Effect of liquid rubber modification on the bond behavior of externally bonded FRP laminate-concrete interface under dynamic loading

Interfacial debonding between fiber-reinforced polymer (FRP) laminate and concrete substrate is one of the critical issues in the externally bonded FRP strengthened concrete members. Existing studies have shown that the addition of liquid rubber into the bonding adhesives can increase debonding resistance of FRP laminate-concrete interface and consequently improve the comprehensive performance of FRP strengthened concrete members under quasi-static loading. The purpose of this study is to clarify the effect of liquid rubber modification on the bond behavior of FRP laminate-concrete interface under dynamic loading. Six groups of double-lap shear specimens with neat or rubber-modified epoxy were tested under static and two dynamic loading rates. The parameters of peak load, FRP strain distribution and interfacial bond stress-slip relationship are analyzed. Test results indicate that the liquid rubber modification can significantly improve the bond capacity of FRP laminate-concrete interface under dynamic loading. Further, the influence mechanism of liquid rubber modification on the dynamic bond behavior of FRP laminate-concrete interface is discussed. Finally, an empirical dynamic bond stress-slip model considering the effect of liquid rubber modification is proposed and validated.