When replacing the flooring, apartment owners often have to deal with the need to repair a concrete floor, which can be either a concrete screed or the floor slab itself. Despite the fact that concrete is a durable and reliable material, under the influence of various factors, potholes and cracks may appear on it. Timely measures are necessary to prevent further destruction, because the service life of the finish floor depends on the condition of the concrete base. We will find out how to repair a concrete coating using special mixtures for repairing a concrete floor.
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Causes of defects on concrete
Defects on the concrete floor can be formed for various reasons, which are primarily associated with violations in the process of its arrangement.
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Cracks often appear due to the absence, untimely cutting or incorrect calculation of the thickness of the joints in concrete floors, designed to prevent concrete stress during thermal expansion and during shrinkage. Properly made temperature-shrink seam will avoid many problems.
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Other causes of cracking include:
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- a large amount of water in the solution when pouring a concrete screed or its lack,
- poor-quality reinforcement,
- lack of waterproofing the base.
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Defects can form even with a job well done. Any coating is subject to natural wear and tear, it is adversely affected by excess moisture. Potholes appear due to physical influences. The influence of external factors on the concrete floor cannot be ruled out. The weak point is the joint of the wall and the floor, cracks often appear there.
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It is necessary to determine the type of damage. This will allow you to draw up a work plan and choose the right material. Often faced with the following varieties:
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- small indentations, potholes,
- cracks of various sizes,
- the finest cracks and chips.
Repair should not be postponed for a long time. The size of the defects can gradually increase, the concrete will begin to crumble and move away in pieces, which will complicate the sealing of problem areas.
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The choice of mixture for the repair of concrete surfaces
Before you start repairing the floor in the apartment yourself, you need to prepare a mixture for the restoration of concrete surfaces and structures. In construction stores, they are represented in large numbers. In order to correctly choose the brand of the mixture, you need to determine the degree of damage to the concrete surface:
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- The first degree - there are shells, shrinkage cracks.
- The second degree is peeling of the surface, small chips.
- The third degree - cracks within 2 mm with a depth of not more than 40 mm.
- The fourth degree - cracks more than 2 mm, depth up to 10 cm.
- Fifth degree - large potholes and cracks, depth more than 20 cm.
The purpose of the repair mixture should be indicated on the packaging. Noteworthy are such manufacturers of concrete restoration mixtures as Emaco, Birss, Ceresit, Bars.
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You can use universal repair mixtures, such as Ivsil Render.
Since the price of special thixotropic compositions containing reinforcing microfibers and polymers is quite high, for a small amount of work, the mixture can be prepared independently. For this, 1 part of PVA glue is taken and mixed with 4 parts of water. In this solution, using a construction mixer or a special nozzle on a drill, a sand-cement mixture is mixed in a ratio of 1: 3.
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After selecting a material for the repair of concrete floors, repair should begin. Initially, the preparatory phase:
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- All foreign objects are taken out of the room.
- Existing rubbish, concrete chips and dust are swept away. Potholes and cracks are thoroughly cleaned with a vacuum cleaner.
- Any dirt, rust, mold or old soil is removed with a hard metal brush.
- To eliminate greasy stains, you need to use a special solution.
- The concrete floor is swept with a wet broom, then it needs to be dried.
- If the reinforcement is visible, then it should be cleaned with sandpaper and primed with a composition with anti-corrosion properties.
Areas of concrete surfaces that have lost strength should be tapped with a hammer and cleaned. The rule applies to the edges of problem areas.
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Potholes in concrete floor
Repair of concrete floors begins with the expansion and deepening of the pothole along the perimeter. It is better to use a grinder with a diamond disk.
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- Propyl is made 1 cm deeper than the defect. In the direction of the pothole expands by 2-3 cm. If necessary, these indicators increase.
- With the help of a puncher or a hammer with a chisel, a recess is made at the place of the pothole, a rectangular recess should be obtained. If a puncher is used, then it is better for outsiders to move away.
- The recess is thoroughly cleaned with a vacuum cleaner and primed.
