Passive, Wireless Corrosion Sensors for Transportation Infrastructure

Many industrial segments including utilities, manufacturing, government and infrastructure have an urgent need for a means to detect corrosion before significant damage occurs. Transportation infrastructure, such as bridges and roads, rely on reinforced and prestressed concrete for structural reliability but corrosion of the reinforcing steel in structural concrete can significantly lower the structural capacity. This proposal aims to develop an inexpensive wireless corrosion sensor that does not require any external power supply. Such a sensor would be very useful tool in evaluating the structural health of the nation’s infrastructure and in turn make our highway travel safer. These sensors will be based on radio-frequency identification (RFID) tags that are used to track consumer goods and are extremely low-cost. The ubiquity of RFID tags in the consumer market allows for the use of proven, off-the-shelf technology and translates into a lower per unit deployment cost. These sensors would be situated on the steel rebar either directly on the metal or over the epoxy coating. They could be fixed to the rebar in the field using a plastic ring that snaps onto the rebar or supplied pre-affixed to the rebar using an adhesive such as epoxy glue. Alternatively, they could be placed at different depths in the structure allowing the monitoring of the diffusion or seepage of corrosive salts into the concrete and provide early detection of potential structural problems. The location and degree of corrosion may be used to intelligently schedule maintenance to optimize resources or to modify the current uses of the structure to prolong the life. The development of such a sensor will allow the engineers to employ “best maintenance practices” that are estimated to save 46 percent of the annual corrosion cost of a black steel rebar bridge deck, or $2,000 per bridge per year.