Do you understand cement and concrete? In modern construction, cement is the primary binding material for concrete, which forms the finished structural element. However, transforming cement into high-quality concrete is more than just the right recipe; it’s also about timing, consistency, and efficient delivery.
Therefore, in modern building construction, from the foundation construction to the rise of tall buildings, concrete is an indispensable core material. A reliable concrete mixer truck is the key link to ensure the efficient and high-quality transformation of concrete from raw materials to finished products. Next, we will analyze the importance of concrete mixer trucks in site construction from multiple dimensions.
How many times have you heard people use the words cement and concrete interchangeably? Probably enough for you to wonder if there is a difference at all. While there are some ways in which the terms are related, the answer is simple: concrete and cement are fundamentally different.
Cement is a fine powder made from minerals such as limestone and clay that are calcined at 1450°C to form clinker and then ground. It cannot be used as a stand-alone building material on its own but is more like the “binding agent” in concrete that holds other materials together.
Despite the hard texture of cement powder itself, it is not an independent building material. In the field of construction, cement is more like a magical “molecular glue”: when it meets water, it rapidly undergoes a hydration reaction, generating a hydration product with gelling properties, like countless nanoscale “molecular arms”, which tightly entangle and wrap the sand and gravel aggregates and mineral admixtures. This unique chemical property makes cement the core component of concrete, giving concrete the magical ability to transform from a fluid to a solid, supporting the steel reinforcement of modern buildings.
Concrete, the “skeleton” of modern construction, is a composite material consisting of cement, water, aggregates (stones, gravel), and sand mixed in specific proportions. Among them, cement acts as a “binder”, firmly bonding the aggregates through hydration; coarse aggregate with a particle size of 5-40mm provides structural support, while fine sand of 0.16-5mm fills the pores, and the three mixed with water to form a malleable slurry, which exhibits strong mechanical properties after curing and hardening.
Its compressive strength varies significantly depending on the scene of use: the compressive strength of concrete required for residential sidewalks is about 3500 psi, which is sufficient to withstand the daily loads of pedestrians and light vehicles; while the core of ultra-high-rise buildings to withstand wind loads and gravity loads at a height of hundreds of meters, the compressive strength of concrete often exceeds 6000 psi, and some landmark buildings even reach 10000 psi.
It is worth noting that adding fly ash, slag, and other industrial solid waste recycled materials, not only can reduce the amount of cement to achieve green emission reduction, but also enhance the permeability of the concrete; mixing water reducing agent, early strength agent, and other chemical additives, can accurately regulate the setting time and freeze-thaw resistance performance so that the concrete to adapt to extreme construction environment.
Relevance of the Distinction
Many people often confuse “cement” and “concrete”, but in fact, cement is only a component of concrete. It is only when this difference is clear that we can realize the importance of precise proportioning, strict time control, and efficient transportation guarantee in the transformation process from cement to concrete.
Understanding Ready Mix
Ready-mix concrete, also known as pre-mixed concrete, is concrete transported by volumetric concrete trucks, which is mixed and/or blended en route to the construction site or on-site. The concrete is delivered in a plastic or unhardened state.
The process from cement to concrete, and transported by concrete mixer trucks, is of great significance. It spans the critical transformation process of construction materials from their raw form to usable finished products, serving as a core component in ensuring the quality and efficiency of construction projects. Selecting a high-quality concrete mixer truck is crucial for the final use of concrete. Next, we will explore how ready mix concrete trucks have become the preferred vehicles on construction sites.
A mixer truck is a specialized vehicle for transporting concrete for construction purposes; it is also often referred to as a snail truck and olive truck due to its shape. These trucks are equipped with cylindrical mixing drums to transport and mix concrete.
In the past, construction sites mostly used on-site mixing of concrete, which was inefficient and difficult to ensure quality. Today, the mobile concrete mixer truck is like a “mobile mixing station”, continuously mixing the concrete during transportation to ensure that it remains fresh and pourable when it arrives at the site.
