It is no longer a problem to summarize the causes of clogged pipes for the most complete mortar spraying machine.
Improper operation can easily cause mortar spraying machine pipe blockage
1.1 operators are not focused on conveying pump operators should concentrate on pumping construction, always pay attention to the reading of pumping pressure gauge, once found that the reading of pressure gauge suddenly increased, should immediately reverse pump 2~3 stroke, and then pump, blocked pipe can be eliminated. If the reverse pump (positive pump several operating cycles, but still do not eliminate the blocked pipe, pipe should be removed in time to clean, otherwise it will make the pipe more serious.
1.2 improper pumping speed selection, speed selection is critical, operators can not blindly map fast, sometimes more haste, less speed. When spraying, because the pipeline resistance is large, at this point should be low speed pumping, pumping normal, can appropriately improve the pumping speed. When there are signs of pipe blockage or when the concrete collapse of a vehicle is small, it should be pumped at a low speed to nip the pipe in the bud.
1.3 when the surplus is improperly pumped, the operator shall observe the surplus material in the hopper at any time, and the surplus material shall not be lower than the stirring shaft. If the surplus material is too small, it is easy to inhale air and cause pipe blockage. The material in the hopper should not be piled too much and should be lower than the protective fence to facilitate the timely cleaning of coarse aggregate and oversized aggregate. When the collapse degree of a vehicle concrete is small, the residual material can be lower than the mixing shaft and controlled above the "S" pipe or suction inlet, so as to reduce the mixing resistance, swing resistance and suction resistance. These measures are only applicable to "S" valve series concrete pumps.
1.4 When a bucket of concrete is found to have a small collapse and cannot be pumped, the concrete should be released from the bottom of the hopper in time. If you want to save time, forced pumping will easily cause pipe blockage. Never mix with water in a hopper.
1.5 if the downtime is too long, the pump should be started every 5-10min (the specific time depends on the temperature of the day, the concrete collapse degree and the initial setting time of concrete) to prevent the pipe from blocking. For the downtime is too long, has been initially set concrete, not to continue pumping.
1.6 if the pipeline is not cleaned after the last pumping, the pipeline will be blocked during the next pumping. So after each pumping must be in accordance with the operating procedures to clean the pipeline. Pipe plugging errors caused by pipe connection problems can easily lead to pipe plugging. The following principles shall be followed when taking over:
1) the pipe shall be arranged according to shorter distance, fewer bends and larger bends to minimize the conveying resistance, thus reducing the possibility of pipe blockage.
2) at the conical pipe of the pump outlet, it is not allowed to directly connect the bend pipe. At least, it should connect the straight pipe above 5mm and then connect the bend pipe.
3) when the pipe is taken over in the middle of pumping, only one pipe can be connected at a time, and the inner wall of the pipe should be lubricated with water to drain the air, otherwise the pipe will be easily blocked.
4) for the vertical downward pipeline, the exit shall be equipped with anti-segregation device to prevent pipe blockage.
5) in high-rise pumping, the length of the horizontal pipeline shall not be less than 15% of the length of the vertical pipeline, and shall be connected to the pipeline cut-off valve in the horizontal pipeline. If the downtime exceeds 5min, the stop valve should be closed to prevent concrete backflow, resulting in pipe blockage. The bending radius of the 90-degree bend when it is horizontal to vertical shall be greater than 500mm.
1) when concrete or mortar meets water, it is easy to cause segregation. Sometimes when pumping slurry pipe blocked, because of the mortar after direct contact with the water in the pipeline, slurry, which is caused by the segregation of prevention measure is: after wet with water pipeline before the pump, the relatively low from the pipe will joint loosen, put off the remaining water all, or after the water pump, pumping slurry before, into a sponge ball, mortar is separated from water.
2) when the pipeline is cleaned after pumping, a sponge ball should also be put in to separate the water from the concrete, otherwise the pipe will be easily blocked. Due to the leakage of mortar, on the one hand, the quality of concrete will be affected; on the other hand, after the leakage of mortar, the collapse degree of concrete will be reduced and the loss of pumping pressure will result in pipe blockage. The main reasons for slurry leakage are as follows:
4.1 loose sealing of conveying pipe joints, loose sealing of pipe joints or damaged sealing ring and leakage of slurry. At this point should tighten the pipe card or replace the sealing ring.
4.2 if the gap between the glasses plate and cutting ring is too large, the gap between the glasses plate and cutting ring will become larger when the wear of the glasses plate and cutting ring is serious. The gap between the glasses plate and the cutting ring must be narrowed by adjusting the special-shaped bolt. If it cannot be adjusted, the worn part should be replaced immediately. These measures are only applicable to "S" valve series mortar spraying machine.
4.3 concrete piston wear operator should observe whether the water in the tank is often murky, presence of mortar, once found in the water water turbidity or mortar, show that concrete piston wear out, at this time should be replaced in time the pistons, or be caused by slurry leakage and pressure loss of blocking pipe, at the same time also exacerbate the piston and cylinder wear.
