Estimation for Drying Shrinkage of Concrete by Composite Model Using Coarse Aggregate Properties

Abstract

The factors which affect drying shrinkage of concrete are material properties and environmental conditions, and so on. It is said that the type of coarse aggregate is one of the most dominant factors which affect concrete drying shrinkage. Therefore, it is important that the length-change properties of coarse aggregate particle are grasped when concrete drying shrinkage strain is estimated. Moreover, it is a practical benefit that concrete drying shrinkage strain is estimated by using coarse aggregate properties to be obtained the result early, regardless of the mix proportion of concrete. From the above backgrounds, in this research, we tried to estimate concrete drying shrinkage strain by composite model which has been proposed by KISHITANI & BABA, and investigated applicability of the model by using the initial tangent modulus or the secant modulus for coarse aggregate. For this study we used 19 types of crushed stone from different regions and of different qualities. As a result, the estimation of concrete drying shrinkage strain by KISHITANI & BABA equation was made different results of accuracy due to types of modulus of elasticity to be used for calculation. The calculated value against the experimental value was a range of-30 to +10% when using the initial tangent modulus, and was a range of-30 to +30% when using the secant modulus.