RFID-Based Crack Detection of Ultra High-Performance Concrete Retrofitted Beams
Department of Civil Engineering, University of Connecticut, Storrs, CT 06269, USA
Author to whom correspondence should be addressed.
Sensors 2019, 19(7), 1573; https://doi.org/10.3390/s19071573
Received: 21 January 2019 / Revised: 19 March 2019 / Accepted: 24 March 2019 / Published: 1 April 2019
(This article belongs to the Special Issue Smart Sensors and Smart Structures)
Ultra-high-performance concrete (UHPC) is a novel material with multiple known uses and many still yet to be discovered. Recently, the use of encasing welded shear studs in UHPC on the web of corroded steel beams was developed. This creates a bearing force transfer mechanism to bypass the corroded web plate. This new material and its uses come with many uncertainties in the short and long term. Structural health monitoring (SHM) can be a tool to observe the development. Specifically, radio frequency technology (RFID) can be used. RFID has existed commercially since the 1960s and has been used as a crack sensor before, but never with UHPC. RFID-based crack sensing is being used to monitor the UHPC retrofit. A crack is simulated on the UHPC specimen and then a commercial, low cost tag is secured. Using backscatter power, the tag reads the crack existence and its increasing volume with every new damage stage. Using a damage index, comparing the uncracked and each cracked stage, this method is not restricted to the raw received signal strength indicator (RSSI), which could be different at each tag. With this sensor, the small cracks that occur in UHPC during its creation can be monitored to ensure the capacity of the retrofitting is maintained. The tested RFID-based crack sensor can be used on various other forms of UHPC.