ASTM A767 - Galvanizing Steel Bars for Concrete Reinforcement - Rebar
ASTM A767, Standard Specification for Zinc-Coating (Galvanized) Steel Bars for Concrete Reinforcement first and foremost specifies the minimum mass (weight) of zinc coating on reinforcing steel bars by size. Number 12 and smaller bar must have a minimum of 3.0 oz./ft2 and Number 13 and larger bars must have a minimum of 3.5 oz/ft2. The specification also calls out specific recommended before galvanizing bending radii. This cold working of the bars causes induced stresses that may be released after the bars are immersed in the molten 850 F zinc bath. Unique to this specification is also the requirement the galvanized bars be immersed in a heated, sodium dichromate solution immediately after the process. This post-treatment helps to prevent the formation of wet storage stain on the bars when they are in bundles at a job site and also promotes good adhesion of the galvanized rebar to the concrete it is placed in. It is important to note reinforcing steel used in conjunction with structural steel, welded to a fabricated assembly is not governed by ASTM A767 but rather ASTM A123, the standard specification for zinc coatings on iron and steel products.