The blind area is an important part in the construction of a house, and in no case should it be neglected, because it protects the foundation of the house from erosion by rains and floods. In addition, she also performs aesthetic function, because a neat path around the house is always beautiful.
The grade of concrete for the blind area must be at least M200 (class B-15). To obtain concrete of this grade, the cement for it must be taken at least grade M400.
Concrete composition
The composition of concrete for the blind area, in principle, is no different from the generally accepted one. It includes cement, water, sand and crushed stone. The size of the crushed stone fractions is very important, as this most directly affects the quality of concrete. The grain size of crushed stone must be no less than 5 mm and no more than 20 mm. Crushed stone made by crushing rocks or river gravel is best suited for these purposes. 
The sand included in the concrete for the blind area must be clean and not contain various impurities, such as silt, clay or limestone.
Recommended proportions of concrete for the blind area: 1 part cement, 3 parts sand, 4 parts crushed stone, 0.5 parts water. To make 1 m³ of concrete you will need: cement - 280 kg, crushed stone - 1.4 tons, sand - 840 kg, water - 190 liters. This proportion of concrete for blind areas is most often used. You can calculate all this on a calculator.
Concrete production
When making concrete for a blind area, you should adhere to a certain technology. First you need to mix cement and water. This must be done very carefully; not a single dry gram of cement should remain in the mixture. Only after this can your water-cement mixture be considered ready for further use.
Then you can gradually, in portions, add it there. Why gradually - so that the cement mortar and fillers form a homogeneous mass and there are no lumps.
Nuances of kneading
In order for the cement for the blind area to be of high quality, you need to take into account some features of its manufacture.
First of all, there is no need to overdo the amount of water in cement mixture. It is necessary that it is completely absorbed into the cement, that is, it is not in a free state. It is excess water that negatively affects the quality of concrete, namely its strength.
So take exactly as much water as indicated in the proportion. And if you use coarse crushed stone, the amount of water can even be reduced.
The blind area should also be filled in accordance with the technology. First you need to remove upper layer soil, including plant roots. The depth of the ditch for the blind area must be at least 20 cm.
Oily clay is placed at the bottom, which is then sprinkled with a mixture of sand and crushed stone or gravel. This layer must be compacted and filled with concrete in a layer of at least 10 cm. The total thickness of the blind area will thus be 30-35 cm.
The blind area is quite important architectural element building. Therefore, when pouring it, certain technologies must be followed. First of all, it is important to prepare the solution correctly. If the proportions of concrete for the blind area are not met, it will not last long in the future.
Purpose
The main function of the blind area in a building is, of course, to protect the underground part of the foundation from rain and melt water. By arranging this architectural element in this way, you can significantly extend the service life of the foundation of the house. If the ground near the foundation remains dry, among other things, the load on it will be reduced in the spring, during soil heaving. Sometimes the blind area in a building also performs another function - it serves as a pedestrian path. If there is a lawn adjacent to the house, it is also very convenient to water from it.
Requirements for the blind area
When constructing this architectural element of the building, the following SNiP standards are observed:
- for class I soil should not be less than 1 m, for class II - 2 m.
- The maximum thickness of compacted soil under a 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.
During the pouring process, the blind area is necessarily reinforced using a metal grid. Crushed stone should be used to create a drainage layer.
What can determine the quality of concrete?
Some owners country houses They believe that since this element of the building’s structure does not bear any special load during operation, any load can be used for it, even not too much. good mixture. However, this is not the case. The proportions of concrete for the blind area must be observed. After all, when it is destroyed (cracks and chips appear), the foundation of the house immediately begins to be exposed to moisture. As a result, the service life of the entire building as a whole is significantly reduced.
According to SNiP standards, for this architectural element of the house it is allowed to use a concrete solution of a grade not lower than M200, which corresponds to class B-15. In order to prepare such a mixture, you should choose the right cement, sand and filler. And, of course, they need to be mixed in the correct proportions.
