On September 29, the Yalong River Lianghekou Hydropower Station was officially put into operation. Lianghekou Hydropower Station has the highest earth-rock dam in China at 295 meters. The total filling volume of the dam is 42.069 million m³. During the construction process, machine-made sand and gravel aggregates are continuously poured into the dam body, and the total amount of concrete aggregates used is nearly 10 million tons. .
Yalong River Lianghekou Hydropower Station
In addition to the Lianghekou Hydropower Station, many hydropower stations put into operation in my country in recent years have adopted machine-made aggregates on a large scale. For example, the dam of the Wudongde Hydropower Station Project contains more than 4 million tons of sand and gravel aggregates, and the Baihetan Hydropower Station contains 19.3 million tons of aggregate. tons of finished sand and gravel aggregate.
In addition to generating electricity, hydropower stations also have the functions and functions of storing water and energy, and improving the shipping conditions of the channel during dry seasons. The economic benefits are very significant. However, the important role of hydropower dams is to play a role in flood control, especially during the annual flood season, the safe operation of each dam is related to the safety of countless people downstream.
Three Gorges Dam
The dam body is made of concrete. The concrete is the supporting skeleton of the building, which bears the load of the structure, such as columns, beams, concrete walls, etc., and the sand-gravel aggregate is the supporting skeleton of the structural concrete. In this regard, the Ministry of Housing and Urban-Rural Development and other departments have issued relevant mandatory national standards, such as the "General Specification for Concrete Structures", in which mandatory provisions are made for sand and gravel materials for structural concrete, such as the firmness of sand and gravel, mud content, Gradation, needle flake content, etc., are used as hardness indicators of sand and gravel materials.
The volume of sand and gravel aggregates in concrete often accounts for 60% to 70% of the total volume. The volume stability and durability of sand and gravel aggregates are higher than those of cement mortar. Therefore, the strength, particle size and needle-like content of aggregates It will have a certain impact on the workability, strength, elastic modulus and impermeability of concrete. For example, the better the gradation of the aggregate, the greater the compactness, the smaller the void ratio and the specific surface area, and the less water is needed when preparing concrete, thereby improving the mechanical properties and durability of the concrete, and ensuring the safety and stability of the building structure.
Take the needle-like aggregate in aggregate as an example. If the coarse and fine aggregates contain a lot of needle-like aggregates, the needle-like aggregates have a special particle shape, which will lead to an increase in the specific surface area, a decrease in the expansion and slump, and a decrease in the fluidity and workability of the concrete. worse. In addition, the more needle-like content in the aggregate, the greater the tendency of water film to accumulate around the particles, resulting in the failure of the cement slurry and the needle-like aggregate to form a good bond, reducing the tensile, compressive, flexural and resistance of the concrete structure. shear strength and other properties. In all kinds of engineering construction, the needle flake aggregate is strictly controlled.
Baihetan Hydropower Station
During the construction of the dam, the requirements for sand and gravel aggregates are very strict. Generally, the content of needle flakes in coarse aggregates is controlled by improving the production process. Some sand and gravel aggregate processing systems use a 4-stage crushing process, namely coarse crushing, medium crushing, fine crushing and ultra-fine crushing, and 3 screenings (one screen, two screen and three screen). Among them, jaw crusher or Gyratory Crusher is used for coarse crushing, first screening is performed after coarse crushing, cone crusher is used for secondary crushing, and then the second screening is performed, and impact crushing is used for fine crushing. This system can produce large , medium and small different types of aggregates. For the needle-like materials in the aggregate, a shaping workshop can be added to the aggregate processing system, and a vertical shaft impact crusher is selected as the shaping equipment to reduce the needle-like content index in the medium and small stone aggregates.
Take Bellian Group's vertical shaft impact crusher as an example, HVI series Sand Making Machine and VSIA7 sand making machine, both of which can be used not only for sand making, but also for the shaping of aggregates.
sand making machine
The two types of sand making machines can effectively make marble, river pebbles, potassium feldspar, iron ore and other stones into stones of different particle sizes, mostly in the form of cubes, and the particle size of the finished product is uniform, effectively reducing needle-like aggregates, and the products produced are of high quality. The aggregate conforms to relevant national standards and can meet the use requirements of various construction projects.
Bellian Group has accumulated rich experience in the development, manufacture, application and service of sand and gravel aggregate equipment for many years, and has built a professional team composed of field engineers + process engineers + R&D engineers, whether it is equipment selection or equipment debugging Operation, Bellian Group engineers can give you professional answers.
