The blind area is a rather important architectural element of the building. Therefore, when pouring it, certain technologies must be followed. First of all, it is important to properly prepare the solution. If the proportions of concrete for the blind area are not met, for a long time thereafter it will not serve.
Appointment
The main function of the blind area in the building is, of course, to protect the underground part of the foundation from rain and melt water. The arrangement of this architectural element, thus, can significantly extend the life of the base of the house. If the ground near the foundation remains dry, among other things, the load on it will decrease in spring, during soil heaving. Sometimes in the building, the blind area also performs another function - it serves as a pedestrian path. If a lawn is adjacent to the house, it is also very convenient to water from it.
Blind area requirements
When erecting this architectural element of a building, the following SNiP standards are observed:
- The width of the blind area for class I soil should not be less than 1 m, for class II - 2 m.
- The maximum thickness of the compacted soil under the concrete strip is 0.15 mm.
- The minimum slope of the blind area is 0.03 m.
- The thickness of the sand cushion under the tape should not be less than 3 cm.
In the process of casting, the blind area is necessarily reinforced using a metal grate. Crushed stone should be used to equip the drainage layer.
What may affect the quality of concrete
Some owners of country houses believe that, since this structural element of the building does not bear any special load during operation, any mixture can be used for it, even not too good. However, this is not the case. The proportions of concrete for the blind area must be observed. Indeed, when it is destroyed (the appearance of cracks and chips), the foundation of the house immediately begins to be exposed to moisture. As a result, the service life of the whole building is significantly reduced.
According to the norms of SNiP, for this architectural element of the house it is allowed to use concrete mortar of a brand not lower than M200, which corresponds to class B-15. In order to prepare such a mixture, it is necessary to choose the right cement, sand and filler. And, of course, you need to mix them in the correct proportions.
What brand of cement to buy
This component to a large extent determines how high-quality the concrete composition for the paving area will ultimately be. The proportions of the remaining components are determined mainly by the amount of cement. For a concrete mix of class B-15, you need to choose a material of the M400 brand. Such cement is characterized by the following technical characteristics:
- The setting time is 2-4 hours at an air temperature of +18 ... + 22 ° C.
- The operating temperature range is from -60 to +300 ° C.
- The service life of structures is up to 100 years.
Ready-made concrete grade M200, made using cement M400, practically does not let water through, is amorphous with respect to most types of solvents and is not afraid of sudden changes in temperature.
What should be the filler
The proportions of concrete for the blind area of the house must be observed, but it is equally important to choose the right filler for the mixture. This element in the solution serves as a kind of "reinforcement", which takes on all the internal stresses. It is allowed to use gravel or crushed stone as a filler for a solution intended under the blind area. If desired, you can replace these elements with a medium-sized rubble stone.
How to prepare sand
The strength of the concrete mix depends on the quality of this component. Sand in this case is better to take a large river. But, of course, not all owners of country houses have the opportunity to purchase such material. If river sand could not be bought, you can replace it with quarry sand. However, before mixing the mixture, such material must be sieved through a grid with a 2-3 mm cell. Perform this procedure better in windy weather. In this case, finely dispersed component (dust) will also separate from the sand.
How to add water
Concrete mixture should be diluted in such a way that it becomes sufficiently plastic and it is convenient to work with it. Warm water should be added to the blind area. You can use a conventional well or well. It is allowed to take water from the summer cottage. But in this case it should be ensured that it is clean.
Ultimately, the diluted solution should not drain off the shovel. Do not make the mixture too thick. If it crumbles or sticks to a shovel in large pieces and it is difficult to clean it off, it should be diluted a little. After mixing, a good solution with the separation of water does not break down.
Proportions of concrete for the blind area: calculation
Of course, to prepare a high-quality solution, you should not only choose suitable materials, but also mix them correctly. The proportions of concrete in this case are usually as follows:
- cement - 1 part;
- sand - 3 parts;
- crushed stone - 4 parts;
- water - 0.5 parts.
Thus, the proportions of concrete for the blind area in buckets are usually determined. For wide tapes, it is better to make a stronger mixture by adding three gravel - gravel or gravel into 1 bucket of cement. When pouring the tape around the outbuilding, you can, on the contrary, save on material and use not three, but four parts of sand.
When calculating the proportions of concrete for the blind area, one can take into account, among other things, the fact that at the enterprises for the preparation of 1 m 3 of the M200 brand solution they take 280 kg of cement, 1.4 tons of crushed stone, 840 kg of sand. All this is filled with 190 liters of water.
Kneading recommendations
Thus, we found out which proportion of concrete for the blind area is the most suitable. But, of course, in order to get a high-quality solution at the outlet, it must also be kneaded correctly. It is worth using a concrete mixer to prepare the material for filling the blind area. In this case, it will turn out much better. The concrete mixer itself should be placed on a flat surface before starting work. The components are poured into it in the following sequence:
- cement;
- sand;
- crushed stone.
After the dry components are mixed, water is added to the drum. The total solution preparation time depends on the type of equipment. For apparatuses of forced action, it usually amounts to 2-3 minutes, and for gravity equipment - 5-6 minutes. It is impossible to reduce or increase the time required to complete the procedure. In the first case, the mixture will turn out to be heterogeneous, and in the second - too dry.
If there is no concrete mixer on the farm, it is allowed to make a solution for the blind area and manually. In this case, the easiest way is to use a trough and a hoe. For manual cooking, all dry ingredients are thoroughly mixed first. Then the required amount of water is added to the trough. With manual mixing, the solution is not as uniform and of high quality as when using a concrete mixer. Therefore, in this case, cement should be taken a little more.
This is how concrete is prepared for the blind area. The proportions of the components for the solution must be observed exactly. In this case, the mixture will turn out plastic, high-quality, and it will be easy to work with it. The blind area itself, made with its use, will come out strong, neat and durable.