Experimental testing correlation of the different aged concrete bond strength involving the new tilted cube test (TCT)

Abstract

The bonding behavior of concrete repairs is highly dependent on the type of applied stresses. The slant shear test is mutually applied in the bonding investigations for its roughness sensitivity and for being a compression shear test indicating the actual members’ state. Cohesive failures are recommended to ensure monolithic behavior; however, adhesive failures are needed for bonding investigations. To better compare the test results, a modified slant shear test was previously developed with an enforced adhesive failure using larger reinforced prisms. This paper presents an application of a newly developed compression shear test with an enforced adhesive failure of unreinforced normal size tilted cubes. The bonding behavior was investigated under different bonding agents, substrate moisture conditions, interface surface roughness, and testing types. A testing correlation was presented between the tilted cube, slant shear, bi-surface shear, and pull-off tests. Since the ACI acceptance criterion for the slant shear test was found more suitable for the concrete repairs of higher than 45 MPa compressive strength, an improved acceptance criterion was presented and classified according to the concrete grade. Moreover, the previously developed pull-off bond strength qualification was extended using the obtained testing correlation of this study to include all the applied testing types. Citing the relevant studies; the obtained test results validated the tilted cube test for investigating the bonding behavior, where the test specimens of SSD, epoxy adhesive, and wire-brushed interfaces presented higher bond strength results.