Formwork for Concrete Structures by R.L.Peurifoy and G.D- By EasyEngineering.net

398 Chapter Fourteen
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FIGURE 14-1 Illustrative patterns of form liners. (Source: Greenstreak Plastic
Products Company, Inc.)
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Sheets of rigid form liners are attached to the formwork or casting
bed prior to placing the concrete. Screws or nails are recommended for
mounting form liners. Following placement and normal curing time,
the formwork and liner are stripped, leaving a textured concrete surface.
The sheets generally are 4 ft wide and 10 ft long with square edges
to allow the placement of adjacent sheets for large areas of concrete.
The hard, void-free surface will not absorb moisture or cause discoloration.
Sheets of rigid form liners are lightweight and easily stripped.
Rustication or reveal strips are recommended at the liner joints
that do not blend with the pattern. A properly sized rustication will
complement the pattern and enhance the overall appearance of the
structure. For uniformity of color and texture, the concrete should be
secured from a single supplier so that all of the ingredients will come
from the same source.
A tremie should be used for placing the concrete to minimize
aggregate segregation. The concrete must be properly vibrated to
eliminate lift lines and minimize air voids. Pumping the concrete into
the formwork from the bottom will generally reduce air voids in the
surface of the concrete. This method will also raise form pressures
significantly, which may damage the form liner.
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