4.4 slurry leakage caused by severe wear of concrete conveying cylinder if the water in the water tank becomes cloudy soon after each piston is replaced, and the piston is good, it indicates that the conveying cylinder has worn out, and the conveying cylinder needs to be replaced at this time. Non - qualified pumping concrete caused by the pipe for pumping concrete must meet the requirements of pumping concrete, not all concrete can be pumped, non - qualified pumping concrete will aggravate the pump wear, and often appear pipe blockage, burst tube phenomenon.
5.1 the collapse degree of concrete is too large or too small, which directly reflects the fluidity of concrete, and the conveying resistance of concrete decreases with the increase of collapse degree. The collapse degree of pumped concrete is generally within the range of 8 ~ 18cm, and the pumping for long distances and large heights should be strictly controlled at around 15cm. If the cave-in is too small, it will increase the conveying pressure, aggravate the wear of equipment, and lead to tube blockage. The collapse is too large, under high pressure concrete easy to isolate and cause pipe blockage.
5.2 sand content is too small and coarse aggregate grading is unreasonable
1) fine aggregate can be divided into river sand, artificial sand (mechanism sand), sea sand and mountain sand according to the source. River sand has good pumpability, while mechanism sand has poor pumpability. Fine aggregate can be divided into coarse sand, medium sand and fine sand according to particle size.
2) coarse aggregate can be divided into pebbles and gravel according to shape. The pumpability of pebbles is better than that of gravel. The larger particle size of aggregate is also related to the smaller diameter of conveying pipeline. The larger particle size of pebble should be less than 1/3 diameter, while the larger particle size of gravel should be less than 1/4 diameter, otherwise it is easy to cause pipe blockage.
3) due to different materials, the content of fine aggregate (that is, sand content) and the gradation of coarse aggregate all have a better value. Under normal circumstances, sand content should not be too low, should be more than 40%, large size of coarse aggregate content should not be too high. Reasonable selection of sand content and determination of aggregate gradation are crucial to improve concrete pumping performance and prevent pipe clogging.
5.3 cement dosage too little or too much
1) cement in pumping concrete cementation and lubrication, cement has a good water retention performance at the same time, makes concrete to secrete in the process of pumping water, the dosage of the cement is also a better value, if the cement dosage is too little, will seriously affect the aspiration of concrete, at the same time make pumping resistance increases, the water retention of concrete, easy bleeding, segregation and blocking pipe. In general, the content of cement in each cubic meter of concrete should be greater than 320kg, but it should not be too large. Too much cement will increase the viscosity of concrete, thus causing an increase in conveying resistance.
2) in addition, the amount of cement is also related to the shape of the aggregate. The larger the surface area of the aggregate, the more cement slurry to be wrapped, and the higher the content of cement. Therefore, it is very important to determine the amount of cement reasonably to improve the pump ability of concrete and prevent pipe clogging.
5.4 the selection of admixture unreasonable admixture of many types, such as: gas agent, water reducer, super plasticizer, retarder, pumping agent, according to the strength of concrete requirements and cement varieties, reasonable choice of admixture, to improve the pumping performance of concrete plays a very important role. Unreasonable admixture will make concrete's pumpability and fluidity become poor, thus leading to pipe plugging. When pumping, part of the mortar shall be absorbed by the main mixing machine, the mixing tank of the concrete conveyor, the hopper and the pipe, etc. If the amount of mortar is too small, part of the conveying pipe will not be lubricated, resulting in pipe blockage. The correct amount of mortar shall be calculated according to the requirement of about 0.5m3 mortar for every 200m pipeline, and about 0.2m3 mortar shall be required for the main mixing machine, hopper and concrete conveying truck. Therefore, the amount of mortar must be calculated before pumping. Too much mortar will affect the quality of concrete or cause unnecessary waste.
6.2 mortar mix ratio unqualified mortar mix ratio is also very critical. When the pipe length is less than 150m, use 1:2 cement mortar (1 part cement /2 part mortar); When the length of the pipeline is greater than 150m, the use of 1:1 cement mortar (1 part of cement /1 part of mortar), too little cement content will also cause pipe blockage. The temperature of the pipe is higher in summer because of the change in temperature. Under the strong sunlight of the pipe, the concrete is easy to dehydrate, which causes the pipe to be blocked. Therefore, wet straw bags or other cooling devices should be covered on the pipe. Insulation measures should be taken in winter to ensure the temperature of concrete. The conclusion above is a summary of several common causes and preventive measures leading to tube blockage. In the actual production process, due to changes in external conditions, the causes of tube blockage are often more than these. But as long as we operate in strict accordance with the operating procedures, to prevent minor errors, and continue to summarize experience and lessons from each blockage, we will be able to plug the possibility of lower.
