The pumped concrete should be designed in strict accordance with the regulations, the slump should be strictly controlled, and the following principles should be followed. (1) The ratio of the large particle size of the coarse aggregate to the diameter of the conveying pipe should be: when the pumping height is below 50 m, the
It should be greater than 1:3, and should not be greater than 1:2.5 for pebbles; when the pumping height is 50-100 m, the ratio should be 1:3～1:4; pumping
When the height is above 100 m, the ratio should be 1:4～1:5. Coarse aggregate should adopt continuous gradation, and the content of needle-like particles should not be appropriate
(1) The water-cement ratio of pumped concrete should be 0.4-0.6.
(2) The sand content of pumped concrete should be 38%-45%. The fine aggregate should be medium sand, and the amount of sand passing through the 0.315 mm sieve should not be less than 15%.
The wrong way of pipe connection can easily lead to pipe blockage. The following principles should be followed when taking over the pipe.
(1) When designing and installing pipes, avoid 90° and S-shaped bends as much as possible to reduce the resistance of pumping concrete, thereby reducing the possibility of pipe blockage.
(2) The taper pipe at the outlet of the pump is not allowed to be directly connected to the elbow. At least 5 m straight pipe should be connected, and then the elbow pipe should be connected.
(3) The outlet of the vertically downward pipeline should be equipped with an anti-segregation device to prevent pipe blockage.
(4) For high-level pumping, the length of the horizontal pipeline should generally not be less than 15% of the length of the vertical pipeline, and a pipeline stop valve should be connected to the horizontal pipeline. When the shutdown time exceeds 5 minutes, the shut-off valve should be closed to prevent the concrete from flowing back and causing pipe blockage. When turning from horizontal to vertical, the radius of the bend should be greater than 500 mm.