Concrete B15 (brand): composition, characteristics

Concrete is perhaps the most demanded building material, widely used in the construction of both private houses and large multi-storey buildings. There are many brands of this material, intended 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 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 variety of structural elements of buildings.

Scope of use

The manufacture of strong durable floors is the main application of this material. The resistance to the effects of adverse weather conditions is at an average level. And therefore it is more expedient to use it inside the premises. Screed with the use of this material is very reliable and durable. In addition , concrete B15 is a brand used for:

• The erection of foundations (mainly economic buildings);
• Pouring walls;
• Manufacture of concrete paths and curbs;
• Pouring the blind area;
• Erection of stairs and fenders;
• Creation of finished reinforced concrete products;
• Pouring columns;
• To create a substrate for road works.

Concrete grade B15: composition

The standard concrete B15 is made using the following components:

• Cement (30 kg).
• Small 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 varies from 6 to 70 mm. When erecting massive structures, it is allowed to use crushed stone with the size of fractions up to 140 mm.

Dry components are pre-mixed thoroughly 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 to it various kinds of minerals, plasticizers, etc.

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

Varieties

Currently, several types of concrete of this class are produced. They can differ, for example, according to the type of filler used. It can be calcareous, granite or gravel crushed stone. There are also varieties of this material with an uneven degree of mobility and rigidity.

Correlation of brand and class

Contrary to popular belief, after 28 days to gain strength, concrete does not stop. This process can last all the time of operation of the structure erected from it. The concrete grade is determined depending on the amount of cement used in its manufacture. This index plays a decisive role in the ability of concrete to resist compression and expansion. It is measured in kgf / cm ³ . Thus, the grade of M200 concrete shows that the 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. With respect to B 15 it is 15 MPa (in 95% of cases). The very class of concrete is indicated by the letter "B".

Previously, the strength of concrete was judged mainly by the brand. Now this material is classified mainly by classes. However, in order for people who are used to navigating the brand, it was more convenient, special tables were created, in which the two indicators were given.

Concrete grades by other parameters

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

Another important parameter is the waterproofness of concrete. In this case, the material can be labeled as W2, W4, W6, W8 and W12. The figures show the water pressure at which a concrete cylinder 15 cm high does not allow water to pass at a certain pressure. Concrete grade B15 characteristics in this regard is very good.

Also, when buying concrete, pay attention to and such an indicator as the sediment of the cone. This parameter defines such a characteristic of the mayoral as mobility. This indicator is marked in the technical passport of the mixture with the letter "P". Most often in construction, concrete is used with mobility P-2 and P-3. Solutions P-4 and higher are used in the event that it is required to fill hard-to-reach places. Plastic concrete is also used when pouring is performed using a pump.

Specifications

What concrete properties distinguish concrete B15 (brand M200), you can find out from the table below.

Cost of material

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

Manufacture at home

Get a quality mixture in this case, you can only use a concrete mixer. Manually good concrete class B15 brand M200 knead will not work. The order of the solution is as follows:

• Preliminary carefully mix sand and cement. At the same stage, you can pour additives that increase frost resistance (for 20 kg of cement 2 kg).
• Then add water, and then rubble.
• The resulting mass is stirred for a minimum of three minutes.

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

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

Batch Example

For one element of a columnar foundation with a volume of 0.11 m ^3, about 19 kg of cement, 41 kg of sand, 78 kg of gravel, and 9 kg of water will be needed. A similar ratio is valid when using M400 cement. To fill the column, you need to do about two such kneading.

Concretes of other brands

Very often in private housing construction, quality concrete M250 (B20) is also used. This variety is somewhat stronger than class B15 and can be used also for pouring floors that do not undergo serious loads. Concrete grade M300 (class B22.5) is most often used for the erection of banded foundations. To fill the solid solid bases under the houses, a solution of M350 (class B25) is often used.

Concrete B15 is a brand, in strength, thus, quite suitable for the erection of most objects in private housing construction. Very good technological characteristics in combination with low cost make it expedient to use it both for pouring screeds and floors, and for erecting foundations (hozpostroek) and partitions.