Corrosion of reinforced concrete structures due to chlorides can result in increased maintenance costs and may reduce the design life of a structure. Existing methods for inspecting and monitoring structures for corrosion related damage, such as visual inspections, chaining/sounding for unsound concrete, and coring to determine the depth of chloride ingress are labor intensive, and often expose work crews to hazardous working conditions in and around traffic lanes. Alternative methods of health monitoring of structures for corrosion-induced damage are needed. A number of devices have been or are being developed to perform health monitoring related to corrosion in reinforced concrete. Virginia Technologies, Inc. (VTI) has developed, and is currently marketing one device, the ECI-1 Embedded Corrosion Instrument, to monitor the rate of chloride ingress and progression of corrosion in reinforced concrete. The device is capable of performing a variety of measurements, including electrical potential, linear polarization resistance (LPR), chloride ion sensing, and resistivity measurements. These measurements can allow corrosion engineers to monitor corrosion activity within reinforced concrete in a non-destructive manner.
The objective of this research was to monitor the ECI-1 devices in a cement-based matrix to evaluate the effectiveness of the ECI-1 in signaling corrosion activity as measured by the devices sensor parameters of chloride sensing, concrete resistivity measurement, and linear polarization measurement capability. The main goal is to provide reliable chloride ion concentration and corrosion rate measurements in concrete. The main thrust of this evaluation was performed in a laboratory on sensors embedded in a cement-mortar matrix. Additional testing was initiated on four ECI-1 devices that were placed into a bridge deck during a bridge deck reconstruction project.
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