Prediction of Stress Development and Cracking in Steel Fiber-Reinforced Self-Compacting Concrete Overlays Due to Restrained Shrinkage

This paper will discuss how shrinkage cracking of self-compacting concrete (SCC) overlays with and without steel fibers has been assessed through laboratory testing and theoretical analysis. Test results verified that steel fiber reinforcement has a crack width limiting effect. However, the contribution in case of fiber contents up to 0.75 volume percent was not found to be sufficient to distribute cracks in situations where bond to the substrate were nonexistent. Thus, even higher steel fiber contents (or other types of fibers) are required in order to control cracks. A distributed pattern of fine cracks was however obtained even for unreinforced SCC within bonded areas of the overlays. This implies that steel fibers, or other crack reinforcement, are not required if high bond strength is obtained. An analytical model, proposed to assess the risk of cracking and to predict crack widths in overlays, was found to give reasonable correlation with experimental results.