In recent years, with the continuous development of social economy, my country's construction industry has developed rapidly, and the number of construction projects has increased. In the construction of construction projects, concrete pumping is one of the essential and important construction links, which directly affects the construction progress and Construction Quality. However, pipe blockage will inevitably occur in concrete pumping, so in this case, it is necessary to find out the cause of the blockage in time, prescribe the right medicine, and reasonably formulate effective solutions and preventive measures, so as to solve the problem more effectively. Blockage problem.
1. Operation errors may lead to blocked pipes
First, the operator is distracted during the actual operation. As a transfer pump operator, during the pumping construction process, you must pay attention and keep abreast of the reading displayed by the pumping pressure gauge. If the reading of the pressure gauge rises rapidly, you need to reverse the pump for two or three strokes in time, and then start the pump. Blockage can be eliminated.
Second, the choice of pumping speed is unreasonable. In the pumping process, the speed (ie the pumping displacement) must be selected reasonably. The operator cannot just pay attention to the speed. Sometimes the speed is not a good thing. When pumping for the first time, because the pipeline resistance is quite large, in this case, it is necessary to pump at a low speed. After ensuring that there is no abnormality in the pumping, the pumping speed can be adjusted appropriately. If there are signs of pipe blockage or the slump of a vehicle concrete is small, it must be pumped at a low speed to avoid pipe blockage.
Third, the control of the remaining material is unscientific. During the pumping process, the operator needs to carefully observe the residual material in the hopper. The residual material must be higher than the 2 stirring shaft. If the residual material is too small, it is likely to inhale air and cause the pipe to be blocked. In addition, the material in the hopper should not be accumulated too much, and it must be lower than the guardrail, so that the oversized aggregate and coarse aggregate on the guardrail can be easily and quickly cleaned up.
Fourth, when the slump of the concrete is too small, the pump operator needs to make an accurate judgment. If the normal pumping cannot be satisfied, the concrete needs to be discharged from the bottom of the hopper immediately. If you want to save trouble, force the pumping. , it is likely to cause blockage. Do not add water to the hopper for stirring.
Fifth, downtime bias. When shutting down, the pump needs to be turned on every five to ten minutes, but the specific time must be determined based on factors such as the temperature of the day and the slump of concrete to avoid blocking the pipe. For some concrete that has been completely set and the downtime is too long, the pumping must be stopped.
Sixth, there are debris or concrete residues in the pipeline. After the last pumping, the pipeline was not cleaned and inspected carefully in time, and there were hard concrete residues left in the pipeline (or someone deliberately put wood, steel bars and other debris into the pipeline), which would lead to the subsequent pumping. Blockage occurred during delivery. Therefore, as long as the pumping is finished, the conveying pipeline must be carefully cleaned according to the various operation steps to avoid debris in the pipeline.
2. Pipe blockage caused by pipeline connection
Improper pipe connection method is likely to cause blockage. The principles that need to be followed in the process of pipeline connection are embodied in the following points: in the process of pipeline layout, it is necessary to reduce the transmission resistance as much as possible according to the largest, the smallest elbow and the shortest distance, which can also reduce the probability of pipe blockage. At the position of the stack pipe at the pump outlet, the elbow cannot be directly connected, and a straight pipe over 500 mm needs to be connected first, and then the elbow is connected (as shown in Figure 1). When connecting pipes in the middle of pumping, only one pipe can be added at a time, and water should be used to fully lubricate the inner wall of the pipe, and ensure that the inner wall of the newly connected pipe fittings is clean and free of debris, otherwise the pipe may be blocked. As far as the pipelines facing vertically downwards are concerned, the upper elbow of the riser must be raised, and an anti-segregation device must be installed at the outlet position, which can prevent the pipe from being blocked.
3.Pipe blockage caused by concrete or mortar segregation
Generally speaking, if concrete or mortar comes into contact with water, there is a high probability of segregation. In most cases, the main reason for the phenomenon of pipe blockage in the process of pumping mortar is the segregation of mortar after the mortar directly contacts the water in the pipeline [2]. Then, for this kind of blocked pipe, the preventive measure is to soak the pipe with clean water before the pump, loosen the pipe joint at the lowest point of the pipe, and drain all the remaining water in the pipe, or before pumping the mortar and the pump After the water, put in the sponge ball and separate the water and the mortar. After pumping, when cleaning the pipeline, it is also necessary to put a sponge ball to separate the concrete and water, otherwise it is likely to cause the pipeline to be blocked.
4. Pipe blockage caused by local slurry leakage
First, the pipeline joints lack strong sealing. The lack of good sealing performance of the joints of the conveying pipeline, coupled with the damage of the sealing ring if the pipe clamp is not fastened, is prone to slurry leakage. Then, in this case, it is necessary to tighten the pipe clamp forcefully or replace the damaged sealing ring immediately.
Second, there is a large gap between the cutting ring and the glasses plate. If the cutting ring and the glasses plate are seriously damaged, the gap between the two will increase. If the gap is too large, the special-shaped bolts must be changed to avoid excessive gap between the cutting ring and the glasses plate. If it cannot be changed, the wearing parts can be replaced directly. This method can be applied to concrete pumps of the "S" valve series, but cannot be applied to other series of concrete pumps.
Third, the concrete piston is excessively worn. For the operator, it is necessary to carefully observe whether the water in the water tank is clean and whether there is mortar. If the water is not clean or there is a lot of mortar in the water, it means that the concrete piston is no longer complete, but has been severely worn, then it must be The worn piston should be replaced directly, otherwise the pipe will be blocked due to loss caused by pressure or slurry leakage, and the wear of the transfer pump and the piston will be more serious.
Fourth, the slurry leakage caused by the wear of the concrete conveying cylinder. If every time the piston is replaced, the water in the water tank becomes dirty, but the piston is intact, which means that the conveying cylinder has been worn out, and the original conveying cylinder needs to be replaced directly.
5. Pipe blockage caused by substandard pumping concrete
The concrete used in pumping needs to meet the relevant requirements of pumping concrete. Not every type of concrete is suitable for pumping. If the pumped concrete does not meet the standard, it will lead to increased wear of the pump and prone to pipe burst. and blocked pipes, etc.
First, the slump of concrete is too large or too small. Concrete slump is a key factor affecting the fluidity of concrete. If the slump is too small, it will easily lead to increased conveying pressure, more serious equipment wear, and blockage of pipes. However, if the slump is too large, the concrete may segregate in a high-pressure environment, resulting in pipe blockage. Therefore, the slump test must be carried out after the pumped concrete arrives at the site to ensure that the concrete slump is within the specification range. As shown in Figure.
Second, the sand content is too large and the coarse aggregate gradation is unscientific. According to different sources, fine aggregates can be divided into various types, such as mountain sand and river sand, etc. The most pumpable is river sand, and the weakest is machine-made sand. According to different particle sizes, fine aggregates can be divided into various types, such as: fine sand and coarse sand, etc., and the most pumpable is medium sand.
Third, the wrong choice of admixtures. Generally speaking, there are many types of admixtures, the most common ones are pumping agents, air-entraining agents and water-reducing agents, etc. Combining the strength requirements of concrete and different types of cement, the correct choice of admixtures is very important. To a large extent, concrete can have stronger pumping performance. If the admixture is selected incorrectly, the concrete will not have strong fluidity and pumpability, which will easily cause pipe blockage.
