A self-loading concrete mixer (or self-loading concrete mixer truck) is a mobile concrete production and transportation equipment that integrates loading, batching, mixing, transportation, and unloading functions. Compared to the traditional model that relies on external batching plants and transport vehicles plus on-site pumping/unloading, self-loading mixers are ideal for projects with dispersed construction sites, complex terrain, or high requirements for material supply rhythm due to their high mobility and on-demand batching and transportation capabilities.
According to industry standards (such as ISO 6085:2023), self-loading concrete mixers are typically mounted on wheeled chassis and consist of a front (or rear) loading system (bucket + lifting arm), a rotating mixing drum, a water injection system, and a batching/weighing system. Given its "fully integrated" nature, to ensure efficient and safe use, it is essential to establish and strictly adhere to operating procedures and safety precautions. This article systematically explains the operating procedures and precautions from the perspectives of both construction workers and safety officers, aiming to provide practical reference for construction sites and ensure safe and efficient operations.
1.1 Vehicle and Equipment Condition Inspection
Appearance and Structural Inspection: Before operation, a comprehensive walk-around inspection of the mixer truck should be conducted, observing for obvious damage, cracks, oil or water leaks, and whether the bucket or hydraulic arm is deformed or loose. Tire pressure and condition must also meet the manufacturer's requirements. Check tire pressure, lights, and emergency braking devices, and fill out the inspection record form for future reference.
Fluid and System Inspection: Check that the engine oil, hydraulic oil, coolant, and other fluids are within the specified range, ensuring the hydraulic system pressure is normal and not adjusting it without authorization. Before starting work, confirm that the hydraulic system is leak-free, the mixing drum rotates flexibly, and the braking system is sensitive and reliable. The quality and quantity of hydraulic oil should meet the requirements of the equipment manual.
Control System and Safety Device Testing: Before startup, all control consoles, instruments, operating handles, alarms/lights/horns, and other safety facilities must be tested to ensure they function properly. In particular, the hydraulic boom, bucket, and mixing drum controls must be reliable.
Ground and Terrain Assessment: Confirm that the construction site ground is flat and firm. If the ground is soft, uneven, or sloping, carefully assess whether it is suitable for operation or whether auxiliary stabilizing devices (such as outriggers, wheel chocks, etc.) are needed. The safety officer must survey the work area to ensure the ground's load-bearing capacity meets the equipment's weight requirements, avoid underground pipelines and overhead lines, and set up clear isolation and warning signs. For sloping sites with a gradient exceeding 5%, reinforcement measures must be taken using shims.
1.2 Personal Protective Equipment and Site Layout
All operators and related personnel on site (loading, monitoring, unloading, transportation, etc.) must wear appropriate personal protective equipment (PPE): safety helmet, safety glasses or goggles, safety boots (steel-toed boots), gloves, and, if necessary, a high-visibility reflective vest. If there is a lot of dust or cement/aggregate splashing on site, dust/respiratory protection should also be provided. Operators must hold a special equipment operation certificate and pass specialized safety training; auxiliary personnel should be familiar with hand signals and avoidance routes.
At the construction site, designated areas should be established for the mixer truck's operation and for pedestrians/other equipment movement, with clear warning signs or protective barriers to prevent unauthorized personnel from entering dangerous areas. During operation, loading, and unloading, ensure that other personnel stay away from the rotating parts of the mixer truck or the unloading port.
The "traffic and operation routes" on site should be clearly defined: routes for self-loading mixer trucks to enter, exit, turn, unload, and load materials should be planned in advance to avoid intersections with manual handling, material storage areas, and personnel passage areas, reducing the risk of collisions and tripping.
2.1 Loading and Batching
Before loading, any accumulated water and debris left in the mixing drum should be drained to avoid adverse effects on concrete quality.
During the loading process, all materials (aggregates, cement, water, etc.) should be accurately loaded according to the design or construction mix proportions. The aggregate particle size must be controlled to not exceed the equipment's rated capacity. Overloading is strictly prohibited. Using "unknown proportions" or arbitrarily adding water/materials is strictly forbidden. If a weighing system is available, it should be used preferentially to ensure stable concrete quality.
When adding materials to the mixing drum, ensure that your body and hands and feet are kept away from moving parts such as the bucket, boom, and feed inlet to avoid injury due to loss of control or misoperation. Run the equipment at low speed for 30 seconds initially, and gradually increase the speed to the rated speed after the materials are evenly mixed. During rainy season operations, the moisture content of the aggregates should be monitored more closely, and the mix proportions should be dynamically adjusted.
2.2 Mixing Process
Before starting the equipment, the control handle should be in the "stop" position. After starting the engine, allow the mixing drum to pre-rotate at low speed (e.g., 3–5 minutes) to preheat the hydraulic oil, ensuring the normal operation of the hydraulic and mixing systems before loading materials.
