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A detailed guide on the entire process of mixing C30 concrete with a 3.5m³drum-type self loading mixer truck

In small and medium-sized construction projects, the 3.5m³drum self loading mixer truck, with its flexible and efficient features, has become an ideal choice for on-site concrete mixing. This article takes the mixing of 3.5m³of C30 concrete in a single batch as an example to systematically explain the complete process from equipment preparation to finished product unloading, helping construction teams achieve standardized operations.

1. Preparations And Equipment Debugging

Site and Equipment Inspection

Site Requirements

Select a flat and open area, ensuring that there are no obstacles within 2m around the mixer truck to facilitate 360°rotation of the room.

Self-inspection of Equipment

Check the hydraulic oil level (above the middle line of the oil window), water level in the water tank (full), and fuel quantity (≥50%).

Start the engine and preheat for 5 minutes, observing the pressure value on the dashboard (hydraulic system 16-18MPa) and the tachometer (idle speed 800-1000 rpm).

Material Ratio Calculation (based on 3.5m³)

Empty-load Test of The Mixing Drum

Rotate forward and backward at low speed for 30 seconds each to confirm there are no abnormal sounds or jams.

Weighing Tools

Use the electronic scale on the mixer truck (accuracy ±5kg) or a ground scale for verification.

2. Loading and Mixing Operations

Automatic loading process

Bucket arm positioning

Lower the bucket to the ground and adjust the bucket arm angle to 45°through the control lever to ensure the bucket teeth are fully inserted into the material pile.

Layered material loading

First scoop

Load crushed stone (1/3 of the total), lift the bucket arm to 1m above the hopper, and slowly tip to unload.

Second scoop

Load cement (1/2 of the totall), use the bucket’s vibration function to reduce dust.

Third scoop

Load medium sand (1/2 of the totall), simultaneously start the low-speed rotation of the mixing drum (5 rpm).

Fourth scoop

Repeat the above steps to complete the loading of the remaining materials, and finally inject 80% of the total water (reserve 20% for fine adjustment).

Intelligent Mixing Control

Mixing parameter settings

Speed:18 rpm (regulated by the hydraulic pump flow valve)

Time: 4 minutes and 30 seconds (the first 2 minutes are in forward rotation, the next 2 minutes are in reverse rotation, and the last 30 seconds are forward rotation for discharging)

Real-time monitoring:

Observe the current value on the instrument panel (during normal mixing, it should be ≤ 120A)

Check the slump once every minute through the sampling port (the target value is 120 ± 20mm)

If there is a tendency of segregation, immediately inject the remaining 20% water and extend the mixing time by 30 seconds.

3. Transportation and Discharge Management

Safety Transportation Standards

Driving speed: ≤ 15 km/h on flat roads, ≤ 8 km/h on slopes, and ≥ 8 meters for turning radius.

Screw bucket condition: Maintain a constant speed of 6 rpm, and check the concrete condition inside the bucket every 10 minutes through the side view mirror.

Emergency Handling: If traffic congestion lasts for more than 30 minutes, switch the vehicle forward and backward every 5 minutes to prevent initial setting.

Efficient Discharge Techniques

Discharge Preparation:

Raise the mixer speed to 12 rpm 3 minutes in advance to ensure the concrete flows well.

Adjust the vehicle position to align the discharge chute with the center of the pouring point, with an error of ≤ 5 cm.

Graded Discharge:

First stage: Quickly discharge 70% of the concrete (2 minutes and 30 seconds), maintaining a 15° tilt angle of the bucket.

Second stage: Slow down to 8 rpm to discharge the remaining 20% (1 minute), while slightly swaying the vehicle to cover the edges.

Closing stage: After closing the discharge door, reverse the bucket for 30 seconds to clear the remaining materials.

4. Immediate cleaning procedure
High-pressure rinsing: Use a vehicle-mounted water gun to rinse the feed inlet, discharge tank, and the blades of the mixing cylinder at a pressure of 15 MPa, with a focus on removing cement lumps.
Cylinder interior cleaning: Inject 200L of clean water and run it at 8 rpm for 5 minutes. Drain the waste slurry through the drainage outlet.
Key parts maintenance:
Lubrication points: Add lithium-based grease (once per shift)
Check hydraulic oil temperature (≤ 80℃) and filter element clogging indicator.
Long-term maintenance points
Daily inspection: Tire wear marks, brake pad thickness, electrical circuit insulation.
Weekly maintenance: Replace the hydraulic oil filter element, tighten the transmission shaft bolts.
Monthly inspection: Check the straightness of the mixing cylinder (error ≤ 3mm), and calibrate the electronic scale accuracy.

5. Quality Control and Emergency Plans
Quality Inspection Standards
Slump: Take samples twice per vehicle trip, with an allowable deviation of ±15mm.
Air Content: Use an air pressure testing instrument, with a target value of 3% ± 1%.
Test Block Production: Leave 1 set (3 blocks) of standard curing test blocks for every 50m³.
Common Problem Handling
Dilatation Phenomenon: Immediately add 0.5% fly ash and stir at high speed for 2 minutes.
Inadequate Workability: Add water reducer (with a dosage of ≤ 1% of the cement weight) and extend the stirring time.
Equipment Failure: Activate the backup mixer truck, and the faulty vehicle should immediately stop and contact the after-sales service.
Through standardized operation procedures, the 3.5 cubic self-feed mixing truck can achieve efficient mixing of C30 concrete. The single operation cycle (including cleaning) can be controlled within 45 minutes, and the material loss rate is ≤ 1.2%. It is recommended that operators participate in practical training every month, and continuously optimize construction parameters based on the data from the equipment intelligent diagnosis system to ensure stable and compliant concrete quality.