Requirements for concrete slump in fine stone concrete pumping
When the concrete with a slump of 10-15 cm is dumped into the hopper, its surface is easily broken; when the slump is less than 10 cm, the concrete is completely broken after tilting, and has a serrated edge, which breaks vertically. into thick blocks; after the high slump concrete is dumped, its surface is not fractured. The conveying resistance of concrete increases with the decrease of slump. The change rate of the conveying resistance of light aggregate concrete with slump is large, especially when the slump is below 15 cm, the conveying resistance increases sharply with the decrease of slump. The volumetric efficiency of the fine stone concrete pump decreases with the decrease of concrete slump, but this change is not obvious when the slump is above 10 cm. This range is 10-23 cm. Concrete with a slump of 10-20 cm has good pumpability.
When the slump is too large, the pumpability decreases significantly, because:
- It is easy to leak slurry when the concrete distribution valve is not closed tightly;
- Concrete is easy to segregate and cause blockage. Especially in the long-distance horizontal transportation, due to the action of gravity, the coarse aggregate gradually drops, and then the cement slurry precipitated in the upper part of the pipeline is squeezed out under the action of pressure. Since the suspended state of the coarse aggregate in the cement slurry is completely lost, the occurrence of blocked.