The efficiency of concrete pumping directly impacts the overall pace of construction. In practice work, pipeline blockages frequently occur, posing significant challenges for many construction teams, particularly during long-distance transportation or high-rise pumping operations. Pipeline blockages often lead to work interruptions, not only reducing construction efficiency but also potentially causing severe schedule delays, material waste, and even concrete pumps damage.
However, blockages do not necessarily hinder your work. By understanding the causes of blockages, mastering handling methods, and using reliable equipment, you can continue to smoothly advance your project. At EPDAS, we will guide you in understanding, resolving, and preventing pipeline blockages during concrete pumping operations.
Concrete pipeline transportation rely on pipeline concrete pumps for transportation. Pipeline pumps are installed on trailers or trucks. These concrete pumps use flexible hoses or steel hoses connected to the pump outlet, which are connected together to deliver concrete to the desired location.
To cope with different working conditions, concrete pipes can adopt various specifications and materials, such as high-strength alloy steel pipes, wear-resistant rubber hoses, etc. They have the characteristics of high pressure resistance, wear resistance, and bending resistance, which can effectively reduce the risk of pipe blockage and extend the service life of equipment. In addition, the connection points of the pump pipes are usually equipped with quick clamps, sealing rings and other accessories to ensure reliable sealing during the operation of the system, prevent leakage and guarantee construction safety.
Delivering More Efficient Concrete Pouring
The core advantage is first reflected in its high-efficiency pouring capability, achieved through continuous pumping by a piston system, which is more than ten times more efficient than traditional transportation methods such as wheelbarrows and dump trucks. Under normal operating conditions, the entire process from preparation to completion of pouring can be compressed to within one hour, and the flexible combination of hoses enables millimeter-level precise material distribution, avoiding errors and rework. The integrated system of pump trucks and mixer trucks eliminates batch waiting times, making it suitable for the one-time pouring of large-volume concrete.
Pumped Concrete is More Durable
In terms of concrete hardness, the pressure in the pumping pipes overcomes viscous resistance, allowing the water-cement ratio of the concrete to be reduced by 15%-20% compared to traditional slope-pouring methods. This results in a significant improvement in compressive strength, a 40% reduction in shrinkage rate, and a 50% increase in crack resistance, thereby significantly reducing post-construction maintenance costs.
Outstanding Mobility
The concrete pipeline pump’s unique 270° free turning capability enables it to easily handle various complex construction environments, including areas with dense reinforcing bars and special conditions such as irregular structures. The minimum bending radius of the hose can reach 1.2 meters. This feature enables it to perfectly adapt to the working requirements in narrow Spaces and expands the construction range.
Notably, the system’s quick-disassembly design improves equipment relocation efficiency by over 60%, with operators able to complete the redeployment of the entire delivery pipeline in just 15-20 minutes. This high-efficiency performance is particularly suitable for construction scenarios requiring frequent changes in pouring locations. This mobility advantage has been fully validated in actual engineering applications. In a certain subway hub project, the construction team completed concrete pumping tasks for multiple work areas in just 3 days, which would have taken a week using traditional methods.
Construction Site Safety and Reliability
Concrete pumping technology, through high-pressure pipeline transportation, has fundamentally changed the traditional manual handling mode of concrete. In the construction of high-rise buildings and deep foundation pits, this system can stably transport concrete to the work surface at a rate of 30-60m³/h, eliminating the safety hazards of workers walking under heavy loads on high-altitude scaffolding or in steep foundation pits.
Equipment and Operational Factors
Unstable concrete pump pressure or mechanical failure is a common cause of blockages. Fluctuations in concrete pump pressure and mechanical failure are frequent causes of pipeline blockages. When hydraulic systems experience oil contamination (solid particle content exceeds standards), metal debris or gummy substances can fill the clearance between the directional valve spool and valve body (typically 8–15 μm), causing the spool to jam during movement. This fault results in abnormal pressure fluctuations in the pump within the range of 12–28 MPa, far exceeding the normal operating pressure fluctuation range of ±1.5 MPa.
As the core actuating component of the concrete pump, the performance status of the piston directly determines the stability of the pumping system. From the perspective of mechanical principles, the piston moves back and forth in a straight line within the hydraulic cylinder barrel, achieving the suction and push of concrete through periodic volume changes. When the piston wears out, the surface metal material is eroded due to long-term friction and the impact of aggregates, resulting in a reduction in the diameter of the piston.
