Concrete B15 (brand): composition, characteristics
Concrete - perhaps the most demandedbuilding material, widely used in the construction of both private houses and large multi-storey 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).
Concrete B15 (grade M200) belongs to the group withan 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
Manufacture of durable floors - the mainscope of use of this material. The resistance to the effects of adverse atmospheric phenomena 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 in 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 / m3.
- Crushed stone or gravel (90 kg). The grain size of this filler varies from 6 to 70 mm. When building massive structures, it is allowed to use crushed stone with the size of fractions up to 140 mm.
Dry components carefully beforehandmixed, 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 all sorts of minerals, plasticizers, etc.
A grade of concrete B15 is produced (GOST 7473-2010)exclusively from quality cement. Most often it 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.
Currently, several types are availableConcrete of this class. 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 daysStrengthen the concrete does not stop. This process can last all the time of operation of the structure erected from it. The grade of concrete 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 / cm3. Thus, the grade of M200 concrete shows that the compressive strength is 200 kgf / cm3.
In addition to the brand, concrete is also divided intoclasses. 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 onbrand. Now this material is classified mainly by classes. However, in order to make it easier for people who are used to navigating the brand, special tables have been created in which the two indicators are consistent.
Concrete grades by other parameters
Strength is not the only parameter thatshould pay attention when buying the 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, in private housing construction, concrete with a frost resistance grade F100-200 is usually used.
Another important parameter is water resistanceconcrete. 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, you should payattention 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 if it is required to fill hard-to-reach places. Plastic concrete is also used when pouring is performed using a pump.
What concrete properties distinguish concrete B15 (grade M200), you can find out from the table below.
F100 (if you freeze and thaw the material 100 times, the loss of strength will be no more than 5%)
W6 (prevents the penetration of water at a pressure of up to 0.6 atm)
Cost of material
Prices for the class of concrete B15 (brand M200) depend onmainly from the variety used in the manufacture of crushed stone. For example, if it is granite, for a cubic meter of concrete, B15 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 thoroughly mix sand and cement. At the same stage, you can pour a supplement that increases 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 of concrete B15 (grade M200)is prepared in the following proportions: 10 liters of cement is taken 19 liters of sand and 33 liters of crushed stone. Consequently, 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%.
For one element of a columnar foundation with a volume of 0.11 m3 It will take about 19 kg of cement, 41 sandkg, crushed stone gravel - 78 kg, water - 9 kg. 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 grade M250 (B20). This variety is somewhat stronger than class B15 and can be used also for pouring floors that are not subjected to serious stress. 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, therefore,which is quite suitable for the construction of most of the 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.