Packaged wireless multisensor module embedded reinforced concrete for monitoring construction characteristics

A packaged wireless multisensor module has been developed and used for monitoring variations of temperature and humidity in reinforced concrete (RC). The multisensor (Sensirion, SHT 75) integrated a microprocessor control unit (MCU) and radio frequency integrated circuits (RFIC) for wireless signal transmission was packaged using poly(methyl methacrylate) (PMMA) to protect the module for avoiding alkali-aggregate corrosion from concrete. The temperature and humidity detection by concrete-embedded sensor modules and signal transmission by RFIC were proposed for real-time and long-term wireless monitoring that can prevent RC deformation caused by temperature and moisture-induced shrinkage stresses, stability and durability. A commercial temperature sensor (Pt-100) and a thermal imaging apparatus (Infrascope TVS200EX) were used to calibration. It is easy to perceive the temperature response comparison between the wireless sensor module and Pt-100 when embedded in concrete. Based on the experimental results, the durability and sensing capability of the proposed wireless multisensor module was investigated and found that can survive the concrete corrosion and stresses. Also it was found RF received long-term outputs that can measure temperature and moisture content with high sensitivity, accuracy and repeatability to reflect the variation in RC construction properties effectively.