Civil Engineering Reference
In-Depth Information
Formwork for Water Tower Place, Chicago, Illinois. (Courtesy of Symons Corporation.)
times, it is normal with proper maintenance to be able to use them approximately 30 or 40
times. After plywood panels are deemed no longer suitable for formwork, they can often
be used by the wise contractor for subflooring or wall or roof sheathing.
Before forms are used, their surfaces should be wetted and oiled or coated with some
type of material that will not stain or soften the concrete. The coating is primarily used to
keep the concrete from sticking to the forms. A large number of compounds are on the
market that will reduce sticking and at the same time serve as sealers or protective coat-
ings to reduce substantially the absorption of water from the concrete by the forms.
Various types of oil or oil compounds have been the most commonly used form-re-
lease agents in the past for both wood and metal surfaces. Many form-release and sealer
agents are available, but before trying a new one on a large job, the contractor would be
wise to experiment with a small application. No material should be used that will form a
coating on the concrete that will, after stripping, interfere with the wetting of the concrete
for curing purposes. In the same manner, if the concrete is later to be plastered or painted,
the coating should not be one that will leave a waxy or oily surface that will interfere with
the sticking of paint or plaster.
