Some areas may be unstable due to heaving soils or high groundwater levels. In this case, it is recommended to use cement grades no lower than M400, and less commonly, Portland cement grade PC500. The material is well suited for areas with sudden temperature changes and high humidity.
What should the filler be?
River sand and medium fraction crushed stone are used as fillers. In some cases, fine gravel is used instead of crushed stone. To reduce the weight and increase the volume of the solution, expanded clay is often added: it is lightweight and is a good mass filler. It must be remembered that medium-fraction crushed stone will require more water than coarse-fraction crushed stone. It is not recommended to use limestone for preparing concrete, as it reduces the strength of the structure.
How to prepare sand
The strength of a concrete structure will depend not only on the binding material, but also on the fillers, one of which is river sand. To prepare the mixture, it is recommended to use coarse sand. It is allowed to use quarry sand, previously sifted through a fine mesh screen. If self-extracted sand has clay particles, they can be removed by simple washing. To do this, a large amount of water is poured into a container with sand, the sand is settled, then washed. Most of the clay impurities will settle to the bottom, and after washing the sand will become so clean that it can be used to prepare the mixture. The higher the grade strength of concrete is required, the less sand will be needed to create the solution.
How to add water
Water should be added to the concrete mixture after all components of the dry mass have been thoroughly mixed. The amount of liquid for mixing the solution in most cases is determined as 1/2 of the volume of cement, but this is not always the case. The grout should form a mixture of such consistency that it is sufficiently plastic and convenient for pouring the blind area. The liquid for diluting the solution must be clean. You can use cold well water or from a well, the main condition is that it does not contain debris and dirty impurities, for example, clay particles. The presence of impurities can reduce the astringent properties of the mixture. The mixer is added in such a volume that the resulting mass does not flow off the shovel and does not stick to it too much. The consistency of the concrete mass should be similar in viscosity to thick sour cream.
Concrete proportions for blind area: calculation
The standard recipe for preparing concrete mortar contains the following components and proportions:
- river sand - 3 parts;
- cement grade M400 - 1 part;
- crushed stone or gravel - 4 parts;
- water - 1/2 part of cement.
By part we mean a measure of materials in 1 bucket. If you plan to install a wide concrete strip (wider than 1 m), then in this case it is recommended to mix the solution in proportions 1: 3: 3 (cement-sand-crushed stone or gravel). If we consider the weight values of the mixture components, then to prepare 1 m³ of M200 concrete mass you will need:
- sand - 750-840 kg;
- cement - 280-300 kg;
- medium fraction crushed stone - 1100-1400 kg;
- water - 140-150 l.
Numerical values are given for tabulated specific densities of materials. The crushed stone fraction can have a size from 5 to 20 mm. Based on empirical data, an approximate ratio of water-cement composition has been derived, which is 0.65:1 (water-cement). But even in this case, the volume of the sealer (water) can vary depending on the degree of sand moisture. There are proportions for the dry mixture. To find out how much dry mass is needed to build a blind area, you need to make the following calculations:
- Decide on the size of the blind area.
- Calculate the area of the building.
- Determine the volume of the structure.
The resulting value should be increased by 10-15% in order to take the mixture with a reserve. The resulting figure will become an indicator of how much dry mixture may be required to build a blind area around the house. For example, the width of the blind area is 1.2 m, the length (in this case the tape will cover the entire house) is 30 m, the height of the structure is taken to be 20 cm. Using the calculation method, the following is obtained:
- Stm = A*B = 1.2*30 = 36 m2.
- Velm = Selm*Helm = 36*0.2 = 7.2 m3.
- Vcm = Velm+15% = 7.2 +15% = 8.28m3.
Design Features
The blind area of the house is a layered structure. Its basic composition (in layers from bottom to top):
- Sand, which performs the function of drainage and compensator of soil pressure during soil heaving, 5-10 cm;
- A layer of crushed stone as a large drainage, 5-10 cm;
- Concrete (cement) mortar, 7-15 cm.
The total thickness of the “pie” must be at least 15 cm. The top layers are laid at an angle so that water falling on the concrete can drain into the ground or drainpipe.
To increase the energy efficiency of the basement, polystyrene foam is laid between the crushed stone and concrete - an insulation material that is not afraid of water and compressive loads. In addition, laying geotextile between sand and crushed stone will help extend the life of the protective tape - the fabric will protect the layers from mixing.
