ASTM Subcommittee A01.05 on Steel Reinforcement has been influencing the development and manufacture of corrosion-resistant reinforcing steel for two decades. Subcommittee Chairman David P. Gustafson describes the many ways the committee has been a force in the industry.

Premature deterioration caused by corrosion of steel reinforcement is the Achilles heel of reinforced concrete structures. Structures exposed to deicing salts, such as highway bridges and parking garages, are prime candidates for premature deterioration. Marine structures exposed to seawater, wastewater treatment plants, and other structures exposed to corrosive environments are also vulnerable to premature deterioration. The ways and means to mitigate corrosion of the steel reinforcement and extending the service life of structures are of worldwide concern.

For over 20 years, ASTM Subcommittee A01.05 on Steel Reinforcement (part of Committee A01 on Steel, Stainless Steel, and Related Alloys) has been developing standards to enhance the corrosion resistance of reinforcement. Six specifications for coated carbon steel reinforcement and a specification for stainless steel reinforcing bars have been published. See the accompanying table are the current specifications.

New Specs
Presently, Subcommittee A01.05 is developing a new specification for stainless steel clad carbon steel reinforcing bars. The Bar Products Task Group, chaired by James G. Hutchinson, metallurgical services manager, AmeriSteel, Knoxville, Tenn., has led the effort to develop a draft standard for letter-balloting. Several subcommittee members, and individuals and organizations outside of A01.05, have contributed to the development of the draft standard.

According to Hutchinson, stainless-clad bars are currently produced by two known processes. In one of the processes, stainless steel strip is formed and welded into a tube shape. Carbon steel granulate is then packed under pressure into the tube to form the core. The ends are crimped to complete the “manufactured” round billet. The billet is then heated and rolled into reinforcing bars. In the other existing process, a carbon steel continuous cast billet is spray metallized with a stainless alloy cladding. Then the billet is heated and rolled into reinforcing bars.

The draft specification intentionally does not restrict the production methods to the currently known processes. In other words, the door is open to other technologies. An advisory note is included in the draft specification that encourages the purchaser to become familiar with a particular producer’s process and its attributes and any limitations.

At this time, Subcommittee A01.05 is also preparing a specification for stainless steel wire and welded wire fabric for concrete reinforcement. Development of this new specification is headed by Roy H. Reiterman, technical director, Wire Reinforcement Institute, Findlay, Ohio, under the auspices of the Wire Products Task Group. Professor Steven L. McCabe, chair of the Department of Civil and Environmental Engineering, University of Kansas, is the task group chairman.

Technology Transfer
Subcommittee A01.05 is at the forefront of new technology for corrosion-resistant reinforcement. One example of this is epoxy-coated reinforcing bars and A01.05’s role in technology transfer. In the 1970s, the basic research and product development of epoxy-coated reinforcing bars was conducted by the Federal Highway Administration (FHWA) and the National Bureau of Standards (now the National Institute of Standards and Technology). The landmark FHWA-NBS research [1] resulted in the creation of a new industry. Today there are some 40 epoxy coating applicator plants in North America, and several plants in the Middle East and Asia. Several of the largest production capacity epoxy coating plants in the world are located in the United Arab Emirates and Saudi Arabia. ASTM A775/A775M, Specification for Epoxy-Coated Reinforcing Steel Bars, was issued in 1981. The popular standard is used in its entirety in many countries or is the basis for the technical provisions in several national standards.

International Work
In 1999, ISO issued three standards for epoxy-coated reinforcement—ISO 14654, Epoxy-coated steel for the reinforcement of concrete; ISO 14655, Epoxy-coated strand for the prestressing of concrete; and ISO 14656, Epoxy powder and sealing material for the coating of steel for the reinforcement of concrete. A standard for zinc-coated (galvanized) reinforcing bars, wire, and welded wire fabric is in the final stages of development, and is expected to be adopted soon by ISO.

The established ASTM standards for epoxy-coated and galvanized reinforcement have had a major influence on the ISO effort. They helped to get the work started within ISO TC 17 on Steel–Subcommittee 16 on Steel Reinforcement, and much of the technical content in the ISO documents is parallel to the requirements in the ASTM specifications.

No Time to Rest
Subcommittee A01.05’s membership, in addition to those from reinforcing bar producing mills, includes representation from several State Departments of Transportation; the FHWA; the epoxy coating, galvanizing and stainless steel industries; consulting engineers; researchers; academia; and other individuals interested in corrosion-resistant steel reinforcement. This pool of expertise and wide range of experience, coupled with the members’ dedication, has translated into a highly productive unit within the subcommittee.

The subcommittee cannot rest on its laurels. It anticipates interest in the development of a new specification for microcomposite steel reinforcing bars. In this case, the steel itself would have a high degree of corrosion resistance through the use of innovative chemical analyses. There should be no requirement for a cladding or a barrier coating to provide the improvement in corrosion resistance.

ASTM, through its technical committee and standards development structure, is making a significant contribution to society's needs to construct more durable, longer-lasting reinforced concrete structures. It is a challenge, and at the same time an exciting and fulfilling experience, to participate in the process of mitigating the corrosion problem. //

Reference

1 J. R. Clifton, H. F. Beegly and R. C. Mathey, “Nonmetallic Coatings for Concrete Reinforcing Bars,” Report No. FHWA-RD-74-18, Federal Highway Administration, Washington, D.C., 1974.

Copyright 2001, ASTM