Behind the rise of high-rise buildings and bridges across rivers, concrete mixer trucks play an indispensable role. As a "mobile mixing station" in modern construction, this special engineering vehicle has become an important equipment in the field of infrastructure construction with its unique functions and wide application.
I. What is a concrete mixer truck
A concrete mixer truck, also known as a mixer truck or a tank truck, is a special vehicle used to transport ready-mixed concrete. Its core structure consists of two parts: a car chassis and a mixing device. The mixing device mainly includes a mixing drum, a drive system, a hydraulic system, and a feeding and discharging device. The mixing drum is the core component of the mixer truck. It is pear-shaped and rotated by a hydraulic motor. During transportation, the mixing drum always keeps a low speed rotation (usually 2-10 revolutions per minute) to ensure that the concrete will not segregate and solidify during transportation and maintain good working performance.
The working principle of the mixer truck is based on the concept of dynamic mixing. In the concrete production process, the mixing drum of the mixer truck mixes raw materials such as cement, sand, gravel, water and admixtures at a high speed (10-14 revolutions per minute) to make concrete that meets the construction requirements; in the transportation process, the mixing drum switches to low-speed mixing to prevent the concrete from settling and caking during long-term transportation; after arriving at the construction site, the mixing drum reverses to unload and transports the concrete quickly and evenly to the designated location.
II. Functions of concrete mixer trucks
1. Mixing function
The mixing function is the core function of concrete mixer trucks. After the initial mixing is completed at the mixing station, the mixer truck can perform secondary mixing or adjustment of the concrete according to the transportation distance and time. If the mixing time of the concrete at the mixing station is insufficient, the mixer truck can continue to mix during transportation to ensure the uniformity and workability of the concrete; when the concrete has insufficient slump, the working performance of the concrete can also be adjusted by adding an appropriate amount of water and mixing.
2. Transportation function
Concrete is time-sensitive. The time from mixing to pouring is usually no more than 2 hours, otherwise it will affect the strength and quality of the concrete. Concrete mixer trucks have efficient transportation capabilities and can transport concrete from mixing plants to construction sites quickly and safely. The tank capacity of mixer trucks ranges from 3 cubic meters to 20 cubic meters. The amount of concrete transported by large mixer trucks in a single trip can meet the needs of large-scale foundation projects.
3. Unloading function
The unloading system of concrete mixer trucks is exquisitely designed to achieve fast and efficient unloading. During unloading, the mixing drum reverses and the concrete is discharged along the discharge port under the push of the blades. By adjusting the speed and inclination angle of the mixing drum, the unloading speed and unloading direction can be controlled to meet the unloading requirements of different construction sites. Some advanced mixer trucks are also equipped with remote control unloading devices, which allow operators to control the unloading process from a safe distance, improving the safety and flexibility of unloading.
III. Uses of concrete mixer trucks
1. Construction projects
In house construction, concrete mixer trucks are the main force in concrete transportation. From foundation pouring to main structure construction, to sporadic concrete pouring during the decoration and renovation stage, the support of mixer trucks is indispensable. Whether it is a high-rise residential building, commercial building or industrial plant, the mixer truck will accurately transport concrete to each construction site to ensure the smooth progress of the construction project.
2. Road and bridge engineering
The demand for concrete in road and bridge construction is huge, and the quality and continuity of concrete supply are extremely high. Concrete mixer trucks can transport a large amount of concrete to the construction site in a timely manner to meet the needs of different construction links such as road base, pavement paving, and bridge pile foundation, pier, and beam casting. In large bridge projects such as cross-sea bridges and urban viaducts, mixer trucks play an irreplaceable role.
3. Water conservancy projects
In the construction of water conservancy projects, such as reservoir dams, hydropower station plants, and canals, a large amount of concrete is required. Concrete mixer trucks can transport concrete to water conservancy project construction sites with inconvenient transportation, ensure the timely supply of concrete, and provide solid guarantees for the construction of water conservancy projects.
4. Municipal engineering
In the municipal construction of cities, concrete mixer trucks also play an important role. Urban road reconstruction, underground integrated pipe corridor construction, subway projects, landscape projects in gardening and greening, etc. all require concrete mixer trucks to transport concrete, which will help improve urban infrastructure and renew the city's appearance.
IV. Types of concrete mixer trucks
1. Classification by chassis type
Heavy truck chassis mixer truck: This type of mixer truck is based on a heavy truck chassis, with strong carrying capacity and large tank volume, generally between 8-20 cubic meters. It is suitable for large-scale construction projects, road and bridge projects and other projects with large concrete demand. Common brands include Shaanxi Automobile, Sinotruk, Foton Auman, etc.
Medium truck chassis mixer truck: The tank volume of medium truck chassis mixer trucks is relatively small, generally between 3-8 cubic meters, with good maneuverability and flexibility, and is suitable for small construction projects, municipal projects and rural construction projects with narrow urban roads and limited construction sites.
2. Classification by driving mode
Mechanically driven mixer truck: Early concrete mixer trucks mostly adopted mechanical driving mode, through the power of the automobile engine, through the transmission, power take-off, drive shaft and other mechanical parts to the mixing drum, driving the mixing drum to rotate. This driving mode has a simple structure, but low transmission efficiency and relatively complex operation, and has been gradually eliminated.
Hydraulically driven mixer truck: Hydraulically driven mixer truck is the mainstream product on the market. It converts the mechanical energy of the engine into hydraulic energy through a hydraulic pump, and then converts the hydraulic energy into mechanical energy through a hydraulic motor to drive the mixing drum to rotate. The hydraulic drive mode has the advantages of stable transmission, convenient speed regulation, and good mixing quality, which can meet the mixing and transportation needs under different working conditions.
3. Classification by mixing drum layout
Self-falling mixer truck: The inner wall of the mixing drum of the self-falling mixer truck is equipped with blades. When the mixing drum rotates, the blades lift the material to a certain height, and then the material falls freely under the action of gravity, and the mixing is achieved through repeated falling and mixing of the material. This mixing method is suitable for mixing plastic and semi-plastic concrete, but the mixing efficiency is relatively low and is currently less used.
Forced mixer truck: The mixing drum of the forced mixer truck is equipped with mixing blades. Through the forced stirring of the mixing blades, the materials can be evenly mixed in a relatively short time. The forced mixing method has high mixing efficiency and good mixing quality. It is suitable for mixing dry hard concrete, lightweight aggregate concrete and high-strength grade concrete. It is the main mixing form of concrete mixer trucks at present.
With the development of the construction industry and the advancement of science and technology, concrete mixer trucks are developing in the direction of intelligence, greening and large-scale. In the future, concrete mixer trucks will be equipped with more advanced intelligent control systems to achieve real-time monitoring and optimization of the mixing process and transportation process; at the same time, new energy mixer trucks will gradually become popular, reduce pollution to the environment, and make greater contributions to the sustainable development of the construction industry.