Concrete mixing station is a kind of mechanical and electrical equipment that measures cement, water, aggregate, admixture, admixture and other materials according to the requirements of concrete ratio, and then becomes qualified concrete by mixing. Concrete mixing plant includes material conveying, metering, storage, mixing, auxiliary and control systems. Concrete mixing plant is mainly used in railway, km, bridge, airport, tunnel, hydropower and water conservancy projects, soil industry, mining and civil construction, as well as commercial concrete and concrete products production. Concrete mixing plant layout in many forms, specifications are different. For example, according to different uses, it can be divided into hydraulic station, nuclear power station, high-speed rail station, pipe pile station, engineering station and commercial mixed station; According to the convenience of relocation can be divided into mobile station and fixed station; According to the number of hosts configured, the system can be divided into two-node and single-node stations.

Mixing plant development history
1. History of foreign development
In 1796, after the British Asptin invented "Portland cement" and the British Parker (J.Pidker) invented "Roman cement", the concrete mixing station was born. In the early stage, the concrete mixing station used a single mixing form, and it really entered the centralized mixing mode after the application of commodity coagulation. Germany was the first to use commercial concrete, and the world's first commercial concrete mixing station was established in Stasbel in 1903. In the early stage of the construction of the station, the concrete was transported by a dump truck or a motor tipper, which made it difficult to ensure the quality of concrete. From the 1960s to the 1970s, the economic development of all countries in the world was rapid, and commercial concrete also developed rapidly. By 1973, there were 3,533 commercial concrete mixing stations in Japan and 10,000 concrete mixing stations in the United States. In the 1980s and 1990s, Japan's commercial concrete fell by 21% compared with 1973 and tended to be saturated. So far, the number of mixing stations in Japan has remained at about 5,000.
2. History of domestic development
Concrete mixing plant in China started late, to the mid-1960s began to produce vertical shaft propeller mixer, began to produce horizontal shaft mixer in the early 1980s, began to produce planetary vertical shaft mixer in the mid-90s, only to the 1980s to the 1990s to really achieve rapid development. In the 1980s, with the rapid development of the national economy, concrete mixing station has been rapid development. At this time, the mixing machine of the mixing station is based on single and double horizontal shafts, the weighing is based on electronic scales and mechanical electronic scales, and the feeding method has various ways such as tape machine material, cantilever pull shovel, lifting bucket feeding, and the control system has industrial computer, MCU and other forms.

Concrete mixing plant finished product classification
Concrete mixing station product installation forms are diverse, generally according to the fixed form can be divided into mobile mixing station, fixed mixing station, ship-borne mixing station, no foundation mixing station. Mobile mixing plant mobility is good, can be moved at any time, suitable for a variety of concrete amount is not large, short construction period of the site, so usually need to be equipped with walking devices. Fixed mixing plant is fixed on the basis of equipment through bolted connection or welding, mainly used in large prefabricated parts factories, commercial concrete factories and hydraulic engineering sites, such mixing plant production capacity is generally large. Ship-borne mixing plant is generally used for cross-river bridge construction, long-span cross-sea projects, etc. This type of mixing equipment is suitable for concrete construction in wide waters away from land, and can be moved with barges in construction waters, and various types of concrete can be mixed. No foundation mixing plant equipment chassis installation and the location of the equipment site foundation is not connected, the equipment disassembly, installation speed is fast, the basic construction amount is small, generally fixed on the installation frame.

2, according to the characteristics of production concrete classification
According to the characteristics of the concrete produced, it can be divided into hydraulic station, nuclear power station, commercial concrete station, high-speed rail station, etc. Hydraulic station refers to the mixing station is mainly used for mixing dam concrete production. The concrete used for culverts, slopes, roads and other auxiliary facilities of power stations has little difference from general engineering concrete. The concrete aggregate size of the hydropower dam is large, and the aggregate gradation is required. In order to make the mixing host of this type of mixing plant able to withstand the impact of the bulk material, the number and Angle of the mixing arm are arranged in some special ways.

The concrete required for the construction of nuclear power plants is usually divided into two categories: conventional island and nuclear island. The concrete required for nuclear island has high performance, and the concrete poured is thick and large, so it is necessary to be equipped with an ice making system, and there are special requirements for the temperature and mixing process of the machine.

Commercial concrete station is used to produce ordinary commercial concrete, which is the most common concrete mixing equipment and the most widely used. High performance concrete produced in high-speed railway station is mainly used in high-speed railway construction. The high-speed rail mixing station should be measured separately to meet the high measurement accuracy requirements for various materials. The production process of concrete in line with high-speed rail construction is complex, the mixing cycle is relatively long, and it is generally 2-3 times for ordinary commercial mixing stations. In general, the mixing efficiency is relatively low, only 1/3 to 1/2 of the ordinary commercial concrete station.

