With the market demand and rapid development of concrete machinery, pumping concrete equipment has been widely used by construction units. However, in the concrete pouring operation, due to improper use, it causes equipment plugging failures from time to time, which not only affects the progress of the project, but also directly affects the quality of the project.
1. Causes of pipe blockage
Under normal circumstances, concrete forms a columnar fluid in the center of the pumping pipeline and flows in a suspended state. The surface of the fluid is covered with a layer of cement slurry. The cement slurry layer acts as a lubricant in contact with the pipe wall, and there is basically no relative movement between the aggregates. When the movement of some aggregates in the coarse aggregate is hindered, the movement speed of the subsequent aggregate gradually slows down due to the influence, resulting in the accumulation of coarse aggregate in the pipeline, the mortar supporting the coarse aggregate is squeezed away, and the remaining gap Filled by small aggregates. In this way, the density of the aggregates increases, causing the aggregates in the section of the pipeline to expand in the radial direction of the pipeline, the lubricant layer of the cement slurry is destroyed, the motion resistance increases, and the speed becomes slower until the motion stops and blockage occurs.
2. Judgment and elimination of the location of the blocked pipe
(1) Blockage at the inlet
Phenomenon: The pumping action and the hydraulic system are normal, there is no abnormal sound and vibration, there is large aggregate or agglomeration in the hopper, which is blocked or arched at the feed inlet and blocked.
Remedy: run the pump in reverse to destroy the agglomeration, return the concrete to the hopper and mix again, then pump forward. If it doesn't work, it needs to be cleaned manually and eliminated.
(2) Blockage at the outlet of the distribution valve
Phenomenon: The pumping system's action is suddenly interrupted, and there is abnormal sound, the equipment has strong vibration, but there is no corresponding vibration in the pipeline.
Removal method: Pour 15-30L cement slurry into the hopper, and start the pump repeatedly in forward and reverse directions to force the passage to open. If this method is not effective, it can only be eliminated manually, remove the connected pipe, and remove the debris in the valve.
(3) Blockage at the S-tube valve
Phenomenon: The blockage at the S-tube valve is gradually formed. The main reason is that after pumping the concrete, it is not washed with high-pressure water in time, causing the concrete to remain in the S-tube.
Remedy: After pumping concrete, be sure to rinse the pump body and S pipe with high-pressure water. When flushing is ineffective, brazing can be used to remove the residue until it is completely clean.
(4) Blockage of concrete delivery pipeline
Phenomenon: When the conveying pressure gradually increases, and the hopper level does not drop, the pipe 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 the clogged part: The clogging generally occurs in the elbows, cones, and vibrating areas. At this time, you can use a small hammer to hit along the pipeline, the dull sound is the blockage; the clear sound is normal. Listening with ears, a rustling sound is normal, and a harsh sound is a blockage.
Exclusion method: When the pipe blockage occurs, the method of repeating the positive and reverse pumps should be taken immediately, and the concrete at the pump outlet is gradually sucked back into the hopper and mixed again before delivery. The method of knocking with a wooden hammer, combined with positive and reverse pumps, can also be used to clear it; when the above method is invalid, it means that the blockage is serious. After identifying the clogged section, remove the pipe and wash it with high-pressure air blow or heavy hammer or high-pressure water. After thoroughly cleaning up, connect the pipeline and continue pumping concrete.
3. Preventive measures for blockage of pumped concrete
(1) When installing and designing the pipeline, avoid 90° and S-bends as much as possible to reduce the resistance of the pumped concrete and prevent blockage.
(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 clogging. If the interval time is longer for some reason, the ??pump or reverse or forward pump should be started several times every 5~10min to prevent blockage.
(3) Pumping concrete should be designed according to the pumping concrete regulations, and the slump should be strictly controlled.
(4) The particle size of the selected aggregate must meet the requirements, generally it should not be larger than 1/4 of the diameter of the conveying pipe.
(5) Before pumping the concrete, the pipeline should be lubricated with clean water, and the mortar should be sent first and then the concrete to prevent clogging.
(6) In the hot summer, the pipeline should be covered with a wet straw bag to prevent the concrete from collapsing too quickly during the pumping process and causing blockage.
