What should a foreman know? Stamps and classification of concrete for treatment facilities

Monolithic concrete as well as reinforced concrete structures are indispensable elements of any building. Therefore, it is very important that these structures have the correct, and most importantly the desired shape.
Concrete is marked depending on the compressive strength in kg per 1 sq. Km. cm.
There are two identical concrete classifiers for compressive strength. The first, the builders from the distant past, got this division into brands – M 50, 75, 100, 150, 200, 250, 350, 400.
We will tell about the second classifier a little later.
Depending on in what sphere concrete will be applied, one or that brand is preferred.
m 150 – light type of concrete, used for the installation of foundations for small buildings, as well as for pouring concrete monolithic slabs;
m 200 – universal concrete, it is used for the installation of various foundations, bays, production of retaining walls. This brand has high strength;
m 300 – used in the installation of monolithic foundations and construction of walls;
m 350 – this brand is used in the formation of foundation slabs of multi-storey buildings, road slabs and load-bearing columns;
m 400 – the strongest and most reliable brand of concrete, but has a very high cost, used in the construction of foundations of buildings with huge areas.

For the foundation of a 3-storey administrative and residential building it is necessary to use concrete grade A 350. And for the production of columns and reinforced concrete trusses M400 concrete is already needed.

If you need material for the construction of hydraulic structures – you need special concrete. Therefore, we will move on to hydraulic concrete.

The practice of operation proves that these concretes must have a long service life, meet the conditions for strength, water resistance, frost resistance. Concrete for mounting and construction concrete and reinforced concrete structures of hydraulic structures or their individual parts must meet special standards.

kinds.
With the help of this concrete, specialized engineering structures are built – dams, piers, breakwaters, cooling towers, treatment plants, supporting parts of bridges.

There are three types of this building material:
– underwater, which is constantly in the water;
– is in an area where the water level sometimes changes;
– Located above the water and washed.

Another difference is divided into massive and non-massive, as well as for pressureless or pressure structures. Also, depending on the use, the classification of water resistance, water resistance (W), frost resistance (F), compressive strength (B) and tensile, limited heat dissipation, limited shrinkage, deformation Abilities, resistance to abrasion by sediments and water.
Strength, water resistance and frost resistance.
The concrete class is correlated with its compressive strength and, conversely, the ability to resist stretching. The compressive strength is measured in a period of 180 days, affecting the cube with a side of 15 cm.
In addition to the classifications described above in the modern regulatory framework, brands of concrete begin with B3.5 and finish B80, but most often builders have to work with brands from B10 to B40.
Tensile strength eliminates the appearance of cracks. The samples will also be tested after a period of 180 days. Concrete classes increase from VT0.8 to VT3.2.
At the same age, hydroconcrete is tested for 4 types of water resistance: W8, W6, W4, W2. According to standard tests, it must not pass water at the appropriate pressure of 0.8 MPa, 0.6 MPa, 0.4 MPa, 0.2 MPa. There are also special additives for water resistance above W12.
Hydraulic concretes are used in moderate, severe and especially severe weather (climatic) conditions. Frost-resistant hydraulic concrete comes in 5 brands: F300, F200, F150, F100, F50. With the help of special additives, frost resistance is increased over F400. This classification is determined by the number of cycles of freezing and thawing of concrete aged 28 days, so that its strength would decrease by no more than 25%. Frost resistance is required for objects that experience double action: water and subzero temperatures.
These characteristics of concrete must be known to the foreman and / or the head of the unit responsible for work on monolithic or precast concrete. The input quality of this material and works will depend on his knowledge and skills, and also how reliable your building constructions will be.