Unexpected Deterioration of Fusion-Bonded Epoxy-Coated Rebars Embedded in Chloride-Contaminated Concrete Environments

Abstract Attempts have been made to understand the causes of the very fast deterioration of fusion-bonded epoxy-coated rebars (FBECR) in chloride-contaminated alkaline environments and the fairly stable behavior of FBECR in neutral chloride solution. To accomplish this, the corrosion studies of FBECR directly exposed to a water solution of 3.5% sodium chloride (NaCl), chloride-contaminated simulated concrete pore solution (SPS), and solid-cast concrete mortars have been performed for more than 1,000 days of exposure. The FBECR under embedded conditions in concrete deteriorate at an unexpectedly faster rate and require only 100 days to 150 days of a wet/dry exposure period before the onset of corrosion. It was observed that fusion-bonded epoxy coating (FBEC) is more prone to the absorption of moisture and chloride in contact with alkaline solution but is very resistant to their diffusion in neutral solution. The presence of defects/cracks in the coating easily allows the penetration of chloride ions at the...