| 摘要 |
PROBLEM TO BE SOLVED: To easily perform degassing work by forming a sleeve penetrating in a cylindrical shape into concrete by filling gas by inserting a balloon having a degassing valve inside a collapsible sleeve member formed in a cylindrical shape. SOLUTION: A sleeve forming tool is molded from a collapsible vinyl chloride sleeve member 1 formed in a cylindrical shape and a balloon 2 being made of rubber and being an almost cylindrical shape at gas filling time. A gas injection valve 4 and a degassing valve 6 are arranged in a side surface prescribed position of the balloon 2, and the balloon 2 is insered inside the sleeve member 1. Next, an air compressor is connected to the gas injection valve 4, air is filled in the balloon 2, the sleeve member 1 is formed in an almost cylindrical shape, and concrete 17 is placed outside the sleeve forming tool. Next, after hardening the concrete 17, a form 15 is removed, the air inside of the balloon 2 is let out, and the balloon 2 and the sleeve member 1 are pulled out to form a sleeve to thereby reduce a cost.
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