Convertible Bond Test Apparatus for EB FRP, NSM FRP, FRCM, and Allied Systems: Proof of Concept

The first phase of this work uses experimental evidence to critique some shortcomings of the so-called improved double-lap bond shear tests regarding their limited application to wet layup fiber-reinforced polymer (FRP) and their inapplicability to pultruded FRP laminates. Even in the case of the wet layup FRP, the study provides some evidence of high chances of obtaining undesirable fiber rupture that preclude the use of the results as reliable means for interpreting the FRP-concrete bond-slip models. Further proposed modifications to overcome these challenges are provided by designing a convertible bond tester applicable to both wet layup and pultruded FRP laminates. Apart from the application of the apparatus to FRP-concrete bond assessment under pure double shear, it proved to be applicable to conducting mixed-mode bond tests. The second phase of the work upgrades the so-designed test apparatus to make it convertible to bond testing of other variants (near-surface mounted [NSM] FRP bars/strips, fiber-reinforced cementitious mortar [FRCM], etc.) of strengthening systems without developing a different apparatus for each. The apparatus allows testing the NSM FRP-concrete bond in a novel manner compared to the traditional practice. Also, given the absence of mixed-mode studies for FRCM, the apparatus provides a pioneer means of conducting the same.