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.
The photo shows the future concrete winding.
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.
Table comparing the two classes used.
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 of a 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 strength characteristics of the concrete mixture of 13.5%.
More about brands
At the same time as the classes, the strength of the mixture can be specified differently. Letter "M" Latin alphabet with a number indicates the maximum compression value 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.
The table shows the increase in cement mass with increasing grade.
- 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.
Aggregate fraction for concrete.
- 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 mortar can be negatively affected by the presence of foreign impurities in the form of construction waste and plant debris.
- 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.
- Plain water is used as a solvent, but it should not contain alkaline or acidic inclusions.
Addition!
Some experts add slaked lime to 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.
Proportions of solutions different brands.
Mixing the solution with shovels.
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 elements into frozen concrete mortar, diamond drilling of holes in concrete is performed.
- 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.
Cement mortar is the main binding material in construction. It is used to create a blind area that protects the foundation from destruction, as well as for concrete works, construction of walls.
Thanks to the strength and reliability of the solution, high-quality results can be achieved. Depending on its type, cement may have various characteristics, for example, waterproofness or plasticity.
A properly prepared mixture guarantees the durability of the structure, the solidity of the building and optimal adhesion of surfaces.
Compound
Basic Components cement mortar:
- Cement;
- Sand;
- Water.
Their quality determines how concrete will behave under different temperatures and what its density will be. To give concrete additional properties V cement mixture sawdust, stone fragments, slag waste, etc. are added.
The prepared mixture can be used for construction and foundations.
Cement: marking
Cement is the basis of the solution for the blind area. He must have high astringent properties, be resistant to chemical and mechanical influences, provide concrete with strength.
Depending on the marking, cement differs in different speeds of hardening, setting and scope of application.
Cement can be pure or with additives. The indices on the bags indicate this:
- D0 – without additives;
- D20 – the amount of additives is 20%.
ABOUT additional characteristics can be judged by the presence of the following abbreviations:
- N– normalized;
- B– fast-hardening;
- PC– Portland cement (a binder obtained from cement, gypsum and additives);
- BC– white cement;
- PL– plasticized and frost-resistant;
- GF– hydrophobic;
- SS– sulfate-resistant;
- WRC– waterproof.
Marking - M - allows you to determine the degree of load per square centimeter that cement can withstand. So, M500 means that this material withstands a load of 500 kg per 1 cm2.
Cement: which one is better to choose?
High-quality blind area and its durability are determined by the strength of cement. The stronger the cement, the higher the service life of the blind area and the lower the likelihood of its repair (read how to repair a blind area).
To create cement mortar, it is better to give preference to Portland cement.
To achieve optimal concrete density, it is recommended to use cement grade no lower than M200. To improve the characteristics of the solution, you can add reinforced or unreinforced gravel from 0.5 to 2 cm in diameter to it.
In unstable areas around a house or building, M400 cement is used. They are quite frost and water resistant. When creating a blind area for industrial facilities Cement with strength M500 or PC500 is mixed into the solution. The material is excellent for areas with high humidity and sudden temperature changes.
Advice! When choosing cement, pay attention to the color of the material. It must be light or dark shade gray, without impurities. The consistency of fresh cement should be soft and crumbly.
Sand: subtleties of choice
The requirements for the choice of sand are the highest. The composition of the material must be free of clay impurities. The best sand option:
- Washed;
- Light color;
- No stones, shells, clay.
A number of companies sell sand. It is mined in quarries by sifting large particles and purifying sandy soil. Before the transaction, the buyer must be provided with a quality certificate, which confirms compliance with all processing standards.
Advice! To check the sand for cleanliness, pour it into a tank of water for a day. If after this time the water becomes cloudy, then clay is present in the composition. This material is not suitable for preparing cement mortar.
Proportions for solution
Each brand of cement requires individual proportions when adding sand. If the ratio is violated, this will certainly affect the quality of the cement mixture.
For the installation of a blind area, it is best to choose cement from M300 to M500. These brands are universal and ideally combine all the necessary functions.
