摘要: |
This project will develop and demonstrate a Kelvin Probe (KP) electrode device for a rapid and stable electrode potential mapping for early corrosion detection in concrete steel reinforcement in highway structures. Work in Stage 1 of the project will focus on scaling up from an existing stationary miniature proof of concept version of KP electrode device to a mobile and practical large size unit suitable for realistic field conditions through three interrelated activities. In the first activity a wheeled platform with automatic gap distance control will be designed and constructed to hold the probe and achieve automatic probe-road surface gap distance control. The gap control will be achieved either by mechanical or electromechanical means. The second activity will scale up the probe sensing disk and working gap to dimensions (e.g. 4 inches, and 1/2 to 1 inch respectively) and ruggedness suitable for use on typical bridge deck environment. The electromechanic driving unit and electronic control system will be scaled up accordingly. The third activity will integrate the outcome of the first two by constructing a working single-probe prototype and optimizing the combination of vibrating frequency, signal processing response time, and gap distance control response to increase usable speed of travel of the prototype. Test runs with the prototype will be conducted on a laboratory platform. Platform trials in this project will be limited to low, hand drawn speeds (e.g. 1-5 mph), but they will however identify factors that will determine the maximum expected speed of production units, and manipulate those factors for optimization. An alternative vibration-less translating probe mode will be explored as a means to allow for faster scanning speed. Work in Stage 2 will demonstrate coordinated operation of probes for effective potential mapping and field operation. Two activities will be conducted. In the first, an array of two independent probes will be constructed and made to operate jointly in wheeled platform in absolute mode (that is, with one master wire connection to the rebar assembly) demonstrating coordinated operation and processing of data. Trial tests of suitable reference contacting arrangements for the more challenging differential mode (no connection with the rebar assembly) will be conducted and issues needing resolution for feasibility of that mode will be established. In the second activity the probe array will be operated on a decommissioned bridge deck experiencing corrosion in an aggressive marine service location at Sunshine Skyway Bridge in Tampa Bay, Florida. The tests will be conducted in cooperation with the Florida Department of Transportation (DOT). Potential maps will be obtained using the KP array and compared with results obtained from conventional reference electrodes in the same locations. This activity will also examine to what extent the KP application is sensitive to variations on concrete surface condition due to moisture, contaminants, and sources of artifacts such as concrete carbonation as noted during the interpretation of the earlier trial tests. The final report will provide all data and test results along with details on using the KP device and plans for its implementation and commercialization. |