisture diffusion within concrete structures. To propose the model of moisture diffusion coefficient, several experiments and numerical analysis were performed. Generally, relative humidity and temperature influence on the moisture diffusion coefficient. Moreover, this coefficient is varied with aging because microstructures of concrete develope as aging, especially at early ages. Therefore, the modified model of moisture diffusion coefficient was proposed considering aging effect as well as relative humidity and temperature in this thesis.
In this study, experiments on moisture diffusion were performed to investigate the variation of moisture diffusion coefficient with age and temperature under three temperature conditions (20, 50, and 80℃). From the experimental results, a new model of moisture diffusion coefficient considering the aging and temperature was developed by numerical analysis. The suggested diffusion coefficient was expressed as a function of pore ratio, humidity and temperature based on the existing equation, which was expressed as the function of humidity and temperature.
