1. Control workability and slump of concrete
The pumped concrete
shall be designed in strict accordance with the regulations, the slump shall be strictly controlled, and the following principles shall be followed. (1) The ratio of the maximum particle size of coarse aggregate to the diameter of the conveying pipe should be: when the pumping height is below 50 m, it is not suitable for gravel
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;
When the height is above 100 m, the ratio should be 1:4~1:5. Coarse aggregate should be continuously graded, and the content of needle-like particles should not be
(1) The water-cement ratio of the pumped concrete should be 0.4-0.6.
(2) The sand content of the pumped concrete should be 38% to 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%.
2. Reasonably arrange the pipeline connection
Incorrect connection of pipes can easily lead to blocked pipes, and the following principles should be followed when connecting pipes.
(1) When designing and installing pipelines, avoid 90° and S-shaped bends as much as possible to reduce the resistance of pumping concrete, thereby reducing the possibility of pipe plugging.
(2) The taper pipe at the outlet of the pump is not allowed to directly connect to the elbow, at least it should be connected to a 5 m straight pipe before connecting to the elbow.
(3) For vertically downward pipelines, an anti-segregation device should be installed at the outlet to prevent pipe blockage.
(4) When pumping at high levels, 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 backflowing and causing pipe blockage. For the 90° elbow when turning from horizontal to vertical, the radius of the elbow should be greater than 500 mm.