CALCULATION OF MOISTURE INDUCED STRESSES AND EVALUATION OF CRACKING RISK IN EARLY-AGE CONCRETE

Taking the cast-in-situ concrete column as an example, an analytic model for moisture induced shrinkage stress calculation in early-age concrete is developed in the present paper. The model relied on the relationship between interior humidity and shrinkage strain and the calculation on moisture field in concrete. The influence of creep of concrete on the stresses is taken into account by relaxation coefficient method. The cracking risk of concrete at early-ages is analyzed. Using the model, the effect of the environment humidity and the size of concrete column on the moisture induced stresses are calculated and analyzed. The results show that the variation of the interior humidity inside of concrete with concrete age is the main factor controlling the magnitude of the moisture stresses. The smaller the discrepancy between interior humidity and environment humidity, the smaller the moisture stresses. The parameters related with concrete creep may greatly influence the moisture stresses. In addition, the dimension of concrete column has certain impact on the moisture stresses as well. Under the same environmental conditions, the larger the column, the higher the moisture stresses and the greater the cracking risks.