any reinforcing steel is placed. To ensure proper
adhesion of the concrete, keep all bond-breaking
materials off the reinforcing steel.
REINFORCEMENTS AND INSERTS
Reinforcing bars (rebar) should be assembled into
mats and placed into the forms as a unit. This allows
for rapid assembly on a jig and reduces walking on the
casting surface, which has been treated with the
Extra rebars must be used at openings. They
should be placed parallel to and about 2 inches from
the sides of openings or placed diagonally across the
corners of openings.
The bars may be suspended by conventional
methods, such as with high chairs or from members
laid across the edge forms. However, high chairs
should not be used if the bottom of the cast panel is to
be a finished surface. Another method is to first place
half the thickness of concrete, place the rebar mat, and
then complete the pour. However, this method must
be done quickly to avoid a cold joint between the top
and bottom layers.
When welded wire fabric (WWF) is used, dowels
or bars must still be used between the panels and
columns. WWF is usually placed in sheets covering
the entire area and then clipped along the edges of the
openings after erection.
If utilities are going to be flush-mounted or
hidden, pipe, conduit, boxes, sleeves, and so forth
should be put into the forms at the same time as the
reinforcing steel. If the utilities pass from one cast
panel to another, the connections must be made after
the panels are erected but before the columns are
poured. If small openings are to go through the panel,
a greased pipe sleeve is the easiest method of placing
an opening in the form. For larger openings, such as
air-conditioning ducts, forms should be made in the
same reamer as doors or windows.
After rebar and utilities have been placed, all
other inserts should be placed. These will include
lifting and bracing inserts, anchor bolts, welding
plates, and so forth. You need to make sure these
items are firmly secured so they wont move during
concrete placement or finishing.
POURING, FINISHING, AND CURING
With few exceptions, pouring cast panels can be
done in the same manner as other pours. Since the
panels are poured in a horizontal position, a stiffer
mix can be used. A minimum of six sacks of cement
per cubic yard with a maximum of 6 gallons of water
per sack of cement should be used along with
well-graded aggregate. As pointed out earlier,
though, you will have to reduce the amount of water
used per sack of cement to allow for the free water in
the sand. Large aggregate, up to 1 1/2 inches in
diameter, may be used effectively. The concrete
should be worked into place by spading or vibration,
and extra care must be taken to prevent honeycomb
around outer edges of the panel.
Normal finishing methods should be used, but
many finishing styles are available for horizontally
Some finishing methods include
patterned, colored, exposed aggregate, broomed,
floated, or steel-troweled. Regardless of the finish
used, finishers must be cautioned to do the finishing
of all panels in a uniform manner. Spots, defects,
uneven brooming, or troweling, and so forth will be
highly visible when the panels are erected.
Without marring the surface, curing should be
started as soon as possible after finishing. Proper
curing is important, so cast panels should be cured
just like any other concrete to achieve proper strength.
Curing compound, if used, prevents bonding with
other concrete or paint.
LIFTING EQUIPMENT AND
Tilt-up panels can be set up in many different
ways and with various kinds of power equipment.
The choice depends upon the size of the job. Besides
the equipment, a number of attachments are used.
The most popular power equipment is a crane.
But other equipment used includes a winch and an A
frame, used either on the ground or mounted on a
truck. When a considerable number of panels are
ready for tilting at one time, power equipment speeds
up the job.
Many types of lifting attachments are used to lift
tilt-up panels. Some of these attachments are locally
made and are called hairpins; other types are available
commercially. Hairpin types are made on the job site
from rebar. These are made by making 180° bends in