In parallel with the blind area, it is recommended to lay a drainage pipe into which rain and melted snow, as well as gutters, flow.
Application and purpose of the component
Cement in blind areas is used as a component that is part of sand-cement and concrete mixtures. The building materials market is replete with ready-made mixtures.
But, if you have the necessary components, you can prepare the composition yourself. It will be much cheaper, and as a polymer that improves the structure of the cement mortar, you can use regular PVA glue, as well as special products.
Cement blind areas perform a protective and decorative function. The recommended width of the structure should be at least 1 m.
Thanks to its properties and quality characteristics, the foundation of the building:
Not exposed to precipitation.- Resists frost.
- Provides strength and durability.
- Correctly distributes the load, preventing cracking.
- Prevents moisture and surface water from entering the base.
- Protected from mechanical damage.
A well-made blind area protects against fungus and mold that may begin to form in the house. At the same time, additional opportunity to move around the house is provided. Decoration for the structure can be achieved by painting or adding a color pigment to the solution, finishing with tiles or paving stones.
In order for all assigned functions to be performed and the foundation to be reliably protected, the cement blind area must be done in strict accordance with technology .
Requirements for the blind area
When designing and installing a blind area, you must adhere to the following standards (SNiP 2.02.01-83*):
The width must exceed the overhang of the canopy by 20 cm, for flat roofs - at least 500 mm from the wall;- The width also depends on the type of soil underneath: for group I = 1 meter, for group II = 2 meters.
- The minimum concrete layer is 7 cm, the maximum is 15 cm;
- The slope of the tape is at least 1.5°;
- The blind area should be made around the house continuously along the entire perimeter.
The presence of a blind area does not guarantee the expected result if the installation of the structure is performed incorrectly.
Waterproofing of concrete is important
When arranging a blind area around the house, you need to know that low grades of concrete have poor frost resistance and water resistance (the lower the grade, the worse the performance).
During the autumn rains, the soil collects a large amount of moisture and freezes in winter. For the foundation, such a phenomenon is detrimental. The water that has penetrated into the surface of the blind area in winter at subzero temperatures will begin to crystallize and increase in volume. As a result, the concrete structure will crack and collapse.
Therefore, water resistance is an indicator that must be taken into account when choosing a brand of concrete for arranging a blind area around a private house. Durable, expensive grades of concrete have high water resistance.
The cost of concrete grade M400 is 1.3 times higher than concrete grade M100. But this building material has high strength characteristics, and it is not advisable to use it for arranging street paths that take on small loads.
DIY blind area
To make a blind area yourself, make a 10-15 cm depression around the wall and carefully compact the soil. Then sand and crushed stone are poured in different proportions. Now you can prepare the concrete and begin making the coating.
The perimeter tape carries a considerable compression load both from the soil during the changing seasons and from external factors - snowdrifts. Accordingly, the solution for the blind area in a frozen state must be able to withstand these loads.
What brand of concrete is needed in this case? Since the blind area takes up a significantly smaller load compared to other load-bearing structures, for its manufacture it is enough to prepare a solution of M200 (B15). However, if the calculation requires changing this parameter upward, this will not be an error. You should be wary if builders suggest using M100-M150 concrete for installation.
Concrete composition: requirements and characteristics
The blind areas around the perimeter of buildings are unloaded concrete screeds. Such paths are not loaded daily with pedestrians and vehicles, so concrete grades with a minimum strength rating are used to fill them.
Basic requirements for street concreting:
- Water resistance of the surface of the blind area. Therefore, it is not recommended to use grade M50 (75) for the construction of blind areas, as they absorb moisture well.
- The cement mortar base must withstand the load of people walking on it, sudden temperature changes, and constant exposure to natural phenomena (rain, hail, snow, wind loads).
Proportions of concrete solution.
When calculating the amount of each component of the solution for pouring the blind area, the necessary indicators of the finished screed are taken into account: water resistance, frost resistance, strength. The higher these indicators are, the longer the operational period of the concrete structure.
How to make concrete yourself
So, the grade of concrete for the blind area is M200 or M250. How can you do this yourself?
