| 摘要 |
PROBLEM TO BE SOLVED: To provide a sleeve which can be easily drawn out although a considerably large strength is required on drawing out the sleeve and hence, it is difficult to draw out it, in such an actual case that a sleeve is fitted in the form when a through hole for pipes or cables is required on the concrete body and concrete is injected and the sleeve is drawn out after curing. SOLUTION: A synthetic resin film 3 having a week water-resistance and alkali-resistance is formed on the surface of a paper tube 2 to constitute a sleeve 1. Further, a water-resistant tape is wound up on the surface of the paper tube 2 in a wider pitch than the tape width or a water-resistant tape provided with appropriate holes thereon is wound up to form the sleeve through which water and moisture can slightly permeate to decrease the strength of the paper tube 2 because the tube gets wet when the concrete cures.
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