Coupled coil sensor for detecting surface corrosion on steel reinforcement

An embedded coupled coil sensor able to monitor the corrosion potential of reinforcement steel in concrete is presented. The sensor is based on coil resonator whose resonant frequency changes with an applied voltage. The sensor state can be monitored externally by a coupled coil. An accelerated corrosion test shows that it can provide useful information about the corrosion state and the level of chloride ingress into the concrete. The wireless sensor is passive and simple in design, making it an inexpensive, batteryless option for remote long-term monitoring of the corrosion state of reinforcing steel.