Shrinkage cracking of restrained concrete slabs

The goal of this investigation was to better understand and predict early-age shrinkage cracking in restrained concrete structures. The threefold aim of this study included: (1) the development of test methods to assess the potential for shrinkage cracking; (2) the development of a theoretical model to predict cracking; and (3) the evaluation of a nonexpansive shrinkage reducing admixture. Two test configurations were used in evaluating the potential for restrained shrinkage cracking, ring-type and slab-type specimens. Experiments were performed on both normal and high strength concrete with 0, 1, and 2% shrinking reducing admixture. Time-dependent material properties were measured and the effect of restraint was tested in both ring and slab specimens. A computer-automated fracture mechanics model was used to successfully predict the age at first cracking. Results exhibit favorable comparison between theoretical modeling and experimental observations.