What brand of cement to buy
This component largely determines how high quality the concrete composition for the blind area will ultimately be. The proportions of the remaining components are determined mainly by the amount of cement. For concrete mixture class B-15 you need to choose material grade M400. This cement has the following technical characteristics:
- Setting time is 2-4 hours at air temperature +18...+22 °C.
- Operating temperature range - from -60 to +300 °C.
- The service life of structures is up to 100 years.
Ready-made concrete grade M200, made using virtually impermeable water, is amorphous with respect to most types of solvents and is not afraid of sudden temperature changes.
What should the filler be?
The proportions of concrete for the blind area of a 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” that absorbs all internal stresses. It is allowed to use gravel or crushed stone as a filler for the solution intended for the blind area. If desired, you can replace these elements with small ones
How to prepare sand
The strength of the concrete mixture also depends on the quality of this component. In this case, it is better to take large river sand. But, of course, not all owners of country houses have the opportunity to purchase such material. If river sand It was not possible to buy it, you can replace it with a quarry one. However, before mixing the mixture, such material must be sifted through a grid with a mesh size of 2-3 mm. It is better to perform this procedure in windy weather. In this case, the finely dispersed component (dust) will also be separated from the sand.
How to add water
The concrete mixture should be diluted in such a way that it becomes sufficiently plastic and convenient to work with. Warm water should be added to the blind area solution. You can use a regular borehole or well. It is also possible to take water from a country storage tank. But in this case, you should make sure that it is clean.
Ultimately, the diluted solution should not flow from the shovel. Don't make the mixture too thick. If it crumbles or sticks to the shovel in large pieces and is difficult to clean off, it should be diluted a little. After mixing, a good solution does not split with water separation.
Concrete proportions for 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 in this case are usually as follows:
- cement - 1 part;
- sand - 3 parts;
- crushed stone - 4 parts;
- water - 0.5 parts.
In this way, the proportions of concrete for the blind area in buckets are usually determined. For wide belts, it is better to make a more durable mixture by adding three pieces of crushed stone or gravel to one bucket of cement. When pouring tape around outbuilding You can, on the contrary, save on material and use not three, but four parts of sand.
When calculating for a blind area, you can also take into account the fact that enterprises take 280 kg of cement, 1.4 tons of crushed stone, and 840 kg of sand to prepare 1 m 3 of M200 grade mortar. All this is filled with 190 liters of water.
Thus, we found out what proportion of concrete for the blind area is most suitable. But, of course, in order to get a high-quality solution at the output, it also needs to be mixed correctly. It is worth preparing the material for pouring the blind area using a concrete mixer. In this case, it will turn out to be of much higher quality. 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 ingredients are mixed, water is added to the drum. Total time The preparation of the solution depends on the type of equipment. For forced action devices it is usually 2-3 minutes, and for gravity equipment - 5-6 minutes. The procedure time cannot be reduced or increased. In the first case, the mixture will turn out to be heterogeneous, and in the second, it will be too dry.
If there is no concrete mixer on the farm, it is allowed to make the solution for the blind area manually. In this case, the easiest way is to use a trough and a hoe. When preparing by hand, all dry ingredients are also thoroughly mixed first. Then it is added to the trough required amount water. When mixing by hand, the solution is not as uniform and high quality as when using a concrete mixer. Therefore, in this case, it is worth taking more cement.
This is how it is done for the blind area. The proportions of the components for the solution must be observed exactly. In this case, the mixture will be plastic, high-quality, and easy to work with. The blind area itself, made using it, will be strong, neat and durable.
Some comrades who are not very familiar with construction perceive an inconspicuous architectural and technical element around the house as a decorative addition or as pedestrian path. In fact, the blind area is a structure that can protect against precipitation, and therefore increase the reliability of the entire building.
How this article will be useful:
Briefly about the advantages
Experts assure that if it is not possible final finishing Houses, concrete blind area still needs to be done, and moreover before the cold weather sets in. This is the only way the owner can feel the functional advantages of this design element:
- protection of the foundation from precipitation and its drainage into storm drains;
- increasing the thermal insulation of the house by preventing soil freezing;
- reducing the degree of soil swelling on appropriate soils;
- decorative functions that give visual completeness to the building.