In the early stages of construction, on-site mixing of concrete is a common practice in the industry. Workers needed to manually operate mixers to proportion cement, sand, and water, which was not only time-consuming and labor-intensive but also depended entirely on the operator’s experience for mixing uniformity, which often resulted in uneven distribution of aggregates and uncontrolled water-cement ratios. Under extreme weather conditions such as high temperatures and sunshine or low temperatures and cold waves, it is difficult to control the speed of the concrete setting, and the strength rate is less than 70% of the standard, which leads to the rework phenomenon.
Nowadays, the concrete lorry, a professional vehicle equipped with double screw mixing blades, is like a movable intelligent mixing station, continuously churning concrete at a precise speed of 2-10 revolutions per minute on the way to the construction site. The tank is made of high-strength, wear-resistant steel, and the hydraulic drive system prevents segregation caused by transportation bumps, and the temperature of the concrete is always controlled in the ideal range of 5℃-35℃ by the additional temperature control device.
When the mixer truck arrives at the construction site, the concrete pouring out of the discharge port has a stable slump and excellent fluidity, which perfectly meets the needs of various types of pouring, and enables the construction project to realize a double leap in quality and efficiency.
The time between mixing and placing is very short, and concrete may harden and become obsolete if it is left to stand for more than 2 hours. Under normal circumstances, the slump of concrete will drop 10-20mm every 30 minutes, and after 2 hours, its working performance will be attenuated by more than 50%, completely losing the ability to pump and pour.
The rotating drum of the concrete agitator churns continuously at 1-4 RPM, just like an intelligent “fresh box”. This seemingly simple low-speed rotation actually contains a precision design: the spiral blades on the inner wall of the drum adopt a double logarithmic helix design, which not only ensures that the concrete continues to make three-dimensional movements during transportation but also avoids segregation of aggregates due to violent churning.
Through this gentle and continuous mixing, the water distribution inside the concrete is always kept uniform, the hydration reaction process is effectively controlled, and the slump loss is reduced to 5-10 mm per hour. even after a long distance of 40 kilometers, the concrete arrives at the construction site still maintains the excellent performance of “freshly baked”, which meets the complex requirements of self-compacting and high-flowability construction.
♦ Hydraulic system: responsible for controlling the lifting and rotating of the drum, it is necessary to check whether there is oil leakage regularly to prevent the mixing function from failing due to insufficient pressure.
♦ Bearing: As the key component to support the rotation of the drum, if the lubrication is insufficient, it is easy to produce abnormal noise or even jamming, so it is necessary to add special grease every 500 hours for maintenance.
♦ Support legs: deployed to support the body during unloading, if not fully extended, the vehicle is at risk of overturning and is an important part of safe operation.
Drum Assembly: The Heart of Homogeneous Mixing
♦ Mixing blades: spiral or paddle-shaped design, pushing the materials to the center by rotating and then throwing them to ensure the uniform mixing of cement, sand, stone, and other materials. The blade angle of some high-end models can also be adjusted to suit different proportioning needs.
♦ Water Tank: Typically 400 – 800 gallons in capacity, this tank is used to refill with water to adjust the consistency of the concrete while in transit. The tank valves need to be cleaned after each use to prevent clogging.
♦ Unloading chute: As a channel for concrete to flow out, if the residual concrete hardens, it will seriously affect the unloading speed. Therefore, it must be thoroughly rinsed with water after each use.
Chassis Components: The Core of Power And Load-Bearing
♦ Engine: High-torque characteristics are required to drive a body loaded with 20 tons of concrete, with common models in the 300 – 450 hp range.
♦ Transmission: Most of them adopt automatic transmission, whose smoothness of shifting can effectively reduce the phenomenon of segregation of materials in the process of transportation.
♦ Suspension system: air springs or hydraulic shock absorbers are the mainstay, which can reduce the damage to the homogeneity of concrete caused by vehicle driving bumps.
♦ Dry material into the cylinder: following a strict proportioning sequence is the basis for ensuring the quality of mixing. Firstly, the stones with large particle sizes are evenly spread into the bottom of the mixing cylinder to form a stable bedding layer; subsequently, river sand or mechanism sand is added to fill the gaps of the stones with its mobility; finally, cement is covered on top of the sand and gravel.
