Corrosion Performance of Concrete Columns After Localized Repairs in a Tropical Coastal Environment

The tropical climate present in the Yucatan Peninsula is one of the most aggressive environments found in Mexico, which results in many concrete structures being affected by corrosion. Several types of primers, which are locally available, are A used as prevention and/or repair methods for reinforcement steel found in concrete structures. Nonetheless, such primers are not designed to be used under alkaline environmental conditions. The objective of this investigation was to evaluate the efficiency of these primers used to repair concrete columns of buildings exposed to a coastal marine environment in southeast Mexico. The repair method used involved the following steps: removal of the old concrete, cleaning the rebar with a brush, applying primer to the reinforcement steel, and finally applying bonding agent and new concrete cover. The electrochemical behavior of repaired and adjacent (non-repaired) zones was monitored based on electrochemical techniques with the use of a commercially confined-current corrosimeter. Variables measured were polarization resistance, corrosion potential, and concrete electrical resistivity. One reference column was used for which primer application was not conducted, and four other repair systems were used for which different permeable primers were tested. Theoretically, the primers used should provide protection mechanisms against corrosion, such as repassivation, inhibition, barrier, and cathodic protection. Results showed that the barrier system worked best, followed by the cathodic protection and inhibitor mechanisms. Overall, these findings suggest that printer quality was the most relevant parameter. Primer application not only decreased the corrosion rate of repaired zones, but also the galvanic couple, which apparently only lasted a few days. Primers tested here proved to be a reasonable, low-cost option for localized repairs in cases where the concrete is of inferior quality. Nonetheless, long-term performance of repaired structures must be evaluated through careful monitoring.