Piston seals are typically made of polyurethane or rubber, which can age and crack under prolonged high-frequency operation. Once the seal fails, the pumping system forms a two-phase flow of gas and liquid, and the compressibility of air causes significant fluctuations in concrete pressure.
As time goes by, the coarse aggregates gradually accumulate to form a clogging core, eventually leading to the interruption of pumping. In addition, poor sealing may also introduce external impurities, accelerating the abnormal wear of the piston and cylinder barrel, thus creating a vicious cycle.
If mechanical components such as gears and bearings inside the cement pump body malfunction, such as severe gear wear or bearing damage, it will significantly affect the normal operation of the pump, leading to discontinuous concrete delivery or unstable speed, and greatly increasing the risk of blockages.
As the core component for power transmission, when the wear on the gear teeth exceeds 0.5mm, the transmission efficiency decreases by 20%-30%, unable to provide sufficient pushing force for the concrete. This causes the flow rate of concrete in the pipeline to drop below the critical value, gradually accumulating and forming a blockage hazard.
Bearings, as components supporting rotating parts, can cause abnormal vibrations during pump operation when balls fracture or the retainer is damaged. This high-frequency vibration disrupts the suspension structure of concrete aggregates, causing coarse aggregates to separate from the mortar and form “stone jams” at pipe bends or diameter changes.
In concrete pumping construction, choosing the appropriate concrete pump equipment is a key link to ensure the smooth progress of the construction. Different engineering scenarios have specific requirements for the types and performance parameters of concrete pumps.The volume of concrete pouring also influences equipment selection; projects with large pouring volumes require high-capacity concrete pumps to meet continuous operation needs and avoid construction interruptions caused by insufficient equipment capacity.
In addition to the type and capacity of the pump, the selection of pipeline diameter is also critical. The inner diameter of the pipeline must maintain a reasonable proportional relationship with the particle size of the coarse aggregate in the concrete. Generally, the ratio of coarse aggregate particle size to pipeline inner diameter should not exceed 1:3. If the pipeline diameter is improperly selected, it can easily lead to pipeline blockage issues.
Mismatched pipe inner diameter and concrete aggregate particle size is a common issue. When the pipe inner diameter is too small, large-sized aggregates are prone to getting stuck inside the pipe, obstructing concrete flow and causing blockages. Using a conveying pipe with an inner diameter of 130mm but combining it with coarse aggregates with a particle size of 45mm, the ratio of coarse aggregates to the inner diameter of the pipe exceeds the safety standard of 1:3, which is very likely to cause blockage in the narrow parts of the pipe. Additionally, issues such as poor sealing at pipe joints or pipe aging can cause leakage, affecting concrete flowability and increasing the likelihood of blockages.
Inadequate pipe cleaning may lead to blockages at areas where old concrete has hardened, potentially causing water seepage and segregation. Defects in joints, gaskets, or welded rings can also result in grout loss. It is also important to ensure that elbows are not too short, too sharp, or too numerous, as these factors can increase concrete pumping pressure.
The pumping speed must be matched with the flow characteristics of the concrete mixture. Excessive pumping speed will cause the concrete to not be evenly distributed in the pipeline in time, increasing frictional resistance and eventually leading to blockage. In addition, an overly fast pumping speed may also cause the separation of water and fine aggregates in the concrete, affecting the strength and durability of the concrete.
Construction workers should reasonably control the pumping speed based on the actual conditions of the concrete (such as slump and aggregate gradation), and avoid blindly pursuing speed. The intelligent pumping control system is adopted to monitor the flow state of concrete in real time and automatically adjust the pumping speed, thereby optimizing the pumping process and improving the construction efficiency and quality.
Firstly, there is a lack of regular maintenance. If concrete pump equipment is not regularly maintained, potential problems cannot be detected and resolved in a timely manner, which can eventually lead to pipe blockages. For example, failure to replace worn seals in a timely manner or failure to clean the inside of the pump body. Worn seals can cause leaks in the pumping system, reducing pumping pressure; concrete lumps and other impurities remaining inside the pump body can mix into the concrete during subsequent pumping, causing pipe blockages.
Secondly, inadequate pipe cleaning. After each construction is completed, if the pipeline is not thoroughly cleaned, the remaining concrete will harden and clump inside the pipeline, becoming a blockage for the next pumping. In addition, if impurities, oil stains, etc. adhere to the inner wall of the pipe, it will also affect the friction between the concrete and the pipe, reduce the fluidity of the concrete, and increase the risk of blockage.
