Update Results of ZnO Behavior as a Corrosion Inhibitor for Rebars

In this paper, studies were conducted in a concrete structure built twenty years ago, approximately, which due to the aggressive atmosphere of exposure (Progreso Port in Mexico), led to their deterioration during an early age. The latest repair (over 4 years ago) was conducted with a partial replacement of concrete which contains different concentrations of inhibitors: 4% zinc oxide (ZnO), 4% of calcium nitrite (Ca (NO₂)₂), and 4% of mixture (2% ZnO + 2% Ca (NO₂)₂), in addition to the repair with conventional concrete. Electrochemical behavior of the repairs was done through the linear polarization resistance technique (Rp) and the corrosion potential by a commercial corrosometer. After over four years of exposure, ZnO is the only inhibitor that shows a clear passivation (Ecorr e <-200 mV and an icorr of <0.2 μA/cm²). On the other hand, there were evaluated steel piles over eight years exposure in a platform located in Lake Maracaibo, Venezuela, lined with concrete in the wave and splash zone. ZnO was added to the concrete in the range of 0.0-3% and the results indicate that only the concrete coating with 1% ZnO performed very well with and without the cathodic protection system installed in the submerge zone. .