Volume 16, Number 1, March 2011
- British Columbia Ministry of Transportation and Highways
- City of Calgary
- City of Winnipeg
- Ministère des transports du Québec
- Nickel Institute
Conventional carbon steel reinforced concrete structures—bridges, parking garages, marinas and highways—are everywhere. Slowing their deterioration and increasing their durability and life span present continual challenges.
For decades, stainless steel (SS) reinforcement has been used in concrete structures to minimize the problem of corrosion, but the practice is limited, partially due to its high initial cost. Recently, the cost has increased significantly with the rising price of nickel, slowing the adoption of SS reinforcement.
New types of SS reinforcement with lower nickel content are thus being evaluated for their corrosion performance under chloride attack and concrete carbonation. A research project investigating the use of new SS types (2304, 2101 and UNS S24100) to improve the durability of reinforced concrete structures has been initiated by the NRC Institute for Research in Construction (NRC-IRC) and its partners. An additional study on the corrosion performance of galvanized reinforcing steel was added at the suggestion of infrastructure asset owners.
Some performance criteria are critical to determining the service life of concrete structures. One is their resistance to chloride attack, usually defined as a threshold chloride concentration for active corrosion to start in the steel.
Another is the corrosion rate after corrosion occurs. Other aspects of corrosion performance continue to be investigated as well, including pitting corrosion resistance, effect of concrete cracking, corrosion initiation and propagation rates of reinforcing steels embedded in concrete.
The NRC-IRC study will lead to a better understanding of the corrosion performance of these new types of SS steels and an assessment of their potential to extend service life and reduce the life cycle cost of reinforced concrete structures.