Accuracy analysis on CFRP-RC interfacial defects detected using electrical measurement: Influence of steel reinforcement

Detection of carbon fiber reinforced polymer (CFRP)-concrete interfacial defects using electrical measurement has been proven to be an effective method. However, due to the influence of steel reinforcement, the detecting accuracy of the method still needs further investigation for reinforced concrete (RC) structures. To this end, nine CFRP-RC specimens, varying the numbers and locations of longitudinal steel reinforcement and the presence of stirrups, were prepared to conduct the electrical measurement tests. In addition, a finite element(FE)model of the electrostatic field at the CFRP-RC interface was also developed to evaluate the effects of rebar diameter, electrode position, and defect length on the detection accuracy. From the test results, the proposed method exhibits favorable identifying accuracy in characterizing the defects at the CFRP-RC interface. However, part of the detecting current flow from the CFRP plate to the test electrode through the reinforcement, and this bypass will affect the accuracy of assessing the location of defects at the CFRP-RC interface. The characteristics of the resistance distribution curves show that the rebar in the RC structure mainly affects the detection results by changing the flow route of the detecting current, and a reasonable relative position of the electrode and the longitudinal rebar is conducive to improving the accuracy of the electrical measurement, and the diameter of the rebar has little effect on the accuracy of the electrical measurement. Furthermore, a defect evaluation model is developed for CFRP-strengthened RC structures considering the influence of reinforcement, and the accuracy is verified by experimental results.