You will need a concrete mixer. If you calculate the required amount of solution, you get an impressive figure. For example, for a house 6x6 meters, we determine the volume of concrete for a blind area 15 cm thick:
Add a slope, we get about 6 m 3 of solution. It is impossible to mix such a volume well by hand. By the way, you can rent a concrete mixer.
The composition of concrete for the blind area is classic:
- Portland cement M400 or M500;
- Water;
- Sand;
- Crushed stone fraction 5-20 mm;
- Plasticizers (recommended).
Proportions of components for concrete on the blind area:
| M400 | 1 : 2,8 : 4,8 | 54 | |
| M500 | 1 : 3,5 : 5,6 | 62 | |
| M250 | M400 | 1 : 2,1 : 3,9 | 43 |
| M500 | 1 :2,6 : 4,5 | 50 |
The average cement consumption per 1 cubic meter of solution is about 240-270 kg.
For convenience, you can calculate the volume in buckets of 10, 12, 20 liters. If we take one bucket as one, then we take the remaining components proportionally.
The amount of water is taken as half the volume of cement, but this indicator can vary - it is necessary to achieve a plastic and workable consistency so that the solution can be laid at an angle and does not flow down.
How to prepare cement mortar?
What is the ratio of sand, cement and other components? The basic “recipe” that all builders adhere to when making a blind area with cement and sand, in parts, is as follows:
- cement – 1;
- sand – 3;
- crushed stone – 4;
- water – 1/2.
Experts recommend laying the cement mixture in the form of concrete mortar, as this will ensure strength and longer service life of the coating. All components are mixed together with shovels or a concrete mixer, and poured into a prepared form from formwork, evenly distributed around the perimeter with a plastering tool.
The larger the crushed stone, the less water will need to be used. Therefore, here there is + (-) in the direction of a slight increase or decrease in fluid flow.
How to calculate how much is needed to fill 1 m2?
Using an online calculator, such as the one on this site, an example calculation might look like this: V = S * t, where:
- V is the volume of cement;
- S – area (1 m2);
- t - thickness of the blind area (20 cm).
V = 1 m2 * 20 cm = 1 * 200 = 0.2 m3 - this is exactly the volume of the mixture that will be needed in this case. To the received quantity, in reserve, another 15% of the finished composition must be added. The calculation of the dry mixture is S multiplied by the height of the structure + 15% of the margin. The determination of the total area of the blind area is determined by multiplying the length and width indicators.
Laying
Installation of the blind area is carried out after the arrangement of the formwork, which consists of only one row of boards - on the other side there is a wall, which is recommended to be covered with a damper tape to compensate for the movement of the structure. Also, for every 10 meters it is necessary to make expansion joints in the form of, for example, rubber tape laid in the formwork or an antiseptic board.
When laying a thick concrete layer, it is advisable to include in the “pie” a reinforcing mesh made of wire with a diameter of 5-8 mm and a cage pitch of 10-15 cm. The frame can be laid on crushed stones 3-4 cm above the level of the crushed stone bed or fixed with wire to the formwork .
Concrete is poured continuously around the entire perimeter, leveling it with a shovel. If necessary, immediately rub with wooden floats to obtain a smooth surface.
The laid blind area is cared for in the same way as conventional concrete structures: covered with a damp cloth or waterproof film, moistened for the first 3-5 days. You can walk on the surface within a week or two.
Prices for work and materials in the Russian Federation
Prices for materials for Russian cities can be presented in the form of a table:
| City | Cement (brand), in rubles | |||
| M 200 (25-40 kg) | M 300 (40kg) | M 400 (50 kg) | M 500 (50 kg) | |
| Moscow | 125 | 175 | 200 | 240 |
| Saint Petersburg | 105 | 160 | 250 | 265 |
| Krasnodar | 100 | 160 | 245 | 250 |
| Krasnoyarsk | 130 | 150 | 315 | 320 |
| Nizhny Novgorod | 110 | 100 | 200 | 275 |
The price of work for laying a blind area m2 in the Russian Federation from official construction companies providing services is as follows:
| City | Cost of work (RUB) from |
| Moscow | 850 |
| Saint Petersburg | 900 |
| Krasnodar | 500 |
| Krasnoyarsk | 600 |
| Nizhny Novgorod | 780 |
An analysis of the construction services market in the cities presented in the table showed that ordering construction services from private individuals costs half as much.
