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Proper Form
properly finished concrete project begins
with intensive pre-planning and shop drawings. After finding and correcting any errors,
shop drawings reflect the exact dimensions
and formwork of the mirrored project designed to withstand the loads incurred during concrete placement. This
is where details, blockouts, and other necessary items,
including form tie layout and types, are to be positioned.
Next is hand-selecting forming materials.This procedure doesn’t cost nearly as much as the potential waste
that can result by not doing it. Straight lumber for subframes will produce a finished product that is straight.
Shaw & Sons always purchases new materials for
each architectural job and will reuse forms only three
times to ensure quality. Up to three laminations
(depending on the radius) are used on radius forms and
fully gun-nailed to ensure that no delamination occurs
during placing of concrete. Radius wallers are prescribed and precisely cut to match exact dimensions of
the radius.Two top plates and two bottom plates are
each laminated together, and are placed not greater than
four feet o.c. horizontally.
Forms should always be attached to a setting pad or
footing, and pinned down three feet o.c. with two drilled
16 penny nails. Adjustable braces ensure the wall tops
will be in-line and plumb.
All cast-in-place walls benefit from crack control reveals,
and as previously described, can fall on four feet or modules of plywood joints. This not only covers the joint with
a detail feature, it also prevents bleed water leakage lines
and will dictate a weakened plane for the wall to crack,
preventing unsightly random cracks (see photo 9). If
details are not used, forms should be removed as soon as
possible and saw cuts should be placed before random
cracking occurs. Walls should be kept wet a minimum of
seven days or a heavy coat of color cure should be applied.
Examples of radius form construction are shown on the
following pages.
A
3
5/8-inch acx plywood is attached to subframe formwork and covered with 3/8-inch M.D.O. plywood.
6
Immediately after form removal, wall joints are determined and
scribed.
9
Alternate crack control method is achieved by placing vertical
trapezoidal-shaped reveals on panel joints.
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