Blind area around residential buildings
usually made of concrete or sand-cement mortars. At the same time, there is a fairly widespread misconception among private developers that the destruction of a concrete blind area occurs only due to the fault of any mechanical loads. In fact main reason is carbon dioxide corrosion of concrete - the formation of dusty microcalcite from free lime and carbon dioxide air. There are other types of corrosion, for example, sulfate, as well as chloride and others. As a result of corrosion processes, not only dust is formed, but also the strength and resistance to abrasion of the outer layer of concrete is significantly reduced. It should be noted that simply increasing the grade strength of concrete does not lead to durable concrete structures.
IN regulatory document SNiP 2.03.11-85 “Protection building structures from corrosion" indicates that when designing concrete structures, protection of concrete and reinforced concrete structures from corrosion. Therefore, owners of private property often face the need to protect concrete surfaces, including blind areas, from the effects of precipitation. For this purpose, along with other types of protective measures, paint coatings. However, it should be noted that when periodically moistened with water or precipitation it is necessary to hydrophobize concrete surfaces special compounds as a primer layer for paint and varnish coatings (clause 2.31, SNiP 2.03.11-85).
Used to protect concrete Various types polymer coatings: from traditional pentaphthalic and vinyl chloride paints and enamels to high-quality epoxy and polyurethane protective and decorative compositions. Polymer coatings are not only characterized by a long service life, but also by high resistance to chemically active substances.
For creating protective coating you can use POLAC EP-52PA enamel, which is a modified epoxy composition. This enamel has an adhesion-inhibiting effect, which significantly increases the protective properties and increases the durability of the coating.
This coating has good moisture resistance, weather resistance, resistance to UV radiation, and chemical resistance. High and stable adhesion of the coating to concrete and other materials is maintained for a long period of time - tens of years. In addition, a color scheme for the blind area is possible.
The most technologically advanced and versatile for protecting concrete surfaces are also impregnations based on polyurethane resins. These substances have high penetrating ability, perfectly bind concrete, quickly harden (polymerize), are chemically resistant, do not cause corrosion of the concrete base, and have very high impact strength and elasticity.
Polyurethane compositions from Western companies such as TIKKURILA, NOVILUX and others are quite well represented on the Russian market. It should be noted that the range of inexpensive and quality materials very narrow. These include products domestic manufacturer polymer coatings - the TEOKHIM company, whose products include moisture-curing compositions of the ELAKOR-PU type.
The protective composition "ELAKOR-PU" based on polyurethane is designed to prevent dust and destruction of concrete bases. The standard applied coating penetrates deep into the concrete by 3-5 mm, forming on the surface protective film thickness 150-200 microns. This impregnation strengthens and hardens the concrete surface, creates reliable waterproofing protection, blocks pores and microdefects in the concrete structure, forming super-strong, impenetrable crystals in it. As a result, the top protective layer is integral with the concrete base, which completely eliminates the possibility of its peeling.
"ELAKOR" strengthens concrete even of grades M100 and less. After treatment, the concrete surface does not slip and becomes more resistant to impact loads and wear. The operating temperature of the coating is from -60 to +100ºС, and the service life is 10-15 years.
In addition, it is possible color scheme blind areas, anti-slip devices, etc. However, for the sake of fairness, it should be noted that over time, under the influence of ultraviolet radiation, the color seems to turn brown.
In addition, polymer paints such as polyurethane enamel, acrylic paint or epoxy primer-enamel. All these polymer coatings have own merits, including the possibility of application without preliminary priming, for example, epoxy primer-enamel “AQUAPOLIMERDEKOR”, application at low temperatures – perchlorovinyl enamel “BETIL”, the possibility of application to freshly laid concrete - water paint"AQUABETOL", weather resistance - acrylic paint "BETYLAT", increased chemical, - wear resistance - polyurethane enamel "POLYMERDEKOR". In addition, the advantages of all polymer paints are impeccable quality, affordable cost and ease of application.
Thus, polymer paint “BETYLAT” forms a durable, vapor-permeable coating that is resistant to atmospheric conditions. It can be used on concrete surfaces with light pedestrian traffic. Available in two types: on acrylic and organosilicon bases.
Before painting, the surface must be cleaned of dust and dirt and dried. Then, before applying the paint, to improve adhesion and harden the surface, it is recommended to treat it with “BETYLATE-PRIMER” and “BETYLATE-IMPREGMENTATION”.
The concrete blind area serves to protect the foundation of the house from the effects of melt and rain water. She happens to be mandatory element any building and is made in the form of a concrete ring strip located along the perimeter of the base. As a rule, after arranging the blind area, it is left in its original form. But sometimes, to improve aesthetic or waterproofing qualities, it is coated with various materials.
