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Stainless Steel Rebar

World-wide, corrosion of the carbon steel reinforcement in reinforced concrete structures has been the principal cause of premature failure resulting in billions of dollars in repair costs or replacement, causing extensive disruption in the process. The drive to produce more durable concrete structures commensurate with a long design life has led to considerable world-wide research into suitable reinforcing materials over the last decade. The conclusion of all these studies is that stainless steel is highly suitable for use in concrete. Recent studies into economic and effective use of stainless steel reinforcement has shown that it is suitable for both new structures and repair of corrosion damaged structures.

Advantages of Stainless Steel

• resistant to high levels of chloride ion in concrete, particularly in concrete with a high pH
• stronger than high yield carbon steel
• requires no added surface protection for corrosion resistance
• is produced in a range of sizes from 3mm to 50mm diameter
• is produced in a range of alloys to suit all environments
• has the same rib configuration and bond strength as carbon steel
• can be used in conjunction with conventional carbon steel to enhance durability for a small increase in capital cost
• can be bent to tight radii
• eliminates the need for additional concrete cover for durability
• eliminates the need for concrete coatings
• reduces maintenance, downtime, and traffic delay
• environmentally friendly
• recyclable

T he use of stainless steel rebar can greatly reduce the overall life cycle cost of concrete structures in corrosive environments. Increasingly, builders will also be concerned with sustainable architecture and sustainable infrastructure. Stainless steel rebar permits the design and construction of long life structures, and the rebar itself , is fully recyclable at the end of its life. Stainless steel rebar is the environmentally friendly choice.

There are currently two standards which deal with stainless steel rebar; British Standard BS6744: 2001, and the American Standard ASTM A955M-96. Stainless steel has now been approved by the Highways Agencies in the USA, Canada, Denmark, and Norway for use in reinforced concrete highway bridges.

MECHANICAL PROPERTIES OF SOME REINFORCING BAR ALLOYS

Carbon grades per ASTM A615M-96a; stainless grades per ASTM A955M-96

"It was concluded that Type 316 stainless-steel reinforcing bars should be considered at the design stage as a potential method for obtaining a 75- to 100-yr design life. These bars had corrosion rates averaging 800 times lower than that of the black bars, even when tested in precracked concrete. It is believed by the researchers that present costs associated with the bars limit their current widespread use in concrete structures. However, for structures where repair to corrosion-induced damage is difficult, the additional costs associated with the stainless may be justified and life-cycle cost studies over a 75- to 100 yr period should be made. Potential use includes marine substructures, tunnels and bridges that carry significant traffic where closure for repair would be problematic."

Source:U.S.Dept. of Transportation: Federal Highway Addministration Publication No. FHWA-RD-98-153, December 1998, "Corrosion Evaluation of Epoxy-Coated, Metallic-Clad and Solid Metallic Reinforcing Bars in Concrete".

Additonal Information

Archived article from Nickel Magazine - http://www.nickelinstitute.org/nickel/0998/1-0998n.shtml
Article from International Stainless Steel Forum - http://www.worldstainless.org/articles/ss_rebar.pdf
A website dedicated to stainless steel rebar http://www.stainless-rebar.org
An approval and application document has been issued by the UK Highways Agency (http://www.highways.gov.uk/home.htm) in their Design for Durability guidelines for the design of highway bridges - http://www.official-documents.co.uk/document/deps/ha/dmrb/index.htm
An order form for the UK Concrete Society's "Guidance on the Use of Stainless Steel Reinforcement" - http://www.concretebookshop.com/acatalog/Concrete_Bookshop_Structures_and_design__CS__35.html (scroll down to ninth item)

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