PREDICTION EQUATION FOR DRYING SHRINKAGE OF CONCRETE FOCUSED ON THE INFLUENCE OF AGGREGATE QUALITY

Abstract

 In design phase, drying shrinkage strain of concrete is often obtained by a prediction equation. In the prediction formula of the current Japan society of civil engineers, a coefficient α indicating the influence of aggregate quality is introduced. It is said that the prediction formula can predict approximately ±50% with respect to the actual measurement values of the concrete drying shrinkage strain. The coefficient α representing the influence of the quality of the aggregate is substituted into the prediction expression by the value of 4 to 6, but the value is not determined by the type of aggregate or the like. In this research, we analyzed that the actual values of coefficient α expressing the effect of aggregate quality by using data of concrete using coarse aggregate including quality other than Japanese industrial standard. In addition, we modified the prediction equation as a function consisting of the each water content in mortar and coarse aggregate. Moreover, we proposed a formula for calculating the coefficient α’ representing the influence of the quality of the coarse aggregate.