The choice of covering the blind area depends on obtaining the desired result. For example, the coating is made to improve waterproofing or for decorative purposes. You can increase the waterproofing qualities of the blind area using roll materials, drooping compounds or staining. To decorate the blind area, you can cover it with paving stones, paving slabs, porcelain stoneware, or simply cover it with colored crushed stone.
The arrangement of the blind area begins with the laying of an internal waterproofing layer made of rolled materials. Upper layer concrete is protected from destruction by painting with polyurethane or acrylic enamels. They are very convenient to use and do not require painting. preliminary preparation surfaces and priming. The main thing is that the concrete screed is completely dry at the time of painting. The paint is applied with a brush or roller in two layers. They cover not only the blind area, but also the adjacent base to a height of ten centimeters. Enamels form a water-repellent layer on concrete and can protect it for five years. After this period, the treatment is repeated. It is not recommended to use the painted surface of the blind area as a sidewalk.
Strengthen Strength concrete screed it is possible using a proven method - ironing. It involves strengthening the surface of concrete by forming a cement crust on it. Ironing is carried out in two ways. The first of them involves backfilling and troweling freshly poured concrete with dry cement. The second method consists of applying and smoothing a thick cement mortar over the hardened surface of the blind area.
For additional protection from destruction, the surface of the concrete blind area can be covered with penetrating waterproofing compounds. The mechanism of action of the mixtures is their penetration into the structure of concrete and filling its pores. Thus, the ingress of moisture into it is completely excluded. Penetrating compounds are applied once, for the entire service life. Such surfaces do not require additional processing. The compositions are applied to concrete using a brush or roller.
A concrete blind area protects the foundation from getting wet by rain and melt water, and the wall from ground moisture, so it’s impossible to imagine the exterior of the house without it. As a rule, the blind area is a concrete rim around the house along the perimeter of the base. In most cases, it is left as is, but some homeowners prefer aesthetics and practicality in everything and cover the structure with additional facing materials.
Why cover the blind area?
The choice of material depends on the desired effect. The coating can be waterproofing (additional) or decorative.
Waterproofing the blind area is used to additionally protect the concrete from water, which means it extends the life of the layered structure. Different methods are used for this:
- coloring,
- penetrating waterproofing,
- roll materials.
The blind area is also lined to give it an aesthetic appearance. Often it becomes a path around the house, especially if the width of the tape is 0.7 meters or more. IN in this case finishing is done with tiles or covered with crushed stone. Looks good combined option embankments with paving stones.
Waterproofing
When installing the blind area, internal waterproofing of the structure is carried out. Usually it is made using rolls or coating materials and is laid under concrete, extending onto the wall in order to protect the load-bearing elements from getting wet. In addition, concrete itself is not afraid of water.
However, secondary waterproofing will help extend the life of concrete.
Coloring
The simplest and affordable way protect the blind area with special compounds. Enamels are suitable for this:
- polyurethane;
- acrylic;
- primer-enamel.
These compounds form a waterproof film on the surface of the concrete stone and protect it from destruction for a long time - up to 5 years.
The advantage of using paints is the ease of working with them - there is no need to pre-prime the surface. Application is carried out on a dry base with rollers or a brush in 1 or 2 layers. It is recommended to treat not only the surface of the blind area itself - you should also paint the base of the plinth to a height of 10-20 cm.
It is worth noting: it is better not to subject the surface treated with painting to mechanical stress; walking around the house is not recommended - the protective layer wears out quickly.
Ironing
Iron waterproofing is an effective and durable way to protect concrete. Processing can be done in two ways:
- Immediately cover the freshly laid concrete of the blind area with dry cement M300-M400 (the higher the grade of binder, the stronger and more durable the coating). Next, the surface is rubbed and polished after hardening.
- On hardened concrete (2-3 weeks after laying) apply a greasy cement mortar and is smoothed clean.
The essence is the penetration of cement into the porous surface of the concrete base and its strengthening. This method is used to strengthen floors in parking lots and industrial hangars. The treated blind area can be loaded and walked on.
Penetrating waterproofing
Special solutions and dry mixtures for treating concrete penetrate its structure to different depths and fill the voids with crystals. The result is a completely waterproof stone through which water cannot filter. It is enough to coat the concrete once; the effect lasts throughout the entire service life of the structure without the need for additional processing.
The medications must be applied according to the instructions. Dry mixtures are diluted with water and applied to the surface with a brush or roller. Ready-made penetrating solutions are also rolled out with a long-haired roller. The crystallization process occurs naturally - the components of the drug absorb moisture from the concrete and, expanding, fill the capillaries in the body of the stone.
