Quantification of Concrete-Concrete Interface Strength – A Review

Abstract

The construction industry is experiencing a significant increase in hybrid concrete structures due to the need for repairing/strengthening of existing structures and the development of novel hybrid structures. The crack development and the ultimate capacity of hybrid concrete structures may significantly be governed by the properties of interface between the two concretes, making the quantification of interface properties essential. A large number of bond tests have been reported in literature but most of them do not result in a failure directly/entirely at the interface (unless the interface is very weak), resulting in only a lower bound estimate of the interfacial strength. Furthermore, the reported interfacial properties are only determined from small-scale bond tests where structural effects (like shrinkage) are limitedly taken into account. In the current study, the most commonly used bond tests are critically assessed in terms of the stress distribution caused by their inherent boundary conditions. Furthermore a testing procedure is then discussed which can allow for the quantification of the interfacial properties. A possible structural test is also designed which forces the failure to localize at the interface and allows to determine interface properties considering structural effects.