Concrete-Related Factors
In terms of aggregates, if the coarse aggregate particle size is too large and the content of needle-like and flaky particles is excessive, they are prone to mutual squeezing when flowing in the pipeline, especially at the bends and diameter changes of the pipeline, which is very likely to cause blockages.
If the mud content in fine aggregates is too high, it will absorb a large amount of water, reducing the fluidity of concrete. It will also affect the hydration reaction of cement, reducing the strength of concrete and making it prone to blockage during transportation in pipelines.
In addition, the type and quality of cement should not be ignored. If expired or damp cement with lumps is used, its activity will decrease, which will cause abnormal setting time of concrete and increase the possibility of clogging.
In concrete mix design, if the amount of cement is insufficient or the water-cement ratio is too small, the concrete mixture will become overly dry and thick, reducing its fluidity and plasticity. The flow resistance in the pipeline will increase, making it difficult to transport smoothly and eventually leading to blockage.
If too much cement is used or the water-cement ratio is too high, it will cause the concrete to segregate and bleed, the aggregates to separate from the cement slurry, and the aggregates to accumulate in the pipeline and block the passage.
Improper sand ratio can also cause problems. If the sand ratio is too low, the concrete will lack sufficient lubrication, increasing pipeline friction. If the sand content is too high, it will increase the consistency of the concrete mixture and reduce its fluidity, causing frequent clogging of pipelines during the pumping process of concrete and seriously affecting the construction progress.
Concrete slump is a key indicator for measuring workability and flowability. Deviations in its values directly impact the quality of pumped concrete construction. When the measured slump falls below the design standard, the concrete becomes excessively dry and stiff, resulting in significantly deteriorated rheological properties—specifically, an increase of over 40% in yield stress and a 60% rise in plastic viscosity. This leads to a sharp increase in pumping resistance and poses a risk of pipeline blockage.
Especially under winter construction conditions, when raw material temperatures drop below 5°C, water evaporation rates decrease by over 50%, and cement hydration reaction rates slow by 70%. The combined effects of these factors exacerbate slump loss.
Operator-Related Factors
During concrete pumping operations, operators must maintain high levels of concentration and monitor changes in pumping pressure. The intelligent pressure monitoring devices installed in the pumping system provide real-time feedback on the pressure status within the pipes. When pressure values abnormally spike, this often indicates an impending blockage.
If operators fail to promptly detect abnormal pressure fluctuations due to negligence, it may result in severe pipeline blockages. Post-incident cleanup not only consumes time for pipeline clearance but also causes delays in the day’s construction schedule and incurs additional economic losses.
In concrete pumping operations, control during the initial stage is particularly critical. Since the inner walls of new pipelines have not yet formed an effective lubricating layer, and concrete must overcome significant static friction, it is essential to use a low-speed pumping mode initially. Once the pumping process stabilizes, the flow rate can be gradually increased.
Pumping operations must adhere to the principle of “slow start, gradual acceleration.” Any reckless approach may backfire. It is recommended that construction companies establish standardized pumping acceleration curves and use vibration monitoring and other methods to continuously assess the flow state of concrete within the pipes, ensuring a balance between construction quality and efficiency.
The height of the remaining material in the hopper must never be lower than the mixing shaft. It is recommended to maintain a safe height of 20-30 cm above the mixing shaft. If there is too little remaining material, the pump is likely to suck in air during operation. Once air enters the pipeline, it will disrupt the continuity of the concrete and cause blockages.
Environmental and Site Factors
Concrete pumping performance is significantly affected by environmental temperature. During hot summer weather, concrete tends to dry out and harden quickly, increasing pumping resistance; in cold winter conditions, concrete becomes less fluid. We must pay special attention to these factors during construction.
In hot weather, moisture in the concrete evaporates rapidly, potentially causing it to thicken before reaching its destination and leading to pipeline blockages. In cold weather, concrete sets slowly, resulting in insufficient early strength. Therefore, different measures should be taken according to the season: in summer, cool water can be used for mixing, and ice blocks can be added during transportation to lower the temperature; in winter, the mixing water should be heated, or some antifreeze agent can be added. As long as the measures are appropriate, smooth pumping can be ensured.
