Effect of aggregate on drying shrinkage of concrete

Abstract

Aggregate accounts for a large volumetric rate within concrete and influences the properties of concrete. In this investigation, the effect of aggregate properties on drying shrinkage of concrete was examined. It had been thought before that aggregate plays a role in restraining the shrinkage of cement paste, and that the shrinkage of aggregate itself can be neglected. However, according to the results obtained by this experiment, the shrinkage of aggregate is not necessarily negligible and it is strongly related to the shrinkage of concrete. Lightweight aggregate with a lower modulus of elasticity offers less restraint on the potential shrinkage of cement paste, then the large shrinkage of concrete is expected, but the actual shrinkage of lightweight concrete is comparatively small. It was demonstrated by this experiment that because of the small shrinkage of lightweight aggregate, shrinkage of lightweight concrete is relatively small. The shrinkage of normal aggregate is generally larger than that of lightweight aggregate, and it is necessary to pay attention to the usage of normal aggregate. Copyright © 2008 Japan Concrete Institute.