Technical status of domestic mixing plant
In the past 30 years, manufacturers in Germany, the United States, Japan and other countries have done a lot of research on concrete mixing stations, and adopted a large number of new processes, new technologies and new materials, which has promoted the continuous development of concrete machinery. At present, in foreign countries, the technical characteristics of concrete mixing stations mainly focus on environmental protection issues and strengthen quality control. With the promotion and popularization of commercial concrete in large and medium-sized cities in China, the necessary equipment for the production of concrete concrete mixing station has also been rapidly developed. So far, China has been able to produce various types of mixing plants with productivity of 60 ~ 300m3/ h. The technical level of many mixing stations of major domestic manufacturers such as South Road Machine has reached or exceeded the imported concrete mixing station. Specifically, this is mainly reflected in the following six aspects:
1. High reliability
The key components of the concrete mixing station, such as the mixing host, the screw feeder, and the main electrical control components and pneumatic components, the performance has been quite stable, and the reliability and service life have been significantly improved.

2. High degree of automation control
At present, most of the control systems are relatively advanced and stable, and the degree of automation is generally high. Especially in recent years, the wide application of ERP system can not only monitor the operation of the whole station in real time, but also greatly improve the management level of customer production and operation. Most mixing stations use industrial computer control, both automatic control and manual operation, the operation is more simple and convenient.

3, high production capacity
At present, the emergence of double station and multi-station has greatly improved the production capacity of major concrete companies, and fundamentally solved the problem of insufficient production capacity of single station.

4, high measurement accuracy
The measurement accuracy of concrete mixing station is divided into four aspects, namely aggregate, cement (or admixtures), water and admixtures, of which the accuracy of aggregate can generally be controlled within 2%, and the accuracy of cement (or admixtures), water and admixtures can generally be controlled within 1%.

5, good mixing quality, high efficiency
When the widely used double-horizontal shaft mixing machine is working, the transmission mechanism drives the two mixing axes to rotate synchronously and reverse, and the mixture moves radial and axial in the middle of the tank to form convection, thus improving the mixing quality.

6. The mixing machine has been basically localization
In recent years, a number of mixing plant manufacturers in China have developed a number of hosts using the absorption of foreign host technology, south road machine mixing host, etc., to solve the problem of unstable quality of domestic mixing host, thus greatly reducing the cost of domestic mixing plant.

Product future development trend
Although the concrete mixing plant has achieved rapid development in recent years, there are still some shortcomings in its reliability, safety, environmental protection and humanization. In the era of "Internet +", people put forward higher requirements for the intelligence of concrete mixing station, so the concrete mixing station will be further developed in intelligent, environmental protection, efficient and reliable.

1, the degree of intelligence is getting higher and higher
Under the promotion of "Internet +", concrete mixing station needs to establish a perfect ERP management system, GPS scheduling system, mixing station control system integration. By opening up the concrete mixing station product online function, the product data can be uploaded to achieve remote control of the concrete mixing station, fault diagnosis, program upgrade, maintenance, etc.

2, environmental protection technology continues to develop
Environmental protection technology has always been one of the core technologies of concrete mixing plant, and it is also an important factor affecting product performance. In the future, more environmental protection technologies will be widely used in concrete mixing stations, such as combined dust removal technology, residual concrete and wastewater recycling technology, waterproof and oil-proof dust cloth technology, intelligent pulse dust removal technology and intelligent control spray dust removal technology.

3, energy-saving technology is widely used
Energy saving is an important indicator of environmental protection of concrete mixing station, the future frequency conversion energy saving technology will gradually expand from the screw machine to the belt conveyor, and even the mixing machine motor. At the same time, more energy-saving new materials, new technologies, new processes, new energy, etc., will gradually be applied to the concrete mixing station.

4. Continuous improvement of production efficiency
With the continuous improvement of the production efficiency requirements of concrete mixing stations, concrete mixing stations with high efficiency will continue to emerge. With the continuous improvement of the design of the mixing machine and the wide application of the double intermediate bin technology, the production efficiency of the concrete mixing plant will be further improved in the future.

5, more fit concrete development
In the future, high performance concrete with obvious advantages in construction and economic performance will become the trend of market development. Therefore, concrete production equipment needs to meet the needs of the development of concrete. Only by mastering the new process and formula of concrete production and preparation can designers effectively guide the technical upgrading of concrete mixing station, continuously improve the quality of concrete production and reduce production costs.

6, the trend of modular design is obvious

Based on the relative independence of the main key components of the concrete mixing plant and the diversified characteristics of customer demand, in order to improve the efficiency of the design of the concrete mixing plant and the reliability of the product, the modular design trend will be more obvious. In the design of the overall and key components of a specific concrete mixing plant, the appropriate key components can be selected for modular "assembly" design according to the individual needs of customers.