Realization of a Passive UHF RFID Sensor Platform for the Detection of Damages on a Concrete Reinforcement

Every year, roads are exposed to chemical stress due to deicing in winter. The chemical composition of road salt causes pitting corrosion of steel used in road constructions, especially in the reinforced concrete of bridges. Due to increasing cracks in the concrete, chloride ions intrude deeper and deeper into the structure over a longer period of time and attack the steel structure. In the worst case, this can lead to structural breakdown. However, early detection of damage in reinforced concrete can prevent such failure. Therefore, this paper deals with the implementation of a passive Ultra-High Frequency Radio-Frequency Identification (UHF RFID) sensor platform as a preventive measure. The sensor data are collected and transmitted to a reader that processes the information about the chloride concentration. For the presented RFID sensor platform, a WISP based Tag was improved and supplemented by additional circuit components. Several modifications and an additional circuit with high input impedance allows the connection of electrochemical probes (sensor). An Impinj Speedway R420 (UHF RFID reader) is used to read the measurement data from the sensor platform which is integrated in the concrete over a distance of 15 cm.