Coating with roll materials
Bitumen roll and coating materials as self-defense blind areas are used extremely rarely - yet their appearance is not aesthetic. Basically, their installation is carried out for subsequent finishing or when processing the foundation demolition of garages, industrial buildings and technical structures.
Coating and roll insulation are combined - the joints between individual sheets of roofing felt and its analogues are treated with a liquid solution.
Lay the waterproofing overlapping the wall and fix the sheet with liquid mastic. It is important to seal the joint between the blind area and the wall with a special cord seal.
After laying, roofing felt materials should be covered with crushed stone, sand or covered with tiles.
Tile covering
If the width of the blind area allows you to organize sidewalk path around the house, it is optimal to line the concrete structure with paving stones or external tiles. True, this should be foreseen in advance in order to deepen the cast-off itself to level the surface of the sidewalk and lawn. The concrete layer, accordingly, will be less thin than in the version without cladding.
Any products are suitable for cladding:
- Concrete paving slabs;
- Porcelain tiles;
- Clinker paving stones.
At correct installation This finishing additionally protects the blind area from mechanical loads and rainwater.
Along the perimeter of the cast-off along the width of the sidewalk, it is necessary to install curbs that will hold the paving stones in place and also complete its appearance. The penetration is usually carried out below the tile level by 300-400 mm.
For finished cast-off concrete, the tiles should be laid not on concrete mortar, but on sand. This will help keep the main structure intact without causing overvoltages.
It’s easy to do the work yourself:
- By concrete base Any type of waterproofing should be carried out (penetrating, roll);
- Next, a layer of dry sand at least 3-5 cm thick is laid and leveled;
- The tiles are being installed. It is not difficult to lay it on sand, it is easy to adjust the location of the fragments and the pattern;
- The seams are rubbed with a dry cement-sand mixture.
As a result, the cladding turns out to be quite high - the thickness of the tiles is usually 3 or more centimeters plus a sand cushion. A properly selected curb stone or a blind area pre-lowered at the base will help hide the rise.
For convenience, sand can be replaced with a cement-sand dry or moistened mixture in a ratio of 1:1 or 1:2.
In parallel with laying the tiles, it is necessary to install gutters to drain water. These can be concrete inserts for the blind area or separate metal or polymer systems.
After completion of the work, the tiles must be watered with a hose or watering can so that the cement-sand mixture is compacted, the binder is activated and hardening processes begin.
Conclusion
Waterproofing and cladding for the blind area will be an additional measure of protection for structural concrete. Coloring is good in itself, it won’t highlight anything appearance iron cast-offs. Ruberoid protection should be used in combination with tiled finishing of the perimeter of the house, as well as penetrating coating.
If the owners of the house want to cover the blind area paving slabs, this needs to be planned in advance in order to correctly calculate the depth of laying the protective structure.
To protect the foundations from rain and flood waters, a blind area is installed around the perimeter of the house. At good quality she not only serves reliable protection from penetration surface waters to the base of the foundations, but is decorative element external landscaping, acting as a kind of sidewalk around the house.
Work on laying the blind area is carried out after the construction of the house is completed, so they often do not pay due attention to it. And this main mistake, which can subsequently lead to the destruction of the blind area itself, as well as the foundation of the building, since the main function of the blind area is to protect the foundation from water.
Concrete blind area is by far the most popular way to protect the foundation.
DEVICE OF CONCRETE BLINDBOARD.
1. Calculation of the thickness of the entire structure, in which all layers must be taken into account.
2. Definition geometric dimensions. On average, the width should be taken within the range of 90-100 cm. The slope from the concrete is 3-5%.
3. Carrying out markings to the area. To do this, the limits of the future structure along the perimeter of the foundation are marked with pegs with a cord stretched along them.
5. The base soil is thoroughly compacted. To provide additional protection from moisture, a clay castle is made.
6. A layer of sand cushion is laid. The sand cushion is made only from coarse and medium sand. The use of fine fractions can lead to large shrinkages, which in turn will cause cracks and damage to the waterproofing. The thickness of the layer is selected depending on the characteristics of the soil. If the soil is strong, then 200 mm of sand is enough. For unstable bases, 500mm of bedding may be required.
7. Crushed stone backfill. The construction of a blind area on such a foundation increases the strength of the soil.
8. Placing the formwork. Formwork is needed to concrete mixture did not flow beyond the markings. When installing formwork, it is important to remember about the expansion joint. It is necessary to install the board directly to the wall of the building. The thickness of the expansion joint is 20-40 mm. The seam is necessary to prevent cracking and deformation of the structure due to different shrinkage of the foundation and blind area.
9. Reinforcement. After the formwork is installed, reinforcement mesh is laid.
10. Installation of cross boards. Transverse boards are installed along the entire perimeter of the foundation to ensure expansion joints. The pitch of the boards is 2 meters.
