| 摘要 |
PROBLEM TO BE SOLVED: To provide a rebound reducing agent and a spraying material which are used when a natural ground surface exposed by boring a tunnel is sprayed with quick setting cement concrete, and capable of reducing the rebound ratio of the cement concrete and enables execution of economical spraying work with the cement concrete, also to provide a spraying method using it. SOLUTION: This rebound reducing agent comprises a polyalkylene oxide and a trisphenol-based condensation product, wherein: the polyalkylene oxide used has an average molecular weight of 1,000,000-5,000,000; and the trisphenol- based condensation product used has an average molecular weight of 10,000-50,000. This spraying material contains a quick setting agent and the rebound reducing agent, or contains a quick setting agent, the rebound reducing agent and cement. This spraying method comprises: mixing cement concrete containing cement and one portion of the required amount of the rebound reducing agent, with a quick setting agent and the other portion of the required amount of the rebound reducing agent, immediately before spraying; and executing spraying work with the resulting mixture. |
