Galvanized Steel Bars

Galvanization is a common method used to protect steel in corrosive conditions and galvanized reinforcing bars have been available for many years. The ASTM specification for galvanized reinforcing bars is ASTM A767/ A767M, Standard Specification for Zinc-Coated (Galvanized) Steel Bars for Concrete Reinforcement. Galvanized reinforcing bar may be ordered either as straight bars that are galvanized prior to fabrication or as bars that are galvanized after the bars have been fabricated. The A767/A767M specification provides for two coating weights, a Class 1 (3.50 oz/ft2) or Class 2 (2.00 oz/ft2). However, there are no guidelines concerning the use of Class 1 or Class 2, although most transportation agencies specify Class 1.

Special considerations for the use of galvanized reinforcing bars includes “chromating” which is reviewed in section 4.3 of ASTM 767, and air or steam wiping which facilitates the ability to bend the galvanized bars with a minimum of coating cracking. The galvanized coating is recognized as being robust enough to handling abuse, however, acceptance of galvanized reinforcing bars is dependent upon; negligible bare spots in the coating, the coating being essentially free of blisters, presence of flux spots, inclusions, dross, and acid or black spots. Additionally there shall be no spikes and bars shall not be stuck together. Note that fabrication tolerances for bend radius are larger than those specified in ACI 318, and that stress relieving may be required for tight radius bends.