In concrete construction, pump pipe cleaning is a critical step. It is to ensure project continuity and the long-term use of equipment. Many construction teams do not pay enough attention to this. This will lead to pipe blockages, equipment wear, and even construction accidents.
This blog provides a comprehensive overview of this matter. It provides professional methods for cleaning concrete pump pipes. Wish it could help you improve construction efficiency and reduce maintenance costs.
Why It Is Important to Clean Concrete Pump Pipe
It is not just a a simple task to cleaning concrete pump pipes after work. It is a vital step to prevent pipe blockages and extend equipment life. Residual concrete hardening inside the pipes can cause serious blockages. It will damage the efficiency of subsequent pumping operations.
Concrete pump pipe cleaning will prevent cross-contamination between old and new concrete. It also ensure the strength and durability of the concrete.
Furthermore, regular cleaning also reduces pipe wear, lowering the frequency of replacements. And therefore, it could significantly save on repair costs and downtime.
Preparations Before Cleaning
After pumping concrete, perform 1-2 reverse pumping cycles to release the pressure in the delivery pipe. If pumping upward, the shut-off valve must be closed first to prevent concrete backflow.
It is crucial to pump 0.5-1 cubic meter of mortar and pump it completely, then stop the machine, switch the plate valve, and release the pressure from the accumulator.
Checking the wear between the cutting ring and the eye plate. It is also essential, because severe wear can affect the cleaning results.
Detailed Main Cleaning Methods
Water Washing Method
The water washing method is the most commonly used, and can be divided into three specific types:
Direct Water Flushing MethodÂ
This water wash method is suitable, if the cutting ring and eye plate are not severely worn (gap < 0.1mm).
After concrete pour, pump 0.15–0.25 cubic meters of mortar, together with a water-cement ratio of 1:1.5 or 1:2. Then, fill the distribution valve with water, start the pump, and continue until clean water flows out from the discharge end of the delivery pipe.
This method does not require disassembling the discharge pipe or adding a cleaning ball. It will save time. And it is particularly convenient for cleaning shorter pipelines.
Discharge Pipe Removal Method​
To use this method, first dismantle the discharge pipe, open the hopper discharge gate, and then use reverse pumping to clean the residual concrete from the distribution valve, concrete cylinder, and hopper.
Then, remove some concrete from the mouth of the first delivery pipe, insert a pre-soaked cleaning sponge ball or a cylindrical cleaning piston, and finally, pump clean water until the piston is expelled from the discharge end of the delivery pipe.
The advantage of this method is that the pipes are cleaned more thoroughly, and the water flow velocity can be lower, and can be paused if necessary.
Piston Method​
Roll 10-20 cement bags into a cylindrical shape, with a diameter slightly smaller than the delivery cylinder diameter, a slightly pointed head, and a length of about 400mm, tightly bound with fine iron wire. And then tie a cleaning sponge ball is lightly with iron wire to the tail of the cylinder and soaked in water.
This method reduces the hassle of dismantling the discharge outlet and elbow pipes, but it requires higher operational skill.
Air Washing Method
Use Air washing to clean concrete pump pipe needs an air compressor. First plug the air-washing ball into the air-washing joint, then connect it to the first straight pipe connected to the reducing pipe, and attach a safety cover at the end of the pipe (with the opening of the safety cover facing down).
Control the compressed air pressure not to exceed 0.8 MPa, open the gas valve slowly, and only open it fully when concrete flows out smoothly. Close the air valve immediately after air washing is complete.
This method requires good pipe sealing, but is not suitable for very long distances. For long pipelines, they can be cleaned in sections. Construction personnel must stay away from the outlet direction, to prevent injury from flying pellets or cleaning balls.
Basis for Selection: Water washing is suitable for most scenarios; air washing is used for longer pipelines or projects without water pressure support.
Cleaning Strategies for Special Situations
Cleaning for Super High-Rise Buildings
For super high-rise buildings (e.g., 300-500 meter pipelines), traditional water washing can not work well. High-pressure gas-liquid mixed system is an innovative solution.
Connect pipes via quick-connect joints and inject high-pressure water and cleaning fluid. It is possible to clean of dozens of meters of pipeline, within seconds without disassembly.
This system mixes high-pressure gas with cleaning liquid. Using the gas-liquid mixed flow to scour the inner wall of the pipeline, wetting, softening, and removing adhered material.
Cleaning Long-Distance Pipelines
If the pipeline is long (exceeding 260 meters), it is suggested to use a specialized water pump for cleaning.
The performance parameters required for this pump are: pressure not less than 4.3 MPa, flow rate not less than 180 L/min.Â
Before cleaning, it is necessary to press in a suitable amount of cement mortar. The packing material (rubber piston, sponge ball, cement bag roll, etc.) must be tightly placed in a reducing pipe.
Cleaning Precautions and Safety Measures
Safety is the primary principle of concrete pump cleaning work. During cleaning, personnel should keep away from pipe openings. And protective devices should be installed to prevent injuries from ejected material. Especially during air washing.
For vertical pumping where the height exceeds 20m, you can tap the bottom elbow of the vertical section with a wooden mallet. If the sound is dull, the elbow may need to be disassembled to remove any accumulated large aggregate.
When water washing is nearing completion, ensure that the water in the pipeline does not flow to the concrete pouring location, to avoid affecting the quality of the concrete .
