Bond behaviour of epoxy-coated reinforcing bars versus that of corroded bars.

Corrosion of reinforcing steel is recognized as the most critical factor affecting the durability of reinforced concrete structures and the primary problem leading to their deterioration. Epoxy coating is one of the most widely used techniques for protecting reinforcing bars against corrosion outside and inside the concrete. Pull-out specimens have been used to evaluate the effects of epoxy coating thickness and the level of bar corrosion on bond behaviour. Epoxy coating has the effects of reducing bond resistance and increasing slip in comparison to uncoated bars, with these effects being increased with increasing coating thickness. However, bars coated within ASTM requirements have comparable bond strength to, but higher slip than, uncoated bars. Corrosion has the effect of reducing bond resistance and increasing slip. Since epoxy coating is used to protect bars against corrosion, it is seen as imperative to have a comparison between bond results of both epoxy-coated and corroded bars. As corrosion progresses beyond the cracking level, corroded bars tend to have lower bond strength and higher slip than bars protected by epoxy coating within the ASTM requirements. However, bars with corrosion below the cracking level have about the same bond strength as, and lower slip than, bars coated within the ASTM limits. (A)