Main components
The quality of the finished concrete depends not only on strict adherence to proportions, it is also related to the quality of the mixed substances and their modification. To make concrete durable, you should follow the basic recommendations.
Cement
Without this component it will not be possible to prepare concrete at all.
Cement affects the strength of the finished product and the speed of its hardening.
Among all the variety of choices on the market, you should choose Portland cement. It will allow you to get the best adhesion of all components.
The main characteristic for choosing cement is the brand. It allows you to determine the type of work for which the manufacturer recommends use. The brand is designated by the letter “M” and is measured in kilograms per cubic centimeter. The strength of the dry mixture depends on it.
In order not to make a mistake in choosing cement based on quality and cost, you should determine in advance the type of work that you plan to perform:
- Masonry. To create a load-bearing wall, cement M400 - M500 is best suited. Other types of structures can be made from a mixture of M300. If you need to create a small structure (a gazebo or a shed), then M200 cement is enough.
- Foundation. If it is necessary to lay the foundation for one-story buildings of modest size (garage or summer kitchen), it is allowed to use M200 cement. If the building should be residential and have several floors, then it is better to choose M400 or M500 binder.
- Blind area. To create a blind area, cement M50 or M150 is suitable. If it is necessary to repair a certain surface, then you can not pay attention to strength at all. But pouring the floors is a different story. Here you should select a specific brand of cement. It depends on the performance characteristics of the floor.
- Plaster. When preparing a mortar for plaster, you should choose a binder with a strength of M300 or M400.
Important! There is no point in buying a lot of cement in reserve at once, because after a month its strength begins to decrease. After two months, 10% is taken away from it, after 6 - 50%, and after a year the material becomes unsuitable for use.
If during the preparation of concrete you have to mix several brands of cement, then the proportions of all components will have to be changed. This is done due to the fact that the content of high-grade cement in the finished solution should be less than that of low-grade cement.
Crushed stone
This ingredient provides the finished composition with high compressive strength.
To prepare a high-quality concrete mixture, it is necessary to select crushed stone with a size of 1-2 cm.
If larger stones are present, it is better to use them for factory work.
You also need to monitor the presence of clay inclusions and the cleanliness of the crushed stone.
Sand
This component is simply necessary for preparing concrete. The best solution would be to take river or quartz sand (it contains shiny crystalline inclusions), the particle size of which is 1.2-3.5 mm.
You should also pay attention to the presence of lumps of clay in the substance. If it is present, then the raw material is second-rate and it is not recommended to use it for preparing concrete. Clay can significantly reduce the strength of the finished solution. In some situations, crushed gravel may be used instead of sand.
Important! Before starting work, it is recommended to sift the sand through a sieve to completely remove any foreign matter.
If the composition is being prepared for small-scale construction, then the type of water is not important; any water can be used.
Advantages and disadvantages of using raw materials
The pros and cons of using the cement component in arranging a blind area lie in a certain characteristic of the material. The advantages of cement are:
excellent corrosion resistance;- frost resistance;
- high adhesion;
- strength and density;
- efficiency in relation to atmospheric changes;
- Possibility of mixing with polymers and water;
- variety of brands.
Cement has few disadvantages:
- the ability to absorb moisture leads to loss of strength qualities;
- Prolonged contact with dry material may cause pulmonary diseases.
There are many more advantages than disadvantages, which is why cement is one of the best environmentally friendly natural materials for building foundations.
Proportions
Buckets can be of different sizes (from 5 to 15 liters), so for accurate calculations it is most convenient to use the weight of the components. If you know the volume of the concrete mixer itself, then it is not difficult to determine the required amount of substances in the buckets. You just need to figure out the brand of ready-made concrete.
To make one cubic meter of concrete, the following amount of materials is required:
| Components | M400 | M500 |
| Cement, kg | 338 | 292 |
| Sand, kg | 642 | 702 |
| Crushed stone, kg | 1250 | 1258 |
| Water, l | 170 | 146 |
This calculation is carried out if the cement is poured in stages (depending on the volume of the concrete mixer), and the process itself does not last long. It should be taken into account that calculations are carried out for laying concrete under normal climatic conditions. Relative air humidity is from 60 to 75%, and temperature is from +15 to +25 C.