In actual engineering projects, proper temperature control can reduce pipe blockages by more than 70%. Therefore, during construction, it is essential to adapt to the weather conditions and adjust the mix ratio and construction methods in a timely manner according to weather changes.
The cleanliness of the pump and hose lines must not be overlooked. If concrete debris or other debris from the previous construction remains in the pipes, it will obstruct the flow of newly poured concrete during transportation and cause blockages.
After each construction, the pipes must be thoroughly cleaned using a high-pressure water jet (pressure ≥ 15MPa) and a pipe cleaner to check the cleanliness of the inner walls to ensure that the pipes are clean and free of debris.
Before concrete pumping operations, thorough pipeline lubrication preparation must be carried out. First, start the equipment and pump an appropriate amount of clean water to fully moisten the hopper, screen, and inner walls of the delivery pipes. This critical step effectively reduces friction resistance during concrete flow and prevents material from adhering to the pipe walls.
And then, a wet pipeline environment helps maintain concrete workability, avoiding reduced workability due to rapid moisture loss. Practical experience shows that proper pipeline pre-wetting can reduce the risk of blockages by over 40%, serving as a crucial safeguard for smooth pumping operations.
During actual operation, water should first be injected into the hopper (with a water volume approximately 1.2 times the pipe capacity), and the pumping system should be started to circulate water within the pipes until water flows out of the pipe outlet with no visible bubbles. It is recommended to use clean water with a pH value between 6 and 8, and avoid using water sources containing impurities that may affect concrete performance.
Before pumping concrete, first pump cement mortar with the same mix ratio as the concrete (excluding coarse aggregate). The cement mortar forms a lubricating film on the inner walls of the pipeline, further reducing the flow resistance of the concrete.
Generally, approximately 1–1.5 cubic meters of cement mortar is required for every 100 meters of pipeline length. For vertical pipelines, it is recommended to increase the volume by 0.3 cubic meters every 50 meters. By strictly adhering to the cement mortar lubrication process, pipeline blockage rates have been reduced by 60%.
To ensure the continuity of concrete pumping operations, it is essential to maintain an adequate concrete level in the hopper at all times to prevent air ingress caused by supply interruptions, which can lead to blockages. By optimizing transportation routes and dispatch intervals, concrete supply can be precisely matched to pumping demand. This collaborative management approach can increase pumping efficiency by over 30% while minimizing the risk of blockages.
Additionally, install ultrasonic level monitoring devices in the hopper. When the concrete level drops below the set value (20 cm above the mixing shaft), the system automatically triggers an audible and visual alarm and sends a replenishment request to the concrete batching plant.
Conveying pipelines should be kept as straight as possible to minimize the number of elbows. If turns are necessary, the turning angle should be gentle (it is recommended to use 120° elbows instead of 90° elbows). In addition, pipeline joints should be tightly connected to prevent leakage. In actual construction, rubber seals and high-strength bolts can be used to ensure the tightness of the joints.
In concrete pumping operations, it is essential to ensure that the piston operates smoothly throughout the entire process. The full-stroke movement of the piston can ensure the uniform push of concrete and effectively prevent the accumulation of materials in the pipeline. Operators need to monitor the operating status of the equipment in real time. One way is to determine whether the running trajectory is normal through the data from the piston stroke sensor. The second is to visually inspect whether the piston movement is smooth.
Avoid abnormal piston movement causing fluctuations in pumping pressure, which may lead to pipeline blockage and other malfunctions. Standardized piston operation management can reduce the risk of pipe blockage by more than 50% and is a key control point to ensure pumping quality.
When starting pumping, the concrete pump should operate at a slow and steady speed and be capable of reversing direction at any time. The pumping speed should follow the principle of starting slow and gradually accelerating.
Generally, the initial pumping speed can be controlled at 30%–50% of the normal speed, and then increased by 5%–10% of the flow rate every 3–5 minutes based on actual conditions (such as pressure fluctuations and concrete flow state).
Concrete pump pipeline blockages typically exhibit noticeable signs, such as a sudden surge in pumping pressure (exceeding the rated pressure by 1.5 times), abnormal operational sounds from the equipment (such as sharp friction noises), and a reduction in concrete output. Inspect sections of the pipeline where flow has stopped or slowed. Common problem areas include elbows, reducers, and joints, where pressure tends to concentrate.
