Concrete mixer trucks (hereafter referred to as mixer trucks) and concrete pump trucks (hereafter referred to as pump trucks) are core equipment in modern construction. Their coordinated operation spans the entire concrete pouring process, from transportation to placement. For large and medium-sized projects, concrete pouring efficiency, quality, and safety are crucial. The mixer truck is responsible for transporting and mixing concrete en route to ensure uniformity; the concrete pump directly transports concrete vertically and horizontally through pipelines, completing the pouring process. This collaborative model significantly improves construction efficiency and reduces manual intervention. It is particularly suitable for projects with high concrete demand, such as high-rise buildings and large foundations. Improper coordination can lead to pipe blockage, segregation, or equipment damage, so strict adherence to operating procedures is essential.
The mixer truck transports prepared "ready-mixed concrete" from the plant (or material yard) to the construction site, while the pump truck unloads the concrete from the mixer truck and delivers it via pipelines or a distribution boom to the pouring site (such as a high-rise building, deep pit, hoisting, or long-distance). The synergy between the two can achieve the following advantages:
Maintaining the fresh state of concrete during transportation and pumping reduces downtime and shortens the pouring cycle. Reference materials indicate that the slurry must remain stirred during truck mixer transportation. The extended reach and height of the truck mixer's boom, through pipes and distributing booms, expands the reach of the truck mixer and enhances pouring flexibility. Collaborative operation optimizes construction organization, reduces material backhauling, shortens pouring intervals, and thus improves project cadence and quality.
However, poor coordination between the truck mixer and pump can lead to concrete pumping delays, concrete segregation, backflow, pouring quality issues, and even safety accidents. Therefore, critical aspects of their coordination must be strictly observed. The following details are analyzed item by item.
1.1 Construction Organization and Workflow Scheduling
Advance Communication and Coordination:
Before the truck mixer arrives on site, the project team must confirm with the truck mixer and pouring team: the location of the truck's distributing boom, piping routing, support base, discharge location, and the proper placement of baffles or hoppers.
The mixer truck driver, pump truck driver, and pouring supervisor should hold a briefing meeting to clarify the unloading time, sequence, connection method, and backup plan.
The pouring plan should clearly define the coordination between the mixer truck and pump truck: for example, the time required for the mixer truck to unload material to the pump truck's hopper after arrival, the time required for pumping to reverse or change pipes, and the time it takes for the next truck to arrive.
Effectively match transportation time with pumping time:
The time it takes for the mixer truck to travel from the material yard to the construction site, as well as the waiting time between unloading and the pump truck, must be controlled within a range that ensures the concrete remains pumpable and pourable. Data indicates that transportation distance, traffic delays, cement hydration, and temperature effects can all reduce the concrete's usable time.
After pumping begins, avoid "waiting" delays caused by the mixer truck being on site but unable to unload material promptly. This can reduce the fluidity of the concrete mix or cause segregation.
If the pump truck is interrupted during operation, the mixer truck should have a backup site or buffer plan to avoid dumping material and wasting material.
Matching the Discharge Rhythm with the Pumping Speed
When unloading a truck mixer, the discharge flow rate must be adjusted according to the concrete pump's capacity. If unloading is too rapid and pumping is not timely, excessive material accumulation in the pump bucket can easily lead to pipe blockage. Conversely, interrupted material flow can cause concrete to stagnate in the pipeline. Dynamic adjustment is recommended through signal linkage (such as hand gestures or radio) between the truck operator and the truck driver.
The pumping capacity must be coordinated with the truck mixer's drum speed: the truck mixer maintains a stirring speed of 2-4 rpm to prevent concrete stratification during transport. When pumping, choose either a high-pressure, low-displacement mode or a low-pressure, high-displacement mode based on actual operating conditions.
Connection between the Discharge Point and the Truck Pump Hopper:
The truck mixer should be parked near the truck pump hopper (or receiving platform) in a convenient location to avoid height differences, bumps, or other unloading difficulties between the rear of the truck mixer or the discharge hopper.
The pump truck's material connection port must be kept clear, and the mixer truck's discharge port, discharge pipe, hopper support, and discharge time must be pre-set.
If necessary, the pump truck's hopper, pipes, or material connection port should be cleaned in advance to prevent debris and pre-set concrete from interfering with discharge.
1.2 Concrete Condition and Mix Control
Concrete Mix Suitability:
Mix trucks transport "pumpable concrete," which takes pumping characteristics into consideration: pumping requires sufficient fluidity, pumping stability, and resistance to segregation. Data indicates that pumpable concrete requires even greater pumpability than conventional concrete.
When loading a mixer truck, verify that the mix ratio, slump, and admixtures (such as pumping agents, water reducers, or retarders) meet pumping requirements. If pumping distances are long or at high vertical heights, the concrete's fluidity should be adjusted appropriately.
Mix truck drivers must confirm that the material yard provides the correct grade and designated pumpable concrete. They must not arbitrarily modify or accept conventional concrete.