11. Pouring concrete. The optimal brand is M300 (B20-B22.5). Such a solution will ensure the durability and necessary strength of the structure. Filling in each compartment is done in one step. After which it is necessary to make a compaction.
12. After pouring, the surface is ironed to increase the strength characteristics.
13. Strengthening and surface care.
14. When the concrete has gained 70% strength, the formwork can be removed.
REPAIR OF CONCRETE BLINDBOARD USING MOUNTAIN CRYSTAL MOUNTAIN ICBM REPAIR COMPOSITIONS.
During operation, due to non-compliance with the blind area device technology or as a result of the use low-quality materials the blind area may begin to collapse. The destruction of the blind area leads to further destruction of the foundation. Therefore, it is very important not to delay repairs. will help you independently resolve the issue of restoring the surface of the blind area and prevent its further destruction.
Types of destruction:
1.cracks
2. bundle
3. crumbling
CRACKS.
Repair work should be carried out in the off-season (very/spring).
Causes of cracks:
If the cover is old, then it is for a long time exposed to atmospheric/natural influences (expansion and compression). As a result, cracks form in the blind area, which will continue to collapse.
Uneven settlement of the building. Violation of the tightness of the joints between the blind area and the basement of the building. As a result, water cannot penetrate there.
Drawdown of the blind area. The reason for this phenomenon is soil subsidence or a violation of the technology for laying the coating around the house.
Stages of work:
1. Preparation. Before carrying out, the surface of the old coating should be cleaned of dust and dirt. Expand and completely remove the destroyed areas. Prime the crack with PrS-03 “Gora Khrustalnaya” primer to improve the adhesion of the repair compound to the old base.
2. Preparation of the solution. Preparation of the working solution of the MBR repair mixture is carried out directly on construction site using a low-speed forced mixing concrete or mortar mixer. For cooking small quantity a low-speed electric drill with a mixer attachment is used to mix the solution, achieving a homogeneous consistency while mixing. Mixing with gravity mixers or by hand is not permitted.
To prepare a working solution of the MBR repair mixture, first pour the minimum calculated amount into a mortar mixer or into a mixing container (calculated taking into account the minimum water consumption value specified in the characteristics of the mixture) number fresh water mixing, then with the mixer constantly running, gradually load the calculated amount of dry mixture and mix for 1-2 minutes until a plastic, homogeneous solution without lumps is obtained. If necessary, to obtain a working solution of a given mobility, the required amount of water is added to it (within the amount specified in the characteristics of the mixture) and additionally mixed for 1-2 minutes.
To obtain complete readiness, let the prepared solution of the MBR repair mixture stand for 5 minutes and then stir again for 30 seconds.
!!!IMPORTANT. The dissolution of special additives in the mixture occurs gradually, so it is extremely important to mix the mixture thoroughly and, if necessary, add water in small doses while constantly stirring the solution.
4. Care of the solution. After completing work on applying a working solution of a thixotropic mixture for repairing MBR concrete, it is necessary to ensure careful temperature and humidity care of the applied coating.Immediately after applying the repair mixture, it is necessary to protect it from rapid drying under the influence of outside air temperature, direct sun rays and wind. For maintenance, standard methods of caring for cement-containing materials are used.3. Laying the solution. Application of the MBR repair mixture solution is done manually with plaster trowels, and compaction, smoothing and leveling of the solution is done with trowels, rules and trowels. It is better to start repairing concrete from the highest point, periodically monitoring compliance with the planned slope. After laying the repair mixture in the defective area, it is necessary to level it. Leveling is the removal of excess mixture in order to level the surface along the appropriate contour and height.
Care can be carried out in various ways:
regular irrigation of the MBR repair coating with a sprayed stream of water starting 2-3 hours (full setting) after its installation during 3 days of hardening at least 2 times a day with a water consumption of 1-3 l/m2. Smallest number moistening of the repaired surface of structures during the day, depending on the average air temperature during the day, is given in Table 1;
If it is impossible to moisten the surface with water, it is recommended to lay damp/wet burlap on the repaired surface or cover plastic film, tarpaulin, rubberized fabric;
treating the surface of the repair coating with film-forming compounds that reduce evaporation ( ).
Table 1
|
№ p/p |
Air temperature, ºС |
Minimum number of wetting of the repair coating |
Failure to take measures regarding humidity conditions can lead to the formation of microcracks on the surface of the hardened layer of the repair coating, especially in hot and dry weather.
DELAYING AND CRUMPING.
Causes of delamination and crumbling of concrete:
Uneven hardening concrete mortar(occurs in spring when pouring concrete on a cold base)
The structure is too thick
Exceeding the norm of air content in the solution
Exceeding the proportion of crushed stone in the concrete solution.
