Determining localized anode condition to maintain effective corrosion protection.

748288772Final report.PDFTech ReportFHWA-OR-RD-10-11SPR 653ZincAnodesUltrasonic testsResistance testsReinforced concreteOregonOregon. Dept. of Transportation. Research SectionNguyen, VinhMeuli, JoshBrooks, BillJansen, HenriWestall, JohnKoretsky, MiloOregon State UniversityUnited States. Federal Highway AdministrationNTL-HIGHWAY/ROAD TRANSPORTATION-MaterialsNTL-HIGHWAY/ROAD TRANSPORTATION-Construction and MaintenanceNTL-HIGHWAY/ROAD TRANSPORTATION-Pavement Management and PerformanceUS Transportation CollectionThermal sprayed zinc anodes used for impressed current cathodic protection of reinforced concrete deteriorate over time.Two different technologies, ultrasound and electrical circuit resistance combined with water permeability, wereinvestigated in the laboratory to determine whether they were feasible methods for estimating anode condition. Theultrasonic method was unable to detect a reflected acoustic signal from zinc-on-concrete specimens due to scattering of thesignal within the samples. Circuit resistance was shown to increase with the electrochemical age of the specimens, but theresistance trend did not correlate with the bond strength trend at later ages. The aged specimens were fairly impermeableto water infiltration presumably due to build up of reaction products in the porosity. Consequently, a method of usingresistance measurements combined with water infiltration to determine anode condition was not successful. It was shownthat the permeability improved if the surface was mechanically perturbed such as creating a pin hole. Improvingpermeability by penetrating the surface could have ramifications for improving anode performance