Rebar in concrete structures is susceptible to chloride-induced corrosion. Impressed current cathodic protection (ICCP) is frequently used to protect rebar against corrosion,. To take advantage of rebar passivity in concrete after ICCP is turned off, the Albany Research Center, in collaboration with the Oregon Department of Transportation and Pacific Northwest National Laboratory, is investigating applications of intermittent cathodic protection corrosion as a means for advancing corrosion control of reinforced concrete structures while extending the service life of thermal-sprayed zinc anodes. Corrosion rates of rebar in deaerated and oxygenated simulated pore water and quartz sand saturated with simulated pore water at pH 7 and 13 were determined using electrochemical and mass loss techniques. The rebar was passive at pH 13, but measurable corrosion occurred at pH 7. The use of sand prevented convective transport of reactants to and from the rebar, thereby substantially reducing the corrosion rate. In-situ Surface Enhanced Raman Spectroscopy (SERS) results indicated the presence of Fe3O4 and Fe (OH)2 on the rebar surface depending upon the polarization conditions. The amount of Fe3O4 decreased while Fe (OH)2 increased as the time of cathodic polarization increased.
Keywords: impressed current cathodic protection, intermittent cathodic protection, rebar, reinforced concrete bridges, passivity, pore water solution, Raman spectroscopy, linear polarization