Evaluation of connectors'' influence on the interface behaviour between concrete layers

The behavior of concrete interfaces cast at different times is influenced by many variables, including material characteristics, interface surface preparation, interface geometry and many more. The performance of such interfaces is not yet fully understood and is particularly challenging to predict. This paper presents and discusses the results of 17 experimental push-off tests, which varied in interface types and connector arrangements. Three types of interface connector arrangements were tested and compared: one perpendicular to the interface and two lattice girder configurations. Interfaces with lattice girder connectors exhibited greater adhesion resistance. Among these, one specific lattice girder arrangement demonstrated the highest resistance to shear following adhesion failure. A second type of lattice girder arrangement was responsible for the lowest interface crack width. When the perpendicular interface connector arrangement was used, the widest interface crack was observed. The experimental specimens also featured different interface surface types: smooth and shear key interfaces. The shear key interface achieved the highest overall shear capacity. Additionally, a novel theoretical model was employed to predict interface behavior up to considerable slippage. The impact of differential shrinkage on the adhesion resistance of the interface was demonstrated using theoretical shrinkage and interface behavior results.