Early age shrinkage and bond at interface between repair material and concrete substrate

Abstract

Very early age shrinkage may have significant effects on induced stresses and bond strength development in the case of a composite specimen comprising freshly cast cementitious material on a hardened concrete substrate. Due to difficulties associated with the fixing of targets on fresh concrete, information about very early age shrinkage was not well documented. The study was firstly focused on the development of a new approach for monitoring very early age shrinkage occurring immediately after mixing the concrete using digital image analysis. Once the new method was established, the phenomena causing the early age total shrinkage of concrete were investigated. With the knowledge of the very early age of concrete, the research extended to investigate the differential shrinkage of composite specimens comprising concrete substrate and freshly cast repair material. Finally, the effect of differential shrinkage of composite on the bond strength development at the interface was measured.