You can obtain M100 concrete in several ways:
- 1 part M300 cement to 2.5 parts sand;
- 1 part M400 cement to 3 parts sand;
- 1 part M500 cement to 4 parts sand.
For concrete M200 you will need to reduce the amount of sand:
- 1 part M400 cement to 2.5 parts sand;
- 1 part M500 cement to 3.5 parts sand.
Low grades of concrete are suitable for creating floor screeds or carrying out plastering works. For the blind area, as well as for pouring strip foundation at home, you will need concrete with a strength of at least M200.
Water plays an important role in the ratio. Its amount, as a rule, is half the weight of cement. For example, for 500 kg of cement you will need 1500 kg of sand and 250 liters of water. If you shift the amount of water downward, the solution will become thicker and its strength will be higher. 
How to calculate how much sand and cement you need
The consumption of cement to create a blind area depends on the brand of the material itself and the brand of concrete that you want to obtain as a result. Preparation is also influenced by factors such as the purity of the components, their size, water quality and other nuances.
On average, per cubic meter of M200 concrete solution requires 490 kg of M400 cement or 410 kg of M500 cement. These proportions are suitable for work on creating blind areas, pouring, and forming garden paths.
The most popular cement is M500. It is suitable for almost any type of activity and allows you to create concrete of any strength. Its ratio per 1 m3 under standard conditions is:
- 170 kg for M100 concrete;
- 200 kg for concrete M150;
- 240 kg for M200 concrete;
- 300 kg for M250 concrete;
- 350 kg for M300 concrete, etc.
When preparing cement mortar, do not forget about the air temperature, which should be at least -5 degrees, and the quality of the components. A mixing speed of 10-12 rpm is enough to prepare the solution in 5-10 minutes.
The composition must be used within an hour after preparation. Only if all recommendations are followed, you can obtain high-quality and durable material.
How to knead correctly cement mortar and what proportions to observe are explained in the following video:
Comments:
Concrete for the blind area can be prepared in different proportions depending on what functions this structural element should perform. The main purpose of creating a concrete blind area is to protect the foundation and other structural elements buildings that are in contact with the ground, from the negative effects of moisture from the soil.
Constant penetration of moisture into concrete, its freezing and thawing lead to negative consequences For concrete structures. Performance characteristics the foundation will be significantly reduced, which can lead to its partial damage or complete destruction. If this happens, the entire building may be at risk of destruction. Moisture from the soil or rainwater flowing from the roof.
In addition, the concrete blind area serves as a path along which it is more convenient to walk along the house. This part of the structure will serve as a kind of sidewalk. The surface of such a path must be flat.
Primary requirements
When preparing concrete for a blind area, it is necessary to take into account that it is desirable to make a blind area that is economical, reliable and easy to manufacture. It must also provide sufficient protection of the structural elements of the building that perform the load-bearing function from moisture.
It should be quite easy to do for the blind area. Only in this case renovation work if necessary, it can be carried out in a timely manner. The base material must be durable and insensitive to temperature changes, and also not deteriorate from regular contact with moisture.
The concrete surface of this structure must be cut with thermal expansion joints in the transverse direction. This will prevent ruptures in severe frosts. To create seams you need wooden slats, which should be soaked in bitumen mastic. Such unique beacons should be located at a distance of no more than 2.5 m from each other.
Concrete for blind areas can be purchased ready-made. Concrete units provide their customers with products highest quality. Special additives are added to professionally prepared solutions to improve their quality. However, if you follow the basic rules of preparation and the requirements for the finished solution, you can prepare it yourself.
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Cooking process
To make the blind area strong and of high quality, you need to pay attention Special attention preparing concrete mortar.
This a budget option for those who cannot afford to purchase ready solution, as well as for those who like to do all the construction work themselves. To prepare a good solution, you must use crushed stone, sand and cement in a ratio of 3:2:1. During the mixing process, you need to carefully monitor the amount of water in the solution. Its consistency should not be too liquid.
