Evaluation of Plastic Shrinkage Cracking of Self-Consolidating Concrete

Abstract

Self-consolidating concrete (SCC) is a fluid concrete, cast without vibration, that has a self-leveling ability that makes it appropriate for flat structures such as slabs or industrial floors. This article reports on a study that evaluated plastic shrinkage cracking of SCC. The authors compared five SCC mixtures with compressive strengths ranging from 30 to 50 MPa to five ordinary concrete (OC) mixtures. Free and restrained plastic shrinkage tests were performed in different drying conditions. When the evaporation rate is moderate (drying at 20 deg C and a relative humidity of 50%), plastic shrinkage occurs before and during setting. When the evaporation rate is high (windy condition), plastic shrinkage occurs only in the plastic state, that is, before setting. In the presence of wind, SCC and OC mixtures have almost the same plastic shrinkage and restrained shrinkage tests reveal that cracks of SCC tend to be less wide than cracks of OC. However, when the evaporation rate is low, SCC mixtures exhibit a higher plastic shrinkage than OC mixtures, due to their lack of bleeding. The authors conclude by recommending curing in order to protect SCC against evaporation at the fresh state.