With the rapid development of highway construction, some domestic and imported pumping concrete distributor equipment have been widely used by construction units. However, in concrete infusion operations, due to improper use, equipment blockage failures occur, which not only affects the progress of the project, but also directly affects the quality of the project.
Under normal conditions, the concrete forms a columnar fluid in the center of the pumping pipe and flows in a suspended state. The surface of the fluid is covered with a layer of cement slurry, which acts as a lubricant in contact with the wall of the tube, with substantially no relative movement between the aggregates. When some aggregates in the coarse aggregate are hindered, the speed of the subsequent aggregates is gradually slowed down due to the influence, resulting in the formation of coarse aggregates in the pipeline, and the mortar supporting the coarse aggregate is squeezed away. Filled by small aggregates. In this way, the aggregate density is increased, so that the aggregate in the section of the pipeline expands radially along the pipeline, the lubricating layer of the cement slurry is destroyed, the movement resistance is increased, and the speed is slowed until the movement stops and the blockage occurs.
2、Judging and troubleshooting method of blocking pipe position
2.1Blockage at the feed port Phenomenon: The pumping action and hydraulic system are normal, there is no abnormal sound and vibration, and there is a large aggregate or agglomeration in the hopper, which is stuck or arched at the feed port and blocked. Remedy: Reverse the pump to destroy the agglomerates, return the concrete to the hopper and stir again, then pump forward. If it does not work, it needs to be manually cleaned up and excluded.
2.2Blockage at the discharge port of the distribution valve Phenomenon: The pumping system is suddenly interrupted, and there is an abnormal sound. The equipment has strong vibration, but there is no corresponding vibration in the pipeline. Remedy: Pour 15~30L of cement slurry into the hopper, and start the pump repeatedly in the forward and reverse directions to force the passage to open. If this method is invalid, it can only be manually removed, remove the connected tube, and remove the debris in the valve.
2.3Blockage of S pipe valve phenomenon: The blockage of S pipe valve is gradually formed. The main reason is that after pumping concrete, it is not flushed with high pressure water in time, resulting in concrete remaining in the S pipe. Causing blockages. Remedy: After pumping concrete, be sure to rinse the pump and S tube with high pressure water. When flushing is not effective, a tapping can be used to remove the residue until it is completely clean.
2.4Blockage of concrete conveying pipelines Phenomenon: When the conveying pressure is gradually increased, and the material level of the hopper does not fall, the outlet of the pipeline does not discharge, the pump vibrates, and the pipeline is accompanied by strong vibration and displacement, it can be judged that the pipeline is blocked. Judgment of the blockage: Blockage generally occurs in bends, cones, and areas with vibration.
At this point, you can use a small hammer to tap along the pipeline, the sound is dull at the blockage; the sound is crisp and normal. Listening with the ear, there is a rustling sound as normal, and a harsh sound is a blockage. Remedy: When a pipe blockage occurs, the method of repeating the forward and reverse pumps should be taken immediately, and the concrete at the pump outlet is gradually sucked back into the hopper and then re-mixed. It can also be knocked with a wooden hammer, combined with the positive and negative pumps to make it clear; when the above method is invalid, it indicates that the blockage is serious. After identifying the blockage section, remove the pipe and flush it with high-pressure wind or heavy hammer or high-pressure water. After thorough cleaning, connect the pipe and continue pumping concrete.
Measures to prevent pumping concrete blockage
(1) When installing and designing pipes, avoid 90° and S-bend as much as possible to reduce the resistance of pumping concrete and prevent blockage.
(2) In order to ensure the continuity of pumping concrete work, ensure 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 once every 5~10min or the pump should be reversed and forwarded several times to prevent blockage.
(3) The pumping concrete should be designed according to the design of the pumping concrete, and the slump should be strictly controlled.
(4) The particle size of the selected aggregate must meet the requirements, and should not be greater than 1/4 of the diameter of the conveying pipe.
(5) Before pumping concrete, apply clean water to lubricate the pipeline, first send mortar, then send concrete to prevent blockage.
(6) In the hot summer, the wet straw bag should be used to cover the pipeline to prevent the concrete from collapsing too quickly during the pumping process.