| Abstract | Repairs to corrosion-damaged reinforced concrete structures are inconvenient and expensive to the users and owners. Estimates place their cost in the billions of dollars, not including the environmental toll of repeated repairs. Corrosion inhibiting systems have long been considered one of the best solutions to the corrosion problem in steel reinforcement, but limited information is available on their actualperformance and effectiveness in the field. The NRC's Institute for Research in Construction has been working with the Ministry of Transportation of Quebec and seven product manufacturers to study the field performance of corrosion-inhibiting systems on the Vachon Bridge near Montreal. Different corrosion-inhibiting systems were applied to eight consecutive spans on one of the bridge's reconstructed barrier walls in 1996. They included concrete admixtures, reinforcing steel coatings, and concrete surface coatings/sealers. Two remaining spans of the barrier wall served as control sections. To monitor the effectiveness of the corrosion inhibiting systems, each span was equipped with embedded temperature and humidity sensors, and reference electrodes. On site corrosion surveys, including half-cell potential and corrosion rate measurements, along with concrete coring were conducted yearly. Although thecorrosion rates measured on the barrier wall reinforcement were still relatively small after 5 years, the results indicate that the concrete admixtures, especially the nitrite-based type, performed better than the other systems in reducing or delaying the corrosion of reinforcement in the concrete. |
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