Skepticism about the insulation of the coating around the building is unfounded - competently performed work will save significant amounts of money in the future for heating the entire room. Also, all underground structures will be free from damage by the roots of various plants.
How to correctly calculate the blind area around the house?
In order for this architectural element to fully perform the functions assigned to it, it is necessary to remember main rules:
- the minimum width of the concrete strip should be oriented towards the roof overhang (eaves) plus 200 mm;
- continuity of the surrounding concrete pavement;
- mandatory presence of a slope that ensures the removal of precipitation (at least 1.5°);
- ready-made concrete for the blind area and its proportions should guarantee the durability and reliability of the structure;
- the wider concrete tape, those more reliable protection from moisture (optimally – 800-1000 mm).
In the case where the building is located on subsiding soils, the width of the blind area should be at least 900 mm, and better yet 1000 mm. The thickness of the top layer for a concrete coating is 150 mm; when using reinforcing mesh, 100 mm is sufficient.
Technological process of arranging a blind area
First of all you should make markings for the entire structure, the width of the tape was written above. Next the process occurs the points:
- along the perimeter of the building along the entire width of the tape, remove soil to a depth of 200-250 mm;
- make formwork;
- compact the soil;
- lay a layer of clay about 50 mm thick and compact it;
- spread a layer of sand about 100 mm thick onto the clay and compact it thoroughly;
- lay a layer of crushed stone 60-70 mm thick;
- to strengthen the structure, install reinforcing mesh;
- organize in the area of connection between the plinth and the concrete strip;
- lay a layer of concrete, compact and level the surface.
It is important not to forget that device expansion joints for concrete blind area needs to be produced every 2-2.5 meters, and at the corners of the house their presence is simply mandatory. To do this, you can use slats that are placed flush with the surface, taking into account the degree of its slope.
To achieve maximum strength of the concrete coating, the so-called ironing performed wet method. Optimal drying is ensured by laying fabric on the tape, which is periodically moistened.
How to prepare concrete for making a blind area and proportions of components
Quite often you can observe when after winter concrete surfaces, subject to temperature fluctuations and precipitation, are partially or completely destroyed. The reason lies in several factors:
- low quality cement;
- absence of expansion joints;
- improperly prepared concrete mixture.
The last point is worth considering in more detail. For cooking cement mortar cement is suitable, starting from brand M200. However, experts do not advise saving and immediately using binders M400 or M 500 having higher compressive strength.
Read more about how to prepare concrete, as well as the exact proportions of the components for the solution. Classic ones proportions of concrete components for the blind area expressed as follows ratio:
- 1 part cement;
- 3 parts sand;
- 4 parts crushed stone;
- 0.5 parts water.
It is worthwhile to dwell on the method of preparing the mixture in a concrete mixer. After pouring water, cement is placed in the mixer and mixed until a uniform mass without lumps. Next, sand is poured in and mixed again. Crushed stone is added last.
We continue to get acquainted with the intricacies of concreting, as well as with the methods and proportions of preparing the ideal concrete mixture for a particular case. We know that concrete is necessary not only in the construction of a house, but also in other concrete structures. In today's article we will look at the features of constructing a blind area with your own hands, as well as instructions for preparing the correct concrete for this purpose.
Before moving on to the main part, let's still find out what a blind area is? This is a path made of concrete, which is made directly around your building, one side adjacent to the house. The blind area varies, but its width most often does not exceed one meter. Of course, you can make any finish to your taste, so the blind area can be a little wider or narrower.
What is the purpose of the blind area? It's no secret that the main enemy of a building and its foundation is precipitation. It is from them that we always strive so hard to protect the building. The blind area is always made at a slight slope so that rainwater flowed down onto the ground from the building. This protects the foundation of the house from the damaging effects of moisture and the walls from splashes, which can result in moss growths on the house. Well, you will agree that it is much more convenient to walk along concrete paths, rather than on the ground.
The cost of such a design should not be high, which is included in the estimate, and ease of use and durability are required. Please note that dismantling, if necessary, should be very simple.