- Potholes can be closed after the soil has dried. The mixture is carefully leveled, it is pierced several times to remove air. You can use a metal pin or trowel. Level the surface using a rule.
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The depth of the pothole matters. If it is more than 5-6 cm, then the composition is poured into several layers. The maximum layer thickness is 2 cm.
Work is recommended in a respirator, goggles and gloves. Windows in the repair process must be open. The floor can be coated with concrete paint, which will provide additional protection. It is selected specifically for residential premises. A floor repaired in this way will last a long time.
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Crack Repair Rules
The process of closing cracks in a concrete floor differs depending on their size.
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- Small slots expand in depth and width by 2–5 cm. To do this, you can use a chisel or grinder.
- The recess is cleaned of pieces of concrete and dust, then treated with a primer.
- To repair cracks in the concrete floor, a homemade PVA-based mixture is used. They fill the crack and wait for shrinkage.
- The second layer is coated, dried and ground.
In those cases when the cut is accompanied by strong dusting, which indicates that the concrete is weakened, it is necessary to use only special thixotropic compounds.
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Crack repair in concrete floors should not be delayed for long. If they are deformation, then they need to be treated with special attention. You can determine their appearance using strips of paper. A few months before the repair, they are glued to cracks in the concrete floor. With shrinkage cracks, the paper remains intact, with deformation strips tear, which indicates their expansion.
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- Such a crack is sawn 5 cm deep and 3 cm wide.
- The edges of the cut are knocked down, a triangular recess is formed.
- After thorough cleaning, the recess is primed.
- Markers are inserted into the crack with a step of 3 m.
Markers are thin, smooth metal rods. You can make them yourself from the spokes of the bicycle wheel.
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Some notice small cracks in the cobwebs on the floor, as in the following photo. Over time, they can become wider. When concrete weakens in this part, they are cleaned and covered with soil. To seal, you can prepare your own composition or use the store.
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To ensure that the furniture is level after repairing the concrete floor in the apartment, it is necessary to use the building level throughout the process.
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Overhaul of concrete floor: cost
In case of severe damage to the concrete pavement or during the installation of the “warm floor” system, it will be necessary to carry out major repairs - a complete replacement of the concrete screed. When contacting specialists, this procedure, taking into account the materials, will cost the following amount:
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- in Moscow - from 420 rubles / m2,
- in St. Petersburg - from 380 rubles / m2.
Dismantling the old concrete screed is not included in this amount, the price depends on the area of work: the larger it is, the cheaper.
How to repair concrete
A few years after the creation of concrete coatings, their surface may begin to dust and crack. For whatever reason this happens, you will need to repair the concrete to prevent further damage and restore the surface to its former strength. Meet the problem fully equipped will help familiarity with the recommendations for the repair of concrete, which are willingly shared by professional builders.
Why concrete breaks down
The causes of cracking and increased dust formation can be different.
- Most often found:
- use of the wrong grade of concrete mortar,
- violation of styling technology (insufficient compaction, lack of care, attempts to walk or ride on a mixture that has not yet hardened),
- the influence of adverse factors (freezing and thawing, the action of moisture, acids or alkalis, increased loads),
- mechanical damage,
- reinforcement corrosion
Destruction of concrete can occur both inside and outside the premises, on horizontal, inclined and vertical surfaces. Stairs, car areas, fences, and other items can become unusable if cracks are not repaired on time.
Preparation for restoration
The first thing that experts recommend is to assess the scale of the damage. Carefully inspect the surface, remove chipping small parts and loose layer. The task is to get to a durable healthy layer and remove impurities: dirt, dust, coatings. If cracks reach the reinforcement, gently clean it from corrosion and treat it with anti-corrosion compounds.
Cracks are recommended to be slightly expanded to remove a loose layer of concrete from the edges. Ideally, their shape is adjusted to an inverted Latin letter V. This guarantees a better restoration of the surface. Next, the damaged area must be subjected to three more operations:
- primer with liquid mixtures with a high adhesive content.
It is important to consider that the primer is made only in warm weather, in the cold this operation can be skipped.
