How to Avoid Pipe Blockage of Concrete Pump (Part 2)

5. Pipe blockage caused by unqualified pumping concrete

The concrete used for pumping must meet the requirements of pumping concrete. Not all concrete can be pumped. Unqualified pumped concrete will aggravate the wear of the pump, and often cause pipe blockage and pipe burst.

1. The concrete collapse is too large or too small

The size of concrete slump directly reflects the fluidity of concrete, and the conveying resistance of concrete decreases with the increase of slump. The slump of pumped concrete is generally within the range of 8-18cm. For long-distance and large-height pumping, it is generally required to be strictly controlled at about 15cm. If the sag is too small, it will increase the delivery pressure, aggravate equipment wear, and cause pipe blockage. If the collapse is too large, the concrete is easy to segregate under high pressure and cause pipe blockage.

2. The sand content is too small and the coarse aggregate gradation is unreasonable

(1) Fine aggregate can be divided into river sand, artificial sand (ie machine-made sand), sea sand, and mountain sand according to the source. Among them, river sand has the best pumpability and machine-made sand has the worst pumpability. Fine aggregates can be divided into coarse sand, medium sand, and fine sand according to their particle size. Among them, medium sand has the best pumpability.

(2) Coarse aggregates can be divided into pebbles and crushed stones according to their shapes. Pebble has better pumpability than gravel. The maximum particle size of the aggregate is also related to the minimum diameter of the conveying pipeline. The maximum particle size of the pebbles should be less than 1/3 of the caliber, and the maximum particle size of the gravel should be less than 1/4 of the caliber, otherwise it will easily cause pipe blockage.

(3) Due to different materials, there is an optimal value for the content of fine aggregate (ie sand content) and the gradation of coarse aggregate. Under normal circumstances, the sand content should not be too low, it should be greater than 40%, and the content of large-size coarse aggregate should not be too high. Reasonable selection of sand content and determination of aggregate gradation are essential to improve the pumping performance of concrete and prevent pipe blockage.

4. The selection of additives is unreasonable

There are many types of admixtures, such as air-entraining agents, water-reducing agents, superplasticizers, retarders, pumping agents, etc. According to the strength requirements of concrete and the types of cement, the admixtures should be selected reasonably to improve concrete Pumping performance plays an important role. Unreasonable admixtures will worsen the pumpability and fluidity of the concrete, leading to pipe blockage.

6. Pipe blockage caused by too little mortar or unqualified mix ratio

1. Too little amount of mortar

Because the mixer, concrete truck mixing tank, hopper, pipeline, etc. must absorb a part of the mortar when pumping for the first time. If the amount of mortar is too small, part of the pipeline will not be lubricated, resulting in pipe blockage. The correct amount of mortar should be calculated based on about 0.5m3 of mortar required for every 200m of pipeline, and about 0.2m3 of mortar is required for the mixer, hopper, and concrete truck mixing tank. Therefore, the amount of mortar must be calculated before pumping. Too little mortar is easy to block the pipe, too much mortar will affect the quality of concrete or cause unnecessary waste.

2. Unqualified mortar mix ratio

The mix ratio of mortar is also critical. When the pipeline length is less than 150m, use 1:2 cement mortar (1 part cement/2 parts mortar); when the pipeline length is greater than 150m, use 1:1 cement mortar (1 part cement/1 part mortar), cement Too little dosage will also cause pipe blockage.

7. Pipe blockage caused by temperature changes

In summer, the temperature is high, and the concrete is easily dehydrated under strong sunlight, which can cause pipe blockage. Therefore, the pipe should be covered with wet grass bags or other cooling products. In winter, insulation measures should be taken to ensure the temperature of the concrete.

The above is a summary of several common causes and preventive measures for pipe blockage. In the actual production process, due to changes in external conditions, the reasons for pipe blockage are often more than these. However, as long as we operate strictly in accordance with the operating procedures, prevent gradual failure, and continuously summarize experience and lessons from every pipe blockage, we will surely minimize the possibility of pipe blockage. We are the hydraulic concrete pump manufacturer, our company provides high-quality hydraulic concrete pumps, if you are interested in our products, please feel free to contact us.