Components and proportions for concrete mixture
How to make a good solution for a concrete blind area, what proportions should be taken into account? Let us note that the concrete must be of high quality, not lower than M-200 grade. Also take into account the frost resistance of concrete and its water resistance, since the blind area will be constantly exposed to precipitation.
It is best to ensure a high-quality mixture by purchasing concrete from the manufacturer's factory, but as practice shows. It is quite possible to prepare a spinal solution for the blind area with your own hands. What will the composition of concrete include? Those who have read more than the first article on our website know for sure that only three components are needed: a base, a binder and, of course, water.
The finished solution and its quality will depend on the material you choose, as well as the proportions you choose. The grade of concrete also depends on the proportion.
Most of the load is borne by the aggregate, which is also the base of the concrete solution. This can be sand, crushed stone, expanded clay, slag, broken bricks and mixtures thereof. Often used when preparing a mixture for a concrete blind area are fine aggregate, sand and coarse crushed stone.
Because We need concrete of grade M200 and higher we start from this when choosing cement. We know the rule that cement should be taken in a grade higher than the grade required concrete twice. This means we need grade M400 and higher. In addition, the higher the cement grade, the lower its consumption for the mixture we need.
For the paths concrete screeds, as well as the blind area we need, they take M200 concrete - the most popular. It's even better to take M250 to give more strength.
What proportions should you take, you ask?
In order to get the classic M200, you will need to take one part of M400 cement, 2.8 parts of sand and 4.8 parts of crushed stone. If you want to make a higher grade, then pay attention to M250 from M400 cement one part, 2.1 parts sand and 3.9 parts crushed stone. For the M300 the ratio will be something different: 1:1.9:3.8.
Try to use the smallest amount of water possible; it is better to use 0.6 water per part of cement. Don't forget about the moisture content of the sand. First add cement to the concrete mixer, then water, mix and then just add crushed stone and finally sand.
Note that different sources have different recipes, so it’s easier to focus on consistency and develop your own recipe through practice. We also offer you a table on how to create from M400 cement different brands concrete:
An area equal to a certain number should be multiplied by 15 cm in height. For example, 30 sq.m. by 0.15 m. We get 30x0.15 = 4.5 m3. This will be the required amount of concrete solution. Don't forget to take some stock as well.
Recommendations for preparing concrete mortar and constructing a blind area
As you understand, in any case there are some peculiarities and nuances. What should you consider if you decide to prepare a solution for the blind area?
- Too much water is bad. The strength of concrete decreases because excess water will not react with cement and will float freely. Therefore, select the proportions so that all the water is absorbed.
- Concrete will depend on the size of the crushed stone fraction. It is better to take a fraction within 5-20 mm. The best would be crushed stone, or river gravel.
- How larger size crushed stone fraction, the less the amount of water you need.
- You cannot take clayey sand, limestone, or various impurities.
- Choose high-quality cement, fresh, from a trusted manufacturer.
- Take exact proportions. The quality of the mixture will depend on the proportions you choose. It is important.
How to make a concrete blind area?
To make a concrete blind area, be sure to prepare everything necessary materials and tools. Of course, if you need to make a path one time, you will not buy a concrete mixer. In this case, it is advisable to mix by hand. Prepare a container for mixing, for example, an old trough or basin. Take a stick for mixing the solution, various shovels for mixing and pouring, water containers, buckets or other containers for dry mixtures.
Now let's move on to the order of work:
- First of all, make the markings. Usually a board is installed parallel to the wall in order to outline the boundaries. We secure it with pegs at the distance we need (this is about a meter from the house).
- We pour our concrete solution into the formwork, which is leveled using a trowel.
- Make a slight slope from the wall to the ground so that there is a slope for rainwater to flow away from the building.
- We fill the blind area around the entire building.
We tried to answer all your questions. Leave your notes in the comments. In addition, we recommend that you finally familiarize yourself with this video on the construction of a blind area:
Any foundation for a building needs protection from erosion, so an additional barrier is created around it from a mixture based on cement, gravel and sand. With its help, you can not only extend the durability of the structure, but also improve the aesthetic characteristics. During the construction process, you will have to find out what kind of concrete is needed for the blind area, which also serves as a path.