Stages of work:
1. Preparation. Before starting work, it is necessary to determine the boundaries of the damage. Cut down the damaged part, remove the destroyed parts and prime the edges of the undamaged concrete.
2. Preparation of the solution (see above).
3. Laying large and deep defects (more than 40 mm) should be filled with repair mixture. held in place by formwork.
4. Caring for freshly laid mortar.
If the damage is not repaired in time, the blind area will subsequently have to be dismantled and a new structure formed. Therefore, it is recommended to carry out everything renovation work in a timely manner.
HOW TO PREVENT THE DESTRUCTION OF A CONCRETE BLINDBOARD.
What should be done to prevent the destruction of the blind area?
If the surface of the blind area will be decorated with stone or tiles, the surface of the concrete should be treated with water-repellent impregnation “Mount Khrustalnaya”.
If the surface will not be decorated, it is necessary to coat the surface with “Gora Khrustalnaya” varnish for concrete surfaces. The varnish will protect the concrete from water penetration, increases the wear resistance of the surface, increases resistance to dirt and makes it easier to clean.
A reliable, time-tested way to protect the foundation from the effects of surface water is to install a concrete blind area around the house. The undoubted advantage of a concrete blind area is its low cost and ease of manufacture.
100% protection from moisture, which is provided by a concrete blind area with a complete coating, cannot be guaranteed by any material (without arranging a multi-tiered “pie”). The condition of the foundation directly affects the position of the entire structure. Therefore, the foundation needs major protection.
This is precisely the main task of the blind area - protecting the foundation and base of the house. In addition to the barrier, it performs several other functions. For example, it allows you to organize more convenient movement along the blind area and gives the building a finished appearance.
Let's take a step-by-step look at how to properly make a blind area around a concrete house with your own hands. We propose to divide all the stages of arrangement into theoretical and applied.
- In the first part, we will look at what you need to know and prepare before getting started.
- In the second - how to prepare the bed and pour it correctly concrete blind area.
Requirements for the blind area and rules for its construction
- width of concrete blind area, according to SNiP 2.02.01-83 should be 200 mm. more than overhang roofing material. If there is a drain, its parameters are also taken into account. The same SNiP regulates the width depending on the type of soil. The traditional (optimal) width of the blind area can be considered 1 meter. This width provides freedom of movement and acts as a path around the house;
- length. Since the foundation needs protection along the entire perimeter of the house, it is logical that the blind area should also completely surround the building. The only exception may be the installation site of a concrete porch;
- depth or level of penetration of the blind area should not exceed half of the calculated depth of soil freezing characteristic of a particular region. This parameter can be viewed in the table or you can request information from the architecture department at the location of the object.
The ability of a concrete blind area to move with the soil gives it its functions. Otherwise, its role will be reduced to draining water, which is not enough to protect the foundation.
Note. The depth of freezing is affected by the presence of communications in the ground.
- concrete blind area thickness. The minimum thickness of the surface layer is 70-100 mm. If increased operational load is planned, for example, car movement, the thickness can reach up to 150 mm;
- slope of the blind area. SNiP III-10-75 recommends what the slope should be - from 10 to 100 mm per 1 meter of width (i.e. 1-10%). The angle of inclination is directed in the direction opposite to the foundation of the house. Slope requirements depend on regional rainfall levels and soil type. In practice, the slope is taken to be 20-30 mm per 1 m (2-3 degrees). If you do more, then in case of icing, it will be difficult to move along such a blind area;
- border. In the case of a blind area, the border is a decorative element and the decision to install it is made based on the preferences of the home owner and his financial capabilities. However, if bushes are planted in the immediate vicinity of the blind area - “root aggressors” (raspberries, blackberries) or trees that have a powerful superficial root system (poplar, sycamore), then installing a limiter is mandatory;
- plinth height. The standards establish a minimum plinth height of 500 mm for a hard type blind area and a minimum of 300 mm for a soft type. Let us remind you that the blind area around a concrete house is of the rigid type;
- height of the blind area from ground level. It is desirable that the blind area be 50 mm higher above the ground level. This recommendation is due to the fact that water should not accumulate on the edge of the blind area and turn into puddles. In winter, this is fraught with freezing and, accordingly, destruction of the structure.
- concrete blind area design has a specific device diagram, which is shown in the drawing below.
Armed with the above data, you can proceed directly to the installation of a concrete foundation blind area.
How to make a concrete blind area around a house
Preparation of material:
- concrete for blind area. Grade is an indicator of the quality of concrete; its value ranges from 100 to 1000. It indicates the proportion of cement content in concrete. The concrete class ranges from B3.5 to B8 and indicates the strength of concrete. Thus, class B 15 indicates that a concrete cube measuring 15x15x15 cm is capable of withstanding a pressure of 15 MPa.