First, water is poured into the concrete mixer (not too much, it is better to add a little later than to prepare a solution that is too liquid), then cement is poured into the water and these components are thoroughly mixed until homogeneity is achieved. Next, add crushed stone and mix well again. Only after this can you fill in the sand. Additionally, you can add ash or potash to the solution. These components must be added to the water before other ingredients are added to it. To strengthen the concrete, if it will not be reinforced, you can add table salt.
The finished solution is poured into a previously prepared trench with formwork, its surface is carefully leveled and compacted. Finally, ironing is performed: the surface is covered thin layer dry cement. For the most effective compaction, you can use a special vibrator. But since the structure is small, this is not necessary.
Around the building, with one side closely adjacent to the wall, and the other edge bordering the soil of the site on which this building is built. Typically its width is 1 m, but this is not a hard and fast rule. Options for both narrower and wider blind areas are possible.
Concrete paths around the building are made in order to protect the foundation and walls from premature destruction under the influence of atmospheric phenomena.
When it rains, dirty splashes remain on wet walls, which contributes to the appearance of moss on the surface of the house (the wall turns green). The problem of getting the foundation wet and the walls dirty is solved by constructing paths around the building, that is, blind areas. Their surface should not be perfectly horizontal; slight slope from the wall in the opposite direction so that rainwater drains naturally.
Materials and their proportions for mixing concrete
Since the blind area does not actually bear any load (unlike the foundation), you can significantly save on materials for concrete. Otherwise, the concrete solution for the blind area is made in the same way as any other. It is mixed from the following components:
- cement;
- sand;
- filler (crushed stone or gravel);
- water.
No use for cement for concreting blind areas special requirements not presented. It is important to remember: the higher its grade, the greater the weight the finished concrete product can withstand, that is, the higher its strength.
If possible, the sand should not be clayey or silty, because this will cause the components of the solution to adhere poorly, which will reduce the quality of the concrete. The purer the sand, the better quality finished concrete product.
The crushed stone should not be limestone, otherwise it will simply dissolve in the concrete. You can even add gravel (instead of crushed stone) to the blind area solution as a filler.
You need the most ordinary water, that is, running tap water will do.
The proportions of cement, sand and crushed stone are 1:3:3. This means that for 1 bucket of cement there are 3 buckets of sand and 3 buckets of crushed stone. Cement and sand are poured into a mixing container, water is added little by little and stirred with a hoe (or shovel).
The proportion of water in the solution is not strictly standardized and is determined during the mixing process: the solution should become thick, like sour cream. When the mass acquires a creamy state, add filler and mix again until smooth. The solution for filling the paths of the blind area is ready.
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Tools needed for mixing concrete
At the stage of pouring the blind area, there is no point in buying an automatic concrete mixer. The solution is mixed by hand. In order to mix the solution yourself, you will need the following tools:
- mixing container (trough, old bath, pelvis);
- something to knead with (chopper);
- bayonet and shovel shovels;
- a water barrel or hose with tap water;
- buckets.
A trough, an old bathtub, or a large basin are well suited as a container for mixing mortar on the blind area. You can mix it manually using a garden hoe or bayonet shovel.
Buckets and shovels are convenient for measuring required quantity components in order to accurately maintain the required proportions. They are also useful for directly pouring the blind area, when you need to remove the finished solution from the mixing container.
Procedure for pouring a concrete blind area
- Mark the boundaries of the blind area. To do this you need to install wooden board parallel to the wall of the house at a distance of 1 m from it, secure with pegs. The formwork for the blind area is ready.
- Pour the mixed concrete solution into the prepared formwork and level it with a trowel.
- Use a trowel to make a small slope from the wall of the house to the opposite edge of the blind area. This is necessary so that rainwater does not linger on the concrete, but naturally flows into the ground.
- In this way, fill the blind area around the entire perimeter of the house.
It is well known that the composition and grade of concrete for a blind area directly depend on its operating conditions. The main functions performed by the blind area are reduced to high-quality drainage of water and the creation of a convenient passage around the building. The blind area should be easy to prepare and cost-effective while maintaining maximum protection for the foundation. At the same time, all strength indicators required to ensure long-term operation must be maintained. Along with this, it must be possible to quickly carry out dismantling work in the event of construction or repair work.
