Promising results found in using stainless steel for rebar
Researchers at the National Research Council's Institute for Research in Construction have been looking into whethe...
Researchers at the National Research Council’s Institute for Research in Construction have been looking into whether stainless steel is a viable alternative material for concrete. De-icing salt causes major corrosion problems in the reinforcement of structures such as highway bridges and parking garages, and researchers have been searching for an answer for decades.
Stainless steel is able to withstand corrosion much more effectively than conventional carbon steel used in reinforcement, but stainless steel is expensive. A solution would be to use it only in select critical areas of a structure, but engineers have been reluctant to specify it because they are concerned that combining the two types of reinforcement could produce galvanic corrosion between the two metals.
A team led by Dr. Shiyuan Qian at the institute’s Urban Infrastructure Program investigated and found some reassuring results, as reported in NRC/IRC’s publication Construction Innovation, June 2004.
They found that in fact the coupling of stainless steel and carbon steel in concrete structures does not increase the risk of corrosion. Indeed, the rate of corrosion was less than when corroded carbon steel was coupled with uncorroded carbon steel.
However, the researchers issue one important proviso. The stainless steel needs to be protected from rust in the carbon steel. If a significant amount of rust accumulates on the stainless steel it can speed the rate of corrosion in the carbon steel.
The report suggests that it might be beneficial to use stainless steel reinforcing in new and repair situations in the following situations: the top layer of reinforcing steel in bridge decks, the lower portion of columns that are exposed to de-icing salt spray, and the splay zone or edge beam of highway bridges.
Supporters of the research were the Nickel Development Institute, Alberta Transportation, City of Ottawa, Quebec Ministry of Transportation and Valbruna Canada.