What brand of concrete is needed for the blind area? To prepare the solution, use cement grade M 200 (class B15).
The parameters (properties) of concrete depending on the brand are shown in the table.
- sand. Which one do you need? For the bottom layer of the pillow, river or quarry sand. The main thing is that it does not contain large impurities that can damage geotextiles;
- crushed stone (gravel). Crushed stone of fraction 10-20 is suitable for the blind area;
- clay or geotexil for hydraulic locking. In practice, this layer is absent in the base cushion, because concrete drains water well;
- cement for ironing.
Composition of concrete mortar for blind area
If it is not possible to use ready-made concrete, you can mix it yourself. To do this you need to prepare:
- cement for blind area. You should know that the grade of concrete is determined by the grade of cement and its specific gravity as a percentage of the components of the solution. For the blind area, cement M400 Portland cement is used. The cement must be fresh; with each month of storage it loses 5% of its properties. It’s easy to check the freshness; just squeeze a little cement in your fist; if it shrinks into a lump, its shelf life is running out; if it crumbles freely, you can work with it;
Note. What cement is best for blind areas? Naturally fresh and of high quality. This will save on cement consumption and prepare a good concrete solution.
- sand. To prepare concrete, you need to take concrete that has been sifted and washed to remove impurities and soil;
- crushed stone It is advisable to use crushed stone of a fraction of 5-10 mm. At the same time, crushed stone is better than, for example, small pebbles;
- water. Should be at room temperature;
- additives. They are needed to give concrete frost-resistant properties. Often used as a supplement liquid glass.
The tools you will need are a concrete mixer or a mixing container, a shovel, a bucket (it’s better to take a plastic one, it’s easier to clean), a measuring container (for water), a hand-tamping log or a vibrating plate.
Preparation of concrete mortar for blind area
In practice, the solution for the blind area is prepared in portions, after all preparatory work. We will provide a ready-made recipe for cement mortar and how to mix it correctly.
The composition of the concrete solution includes: cement, crushed stone, sand, water and various additives that increase its strength. The durability and strength of the blind area depends on the ratio (proportions) of these components.
Note. Components are measured by weight only.
Proportions of solution for blind area
Note. 1 cubic meter of sand is on average equal to 1600 kg, 1 cubic meter of crushed stone is on average equal to 1500 kg.
Depending on the brand of concrete, the proportions will differ. SNiP 82-02-95 regulates the composition of the mixture for producing concrete of a certain grade.
The concrete mixture is very demanding on the amount of water supplied. Its excess reduces the strength of concrete, because removes cement flour to the top layer of the solution. This leads to the fact that the strength is distributed unevenly. In practice, it is calculated that water should be approximately half the amount of cement. More accurate data is contained in the table (water-cement ratio (W/C) for concrete).
The order in which the components are added to the solution also matters. Cement is first poured into a mixing container or concrete mixer and water is added. By mixing, the so-called cement laitance is obtained. Next, the remaining components are added to it. First, sand is poured in small portions, and then crushed stone (gravel).
Note. Professionals advise maintaining an interval of 5 minutes. between feeding components. This way the mixture mixes better.
Technology for constructing a blind area made of concrete with insulation
Step-by-step instruction:
Preparing the base for the blind area. To do this, the top layer of soil is removed, all roots, stones, etc. are removed. Using a blanket herbicide will eliminate activity under the substrate. For example, the drugs Agrokiller or Tornado.
Advice. Considering that the blind area must exceed the edge of the roof slope by 200 mm, it is recommended to use a plumb line to accurately mark the boundary of the blind area.
Marking. To do this, we pull the rope onto the stakes hammered in the corners. To avoid sagging of the rope, you need to install intermediate stakes (at a distance of 5-6 m from each other).
Advice. How to determine the required angle of inclination of the blind area? Craftsmen install additional beacons (stretch a rope) on the base of the house. Fastening is done every 1-1.5 meters.
Hydraulic lock device. To do this, lay fatty clay in a layer of 100-150 mm or cover the bottom with geotextiles (roofing felt, PVC film, advertising banner, etc.). Please note that to prevent the film from tearing, it is better to pour a layer of sand of 50-100 mm at the bottom of the trench. A layer of sand of the same thickness is also poured on top of the film. The sand is leveled, moistened and compacted. In the case of a clay hydraulic lock, there is only one sand layer. When laying the film, you should avoid tension. It must be able to move freely with the ground.
Note. Experts advise making high-quality drainage near the hydraulic lock. To do this, you need to dig a trench 100 mm deep and 200 mm wide and fill it with crushed stone or lay a drainage pipe in it, wrap it with geotextile and fill it with crushed stone. This will increase the rate of water drainage.
