High-strength concrete is one of the modern building artificial materials. It differs from the classic version in operational properties and technical indicators.
Products containing high-strength concrete are much more reliable than from conventional solutions. Structures made of this material will be of high quality and durable.
Features and classification
High-strength types of concrete include fine-grained and heavy compositions, which have different grades. Let's consider each of them in more detail.
M600, M700 and M750
These brands of high-strength concrete have good density and strength, and are also characterized by a high degree of water resistance. Such concrete is used in the construction of stairs, bridges, pools, basements, various supporting structures.
M800
It has not only high strength, but also resistance to aggressive environments. That is why such concrete is often used during the construction of facilities with a specific specific purpose.
M900
Concrete of this type has an increased strength parameter. Such material is used in areas where it is necessary to build particularly reliable structures.
M1100
This is concrete for special purposes. It is not only extremely durable, but also resistant to moisture and aggressive environmental factors. Usually this material of this brand is used during the construction of hydraulic and military facilities, bridges, mines.
As for the minimum value of compressive strength, this is class B60. Valid values are higher.
A feature of high-strength concrete is that it hardens quickly. Due to this, their strength characteristics increase.
Composition
Substances that are part of the mortar affect the resulting product.
The basis is the following components:
- Astringents. Typically, their role is played by the most active Portland cement with a certain indicator of consistency. Experts advise using components with a density of 25%. The minimum activity indicator should be approximately 500-600. Since the resulting concrete gains strength at an accelerated pace, it is not necessary to use various additives that will speed up the solidification of the composition.
- Sand. The production of building mixtures with high strength cannot be carried out without the use of quartz sand feldspar type with a small or large fraction. Particles having sizes from 0.14 to 0.63 mm are suitable for fine-graded varieties, and from 1.25 to 5 mm for coarse-grained varieties. In order for the building composition to fit better during its application, more than the first components are used. In some cases, the ratio of large and small particles is leveled. In some brands (up to M800), only medium or large sand is used. At the same time, state standards are always taken into account.
- Large aggregate. In such compositions, gravel plays a similar role. The compressive strength at high humidity should be 1.5 times greater than that of the solution. Before adding such a filler, it is sorted, cleaned. Particles are divided into fractions of 0.5-1 cm, 1-2 cm, as well as 2-4 cm. The type of crushed stone is selected depending on the reinforcement used and the planned width of the future product. If the reinforcement of the structure is weak and the walls are thick, then particles up to 7 cm in size are used. For concrete with increased strength, only dry aggregate that meets the requirements of GOST is used.
- Fine-grained additives. Silica dust is added to concrete with increased strength. But this is not always practiced. For example, if the strength index is C 55/67 or C 60/77, then you can not use such an additive. Silica dust is obtained during production using flint. She performs several main tasks. Firstly, it enters the empty space between the particles of the main components. Due to this, the density of the concrete product increases. Secondly, it interacts with slaked lime, due to which the strength index increases even more. Thirdly, the reaction between cement and sand also becomes much better.
In addition to the listed components, artificial type plasticizers can be used in the concrete of the type under consideration.
Main characteristics
High-strength fine-grained concrete has many advantages, due to which the duration of operation of the resulting products increases.
A solution of concrete in liquid form has the following characteristics:
- Exfoliation is minimal.
- The amount of oxygen in the mixture is not more than 1%.
- The density of the structure ranges from 1-1.4.
- Rheological characteristics are maintained up to 4 hours.
A distinctive feature of concrete with high strength is that its working properties are preserved for a long time. This is important because the material can be transported to the place where all work is carried out within two hours. But also affects the density of the mixture. It must be homogeneous, otherwise the likelihood of its delamination in the future increases.
Frozen concrete monoliths with high strength have the following properties:
- The curvature is minimal.
- Resistance to wear is high.
- Press strength - from 50 to 100 MPa.
But you need to remember that there is a likelihood of microscopic cracks in concrete with high density during compression and simultaneous contact with water.
The use of high-strength concrete
Such materials are used during the construction of facilities where it is required to reduce the weight of the building and reduce the size. They are used when you need to create a reliable, high-quality product.
Typically, high-strength concrete is recommended in the following cases:
- Flooring in industrial buildings.
- Creation of warehouses for the placement of radioactive components.
- Construction of bridges, other similar structures.
- Create multi-level buildings.
Concrete with high strength are quite popular among all building materials.
Production
The main feature of the production process for the creation of high-strength concrete is the implementation of the natural workability of the material during all construction works.
This can be achieved if the following rules are observed:
- To create a mixture using special high-speed mixing devices.
- It is required to constantly monitor the moisture content in the fillers.
- It is important to compare the pour time and the transport time.
- Always observe proportions, dosages.
- Always add the ingredients in the correct sequence as indicated in the recipe.
The quality of high-strength concrete also depends on the proper care of the product received. The material must be coated with a damp composition in the first 3 days. Due to this, the increased resistance of the obtained product to the destructive factors of the external environment will be ensured.
To maintain the high quality of concrete, specialists always monitor the components of the mixes. They check the operability of equipment, the characteristics of fillers, various components, monitor workers. If necessary, determine the factors of non-compliance.
Conclusion
High-strength lightweight concrete is used in various industries. This material provides the reliability and durability of the constructed building. Before choosing a particular option, it is recommended that you first consult with an experienced builder.