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

248 Chapter Nine
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FIGURE 9-14
Coil tie. (Source: Dayton Superior Corporation)
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The external members of the assembly consist of two coil bolts whose
threaded ends are screwed into the coils to transmit the loads to the
wales. A flat steel washer is used under the head of each bolt to provide
adequate bearing area against the wale.
A wood or plastic cone may be installed at each end of the inner
member to serve as a form spreader and to hold the metal back from
the surface of the concrete wall. Wood cones absorb moisture from the
fresh concrete and swell slightly. After the forms have been removed,
the wooden cones dry out and shrink, allowing them to be removed
easily. Plastic cones may be loose or screwed onto the helical coil. After
cones are removed, the holes are filled with cement mortar.
For walls of great thickness, two inner members connected with a
continuous threaded coil rod of the proper length may be used to
produce any desired length.
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