| 摘要 |
PROBLEM TO BE SOLVED: To provide a rebound decreasing agent capable of decreasing a rebound ratio in a spraying process and used for the spraying process at tunnel and the like, a cement concrete using it, and a manufacturing method for the cement concrete and the spraying process using the cement concrete. SOLUTION: The rebound decreasing agent contains polyethylene oxide of which the average molecular weight is 1,000,000 to 5,000,000, condensate of a 1-4C alkylnaphthalenesulfonic acid with formalin and urea as effective components. The cement concrete consists of a cement composition which contains cement and the rebound decreasing agent. A part of available component of the rebound decreasing agent is mixed with quick setting cement mixture immediately before the spraying process.
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