At the beginning stage of pumping, the piston compresses the concrete mixture, the pressure in concrete cylinder increases rapidly and the air in concrete mixture is compacted and excluded.

• 在泵送开始阶段，活塞压缩混凝土拌和物，混凝土缸压力在很短的时间内迅速上升，此时混凝土拌和物中的空气得到压实和排出；