In buckets
To calculate the amount of materials in buckets, the indicated numbers are converted to liters. The values are not completely accurate due to the variable density of bulk materials, but they are enough to prepare workable concrete. The bulk density of cement is 1200 kg/m3, sand - 1440 kg/m3, and crushed stone - 1600 kg/m3.
After translation, the following values are obtained:
| Components | M400 | M500 |
| Cement, l | 281 | 243 |
| Sand, l | 445 | 487 |
| Crushed stone, l | 781 | 786 |
Now the obtained indicators are converted into buckets and it is calculated how many of them will be needed to fill the concrete mixer. Most often, 10 liter buckets are used in construction, and calculations will be made with this. But concrete mixers differ in size. For home use, novice builders buy devices with a volume of 70 to 250 liters. Since concrete mixers work in an inclined position, the amount of concrete produced will be less. Therefore, the calculation will be carried out for an average 55% occupancy rate.
The numbers next to each ingredient indicate the number of buckets for preparing concrete:
| Concrete mixer volume, l | Concrete grade, M | Cement | Sand | Crushed stone | Water |
| 70 | 400 | 1,1 | 1,8 | 3,1 | 0,7 |
| 500 | 1 | 2 | 3,1 | 0,6 | |
| 100 | 400 | 1,5 | 2,5 | 4,3 | 1 |
| 500 | 1,3 | 2,7 | 4,3 | 0,8 | |
| 120 | 400 | 1,8 | 3 | 5 | 1,1 |
| 500 | 1,6 | 3,2 | 5 | 1 | |
| 140 | 400 | 2,2 | 3,5 | 6 | 1,3 |
| 500 | 1,8 | 3,7 | 6 | 1,1 | |
| 160 | 400 | 2,5 | 4 | 7 | 1,5 |
| 500 | 2,1 | 4,3 | 7 | 1,3 | |
| 180 | 400 | 2,8 | 4,5 | 7,7 | 1,7 |
| 500 | 2,5 | 4,8 | 7,8 | 1,5 | |
| 200 | 400 | 3 | 5 | 8,5 | 1,9 |
| 500 | 2,7 | 5,5 | 8,7 | 1,6 | |
| 220 | 400 | 3,5 | 5,3 | 9,5 | 2 |
| 500 | 3 | 6 | 9,5 | 1,8 | |
| 250 | 400 | 3,8 | 6,1 | 10,7 | 2,3 |
| 500 | 3,3 | 6,7 | 10,8 | 2 |
In everyday life they operate according to a simplified scheme. To mix concrete, use the following proportion: 1 bucket of cement, 0.5 buckets of water, 2 buckets of sand and 4 buckets of crushed stone. If a plasticizer is added, then this is done in a thoroughly mixed material, after which the concrete mixer is started for another couple of minutes.
For the foundation
For the construction of the foundation, depending on its type, the following grades of cement are used: M200, M400 and M500. The calculation is carried out according to the same scheme as described above. The proportional ratio for the solution is selected 1:3:5 or 1:2:4 (cement:sand:crushed stone).
[ratingelements >Not all craftsmen know how to properly prepare concrete so that all components are thoroughly mixed. It is important to ensure that the consistency of the composition is thick and does not stick.
To solve these issues, it is necessary to clearly know the proportions of the components and the order of loading the concrete mixer. Before starting cooking, it is better to carry out calculations and prepare the ingredients so as not to be distracted during the process.
The procedure is as follows:
- 1/2 part of the water is poured into the container.
- Almost all the crushed stone is filled in, and the concrete mixer is turned on. At the beginning, you need to put crushed stone so that it can cope with breaking up the thick solution in the container. This will avoid clumping.
- The entire volume of cement spills out. Knead the resulting mixture until it becomes homogeneous.
- Now, without stopping the machine, pour out all the sand. At this stage you need to be especially careful and attentive. The resulting composition should look homogeneous without lumps of sand.
- To complete the preparation, the remaining part of the crushed stone is poured into the concrete mixer. When the device thoroughly mixes all the ingredients, the rest of the water is added to the container. After this, the composition is brought to a homogeneous state.
- When the mixture is ready, it must be carefully poured. To do this, the rotating concrete mixer is turned down so that the solution pours into the prepared bucket.
