| 摘要 |
The device is formed of a strand of flexible material that is helically coiled in the form of a preformed elongated member having adjacent coils removably bonded together. In using the device, the preformed member is embedded in concrete when in a wet state with one end of the preformed member extending at or close to the surface of the concrete. After the concrete has solidified, the end of the preformed member is pulled to break the bonds between adjacent coils to lengthen and reduce the diameter of the member to allow the strand to be removed from the concrete to form an aperture in the concrete from the surface.
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