How to eliminate the pipe blockage of pumping conc

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With the rapid development of highway construction, some domestic and imported pumping concrete equipment have been widely used by construction units. However, in the concrete pouring operation, due to improper use, equipment pipe plugging failures occur from time to time, which not only affects the project progress, but also directly affects the project quality

1. Reasons for pipe plugging

in order to improve the safety of food, extend the shelf life and minimize the use of chemical preservatives, under normal circumstances, the concrete forms a cylindrical fluid in the center of the pumping pipeline and flows in a suspended state. There is a layer of cement slurry on the surface of the fluid. As a lubricant, the cement slurry layer contacts the pipe wall, and there is basically no relative movement between the aggregates. When the movement of some aggregates in the coarse aggregate is blocked, the movement speed of the later aggregates gradually slows down due to the impact, resulting in the formation of aggregates in the pipeline, the mortar supporting the coarse aggregate is squeezed away, and the remaining gap is filled by small aggregates. In this way, the aggregate density increases, which makes the aggregates in this section of the pipeline expand radially along the pipeline, the cement slurry lubrication layer is damaged, the movement resistance increases, and the speed slows down until the movement stops, resulting in blockage

2. Judgment and elimination of pipe plugging position

2.1 blockage at the feed inlet: the pumping action and hydraulic system are normal, without abnormal sound and vibration, there are large aggregates or lumps in the hopper, which are stuck or arched at the feed inlet and blocked

Troubleshooting: reverse the pump to destroy caking, return the concrete to the hopper for re mixing, and then pump it forward. If it doesn't work, it needs to be cleaned manually and eliminated

2.2 blockage at the outlet of distribution valve: the action of pumping system is suddenly interrupted, and there is abnormal sound. The equipment has strong vibration, but there is no corresponding vibration in the pipeline

Troubleshooting: pour 15~30l cement slurry into the hopper, start the pump forward and backward repeatedly, and force the passage to open. If this method is invalid, it can only be eliminated manually. Remove the connecting pipe and remove the sundries in the valve

2.3s pipe valve blockage: the blockage at the S pipe valve is gradually formed. The main reason is that after pumping the concrete, it is not washed with high-pressure water in time, resulting in the concrete remaining in the S pipe, which is gradually thickened over time, accumulated and consolidated, resulting in blockage

Troubleshooting: after pumping concrete, be sure to wash the pump body and S pipe with high-pressure water. When the flushing is ineffective, brazing can be used to remove the residue until it is completely clean according to the statistics of more than 150 years

2.4 blockage of concrete conveying pipeline: when the conveying pressure gradually increases, the hopper level does not drop, the pipeline outlet does not discharge, the pump vibrates, and the pipeline is also accompanied by strong vibration and displacement, it can be determined that the pipeline is blocked

judgment of blocked parts: blocking usually occurs in elbow, cone tube and vibration section of screen impact testing machine. At this time, a small hammer can be used to knock along the pipeline, and the place with dull sound is the blockage; If the sound is clear, it is normal. Listen with your ears. A rustling sound is normal, and a screeching sound is a blockage

Troubleshooting: in case of pipe blockage, the method of repeatedly pumping forward and backward should be immediately adopted to gradually suck the concrete at the pump outlet back to the hopper for re mixing and then transporting. It can also be dredged by knocking with a wooden hammer, combined with positive and reverse pumps; When the above measures are invalid, it indicates that the blockage is serious. After finding out the blocked section, remove the pipe, blow it with high-pressure air or strike it with a heavy hammer or wash it with high-pressure water. After it is completely cleaned, connect the pipe and continue pumping concrete

3. Measures to prevent pumping concrete from blocking

(1) when installing and designing pipelines, try to avoid 90 and S-shaped bends to reduce the resistance of pumping concrete and prevent blocking

(2) in order to ensure the continuity of pumping concrete operation and the quality of concrete pouring, the interval between operations should not be too long to prevent blockage. If the interval is long for some reason, the pump should be started every 5~10min or so, or the reverse or forward pump should be turned several times to prevent blockage

(3) the mix proportion of pumped concrete shall be designed in strict accordance with the provisions of pumped concrete, and the slump shall be strictly controlled

(4) the particle size of the selected aggregate must meet the requirements, and generally should not be greater than 1/4 of the conveying pipe diameter

(5) before pumping concrete, the pipeline shall be lubricated with clean water, and the mortar shall be sent first, and then the concrete, so as to prevent blockage

(6) in hot summer, wet straw bags should be used to cover the pipeline to prevent pipe blockage caused by rapid soil collapse in technical specification for soil nailing support of concrete foundation pit CECS 96:97 during pumping

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