Concrete B15 (brand): composition, characteristics

Concrete is perhaps the most sought-after building material, widely used in the construction of both private houses and large multi-story buildings. There are many brands of this material designed for use in a variety of purposes. One of the most popular is concrete B15 (class) or M200 (brand).

General characteristics

Concrete B15 (grade M200) belongs to the group with an average degree of strength of 196 kgf / sq.cm. It is produced taking into account GOST standards on modern equipment, on automated lines. The result is a very high-quality material, suitable for the construction of a wide variety of structural elements of buildings.

Scope of use

The manufacture of durable durable floors is the main field of application of this material. Resistance to the effects of adverse atmospheric phenomena is at an average level. And therefore it is more expedient to use it indoors. The screed with this material is very reliable and durable. In addition, concrete B15 is a brand used for:

• construction of foundations (mainly farm buildings);
• pouring walls;
• production of concrete walkways and borders;
• filling the blind area;
• the construction of stairs and porches;
• the creation of finished reinforced concrete products;
• pouring columns;
• to create a substrate for road works.

Concrete brand B15: composition

Standard B15 concrete is made using the following components:

• Cement (30 kg).
• Fine aggregates (40 kg). It is allowed to use sand with a particle size of 0.15 to 5 mm. Its density should be 1790 kg / m ^3.
• Crushed stone or gravel (90 kg). The grain size of this filler ranges from 6 to 70 mm. When erecting massive structures, it is allowed to use crushed stone with a size of fractions up to 140 mm.

Dry components are thoroughly mixed beforehand and then diluted with water in an amount of 20% of the total volume. Sometimes manufacturers to improve the quality of the finished product add various kinds of mineral substances, plasticizers, etc.

The concrete grade B15 (GOST 7473-2010) is made exclusively from high-quality cement. Most often this is a product of the M400 brand. The mass ratio of cement * sand * crushed stone in proportions will be as follows: 1 * 2.8 * 4.8.

Varieties

Currently, several types of concrete are produced in this class. They can differ, for example, by the type of filler used. It can be calcareous, granite or gravel. There are also varieties of this material with varying degrees of mobility and stiffness.

The ratio of brand and class

Contrary to popular belief, after 28 days, concrete does not stop gaining strength. This process can last all the time of operation of the structure constructed from it. The brand of concrete is determined depending on the amount of cement used in its manufacture. This indicator plays a crucial role in the ability of concrete to resist compression and expansion. It is measured in kgf / cm ³ . Thus, the concrete grade M200 shows that the ultimate compressive strength is 200 kgf / cm ³ .

In addition to the brand, concrete is also divided into classes. This indicator determines the maximum pressure that the finished material can withstand in megapascals. In relation to B 15 it is 15 MPa (in 95% of cases). The concrete class itself is indicated by the letter "B".

Previously, concrete strength was judged mainly by brand. Now this material is classified mainly by class. However, in order to make it more convenient for people who are accustomed to focus on the brand, special tables have been created in which the correspondence of these two indicators is given.

Concrete grades according to other indicators

Strength is not the only parameter that you should pay attention to when buying a mixture. A very important indicator is also the brand of the solution for frost resistance. It is denoted by the letter F and numbers starting with 25. In practice, in private housing construction, concrete with the frost resistance brand F100-200 is usually used.

Another important parameter is the water resistance of concrete. In this case, the material may be marked as W2, W4, W6, W8 and W12. The numbers show the water pressure at which a concrete cylinder with a height of 15 cm does not let water through at a certain pressure. Concrete brand B15 characteristics in this regard is very good.

Also, when buying concrete, you should pay attention to such an indicator as sediment cone. This parameter defines such a characteristic of the material as mobility. This indicator is marked in the data sheet of the mixture with the letter “P”. Most often, concrete with mobility P-2 and P-3 is used in construction. Solutions P-4 and above are used if it is necessary to fill in inaccessible places. Plastic concretes are also used when pouring is carried out using a pump.

Specifications

What specific properties are the concrete B15 (grade M200) different from can be found in the table below.

Material cost

Prices for concrete class B15 (grade M200) mainly depend on the type of crushed stone used in the manufacture. For example, if it is granite, you will have to pay about 3850 rubles per cubic meter of concrete B15 (data for 2015). For the option with gravel filler - about 3600 p.

Home-made

In this case, you can get a high-quality mixture only using a concrete mixer. Manually good concrete of class B15 of the M200 grade cannot be kneaded. The procedure for preparing the solution is as follows:

• Sand and cement are thoroughly mixed beforehand. At the same stage, you can add an additive that increases frost resistance (by 20 kg of cement 2 kg).
• Next is added water, and then crushed stone.
• The resulting mass is mixed for at least three minutes.

In volume ratio, concrete B15 (grade M200) is prepared in the following proportions: 19 liters of sand and 33 liters of crushed stone are taken per 10 liters of cement. Therefore, in ten-liter buckets, the ratio will be approximately as follows: 1x2x3.5.

In the manufacture of concrete of this brand, deviation from specified quantitative ratios by no more than 1% is allowed.

Kneading example

For one element of a columnar foundation with a volume of 0.11 m ^3, cement will need about 19 kg, sand - 41 kg, gravel gravel - 78 kg, water - 9 kg. A similar ratio is valid when using cement brand M400. To fill the pillar, you will need to make about two such batches.

Concrete of other brands

Very often in private housing construction is used and high-quality concrete brand M250 (B20). This variety is somewhat stronger than class B15 and can also be used for pouring ceilings that are not exposed to severe loads. M300 brand concrete (class B22.5) is most often used for the construction of strip foundations. For pouring slab solid bases under the houses, M350 solution (class B25) is more often used.

Concrete B15 is a brand of strength, thus, quite suitable for the construction of most objects in private housing construction. Very good technological characteristics, combined with low cost, make it advisable to use it for pouring screeds and floors, as well as for the construction of foundations (industrial buildings) and partitions.