每一振点的振捣延续时间应使混凝土表面呈现浮浆和不再沉落为止，约20 ~ 30s。
For every vibrating point, the vibration shall go on till free mortar appears on the concrete surface and not sinks any more, normally 20 ~ 30s.
如果再加上振捣不合理，大气泡不能完全排出，肯定会给硬化混凝土结构表面造成蜂窝麻面。
If the unreasonable vibration, large bubbles can not be completely discharged, would certainly have resulted in hardening the surface of concrete structure surface cellular Ma.
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