Behaviour of EBRIG CFRP sheet-concrete joint: Comparative assessment with EBR and EBROG methods

Abstract

• This study was the first attempt to evaluate the behavior of EBRIG FRP-concrete joints in comparison with EBR and EBROG joints. • A novel setup was developed to prepare the EBRIG specimens and carry the lap-shear tests on them. • The results including bond strength, failure modes, and other bond properties, confirmed the significant superiority of EBRIG installation method over the EBR and EBROG ones. • PIV technique was adopted to achieve the deformations fields and other bond properties. Grooving methods (GM) have remarkably shown higher efficiency than Externally Bonded Reinforcement (EBR) in anchoring the Fiber Reinforced Polymers (FRP) used for flexural retrofitting concrete structures. They are categorized into two types: Externally Bonded Reinforcement on Grooves (EBROG) and Externally Bonded Reinforcement In Grooves (EBRIG). The behavior of the EBR and EBROG joints were evaluated in many studies, but the behavior of EBRIG ones has not been assessed yet, and the present study is the first attempt to achieve the above aim. Accordingly, 12 concrete prisms were strengthened using one or two-layer of Carbon FRP (CFRP) sheets bonded via the EBR, EBROG, and EBRIG methods and then tested by a single lap-shear setup. In addition to evaluating bond strengths and failure modes, the bond behavior, including load-slip and shear stress-slip curves, and the slip, strain, and shear stress longitudinal profiles were acquired by Particle Image Velocimetry (PIV) technique. The results indicated substantial enhancement in the bond properties of specimens strengthened using grooving methods over the EBR. Besides, the EBRIG joint revealed a higher performance compared to the EBROG joint. For instance, applying the EBRIG method instead of EBROG led to 39% and 120% bond strength enhancement for one and two-layer FRP reinforced specimens, respectively. Additionally, all the EBROG joints failed due to cohesive debonding, whereas FRP sheets either ruptured or deeply debonded in the EBRIG joints reinforced with one or two layers of FRP.