METRIC DESIGN GUIDE
Metric projects have used ASTM A615M reinforcing bars for general purpose
applications. The M after A615 indicates a metric specification. A615M reinforcing bar
comes in Grades 300 and 400, indicating 300 and 400 MPa yield strength.
There are 8 bar sizes, which replace the 11 English bar sizes. The Concrete Reinforcing
Steel Institute (CRSI) is requesting that ASTM develop a new metric standard as the
existing one uses bar numbers that are neither the bar diameter nor the overall diameter.
The existing metric standard is merely different, it was never a truehard dimensioned
product. Project managers are advised to check with the State Department of
Transportation in their area to see what they are currently specifying as highways use
proportionally more of this product than buildings.
While many firms can make metric rebar, and there are fewer sizes to evaluate and install,
minimum order quantities apply. Canadians add M after each bar size to avoid confusion
with larger English sizes.