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Concrete Decor - Index

Concrete Decor - Concrete Decor Magazine, The Journal for Decorative Concrete - Index

Transferring that rule of thumb to
curved shapes, it’s easy to imagine the
type of areas that would host runaway
cracks. “What’s tough is where you
get into areas with where you start to
get sharper points, for lack of a better
description,” Riggs says.
By way of example, imagine a pieshaped
section of concrete. The narrow
area will have a tendency to crack off, as
though someone has taken a bite of it.
Crack control
Hand-tooling curves at Progressive
Concrete is often done freehand with
the same joiner one might use for linear
control joints, according to Riggs.
Progressive Concrete professionals
typically mark a few points to use as
guideposts.
But saw-cut joints, defi ned by the
American Concrete Institute as those
cut at less than full depth with special
equipment in hardened concrete, are
generally approached differently on
curves than on straight lines. With the
minimum recommended depth of one
fourth of the thickness of the concrete,
getting the saw to turn can be very
tough.
“You really can’t cut a tight radius
control joint, because the saw blade will
bind up,” Riggs says. “You can do it,
but only on a real wide-sweeping turn.
Anything tighter, and you need a drycut
saw and the joint will be more for
aesthetic reasons than crack control.”
Allen Roeber, president of Best
Stamped Concrete Inc., based in
Huntsville, Ala., combines saw cuts with
hand-tooled contraction joints whenever
he can.
“We like to go back the next day
and saw-cut them to make sure the
concrete cracks on that joint,” Roeber
says. “On 4-inch concrete, 80 percent of
the time a 1-inch control joint is going
to do the job, but for extra insurance
why not saw cut it 2 inches deep? You’re
pretty much guaranteed it will crack in
the joint.”
Rather than working freehand,
Roeber’s Best Stamped Concrete crews
work with guides, using a 2-by-4 as a
guide for a straight joint, PVC pipe for a
curved joint.
Especially when following tight
curves such as those found near the
center of radial patterns, decorative
concrete specialists are more likely to
work with shallower joints.
The very best joints will not only
blend in, but help bring together design
elements of the hardscape and nearby
structures. “The trick is to make your
eyes follow elements such as shapes
and colors within the architectural
joints and not focus in on the structural
control joints,” says Riggs. “But this type
of fi nesse doesn’t always show up on
blueprints. That’s something you need
to point out to the architects, because if
they don’t know what you’re going to do,
they might think you’re going to destroy
their design.”
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control joint
Dec. ’07/Jan. ’08 | www.ConcreteDecor.net | 75