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Forms play a major role in concrete construction. They give the plastic
concrete its shape and hold it until it hardens. Forms protect the concrete,
assist in curing it, and support any reinforcing rods or conduits embedded
in the concrete. This chapter familiarizes the carpenter with the design
and construction of various types of forms.
FORM DESIGN
Forms for concrete must be tight, rigid, and strong. If forms are not
tight, loss of concrete may cause honeycomb effect, or loss of water may
cause sandstreaking. The forms must be braced enough to stay in alignment.
Special care is needed when bracing and tying down forms used in applications
such as retainer walls, where the mass of concrete is large at the bottom
and tapers toward the top. In this type of construction and in the first
pour for walls and columns, the concrete tends to lift the form above
its proper elevation. (Field Manual 5-742 gives formulas and tables for
designing forms of proper strength.)
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