| 摘要 |
PROBLEM TO BE SOLVED: To cut off water by corresponding to a joint opening amount of a construction joint by forming a groove on a tip face on a following concrete wall side and arranging a bentonite water cut-off material expanding due to the reaction with water in the groove to place and join a following concrete wall. SOLUTION: A bentonite water cut-off material 15 is used as a water cut-off material and expands due to the reaction with underground water when the underground water enters a construction joint of an underground concrete structure. Furthermore, the construction joint is blocked due to clogging of the construction joint, and the construction joint is blocked to cut off water even when a joint opening amount of the construction joint is large. In this case, it is unnecessary to predict the construction joint opening amount of the construction joint in advance to correspond flexibly in accordance with the construction joint opening amount. Even when a concrete wall is wet, the bentonite water cut-off material 15 reacts with water, expands, and adheres closely on the concrete wall to cut off water. Consequently, it is possible to position and fix the bentonite water cut-off material 15 easily at a low cost by arranging the bentonite water cut-off material 15 in a groove 21.
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