Important! After finishing mixing, it is necessary to wash the concrete mixer. To do this, use water and a trowel. This rule cannot be neglected, even if another batch of concrete is planned that day. Due to the remnants of the old mixture, lumps often appear in new concrete.
Brand of concrete sweep
When selecting a brand of concrete for pouring a blind area of a private house, it is necessary to take into account the further conditions of its operation:
- soil characteristics and climate in which the building is located;
- expected load on the cement surface.
Requirements for concrete that can be used for arranging the blind area of a country house:
- minimum grade - M200;
- minimum frost resistance - F150;
- minimum strength - B15.
This is one of the most popular building materials, which is used for arranging floor screeds, landings and steps, foundations and blind areas of buildings.
To prepare the cement mixture, cement M400 (500) is used.
If construction work is planned on heaving soils, the requirements for building materials increase by 1-2 points in all respects.
If in the region where the concrete structure is located there are significant temperature changes and a large amount of precipitation falls annually, it is better to use the M250 grade composition. Intermediate grade concrete can be used for the construction of lightly loaded structures and strip-type fences. This material is resistant to cracking, heat and frost.
Tips and tricks for making the mixture
- When making concrete at home, they use precise technology. To make the composition strong and durable, you cannot ignore the nuances:
- If errors were made when pouring concrete, voids will form in the finished material. To prevent this from happening, a special vibrator is used.
- To pour a strip foundation, select grades of concrete higher than M200.
- Pouring concrete at low temperatures is not recommended. Otherwise, weather conditions will destroy the structure of the composition, which will have a detrimental effect on the quality of the finished object.
- If pouring is carried out at high temperatures, the concrete should be moistened for 10-14 days after pouring. Otherwise, cracks will form on the surface.
When building a house yourself, you have to prepare the concrete composition at home. To make the structure durable, you should adhere to clear recommendations, accurately calculate the components and follow the loading sequence. Don't be afraid to mix ingredients and pour concrete, even if you have no construction experience! If you take this task carefully, you will end up with a strong and durable structure.
How to finish the finished structure?
To give the structure an aesthetic appearance, strengthen it and enhance its waterproofing qualities, you can decorate the surface. Options for finishing a cement blind area are:
- Coloring. Enamels and polymer paints intended for concrete surfaces are used after mandatory priming.
- Application of a protective composition . The use of Elakor will increase strength, reduce slipping, prevent dust and moisture, and add shine to the path.
- Ironing. This technique is performed dry or wet, and consists in applying dry concrete to the drying surface - it is spilled and leveled in an even layer. The surface becomes more durable, strong and rich in color.
- Impregnation. Application of a special composition, in finished form, can add shine to the surface and enhance its water-repellent qualities.
- Laying paving slabs . After the blind area has hardened, curbs are installed and tiles of any size, texture and color are laid, in accordance with construction laying rules.
Any of the selected methods can extend the life of the structure. Which one to choose is up to the individual to decide for himself.
Briefly about the advantages
Experts assure that in the absence of the possibility of final finishing of the house, the installation of a concrete blind area should still be completed, and even before the onset of cold weather. This is the only way the owner can experience 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.
What mistakes should you avoid?
When arranging a cement blind area, you should try to avoid the following mistakes:
Uncompacted base . If the cushion does not compact the soil sufficiently, the structure may sag and crack over time.
- Failure to comply with the angle of inclination . The absence of a slope will contribute to faster wear of the surface, cracking and precipitation.
- Construction of the structure on fertile soil . Poor cleaning of the outer layer will promote plant germination, fungus formation and structural destruction.
- Wide blind area . A base that is too wide does not make any sense, since additional consumption of cement and other components will be required.
- Incorrect arrangement . The blind area should be done only after the work on the plinth is completely completed. It must be correctly positioned relative to the plumb line of the roof.
- Wrong brand of cement . If the material is chosen without taking into account the natural terrain, the level of soil freezing and atmospheric climate conditions, then it will last much less and will quickly deteriorate.
- No expansion joints . If you make the surface monolithic, then cracks will become inevitable due to shrinkage of the house and atmospheric fluctuations. Sutures help prevent this process.
In order for the blind area to last longer, it is advisable to provide for drainage outflow. It is undesirable to arrange bushes and grow trees near the path, as their roots have a destructive effect.
