Passive Wireless Detection of Corrosive Salts in Concrete Using Wire-Based Triggers

Abstract

This paper presents an iron wire trigger mechanism that will be used for a new generation of low-cost corrosion sensors that are wireless and do not require batteries or any other external power sources. The corrosion of thin sensor wires, 0.065 to 0.25 mm in diameter, were investigated in sodium chloride solutions and compared with the mass loss from steel coupons under similar conditions. The 0.125- and 0.065-mm wires were embedded in concrete and subjected to accelerated corrosion testing. These wires are suitable for use as triggers for corrosive salts. They behaved similarly to mild reinforcing steel used in concrete structures and their resistance increased significantly at predictable chloride levels. Prototype sensors, constructed using commercial radio frequency identification tags with a section of the antenna replaced by a wire trigger, were embedded in concrete. These results demonstrate the methodology to create successful radio frequency identification based sensors for the egress of corrosive agents, such as chlorides, into concrete.