Table 7-3.Comparison of U.S. Customary and Metric Rebar
U.S. Standard Bar
Area Sq. Inches
Area Sq. Inches
3 .5% larger
3 .0% smaller
*NOTE: % Difference is based upon area of rebar in square inches.
Reinforcing bars are hot-rolled from a variety of
steels in several different strength grades. Most
reinforcing bars are rolled from new steel billets, but
some are rolled from used railroad-car axles or
railroad rails that have been cut into rollable shapes.
An assortment of strengths are available.
The American Society for Testing Materials
(ASTM) has established a standard branding for
deformed reinforcing bars. There are two general
systems of bar branding. Both systems serve the basic
purpose of identifying the marker size, type of steel,
and grade of each bar. In both systems an identity mark
denoting the type of steel used is branded on every bar
by engraving the final roll used to produce the bars so
as to leave raised symbols between the deformations.
The manufacturers identity mark that signifies the
mill that rolled the bar is usually a single letter or, in
some cases, a symbol. The bar size follows the
manufacturers mark and is followed by a symbol
indicating new billet steel (-N-), rolled rail steel (-I-),
or rolled axle steel (-A-). Figure 7-2 shows the
two-grade marking system.
The lower strength reinforcing bars show only
three marks: an initial representing the producing
mill, bar size, and type of steel. The high strength
reinforcing bars use either the continuous line system
or the number system to show grade marks. In the line
system, one continuous line is rolled into the
60,000 psi bars, and two continuous lines are rolled
into the 75,000 psi bars. The lines must run at least
five deformation spaces, as shown in figure 7-2. In the
number system, a 60 is rolled into the bar following
the steel type of mark to denote 60,000 psi bars, and a
75 is rolled into the 75,000 psi bars.
Expanded Metal and Wire Mesh
Expanded metal or wire mesh is also used for
reinforcing concrete. Expanded metal is made by
partly shearing a sheet of steel, as shown in view A
figure 7-3. The sheet steel has been sheared in parallel