How to correctly calculate the blind area around the house?
In order for this architectural element to fully perform the functions assigned to it, you must remember the 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 the concrete strip, the more reliable the 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.
Another important aspect is expansion joints , which are often neglected by inexperienced builders. To make seams, it is enough to use vinyl tape or pieces of EPS with a thickness of 5-10 mm, which are laid between the foundation and the blind area. In addition, it is advisable to break the concrete covering in the same way crosswise every 2 meters. When reinforcement is not used, this operation is especially important.
Brand according to SNiP
Modern norms and rules in force in construction recommend adhering to all proportions of ingredients using the specified brand of cement, otherwise weak concrete will not be able to provide complete protection to the base.
All ingredients necessary to obtain the M200 brand mixture must be high quality and pure , free from impurities and foreign inclusions.
In conclusion, it is worth noting that construction is carried out at temperatures not lower than -5°C. If it is necessary to carry out all the work in a colder period of the year, it is necessary to warm up the working solution.
How to install a circular blind area made of concrete for a private house
The implementation of this operation, like all construction processes, consists of performing a set of specific works. Let's briefly look at some of them.
Tools and materials
It makes no sense to talk once again about the need to use high-quality materials, however, it is worth recalling that the proportions of the components when preparing concrete for the blind area directly depend on their characteristics .
The list of required materials is as follows:
- clay - for making the underlying layer;
- sand - for a separating layer over clay;
- crushed stone - for forming a drainage layer (fractions up to 20 mm) and preparing a concrete mixture;
- hydrophobic material - roofing felt or polyethylene for waterproofing;
- metal mesh for reinforcement;
- boards for formwork 20 mm thick.
List of equipment for work:
- building level;
- two-meter rail;
- plastering tools;
- equipment for digging and carpentry;
- vibrator for compacting the mixture.
Technological process of arranging a blind area
First of all, markings should be made for the entire structure; the width of the tape was written above. Next, the process occurs step by step :
- 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 an expansion joint in concrete in the area of the 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 the installation of expansion joints for concrete blind areas must be done 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.
The so-called wet ironing will help to achieve maximum strength of the concrete coating. Optimal drying is ensured by laying fabric on the tape, which is periodically moistened.
Brands of mixture used
For blind areas, the brand of the resulting mixture is important - an indicator of compressive strength. According to the technical specifications, concrete blind areas must comply with GOST 7473-94 (9128-97). The selection of brand is based on the expected load, climatic conditions, and soil quality.
The following brands are used:
- M 200;
- M 300;
- M 400;
- M 500.
The first brand (M 200) is considered the most popular; it has minimal frost resistance and is more suitable for regions with minor temperature fluctuations. For cold regions, experts recommend cement grade M 400 or M 500, and grades 300 and 400 are suitable for central Russia.
Each grade is durable and resistant to seismic vibrations . Heat, frost or cracking are not a problem for high-quality material. Affordable quality and reasonable cost allow you to create the perfect surface.
Brands M 100 and M 150 are categorically not suitable for street construction; they quickly fail. They can only be used indoors.
Common mistakes when creating a blind area
Often, owners of private houses do not get the expected effect from the blind area because they make a number of mistakes. Even the smallest flaws can minimize the beneficial effect of the design. Most often, problems can arise when:
- Poor quality compaction of backfill. It causes shrinkage, which causes the waterproofing material to collapse and may even cause cracks to appear on the surface of the concrete.
- Debris getting into the backfill can also lead to damage to materials and deterioration of their performance characteristics.
- Poor compaction of the base and non-compliance with the slope can lead to an uneven layer of crushed stone, which will cause improper distribution of the load and cause cracking of the concrete.
- The absence of transverse seams in the formwork and an expansion joint between the blind area and the base can lead to the formation of cracks.
It is also worth noting that if there is a watering tap in the base, then a separate gutter should be provided for water drainage so that it does not fall directly on the surface of the concrete and spoil it.
Concrete blind area: work progress, concrete calculation
A blind area is a concrete path around a building, with one side closely adjacent to the wall, and the other edge bordering the soil of the area on which the 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.
Types of blind area at home.
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; a slight slope from the wall in the opposite direction is needed so that rainwater drains away 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.
Concrete proportions table.
