Implementing RFIC and sensor technology to measure temperature and humidity inside concrete structures

In this study, a new measurement technique was developed that enables direct, real-time measurements and continuous monitoring of concrete internal temperature and humidity via wireless signal transmission. The RFIC transmitter was designed based on the integration of a Radio Frequency Integrated Circuit (RFIC) and temperature/humidity sensors. Temperatures measured were compared with those measured by a Pt-100 resistance thermometer. The design of the enclosure and its sealing creates space for measuring the internal temperature and humidity of the concrete and mitigates the chance of damage to the RFIC transmitter due to concrete slump during the construction stage. Experiments show that the amount of reinforcing steel and RF signal strength are negatively correlated. The effective reception distance for concrete without steel bars is 19 m when there is no blocking obstacle and 12.2 m when a blocking obstacle is present. However, the effective reception distance for reinforced concrete without a blocking obstacle is only 12 m; with blocking obstacles, this is further reduced to 7.3 m.