It is worth noting that many people ignore this stage of work. In practice, this attitude results in the fact that the water passing through the expansion joint goes directly under the foundation, and when it freezes, it leads to an increase in pressure on it.
Backfilling of crushed stone. The layer thickness varies from 50 to 100 mm. The gravel is leveled and compacted. Since crushed stone is difficult to compact, some recommend using a special grid for laying it, which is used in landscape design for the construction of gravel paths. We note right away that this will increase the cost of the blind area without much need.
Backfilling with sand.
Laying communication pipes. To do this, make a depression in the sand for pipes and storm drains.
Insulation of the blind area. Expanded polystyrene or penoplex is laid on the compacted sand with which crushed stone and communications are covered. Only hard insulation is suitable for the blind area, but it is afraid of point loads, so it must be laid on a sand cushion.
Advice. Cold bridges can be eliminated by laying insulation in two offset layers.
Reinforcement of concrete blind area. This is done by laying reinforcement mesh with cells of 50x50 or 100x100 mm or by knitting a reinforcement cage.
Advice. Chain-link mesh is not suitable for reinforcement - it is too flexible.
If insulation is not intended, the reinforcing mesh is laid directly on the crushed stone to a height of 20-30 mm. Which will contribute to better distribution of concrete.
Formwork installation. Boards or plywood are installed strictly according to level. To level out the pushing force of concrete, the formwork is reinforced with stakes that are installed on its outer side. During installation, do not forget that the formwork is removable, which means that all seams will be visible after its dismantling. In this case, the blind area will have an ugly appearance. Therefore, when installing boards, you need to ensure that internal seams were invisible.
Construction of expansion joints. To do this, we install wooden slats and boards (on edge), which are pre-treated with an antiseptic or tarred. The recommended distance between the expansion joints of the blind area is 2-2.5 meters. Expansion joints must be made diagonally in the place where the formwork turns (at the corners). The purpose of the expansion joint is to compensate for the thermal expansion of concrete during operation. They are installed level, taking into account the angle of inclination of the formwork, because When pouring concrete, they are guided by them. An alternative to wood can be Guerlain butyl rubber tapes (10 RUR/m) or a hydro-swelling elastic cord, for example, Penebar Rapid SW45 A/B.
How to seal the seams in the blind area?
According to reviews, those who ignored the formation of expansion joints had cracks after the first winter. Many people believe that wood swells and allows moisture to pass through. You can seal the resulting cracks with special sealants, such as TEKTOR 103 mastic (225 rubles/piece), ISOSEAL P-40 (280 rubles/piece).
Pouring a concrete blind area. When pouring concrete, you need to ensure that no air pockets are formed and that the cement mixture evenly fills the entire space. It is important that no bumps or depressions appear when pouring. Their presence will lead to stagnation of water in these places. If it is not possible to do the entire blind area at one time, part of it is poured, and then work is resumed.
Advice. When pouring a blind area, you can use a technique for uniform distribution of concrete - bayoneting. To do this, the concrete is “pierced” with a rod, and the solution fills the entire space.
How to properly pour a concrete blind area around a house - video
Protection of concrete blind area from destruction
Many people are interested in how to cover the concrete blind area around the house. After all, after pouring the solution, the blind area must be protected from heaving, deformation, destruction, and exposure to moisture, rain, and snow. Let's consider how and what is the best way to do this.
Ways to protect the foundation blind area:
Ironing of concrete blind area around the house
How to iron a blind area with your own hands?
- Dry ironing method - freshly poured concrete is sprinkled with a layer of cement (2 mm) followed by grouting. Dry cement binds to the concrete mortar and increases its ability to withstand the effects of water.
- Wet ironing method - 12-14 days after pouring (when the concrete has dried), you need to walk over the surface of the blind area with a cement-sand mortar (1:1) with the addition of lime paste (10% of the volume of the mixture).
Coating the blind area with a primer
Primers are suitable for this deep penetration, such as AURA Unigrund KRAFT (90 rubles). Primer solutions are used when additional finishing is planned. For example, tiling or painting. If this is not in the plans, it is better to use a water repellent, for example, Eskaro Aquastop Waterproof W (1200 rubles) or GKZh-11 (195 rubles/5 l). Concrete hardeners such as Monopol 1 (1,600 rubles/5 kg), Monolit-20M (1,200 rubles/10 l), Protexil (3,600 rubles/20 l) or Ashford Formula ($120/10 l) are gaining popularity.
Protecting the blind area with liquid glass
A solution of liquid glass and cement is a more budget option protective composition(primer, water repellent), providing a similar result. A solution with liquid glass is prepared from a mixture of cement, water and liquid glass in a proportion (ratio) of 1:1:1.