There are no special requirements for cement for concreting a blind area. 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 the quality of the 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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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 bathtub, basin);
- something to knead with (chopper);
- bayonet and shovel shovels;
- a water barrel or hose with tap water;
- buckets.
Tools for working with concrete.
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 the required amount of 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 a wooden board parallel to the wall of the house at a distance of 1 m from it, secure it 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.
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Diagram of a concrete blind area with approximate dimensions.
The blind area is a rather thin and narrow concrete slab that closely surrounds the perimeter of the building. In order to calculate the amount of concrete to pour, you need to find the volume of this slab. It's quite easy to do this:
- We calculate the surface area of the blind area (we multiply the width of each rectangular section by its length).
- We multiply the resulting area by the height of the blind area.
For example, the surface area of the blind area is 20 square meters. m, and its height is 15 cm. This means 20x0.15 = 3 (cubic meters of concrete solution).
To this amount should be added 10-15% in reserve. As a result, 3.5 cubic meters of solution will be required for filling.
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Concrete setting is not the same as concrete drying. On the contrary, concrete that does not have enough moisture during hardening becomes very brittle, fragile, cracks and quickly deteriorates. Creating blind paths in the hot summer (that is, in hot and dry weather) requires mandatory forced moistening of the concrete that has not yet hardened in the first day or two after pouring. It’s enough just to water it with a hose from time to time without letting it dry out.
A concrete blind area, like any unprotected concrete surface, is subject to the destructive effects of the environment. If you pave it, for example, with paving slabs, its service life will increase several times.
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Existing markings
This material has very high strength . This is one of the circumstances affecting the durability of concrete elements and structures. The brand of the building mixture indicates the limit of its compressive strength, which is measured in kgf/sq.cm (kg force per sq.cm).
The marking is indicated by the letter M, followed by numbers indicating the average strength of concrete. The higher the grade, the more durable the material and the less it absorbs moisture.
Concrete is marked with letters and numbers. Decoding letters:
- M (brand);
- B (class);
- P (mobility);
- F (frost resistance);
- W (waterproof).
Most popular
Let's look at the most popular brands of concrete.
M100/B7.5, M150/B12.5
It is used for the construction of foundations and the production of solid slabs . It is used in road construction, as a concrete pad and to strengthen curbstones. M150/B12.5 is used for pouring floors and foundations of small buildings.
Advantage: low cost, which makes it possible to reduce the cost of work when there is no need to use expensive grades of concrete mortar. Disadvantage: low strength of the material after the solution hardens, formation of cracks and deformation of the coating. Not suitable for the construction of blind areas.
M200/B15
One of the most popular brands of concrete. Used in the construction of foundations, platforms, floor screeds, retaining walls. Large enterprises produce platforms and road slabs from M200/B15.
Advantage: availability of material . Disadvantage: M200 is not used on heaving soils, as well as in areas with sudden temperature changes. It is allowed to use blind areas for construction.
M250/B20
Used for the manufacture of slab foundations (strip, pile-grillage), paths, retaining walls, stairs. Suitable for pouring blind area.
Advantage: resistance to temperature changes and cracking. Disadvantage: cannot be used in the construction of multi-story buildings, since vibrations from buildings can destroy concrete.
M300, M 350/B 25
These grades are used for casting solid foundations, concrete stairs, fences, beams, floor slabs, and retaining walls. M 350/B 25 is used for the production of PAG road slabs, which are intended for use at airfields and monolithic foundations.
Advantages:
- It has a high strength coefficient, which allows it to withstand load changes.
- Can be used in regions with harsh climates.
- The presence of plasticizers in the composition allows you to adjust the poured solution.
Flaws:
- cannot be diluted with water;
- the presence of a plasticizer in the composition can have a negative impact on the health of workers.
Can be used to construct blind areas.
M400/B30, M450/B35, M500/B40
These grades are used to produce bridge structures, hydraulic structures, and bank vaults. Used in the construction of swimming pool bowls, crossbars, beams, columns. M450/B35 and M500/B40 are used in the construction of subways, dams, dams, and structures that have special requirements.
Advantages:
- lasting;
- frost-resistant;
- withstands temperature changes.
Disadvantage: it hardens quickly, which does not allow the solution to be transported over long distances.
The use of these brands for blind areas is unprofitable due to their high cost, but acceptable.
