Prediction of the drying shrinkage of concrete based on micro-mechanics

The drying shrinkage of concrete has been concerned by engineers and researchers for a long time. This paper analyzes the ratio of concrete/cement drying shrinkage by using micro-mechanics. Assuming concrete as a two phase composite material composed of cement and aggregate and according to the change of the volume of concrete to the same as that of the sum of all the constituents, the drying shrinkage of concrete is respectively obtained by using the Mori-Tanaka method based on Eshebly equivalent inclusion theory and the method of micro-mechanics based on load superposition. The study shows that the numerical results obtained from the methods of Mori-Tanaka and self-consistent are consistent with that of the empirical formula. Hence the methods can be used to analyze the drying shrinkage of concrete. The ratio of concrete/cement drying shrinkage decreases with the increase of the volume fraction of aggregates, but increases with the increase of the Poisson's ratio of the cement. The increase of the ratio of aggregate/cement matrix bulk modulus will decrease the drying shrinkage, but it has little effect when the ratio exceeds 5. The methods used in this paper have clear physical meaning and easy calculation. It also can reduce the experimental works and provide useful suggestions for the design of concrete structures. ©, 2014, Tsinghua University. All right reserved.