Bonding Properties of Embedded Fiber Reinforced Polymer Strip-Engineered Cementitious Composite Joints

The combination of fiber reinforced polymer (FRP) and engineered cementitious composite (ECC) has emerged as a promising method for strengthening reinforced concrete (RC) structures. By embedding FRP within an ECC to form a composite reinforcement layer, the advantages of both materials can be effectively harnessed, and the dense ECC matrix can be employed to safeguard FRP from adverse environments. Significantly, the interface bonding property constitutes the key for the two materials to collaborate effectively. In light of the research gap related to the bonding performance of embedded FRP strips in ECC joints, this study conducted a bench-scale investigation into the pull-out behavior of carbon FRP (CFRP) strips within an ECC. The relationship between the average bonding strength (2.84 MPa~4.77 MPa) and the embedded length of FRP strips was established. Additionally, the pull-out mechanism of FRP strips within an ECC matrix was utilized to elucidate the influence of the embedded length on the distinct behavior of FRP strips within an ECC. An analytical method for predicting the full-range behavior of embedded FRP strip-ECC joints by using a trilinear bond-slip relationship was introduced. Four key parameters of the trilinear bond-slip relationship for embedded FRP strip-ECC joints were provided to meet the requirements of future engineering applications.