Reversible shrinkage of concrete made with recycled concrete aggregate and other aggregate types

Drying shrinkage gradients through the depth of a concrete slab can be divided into permanent and transient components because a portion of shrinkage is reversible. As there has only been a small amount of research on this topic in the past 60 years, the goal of this study was to characterize the amount of reversible shrinkage for standard paving concrete made with virgin, recycled concrete, and lightweight aggregates. This research found that approximately 30% of shrinkage was reversible for standard paving mixtures exposed to cyclic wetting and drying, regardless of the type of aggregate used. However, the level of reversible shrinkage increased significantly under long-term initial moisture curing. This research also corroborates the long-held assumption that the length change of concrete specimens is proportional to their weight change due to moisture movements. Copyright © 2013, American Concrete Institute.