This layered feeding method can effectively prevent the cement from directly contacting the cylinder wall, preventing the cement from hydrating and caking in advance due to the local water shortage, and also ensure the rapid integration of the components when adding water for subsequent mixing.
♦ Mixing with water: The mixing process adopts a staged water injection strategy. First, 50% of the total water is injected, and the mixing drum is allowed to run at a low speed of 8-12 revolutions per minute so that the sand and gravel are initially wetted to form a semi-dry state. During the continuous rotation of the drum, the remaining cement and admixtures are added simultaneously, and the centrifugal force is used to throw the materials to the wall of the drum for full collision and mixing.
♦ Finally, the remaining 50% of water is injected and the mixing speed is increased to 14-18 rpm to achieve the desired slump through strong shearing. The whole mixing cycle should not be less than 3 minutes, and the mixing time should be prolonged for special proportions or high-performance concrete, so as to ensure the uniform distribution of each component and the strength of the concrete.
While traveling, the mixing drum rotates positively (“feed direction”) at a low speed of 1-3 rpm, creating a unique three-dimensional mixing motion by means of a double helix with logarithmic blades. When the transport distance exceeds 15 km or the time taken exceeds 30 minutes, it is necessary to add 0.1%-0.3% of sodium gluconate retarder according to the proportion, which extends the initial setting time of the concrete to 4-6 hours by inhibiting the hydration reaction of the cement and thus maintains its fluidity and plasticity.
After the truck arrives at the site, the operator switches the mixing drum to 10-14 rpm reverse mode (“discharge direction”) through the hydraulic control system to push the concrete to the tilted discharge chute with the reverse thrust of the blades.
Immediately after discharge, the on-board water circulation system should be activated and a high-pressure water jet with a pressure of 8-10MPa should be used to rinse the inner wall of the drum, the gap between the blades and the discharge opening in all directions, to ensure that there is no residual concrete adhering to the drum.
If not cleaned for more than 30 minutes, the hardened concrete will form stubborn lumps, which not only affects the mixing efficiency but also may damage the mixing blades.
♦ Quality Assurance: Mechanical mixing is more uniform than manual mixing, and can reduce the dispersion of concrete strength by more than 15%.
♦ Increased efficiency: Eliminating the need for on-site mixing, the construction team can proceed directly to the pouring operation, significantly reducing the construction period by up to 30%.
♦ Controllable cost: Mixing on demand reduces material waste and saves $20 – $50 per cubic meter of concrete.
♦ Flexible adaptation: the proportion can be temporarily adjusted according to construction needs, such as adding an early strength agent to cope with the low-temperature construction environment.
♦ Remote construction tool: no need to rely on the nearest mixing plant, can directly transport raw materials to mountainous areas, suburbs, and other remote sites.
♦ Safety Upgrade: Reducing workers’ exposure to cement dust reduces the risk of pneumoconiosis; mechanical unloading avoids the damage that may be caused by manual handling.
♦ Consistency Guarantee: Each batch of concrete has stable performance, effectively avoiding potential structural safety hazards caused by manual proportioning errors.
♦ Bonus points for environmental protection: the use of industrial wastes such as fly ash to replace part of the cement helps to reduce carbon emissions.
♦ Dynamic adjustability: volumetric mixers can adjust the water-cement ratio in real time on-site to meet the individual needs of special projects.
♦ Significant return on investment: the average daily cost of renting a mixer truck is about $800 – $1,500, but it saves the wages of 3 – 5 workers, and the overall efficiency is increased by 40%.
Projects with minimal work, such as yard repairs, or narrow construction sites that are difficult for mixer trucks to access.
Special projects that require immediate adjustment of ratios and specialized technicians on site.
Scale construction: when the volume of a single pour exceeds 50 cubic meters, the cost of transporting with a mixer truck is 25% lower than on-site mixing.
Controllable quality: The factory-based proportioning management mode can effectively avoid human errors on site.