Mixing and Maintenance During Transportation:
During transportation, the mixer truck should maintain a drum speed (generally 2-6 rpm or as recommended by the manufacturer) to prevent initial setting, segregation, or stratification of the concrete.
If transportation takes a long time or there are traffic jams or hot weather, consider adding a retarder or extending the mixing time to ensure that the concrete is still pumpable upon arrival at the construction site.
After the mixer truck arrives at the unloading point, it should continue to roll (rotate) until ready to unload into the pump truck hopper. Avoid prolonged stagnant time.
Residual concrete after the mixer truck unloads should be cleaned or rinsed promptly to prevent hardening and clogging of the drum.
Synchronized Unloading Control:
The mixer truck driver must wait for the pump truck operator to confirm that the hopper and piping are in good condition and ready for loading before unloading. This prevents backflow or spillage of the unloaded material due to the pump truck not being in place or pumping being stopped.
Observe the concrete during unloading: If segregation, excessive backwater, or blocks larger than permitted specifications are observed, unloading should be stopped immediately and the pump truck operator or the material yard should be notified.
The unloading speed should match the pump truck's receiving speed. If the mixer truck unloads too quickly and the pump truck cannot pump away in time, it will cause a backlog in the hopper and make pumping difficult. If the unloading is too slow, the construction schedule will be affected.
1.3 Coordination of Pump Truck Equipment Condition and Piping Layout
Pump Truck Positioning, Supporting, and Piping:
Before unloading, the pump truck must complete outrigger support, stable baseplate installation, piping installation, or boom deployment. Documentation indicates that the positioning and stability of the pump truck equipment are critical to pumping safety.
The mixer truck should be scheduled to arrive on site after the pump truck equipment is positioned and supported to avoid interference with the mixer truck's docking or unloading due to outrigger deployment or piping operations.
The mixer truck driver should cooperate with the pump truck driver to select an appropriate parking location to avoid blocking the pump truck's outriggers, piping paths, or interfering with the pump truck's boom movement.
Matching and Cleaning the Material Inlet:
The pump truck hopper inlet should be properly aligned with the mixer truck discharge port to ensure smooth concrete discharge from the mixer truck into the pump truck without spillage or spillage.
Before unloading, the pump truck hopper, feed pipe, and hopper screen should be cleaned, moving parts lubricated, and free of residual material blockage. The document mentions that cleaning and inspection before pumping are mandatory.
The mixer truck discharge port should also be kept clean and unobstructed. The discharge pipe or bucket should be aligned with the pump truck to prevent material from flowing sideways or hitting the pump truck, potentially damaging the pump truck hopper.
1.4 Casting Process and Time Control
Pumping Rhythm and Mixer Truck Waiting Time Control:
Upon arrival of the mixer truck, unloading should be carried out as quickly as possible to avoid prolonged waiting. If the pump truck is delayed due to piping, outrigger adjustments, or boom adjustments, discuss a waiting plan with the mixer truck driver or have the mixer truck temporarily move to a standby area.
During the pumping process, the mixer truck should be prepared for the next truck's arrival time, route, and docking location to maintain continuity and avoid pumping pauses. This also prevents pump trucks from constantly waiting for mixer trucks, which wastes resources.
Monitoring the concrete delivery process:
While the mixer truck driver is primarily responsible for transporting and unloading, he or she should also cooperate with the on-site team to monitor the concrete's condition after entering the pump truck's hopper (e.g., signs of backflow, bubbles, or segregation), the pumping speed, and any abnormal vibration or blockage in the pumping pipeline.
If any abnormality is detected (e.g., a sudden drop in pumping speed, increased pipeline backpressure, concrete separation, or pump backflow), the pump truck operator and on-site technicians should be notified immediately, and the mixer truck's subsequent unloading schedule should be adjusted or returned to wait.
Prepare backup and emergency plans:
A backup mixer truck or pump truck should be prepared, especially when the construction site is remote or difficult to pump (e.g., high-rise buildings, basements, or bridges). This ensures that delays or failures of a particular truck do not disrupt the overall pouring schedule.
Truck mixer drivers should carry concrete quality reports and pumping suitability confirmation documents on board so they can quickly determine whether to continue pumping or change plans in the event of an emergency.
1.5 Quality, Safety, Environmental Protection, and Post-Cleaning
Pouring Quality Control:
The concrete delivered by the truck mixer must meet design strength, mix ratio, slump, pumpability, and other specifications. Otherwise, even if the pump truck delivers the concrete smoothly, the quality of the poured concrete may deteriorate. The truck mixer operator should obtain the concrete trial mix report and confirm that on-site conditions are met.
During the unloading and pumping process, if concrete separation, excessive backwater, or pumping interruptions occur, these may lead to pouring defects such as bleeding, segregation, and strength loss. Immediate on-site measures (such as batch replacement, correction, or refilling) must be taken and documented.
Safe Operation:
Clear access routes, personnel isolation areas, and warning signs should be established in the truck mixer parking, unloading, and pump truck receiving areas to prevent personnel from accidentally entering the unloading area or pump truck work area. Documents indicate that during pumping operations, special attention should be paid to outrigger stability, pipeline pressure risks, and personnel coordination.
