(A) study on moisture diffusion and drying shrinkage of concrete at different temperatures

Abstract

This study mainly dealt with moisture diffusion problem. Based on moisture diffusion theory and finite element method, analytical method was developed to estimate the moisture distribution in concrete and verified by experimental results. Internal relative humidity in concrete at different depths of drying specimen at early age was measured not by probe or traditional capacitance but using embedded humidity sensors. The moisture diffusion of concrete is significantly influenced by ambient temperature. Increasing temperature of ambient air results in decreasing moisture diffusion in concrete which was exposed to environmental temperature of chamber at very early age after casting. Also, the shrinkage strain of concrete exposed to higher temperature at early age after casting is lower than that of lower temperature. Numerical analysis of moisture diffusion is performed by using finite element analysis program CONSA/HS (CONcrete Stress Analyzer/ Hydration and Shrinkage), based on moisture diffusion theory with some modifications due to properties of diffusion of early age concrete. Analytical results are in good agreement with the experimental results.