During mixing, maintain focus and avoid distractions unrelated to the operation; working under the influence of alcohol or while fatigued is strictly prohibited.
If the site is uneven or sloping, avoid mixing on inclined surfaces; stop the machine and adjust its position if necessary.
2.3 Concrete Maintenance During Transportation
When transporting concrete to the construction site, the mixer truck should continuously and slowly rotate the mixing drum to prevent concrete segregation. The mixing drum should not be stopped for extended periods during concrete transportation.
During driving, avoid sudden braking, sharp turns, or high-speed driving; maintain a safe following distance and be aware of pedestrians and construction equipment, especially when turning and moving within the construction site or confined spaces.
During concrete transportation, ensure the unloading hopper/chute is securely locked to prevent loosening that could cause concrete to spill or the chute to sway, posing a danger to personnel or equipment. Operators should maintain visual communication with the pouring point, using a dual confirmation mechanism of walkie-talkie and standard hand gestures.
2.4 Unloading and On-site Pouring
Before unloading, ensure the unloading area is flat, unobstructed, and free of unrelated personnel and equipment. If necessary, establish a safety perimeter or warning zone.
During unloading, control the mixing drum's reversal speed and tilt angle to smoothly discharge concrete. Avoid significant tilting or rapid unloading to prevent splashing, spillage, safety hazards, or material waste.
After unloading, promptly clean up any concrete residue to prevent slippery surfaces, personnel slipping, or disruption to subsequent operations.
After each day's operation, thoroughly clean the mixing drum's inner wall, blades, unloading chute, bucket, and boom—all parts in contact with concrete—to prevent concrete from hardening and adhering, which could damage the equipment or cause malfunctions.
Regularly inspect and maintain the hydraulic system, bucket mechanism, rotating mechanism, tires, braking system, lights, horn, warning signs, etc., promptly replacing vulnerable parts or repairing faulty components to ensure long-term safe and reliable operation.
All maintenance/repair work should ideally be performed by authorized or trained personnel, and maintenance records should be kept to track equipment status and develop maintenance plans.
From the perspective of overall on-site safety management, strict systems and supervision should be implemented for the use of self-loading concrete mixer trucks. The following are recommended, but not limited to:
Operator Qualifications and Training: All personnel driving and operating the mixer truck must hold a valid driver's license and have undergone certification training from the equipment manufacturer or project owner. They must be familiar with the equipment structure, controls, emergency shutdown, maintenance, and safety procedures. Unauthorized operation or delegation to others is prohibited.
Safety Officer/On-site Supervisor Responsibilities: A designated on-site safety officer should be responsible for supervising the mixer truck's operating area and personnel movement, ensuring that non-operating personnel stay away from danger zones. When the vehicle starts, moves, or unloads, the safety officer should guide the vehicle via walkie-talkie/signals, clearly indicating the route and parking area.
Prohibition of Violations and Fatigue Operation: Driving under the influence of alcohol, being inattentive, driving without a license, or driving while fatigued is strictly prohibited. During construction, attention should be paid to shift work and rest to avoid accidents caused by judgment errors or operational mistakes due to fatigue.
Emergency Response Plan and Accident Handling: First-aid facilities, fire extinguishers, and spare tools should be provided on-site, and emergency contact numbers should be posted. Operators must be familiar with emergency procedures such as emergency stops, power/hydraulic outages, and pressure relief to ensure rapid response in case of equipment failure, oil leaks, or personal injury.
Construction and Environmental Protection Coordination: During unloading, cleaning, or concrete wastewater treatment, proper collection of slag and liquid, wastewater treatment, and waste cleanup should be implemented to prevent pollution of the site and impact on the surrounding environment. Simultaneously, attention should be paid to minimizing noise and dust emissions on construction workers and nearby communities.
Self-loading concrete mixer trucks, due to their advantages of "integration, high mobility, and adaptability to complex sites," have significant advantages in modern building and infrastructure construction. Standardized operation and systematic management are the core guarantees for maximizing the efficiency of self-loading concrete mixer trucks. Construction companies should establish a four-in-one prevention and control system integrating "human, machine, environment, and management," and build an inherently safe construction site through standardized operating procedures and continuous training.
However, to truly transform the efficiency advantages of this equipment into stable, compliant, and safe construction productivity, a comprehensive system and set of practices must be established across multiple dimensions: equipment, personnel, on-site management, and maintenance.
For construction companies, operating procedures, safety awareness, and maintenance management should be incorporated into on-site management systems and strictly enforced. For operators, understanding of the equipment structure and safety risks, along with a strong sense of responsibility, should be paramount. Only in this way can the high-efficiency advantages of self-loading concrete mixer trucks be fully realized while minimizing the risks of accidents, quality problems, and equipment damage.