Covering the blind area with a layer of enamel
The enamel must match certain parameters in terms of frost resistance, vapor permeability, moisture resistance, and environmental friendliness. Polyurethane enamel ELAKOR-PU (220 rubles/kg) has proven itself to be excellent.
Covering the blind area with tiles and stones
Lay tiles (ceramic, clinker, paving), pebbles or a natural stone. In this case, concrete acts as a binding solution.
- It is advisable to install a storm drain near the blind area, which will drain the flowing water and prevent siltation of the area;
- To ensure uniform drying of the poured concrete, the blind area is covered with film. Thus, evaporated moisture will be retained on its surface. Since it is difficult to cover a wide blind area with film, it can be periodically moistened. The time until complete hardening with a blind area thickness of 100 mm is 1.5-2 weeks;
- After the concrete has completely dried, the blind area is removed. You should be careful here, because... Removing the blind area can lead to damage to the edges of the blind area.
This order of work and taking into account all these nuances guarantees the long-term full functioning of the concrete blind area.
Do-it-yourself concrete blind area around the house repair
The most common problems include:
The appearance of cracks in the blind area
How to repair cracks in the blind area?
Elimination depends on the depth of the damage (cracks, crevices, concrete breaks):
- no more than 1 mm. Self-healing is used. Such a crack is not dangerous and is usually rubbed away by friction during walking;
- no more than 3 mm. Involves the use of “cement dough”. Shallow cracks can be sealed (filled) with a liquid cement solution (1 part cement to 1 part water);
- 3-30 mm. Such cracks are considered large. To eliminate them, you can use a special sealant such as the above-mentioned TEKTOR 103, ISOSEAL P-40. You can seal the crack with freshly prepared concrete mortar. However, before this the crack needs to be widened. In cross section it should resemble a cone. Apply primer over the entire area of the crack. Any will do, for example, Ceresit ST-17 (450-500 rubles/10 l). Next, the solution is poured. You can use the so-called hydroseal, a special cement-based solution that hardens in 15 minutes. An example is Lugato 5-Minuten Mortel putty (410 RUR 5 kg)
- crack depth exceeding half the thickness of the blind area, this is already a cracking of concrete and refers to significant damage. It can only be eliminated by expansion followed by pouring new concrete.
Delamination of the surface of the blind area over the entire area
In the language of masters, this process is called concrete dusting or delamination (delamination). The reason for this phenomenon may be several factors. For example, uneven hardening of concrete happens if you pour concrete mortar onto a cold surface (observed when working in early spring) or make the blind area thicker. Increased air content in the concrete mixture. Excess of crushed stone parts in the concrete composition.
What to do if the concrete blind area crumbles?
If the process is just beginning, then the surface should be covered with “cement paste” or a composition that contains liquid glass (proportions: cement, water and liquid glass - 1: 1: 1).
If the damage has reached significant proportions, then radical measures must be taken:
- determine the boundaries of the damage to prevent its spread;
- cut out part of the concrete;
- cover the edges of the blind area with a primer;
- apply a new layer of solution;
- cover with film until completely dry.
If you start it, you will have to completely dismantle the blind area and fill in a new one. The measures described above will help extend the life of the blind area and save on alterations and reconstruction.
The cost of installing a concrete blind area without material
And the last thing that interests everyone who wants to order the construction of a blind area is the prices for a concrete blind area. If you entrust the work to craftsmen, then the estimate must contain the costs of the work, which are presented in the table (approximate data as of the end of 2015)
| Service - work on the blind area of a private house | Doing the work yourself | The cost of a master’s work per sq. m. |
| Material price | We do not take into account, because the cost will be the same | |
| Removing the old blind area (dismantling) | 0 | 65 |
| Marking and excavation (depth 600 mm) | 0 | 300 |
| Hydraulic lock made of clay | 0 | 100 |
| Laying film or geotextile | 0 | 40 |
| Backfilling the sand layer + tamping (5 mm.) | 0 | 80 |
| Formation of crushed stone layer (100 mm) | 0 | 80 |
| Installation of a storm drain | 0 | 250 |
| Pipe laying (per m.p.) | 0 | 50 |
| Construction of a concrete blind area (ready-made concrete) | 0 | 300 |
| Construction of a concrete blind area (mixing concrete) | 0 | 650 |
| Total | Saving | About 1200-1400 rubles |
Please note that it is unlikely that you will be able to negotiate a significant discount here. After all, this price does not take into account the cost of materials. For a complete picture, we recommend that you familiarize yourself with the cost of materials for the production of a concrete blind area per 1 m.
Conclusion
Agree, it’s a good incentive to make a concrete blind area with your own hands. Moreover, from the given instructions it is clear that this work does not require special tools, any special materials, only the desire to protect the foundation of the house with a reliable barrier.
