Experimental study on fracture properties of CFRP-to-concrete interface subject to salt water

The mechanical property degradation of bonding interface between FRP (fiber reinforced polymer) and concrete has an adverse effect on the performance of FRP strengthened concrete structures. In order to increase the durability database and have a better understanding of the degradation mechanism, the effect of NaCl solution on CFRP (carbon fiber reinforced polymer)-to-concrete interface under mode I and mode II loading is studied by using pulling test and wedge driving test method, respectively. The relationship between salt water content and fracture energy release rate of CFRP-to-concrete interface is studied. Because the interfacial salt water content cannot be measured directly, a finite element simulation is established based on salt water uptake tests of component materials. The results show that both mode I and mode II fracture energy release rate of CFRP-to-concrete interface decrease nonlinearly with salt water content, and the change of failure mode from debonding within the concrete layer to cohesive failure along the interface is also observed.