The operating conditions of the blind area are quite difficult, since depending on the season it is subject to various adverse effects:
- Temperature difference;
- Atmospheric precipitation (snow, rain).
In this regard, concrete for the blind area must have high frost resistance and provide maximum water resistance. When purchasing factory-mixed concrete in a mixer, you don’t have to worry about its quality, because they will be used for its preparation. quality cement, sand and crushed stone in the required proportions with the addition of water and plasticizers. But if the budget or volumes do not allow purchasing the mixture at the factory, then concrete can be prepared on your own.
Quality and composition of concrete
Any concrete consists of the following main components: binder, aggregate and water. The amount of aggregate is more than 70% of the total volume of concrete; it takes on the bulk of the load. The following is used as a filler:
- Sand;
- Expanded clay;
- Crushed stone;
- Dump slag;
- Brick break.
When preparing the mixture for the blind area, you can use both coarse crushed stone and fine sand as filler. It is customary to use cement grade M300 - M500 as a binder. The volume of prepared concrete of the required strength largely depends on the brand of cement. The mixture must be well mixed - the presence of lumps of binder (cement) is not allowed.
Often, novice builders observe destruction and cracking of the concrete blind area after the first winter. The main component of the mixture, on which the quality of operation of the blind area largely depends, is cement. Unscrupulous manufacturers resort to replacing part of the cement with lime flour, ash or dolomite, which leads to a significant reduction in the grade of concrete.
To avoid troubles, it is better to purchase cement from official suppliers or trusted manufacturers. Cement, subject to storage conditions, can retain its properties for no more than 90 days, after which it loses more than 30% of its strength properties. Therefore, an important criterion when purchasing cement should be the date of its production; it is recommended to give preference to bags with second-by-second markings. It is impossible for two bags to have exactly the same date (with second-by-second markings), whereas counterfeit bags are marked with a manufacturing date of the same day.
By the grade of concrete you can determine what compressive strength it has. Grade M200 is the most popular concrete used in construction work. Its scope of use is quite large; it is used for the device:
- Concrete screeds;
- Blind areas;
- Stairs;
- Paths.
Concrete grade M300 is used for construction:
- Blind area;
- Paths;
- Foundations;
- Floor slabs;
- Retaining walls.
Concrete grade M250 is considered intermediate between the grades discussed above; it is used to create:
- Lightly loaded floor slabs;
- Strip fences;
- Concrete blind areas.
When preparing the solution, you need to pay attention to the following nuances:
- A significant amount of water has a bad effect on the strength properties of concrete. This happens because not the entire volume of water reacts with cement; some of the liquid may remain inside the solution in its own pure form. When preparing the mixture, you need to ensure that all the water is absorbed into the cement.
- The quality of concrete is significantly influenced by the fraction of crushed stone used as aggregate. For the blind area you can use crushed stone of a fraction of 5 – 20 mm. The best option The use of crushed stone prepared by crushing river gravel or rock is considered.
- The size of the crushed stone fraction affects the volume of water used. The finer the fraction, the more water is required.
- It is recommended to sift the sand before use. It should not contain any inclusions of limestone, clay or silt.
Mixture recipe for the device
To construct a blind area, you can use concrete, the grade of which will not be lower than M200. The recipe for its preparation is quite simple. To prepare M200 grade concrete from M300 cement, you need to mix the materials in the following proportions: 1 part cement; 1.9 parts sand, 3.7 parts crushed stone. It is worth noting that the proportional ratio of materials with M400 cement will be 1X2.8X3.9.
The amount of water should be minimal. Ideal option It is considered to add 0.65 parts of water to 1 part of cement. When using fine-fraction crushed stone, the amount of water can be increased; when using coarse-fraction crushed stone, on the contrary, it can be reduced.
When preparing concrete, you need to adhere to the following procedure: first pour in water, and then add cement. After thorough mixing and obtaining “cement milk”, crushed stone should be added and only after thorough mixing – sand. The resulting mixture remains to be poured and compacted thoroughly.
To concrete blind area served long years, it is necessary not only to maintain the given proportions, but also to pay attention to the quality of the materials used.