Time Management: Delivery can be booked according to the construction progress, no need to stop work to wait for materials, to ensure the continuity of construction.
Points for Safe Operation and Maintenance of Concrete Mixer Trucks
Explanation of Modern Safety Configurations
Intelligent braking system: detects obstacles ahead through radar and automatically slows down when it encounters danger to avoid collision accidents.
360° Surround View Camera: Eliminate the blind spot of the vehicle and clearly observe the position of workers around when unloading to protect the safety of personnel.
Tip-over warning: The sensor monitors the tilt angle of the body in real-time, and once it exceeds 5°, it will immediately issue sound and light alarms.
Norms of Daily Operation
Before unloading, all support legs must be fully extended and the ground bearing capacity ≥ 20 tons / square meter must be verified.
When the mixing cylinder is rotating, it is strictly forbidden for people to approach, it to prevent clothes, etc. from being caught in the blades and causing danger.
Regularly check the hydraulic oil level every month, if it is lower than the scale line needs to be replenished immediately to prevent the system from overheating and damage.
Practical Cases: The Outstanding Effectiveness of Concrete Mixer Trucks
Residential Community Projects: Improving Both Efficiency And Quality
In a building foundation pouring project, by using three 12-meter concrete mixer trucks to circulate the material supply, the daily pouring volume reached 240 cubic meters, which is two times more efficient than the traditional on-site mixing method, and the concrete strength pass rate reached 100%.
Bridge Construction: Meeting the Challenges of Very Long-Distance Transportation
During the construction of a cross-river bridge, concrete mixer trucks had to transport concrete from a mixing plant on the other side of the river, which took 45 minutes each way. By adding an efficient retarder and optimizing the drum speed, the concrete arrived with a slump retention rate of 85%, successfully meeting the pumping requirements.
Tank capacity: 8 – 10 cubic meter mixer trucks are available for small sites, while 12 – 16 cubic meter models are suitable for large projects.
Emission standards: urban construction needs to use vehicles that meet the National VI emission standards, and remote areas can consider National V models to reduce costs.
Additional features: Prefer mixer trucks equipped with intelligent configurations such as electronic weighing systems and remote troubleshooting.
Choosing a diesel or electric engine is another key decision when buying a concrete mixer truck. Diesel engines are known for their ruggedness and high torque, making them ideal for heavy-duty applications.
In addition to the engine type, the horsepower and torque requirements of the mixer truck must also be considered. A powerful engine ensures efficient mixing and transportation of concrete, especially in rough terrain or adverse weather conditions.
The efficiency and speed of the mixing and unloading unit significantly affect the overall productivity of a concrete mixer truck. Different mixer trucks utilize different types of drum rotation, such as tilting or non-tilting, and each type of rotation affects the mixing process and concrete quality.
In addition, discharge systems play a vital role in ensuring that concrete reaches the job site in a timely and accurate manner. Devices such as hydraulic chutes or conveyors allow for smooth, controlled discharging to reduce waste and maximize efficiency.
Every construction project has its own unique requirements and challenges, so concrete mixer trucks need to be equipped with customizable features and configurations. Whether it’s extra storage bins, auxiliary lighting, or specialized mixing attachments, customizing your vehicle allows you to tailor it to specific site conditions and operational preferences.
EPDAS offers a range of additional features and accessories that can be integrated into its mixer truck models, allowing you to build a customized solution that meets your exact needs. By working closely with the manufacturer or distributor, you can design a mixer truck that maximizes the efficiency, productivity, and versatility of your construction project.
Concrete Mixer Trucks – A Key Force in Modern Infrastructure
From urban skyscrapers to rural highways and bridges, concrete mixer trucks are like mobile “construction blood pumps”, efficiently transforming basic materials into solid structures that support modern society. In the pursuit of construction efficiency and quality, a reliable concrete mixer truck is no longer just a construction tool, but also a core element that determines the success or failure of a project.
Contact us now to customize an exclusive concrete mixer truck solution based on the actual size of the project, so that every party of concrete can give full play to its value and help the construction of the project to move forward smoothly.
