In the United States, the size and grade designations of these carbon (or "mild") steel bars used to reinforce concrete are set by ASTM International. Besides mild steel, rebar is also produced in stainless steel and other specialty alloys. Included in ASTM bar specifications are carbon steel bars with epoxy and/or zinc coatings used to resist corrosion.
Rebar is available in Grades and specifications that vary in yield strength, tensile strength, chemical composition, and percentage of elongation.
The Grade designation is equal to the minimum yield strength of the bar in ksi (1000 psi) for example Grade 60 rebar has a minimum yield strength of 60 ksi. Rebar is typically manufactured in Grades 40, 60, 75, 80, and 100.
Current ASTM Bar Specifications include:
ASTM A615/A615M: Deformed and Plain Carbon-Steel Bars for Concrete Reinforcement
ASTM A706/A706M: Deformed and Plain Low-Alloy Steel Bars for Concrete Reinforcement
ASTM A767/A767M: Zinc-Coated (Galvanized) Steel Bars for Concrete Reinforcement
ASTM A775/A775M: for Epoxy-Coated Reinforcing Steel Bars
ASTM A934/A934M: Epoxy-Coated Prefabricated Steel Reinforcing Bars
ASTM A955/A995M: Deformed and Plain Stainless-Steel Bars for Concrete Reinforcement
ASTM A996/A996M: Rail-Steel and Axle-Steel Deformed Bars for Concrete Reinforcement
ASTM A1035/A1035M: Deformed and Plain, Low-carbon, Chromium, Steel Bars for Concrete Reinforcement