| 摘要 |
PROBLEM TO BE SOLVED: To obtain an agent for reducing rebound, capable of reducing the rebounding rate at the time of spraying, and usable for the spraying to a tunnel or the like, and further to provide a cement concrete by using the agent, and the spraying method by using the cement concrete. SOLUTION: This agent for reducing the rebound comprises polyethylene oxides especially having 1,000,000-5,000,000 average molecular weight, formalin condensates of a naphthalenesulfonic acid and urea as active ingredients. The cement concrete contains the agent for reducing the rebound, and the spraying method comprises mixing a part of the active ingredients of the agent for reducing the rebound with a quick-setting cement mixture especially just before the spraying. |
