With the rapid development of highway construction, a number of domestic and imported pump delivery device has been widely used in concrete construction units. However, in the concrete pouring operation, due to improper use, causing equipment plugging failure occurs, which not only affects the progress of the project, but also directly affect the quality of the project. 1 plugging the reason Normally, concrete forms 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 grout, which acts as a lubricant in contact with the wall of the pipe, with virtually no relative movement between the aggregates. When some aggregates in the coarse aggregate are obstructed from moving, the velocity of the aggregate behind gradually gets sluggish, resulting in the accumulation of coarse aggregates in the pipe. The mortar supporting the coarse aggregate is squeezed away and the remaining gap Filled with small aggregates. In this way, the aggregate density increases, so that the section of the pipeline along the pipeline radial expansion of the composition, the cement slurry lubrication layer is destroyed, increased resistance to movement, slow down, until the movement stops and clogging. 2 plugging tube position to determine and eliminate methods Blocking at the feed inlet Phenomenon: pumping action and hydraulic system are normal, no abnormal sound and vibration, the hopper has a larger aggregate or caking, stuck in the feed port or arched and blocked. Remedy: Turn the pump in reverse to destroy the agglomerate, return the concrete to the hopper, re-mix and then pump it forward. If it does not work, you need to manually clean up, to be excluded. Discharge valve blockage at the outlet Phenomenon: Sudden interruption of pumping system action, and abnormal noise, the device has strong vibration, but no corresponding vibration within the pipeline. Remedy: Pour into the hopper 15 ~ 30L grout, repeatedly positive and reverse pump, forcing the access open. If this law is invalid, it can only be manually excluded, remove the connected pipe, remove the valve debris. S tube valve blockage Phenomenon: S tube valve blockage is gradually formed, the main reason is pumping finished concrete, there is no timely flush with high pressure water, resulting in concrete remaining in the S tube, over time gradually thickening, accumulation, resulting in blockage. Remedy: After the pumping of concrete, be sure to use high-pressure water to clean the pump and S tube. When flushing is ineffective, brazing can be used to remove the debris until it is completely clean. Concrete delivery pipe blocked Phenomenon: When the delivery pressure is gradually increased, and the hopper level does not decline, the pipe outlet does not discharge material, the pump vibrates, the pipe is also accompanied by strong vibration and displacement, it can be judged as pipeline blockage. Blockage of the judgment: Blockage generally occurs in elbows, cones, and the vibration of the lot. At this point, you can use a small hammer along the pipe beat, the sound dull at the block; sound crisp at normal. Listen with ears, rustle sound as normal, there is a harsh sound for the blockage. Remedy: When the plugging occurs, it should immediately take positive and negative pump method, and gradually pump the concrete pump back to the hopper to re-mix before delivery. Also available wood hammer percussion method, combined with positive and negative pump to make it clear; when the above method is invalid, indicating serious blockage. Identify the blockage, the pipe removed, with high-pressure wind or heavy hammer percussion or high-pressure water rinse, to be thoroughly cleaned, and then connect the pipeline to continue pumping concrete work. Measures to prevent blockage of pumping concrete (1) When installing and designing pipelines, avoid 90 ° and S-bend as much as possible to reduce the resistance of pumping concrete and prevent clogging. (2) In order to ensure the continuity of pumping concrete work and ensure the quality of concrete pouring, the interval time in operation should not be too long to prevent blockage. If for some reason a long time interval, it should be about every 5 ~ 10min start a pump or anti-positive pump several times to prevent clogging. (3) pumping concrete should be strictly in accordance with the provisions of pumping concrete design mix, strict control of slump. (4) The selected aggregate size must meet the requirements, generally should not be greater than 1/4 of the delivery pipe diameter. (5) Before pumping concrete, apply clean water to lubricate the pipe, first to send the mortar, and then to send the concrete to prevent blockage. (6) In the hot summer, the wet grass bag should be used to cover the pipeline to prevent the concrete from slumping too fast and causing the tube plugging during the pumping process.