During unloading, no unauthorized personnel are allowed near the discharge port or the pump truck hopper. If the pumping pipeline is blocked or backpressure occurs, the machine should be stopped and inspected immediately to prevent pipe bursts or concrete splashing.
The mixer truck driver should ensure the vehicle is in a stable position (by using the parking brake, engaging gear, and supporting wheel blocks). During unloading, avoid operating on slopes, soft surfaces, or areas where the pump truck is not securely attached.
Environmental Protection and Cleaning:
After unloading, the drum, discharge chute, and drainage trough of the mixer truck should be cleaned promptly to prevent hardened concrete from contaminating the next truckload or increasing the vehicle's load. The document mentions that cleaning residual concrete from the mixer truck and pump truck is a crucial step.
After pumping, the pump truck pipeline and hopper should be cleaned promptly, and the mixer truck should also cooperate in site cleaning to keep the construction site clean and accessible.
1.6 Precautions for Special Conditions
Long-Distance or High-Rise Pumping:
When pumping over long distances or at high levels is required, the coordination between the mixer truck and pump truck becomes more complex. Truck mixers should ensure that the concrete remains suitable for pumping during transportation and unloading onto the pump truck. Data indicates that for high-rise or long-distance pumping, pumpable concrete should be used and professional piping should be coordinated with the pump truck.
Truck mixer drivers should work with the pump truck to select the optimal unloading location, minimize the length of the delivery pipeline and pumping resistance, and reduce pumping pressure, thereby minimizing risks associated with the concrete being pumped by the truck mixer.
The maximum pipe length, vertical height, pumping pressure, and concrete viscosity that the pump truck can withstand must be confirmed in advance. Truck mixers should also obtain information on the concrete type, slump limit, and maximum stone size that the truck can pump.
Inclement Weather or Extreme Temperatures:
If the construction site is hot, sunny, or windy, the time it takes for the truck to transport and unload concrete must be shortened, and the pump truck piping and boom preparation must be accelerated.
In rainy or cold weather: During transportation, unloading, and pumping, the concrete may cool, initial setting may be accelerated, and pumping may become difficult. The mixer truck driver should communicate with the pump truck in advance whether the mix ratio needs to be adjusted or the truck needs to be stopped and waited.
During nighttime or low-light operations: The unloading area, pump truck piping area, and mixer truck parking area should be adequately illuminated to ensure smooth unloading, receiving, and safe operation.
The mixer truck driver and the mixer truck management team have the following responsibilities and recommendations when coordinating with the pump truck operator:
Before receiving a task, they should confirm that the concrete is "pumpable" and that the pump truck operator has confirmed its receiving capacity.
Ensure on-time dispatch, a smooth route, and that all preparations (parking, docking at the discharge port, and personnel coordination) are in place upon arrival to avoid causing the pump truck to wait.
Upon arrival, promptly communicate with the pump truck operator on-site regarding location, discharge port, docking piping, and signaling to avoid misunderstandings.
During unloading, keep the drum rotating, observe the concrete condition, coordinate with the pump truck operator, and communicate promptly if any abnormalities occur.
After unloading, clean the truck promptly to ensure that residual material does not affect the next truck. Also, inspect the truck and clean the drum between pumping operations.
Comply with on-site safety management requirements. Parking and unloading operations must comply with site access, safety, and crowd isolation requirements.
During the entire process, if the pump truck is found to be slow, experiencing equipment failures, piping changes, or poor concrete condition, proactively request a return or rescheduling to avoid quality loss due to overdue concrete or pumping failures.
It is recommended that project management establish a "mixer truck-pump truck" operational checklist, including timelines, on-site sequence, signal communication, responsible personnel, and emergency response plans, to improve collaborative efficiency.
3.1 Periodic Inspection Items
Mixer trucks: Check the reducer gear oil level and hydraulic system seals daily; test the roller bearings for wear weekly.
Concrete pumps: Focus on distribution valve wear and regularly replace the cutting ring and eyepiece plate to ensure proper sealing.
3.2 Fault Warning Indicators
If the pumping pressure consistently exceeds 25 MPa, immediately check for pipe blockage. Abnormal noise from the mixer truck drum may indicate blade loss or a reducer failure.
3.3 Collaborative Management Optimization Suggestions
Digital Dispatch System Application: Real-time monitoring of the mixer truck's location through GPS positioning allows for intelligent allocation of transport tasks based on the truck's operating status, reducing on-site waiting time.
Personnel Training System: Equipment operators require cross-equipment training to develop bidirectional fault identification capabilities, such as the ability to identify abnormal concrete conditions based on changes in pumping pressure.
The coordinated operation of mixer trucks and pump trucks is a common and critical component of modern concrete pouring. For readers of this truck mixer column, the key is timely, accurate, and coordinated operation of the pump truck equipment to ensure controllable concrete conditions throughout the entire process, from transportation to unloading and pumping. Poor coordination not only impacts construction efficiency but also potentially leads to reduced pouring quality and increased safety hazards.
