Reasons and Preventive Measures of Plugging Pump in Concrete Pump

Concrete pump is currently the concrete construction of essential equipment, in the course of the work because of various factors leading to concrete pumping pump blocking the phenomenon have occurred. 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. 1, the reasons for the concrete pump plugging 1.1 bad mix ratio of concrete Mixture of poor concrete pressure gradient in the larger Department, the water will penetrate the gap through the aggregate, aggregate agglomeration caused by plugging, occurred in the pipe bending , Diameter reduction and the middle of the pipeline layout hose; In addition, the concrete is too easy to segregate when the water-cement ratio is too large, resulting in the separation of mortar and aggregate plugging, more common in long-distance horizontal pumping "segregation" plugging and vertical Straight down the pipe under the tube segregation tube. When the amount of cement is too low and the sand rate is too low, the workability of the concrete is poor and the deformation is difficult. The friction resistance in the pipe increases and the pipe can be easily plugged. Concrete slump is too low (80mm below), the pumping resistance increased significantly, so that pumping can not be carried out. 1.2 The particle size of sand is not reasonable When the fine sand through 0.315mm sieve content is small, even if the other specifications of concrete meet the requirements will be blocked. Because these fine sand plays a ball-like role in concrete, it can reduce the friction between the pipe wall and the concrete, improve the fluidity, increase the cohesion and water retention, and greatly influence the pumpability of the concrete. Therefore, JGJ / T10-95 "Concrete Pumping Construction Technical Regulations" provides that the sand through the 0.315mm sieve should not be less than 15%. 1.3 Foreign body plugging tube In theory, the plugging tube most likely to occur in the three big boulders meet in the same cross-clamping, when most of the cross-section is occupied by stones, the flow area is small. Usually the maximum diameter of the stone and the pipe diameter d: D 2, the concrete pump easy to plug the pump position and the exclusion method 2.1 feed inlet blockage feed inlet blocked, usually pumping and hydraulic system are normal, no abnormal sound And vibration, hopper has a larger aggregate or caking, stuck in the feed inlet or arching. 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. 2.2 Dispense valve at the discharge port blocked the discharge port blocked, usually pumping system suddenly interrupted, and there is abnormal noise, the device has a strong vibration, but no corresponding vibration within the pipeline. Remedy: Pour slurry into the hopper, repeatedly positive and reverse pump, forcing the access open. If this method is not daring, it can only be manually excluded, remove the connected pipe, remove the valve debris. 2.3 plugging at the pipe valve blockage at the valve is gradually formed, the main reason is that after pumping concrete, there is no timely flush with high pressure water, resulting in residual concrete pipe, over time gradually thickened, pile consolidation, 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. 2.4 Concrete Conveying Pipeline Clogged When the conveying pressure is gradually increased, while the hopper material level does not drop, the pipe outlet does not discharge material, the pump vibrates and 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. 3, to reduce the pump concrete pump prevention measures (1) in the installation and design of the pipeline, as far as possible to avoid 90. And S-shaped bend. Try not to use the pump tube with obvious dimples to reduce the resistance of pumping concrete and prevent clogging. Should always check the pump tube, pump tube in one direction if a greater degree of wear and tear, the tube in a timely manner to switch positions, if the pump tube thickness is too thin should be replaced in time to prevent the tube in the course of the pump explosion or replacement pump Long tube caused by the plugging phenomenon. (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 20 minutes to start a pump or anti-positive pump several times, if necessary, to play circulation pump to prevent blockage. (3) Pumping concrete should meet pumpability requirements, if necessary, determine the mix ratio of pumping concrete by test pump. First of all, determine the ratio of the maximum particle size of coarse aggregate to the diameter of the delivery pipe. Concrete pump delivery height below 50m, the gravel should not be greater than 1: 3, for pebbles should not be greater than 1: 2.5; pumping height of 50 ~ 100m, should be in the range of 1: 3 ~ 1: 4; pumping height In more than 100m, should be between 1: 4 ~ 1: 5. Flaky particles should not be greater than 10%. 3.3.2 For different pumping height, the slump of man-made concrete can be selected (as shown in Table 1).