| 摘要 |
The storage and processing times of sprayed concrete can be signifi- cantly extended by the addition of a retarder, a chemical compound which is capable of chelating with calcium ions. Preferred retarders are phos- phonic acid derivatives which have at least one amino and/or hydroxyl group. The retarder can be used for both wet- and dry-sprayed concrete, the usual accelerators can be used for activation, and the strength is not adversely affected.
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