Electrical resistivity and chargeability to assess cracking in concrete

Non-destructive crack assessment can promptly warn engineers to take proper remedial work. This study investigates the effectiveness of the combined method of electrical resistivity (ER) and time-domain induced polarization (IP) as a monitoring tool to detect the potential failure of the reinforced concrete in tension. In the series of laboratory-scale experiments, multiple ring electrodes are devised and embedded in 2-meter-length concrete beams. The ER and IP values of the concrete are ontained using four-point measurement during three points flexural tests of the concrete beams with dynamic and incremental stepwise loading to artificially induce cracks. Particle Image Velocimetry (PIV) is also carried out by taking sequential photographs to capture the microscopic crack propagation presented on concrete surface. Experimental results show that the measured ER increases as the applied load increases with larger crack development, but the measured ER is also influenced by highly conductive metallic reinforcement structures such as steel rebars and stirrups (hoops). However, the normalized IP (IP divided by ER) is mostly controlled by the steel elements, and not significantly affected by the cracks. Therefore, the normalized IP value can be utilized to isolate the effect of the steel elements, influencing the ER measurement for crack assessment. In conclusion, a more reliable assessment of concrete cracking can be achieved by using the combined IP and ER methods.