When these conditions are detected, construction personnel should immediately stop pumping and inspect the pipeline for blockages. Blockage locations can be identified by tapping the pipeline and assessing the sound: areas with a dull sound are likely blockage points. Additionally, pipeline detection instruments (such as radar detection equipment) can be used for precise localization, with an error margin of ±0.5 meters.
Once the blockage location is identified, you can first try reversing the pump to use the suction force generated by the reverse rotation to draw the blocked concrete back into the hopper. If reversing is ineffective (after three attempts), the pipeline must be disassembled for cleaning. Before disassembling the pipeline, ensure that the pressure inside the pump has been fully released (pressure reduced to 0 MPa) by opening the relief valve to prevent accidents.
After pressure release, use a sponge ball to remove any remaining debris from the pipeline. The sponge ball can remove hardened concrete and other residues causing the blockage. Before inserting the sponge ball, ensure the pipeline can be safely opened and all remaining concrete has been removed.
During cleaning, specialized tools (such as pipeline cleaning rods, high-pressure water jet equipment) can be used to remove the blocked concrete. After cleaning, reinstall the pipeline and perform a pump test.
If you have tried these steps but the clogging problem still persists, please call an expert. The professional technical team of EPDAS concrete pumps is always ready to support you. We offer 24-hour all-weather service. Whether it’s remote guidance over the phone or on-site emergency support, EPDAS can help you quickly solve the problem of pump blockage and ensure the concrete pump returns to normal operation.
Rather than passively dealing with congestion problems, it is better to take the initiative to prevent them. The risk of clogging can be significantly reduced through regular equipment maintenance and upkeep, standardized operation training, and the selection of high-quality concrete pump equipment such as EPDAS. Selecting reliable equipment is the key to ensuring the smooth progress of construction. EPDAS concrete pumps, with their high efficiency and durability, can effectively avoid common pumping problems.
Concrete pump operators must receive training, covering equipment installation and commissioning, operation norms, maintenance and upkeep, as well as safety emergency handling, etc. Construction enterprises can cooperate with professional training institutions to organize operators to participate in refresher training on a regular basis (every six months) to update their knowledge and skills and improve their operational proficiency.
Operators must fully understand the performance and usage limitations of concrete pumps and are strictly prohibited from operating beyond the prescribed range. For instance, different models of pumps have different maximum pumping heights and distances (for example, the maximum vertical pumping height of the DHBT60 pump is 100 meters and the horizontal pumping distance is 400 meters). Exceeding these limits not only affects the construction quality but may also cause equipment failure and safety accidents. It is recommended to post clear performance parameter labels on the equipment operation panel and set up an automatic alarm device for over-range operation.
In the concrete pumping work, a clear communication mechanism should be established among the operators, construction workers and managers. Communication can be carried out through gesture signals, walkie-talkies and other means to ensure accurate and timely information transmission and avoid operational errors caused by poor communication.
Reasonable operation arrangement and personnel coordination are the keys to ensuring construction safety and efficiency. Before working, a detailed operation plan should be formulated, clearly defining the responsibilities and tasks of personnel in each position (such as pump truck operators, pipeline supervisors, dispatchers, etc.). During the construction process, on-site management should be strengthened.
The working status of each position should be monitored in real time through the management platform, and problems that arise should be solved promptly to ensure that all work proceeds in an orderly manner.
In concrete pumping operations, work at heights is often involved, and effective fall protection measures must be implemented. Sturdy guardrails (height ≥ 1.2 meters, horizontal bar spacing ≤ 0.6 meters) must be installed.
Workers must wear five-point safety harnesses and secure them to reliable anchor points (such as dedicated anchor points or lifeline systems).Additionally, fall protection nets (mesh size ≤ 10 cm × 10 cm, load-bearing capacity ≥ 1.5 kN) and other protective facilities can be installed to reduce the risk of falls.
Concrete pump pipeline blockage is a common problem in construction sites. Knowing the causes of blockage, taking effective preventive and solution measures, and strictly following safety operation procedures, the probability of blockage occurrence can be greatly reduced, ensuring the smooth progress of concrete pumping operations.
As one of the world’s leading suppliers of concrete pumps and concrete pouring solutions, EPDAS can help you clear the clogging problems of concrete pumps in your pipeline system. We also offer reliable and durable pumps to ensure the smooth progress of your project. We offer round-the-clock technical support, allowing you to rely on us when facing challenges. Contact us immediately for more information.