About the material used
The hardened mixture is fake diamond, which is widely used in the construction industry. Modern material based on a binder has been used since 1844. Over time, special additives began to appear in its composition to improve its performance.
Applicable classes
The basic indicator characterizing the composition is compressive strength, which allows the prepared mixture to be classified into a certain category. When carrying out work, it is necessary to select the correct class of concrete for the blind area so that its strength characteristics are suitable for specific operating conditions.
SNiP 2.03.01-84 directly uses the designation of categories with the Latin letter “B”, next to which there is a number reflecting the transferable pressure in MPa. However, the composition class is a numerical characteristic with a guaranteed security of 0.95. Thus, in 5 cases out of 100 the condition may not be met.
| Class | Matching Brand | Strength in kgf/sq. cm |
| B15 | M200 | 196 |
| B20 | M250 | 262 |
| B22.5 | M300 | 295 |
| B25 | M350 | 327 |
| B30 | M350 | 360 |
Note!
Knowing the class suitable composition, you can easily understand what brand of concrete is needed for the blind area.
The table shows correspondences with a coefficient of variation of the mixture of 13.5%.
More about brands
At the same time as the classes, the strength of the mixture can be specified differently. The letter “M” of the Latin alphabet with a number indicates the limit value for compression in kgf/cm².
The grade of concrete for constructing the blind area should not be lower than M200, otherwise damage to the created platform may occur.
- M200 - the main purpose of the composition is to create structures with a small load on the surface.
- M250 - the mixture can be used for structures that are exposed to moderate impacts.
- M300 is the most common grade of concrete for blind areas, as it can withstand quite significant loads.
- M350 - a similar solution for constructing a protective barrier around a building is rarely used.
Attention!
The price of the composition increases with the grade, therefore, in order to save money, it is recommended to select it as accurately as possible, taking into account the possible loads on the surface.
Requirements for main components
All materials included in the concrete for the blind area must meet certain conditions, otherwise it will simply not be possible to obtain a high-quality mixture.
In this regard, the service life of the structure may be significantly reduced.
- The basic ingredient is cement, which binds the components into a single whole. The main task is to choose the right brand of binder. The presence of impurities must also be taken into account.
- To prepare the mixture, it is recommended to use sand, the fraction of which ranges from 1.5 to 5 mm. The strength characteristics of the solution can be negatively affected by the presence of foreign impurities in the form construction waste and plant residues.
- The best filler is a material made from crushed rock, which allows for high-quality adhesion to other components. Suitable gravel sizes range from 8mm to 35mm.
- Used as a solvent plain water, but it should not contain alkaline or acidic inclusions.
Addition!
Some experts add slaked lime into the mixture to make installation easier.
This option makes it easier to level the surface.
The process of preparing the solution
In the process of work, the composition most often used is M300, which belongs to class B22.5. Therefore, it is worth considering its preparation. The following are instructions for preparing the mixture without a concrete mixer.
It shows the basic proportions of concrete for the blind area.
- 2 buckets of sand are poured into the prepared container to make a small slide.
- A bucket of M400 cement is added, after which the two components are thoroughly mixed dry.
- Gradually water is added to the composition, the amount of which is usually 0.5 mass of binder.
- After mixing in liquid mixture 4 buckets of gravel filler are introduced.
Important!
When mixing the concrete composition with your own hands, you cannot add too much water, otherwise the porosity will be very high, and this will lead to a decrease in strength qualities.
- If, after the mixture has hardened, it is necessary to separate a fragment of the blind area, then the reinforced concrete is cut with diamond wheels.
- The finished composition must be poured within 24 hours until it has set, otherwise notches are made.
- To insert pipes or other mortar, diamond drilling is done into the concrete.
- If the blind area is made in the cold season, then the solution must be heated.
As a conclusion
The preparation of the concrete composition must be carried out taking into account clauses of SNiP 5.01.23-83 and GOST 7473-94. The submitted documents reflect general rules, taking into account the density and ratio of materials. More detailed information on this topic is presented in the video in this article.