When the concrete pump works under the rated delivery capacity, the flow velocity of concrete in the pipeline decreases with the decrease of diameter, and the pumping resistance increases. Therefore, the choice of different diameter of the pipeline will affect the pumping resistance. See the relationship between diameter and flow rate and flow rate. It can be seen that in the case of the same conveying pipe diameter, the flow rate of the concrete in the pipe is proportional to the flow rate, and the flow rate is also proportional to the pumping resistance. In addition, the concrete pouring distance is also proportional to the pumping resistance. The longer the pipe, the greater the frictional surface of the concrete pipe wall, the greater the pumping resistance. Pumping resistance of concrete is also proportional to the height of pouring point of concrete. In addition, the curved pipe will also increase the pumping resistance of concrete, the added value of the size depends on the angle and radius of the elbow. Generally can be converted into a straight pipe elbow, and then superimposed on the actual length of the pipeline to go. For a variety of angles and diameter conversion value. If there are more pipe bends in the pipe, the following empirical formula can be used for conversion: Considerable horizontal length (m) = sum of all elbow angles / N Influence of concrete mass on pumping resistance Concrete is a non- Quality materials, its own quality advantages and disadvantages of the pumping resistance is also great, mainly by the slump of concrete and the content of fine materials. Influence of slump of concrete Slump is one of the important factors affecting the pumping resistance of concrete. Concrete with a large slump has better fluidity than a concrete with a low slump and a low pumping resistance, so the required pumping pressure is also small. Changing the water content of concrete can change its slump, so that the pumping resistance also changes accordingly. When the concrete slump is large, the effect of increasing water volume on pumping resistance is small. When the slump is small, adding a small amount of water will greatly reduce the pumping resistance. In concrete construction, increasing the amount of water, if the same amount of cement, the water-cement ratio increases, seriously affecting the strength of concrete. Concrete pumping resistance and slump relationship see. The effect of fine material content Fine material refers to the cement and fine material with particle size less than 0.2mm. Cement plays a role of reducing the friction between the aggregate and the inner wall of the pumping pipe in concrete pumping. Usually the amount of cement is determined according to the mix of concrete, but for pumping concrete, we must also consider the conditions to meet the requirements of lubrication and pumping pipeline and to overcome the inner wall friction resistance. Conclusion A large number of engineering practice has proved that in the use of concrete pumps, we should fully understand the various factors that affect the resistance of concrete pumping, select the appropriate type of concrete pump, pumping to meet the pumping requirements as much as possible under the premise of reducing pumping resistance, Increase the service life of concrete pumps to maximize their effectiveness in large and ultra high-rise projects.
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