1. Before pumping, the equipment shall be fully inspected
① The main system pressure can be adjusted to 32MPa, mainly considering the high pumping pressure and overflow of the main safety valve.
② The displacement of the main oil pump shall be adjusted to the minimum, the pressure of the sequence valve shall not be lower than 10.5MPa, and the nitrogen in the accumulator shall be sufficient.
③ The seal of slide valve oil cylinder shall be free of internal leakage, the buffer of oil cylinder shall be properly small, and the lubrication shall be sufficient and smooth, otherwise, the ram will be lifted slowly or not in place due to the high viscosity and resistance of concrete, which will cause internal slurry leakage and cause the Y-shaped pipe or reducer to be blocked.
④ The wear clearance of ram shall not be too large, otherwise the same failure will be caused by internal slurry leakage.
⑤ The Y-shaped pipe and the upper shell must be tightly sealed, otherwise the pipe will be blocked due to slurry leakage, which will bring unnecessary losses to the construction.
2. Requirements for pipe laying
① Long distance pumping has large resistance, so bends shall be minimized during pipe laying, and large bends shall be used instead of small ones. Practice proves that every additional 90 º × R1000 elbow is equivalent to adding 5m horizontal pipe. So only 4 pipes are used φ 90 º for 125A × R1000 elbow, others φ 125A × 3m straight pipe and φ 125A × 2m straight pipe, with a total length of 310m.
② Attention shall be paid to the reinforcement of pipes and the fastening of pipe clamps. This kind of long-distance pumping will encounter such phenomena as increased pipe runout, pipe burst, pipe clamp explosion, etc. Therefore, it is necessary to fully reinforce the corners and some straight pipes to reduce their impact.
3. Before pumping, do not pump too much water, and pump a proper amount of water to lubricate the pipeline
Some operators may misunderstand that due to the long pipe, enough water should be added to fully lubricate it. During the construction, too much water was pumped, resulting in the skin ring at some pipe clamps being damaged and leaking. When making mortar, as the interface between mortar and water is immersed in water for a long time, the water will take away the cement slurry, causing mortar segregation, increasing the pumping resistance, causing the cement slurry to squeeze out from the damaged leather ring, thus causing pipe plugging.
4. The concrete is difficult to pump because of its high grade and viscosity
For C60 high-grade concrete, the coarse aggregate size is less than 30mm and the grading is reasonable; Sand ratio 39%, medium fine sand; And the cement consumption can meet the pumping requirements. However, due to the restriction of strength, the water cement ratio is between 0.2 and 0.3, resulting in a slump of about 12cm, which affects the fluidity of concrete during pumping and increases the resistance. Increasing the sand ratio can improve its pumpability, but it affects the strength and cannot meet the design and construction requirements. Therefore, the only way to solve this problem is to add water reducing agent, which will not affect the strength but also increase the slump. No water reducer was added at the beginning of pumping, the pumping pressure was 26-28MPa, the pumping speed was slow and the effect was poor. The stability and reliability of the concrete pump will be affected if it is transported under high pressure for a long time. Later, a certain amount of water reducing agent (NF-2) was added, the slump reached 18-20m, and the pumping pressure decreased significantly, only about 18MPa, which doubled the pumping efficiency. In addition, during the pumping process, the operator should also be reminded that the concrete in the hopper must be above the centerline of the mixing shaft, otherwise it will cause the concrete to splash around and hurt people, or the pipe will be blocked due to suction and gas.
Post time: Oct-18-2022