How to repair the coating
In most cases, concrete walls, cracks and screeds can be repaired with concrete mixtures. They are divided into two types:
- injection molding (for horizontal sections),
- thixotropic (when using them, you can do without formwork).
When choosing the type and composition of the mortar, you need to take into account the brand of concrete that you are going to restore, as well as the operating conditions of the coating. When repairing small areas of concrete coatings and structures, ready-made mixtures can be used. They include polymer fiber, moisture-resistant cement and fine-grained filler. Most of the finished compounds are non-shrink type.
If you have to repair a large area, it is worth using a reinforcing mesh. It will further strengthen the structure and prevent further destruction of the concrete coating. The fittings are mounted on dowels. In addition, with serious amounts of work (for example, restoration of a concrete pool, foundation, fence of a network of paths in the garden) it makes sense to order ready-made concrete mixes. About the composition of concrete for repair and calculation of its volume for restoration, you can consult with specialists of the company "Eurobeton".
Getting to work
It is not necessary to wait for the primer to dry. The first to close the cracks, trying to fill them as carefully as possible. Then you need to take a small spatula and evenly distribute a small amount of solution over the entire surface of the prepared base.
The main layer is applied with a rectangular trowel, carefully pressing it to the surface. After 20-30 minutes, when the concrete begins to set, the surface is leveled. At this stage, it is convenient to form volumetric parts (corners, ledges), as well as to give the tracks anti-slip properties using small pebbles buried in the surface layer. The restored surface must be covered with a damp dense cloth or film, and at a negative temperature - insulated with rags. This will provide favorable conditions for the setting and final hardening of concrete.
Compliance with the recommendations for the repair will fully restore the properties of the walls, platforms, stairs or other concrete structures. And as preventive measures, it is possible to recommend the use of impregnations that increase the water resistance and strength of artificial stone.
Why do concrete defects appear?
The reasons that reduce the reliability and service life of concrete products are many. The most significant factors are:
- Incorrect design calculation
- Installation errors,
- Exposure to chemicals
- The influence of extreme temperatures,
- Mechanical damage.
All these effects can be divided into two main groups: factors that destroy the material by physical action and those that affect the composition of concrete. Of course, before taking measures to restore the product, it is worthwhile to determine the cause that led to the problem and, if possible, eliminate it or reduce the level of its effect on the material. This can be waterproofing, creating a cushioning layer, a change in the design and location of the concrete element. Having performed such work, you will get rid of the need to soon again resort to the correction of defects and maintain an attractive surface.
1. We repair concrete steps
Concrete steps are very common, and in some cases their appearance does not play a big role. But if these structural elements are part of the porch of a house or office, then the daily contemplation of jagged edges and cracks is unlikely to please you and your guests. An excellent solution to the problem, with relatively small defects, can be polymer resins for the repair of concrete and cement screeds, such as the Belarusian Silikal. Resins of this type can be applied to the cleaned concrete surface with a layer of up to 5 mm, which is enough to seal chips and cracks, as well as to restore slightly lost geometric shape ribs.
But in cases where the damage to the stage is more widespread and it is necessary to correct large flaws, it is better to use radical methods. The simplest and most elegant of them can be called the facing of the concrete staircase that has lost its attractiveness with ceramic floor tiles. This repair method will not only make the steps aesthetic, but also help protect them from external influences in the future.
A more troublesome way is to restore the geometry by pouring concrete. In this case, it is necessary to expose the formwork and reinforce the places that will be filled with steel wire, firmly fixing it in the holes drilled in concrete. A high-quality restoration will return the stairs to their original appearance and they will serve for a very long time.
2. Restoring the concrete alley
Of all the materials common today, concrete is best suited for arranging garden paths, alleys and sidewalks. Not too decorative appearance of the coating in this case is offset by high strength and its simple maintenance. But damage to concrete malls is not uncommon. Shrinkage cracks and delamination of surface areas are most often the result of a violation of technology in the manufacture of concrete mix and its laying. Fortunately, track repair can be done on their own using special solutions made by domestic and foreign manufacturers or even with their own hands.
The materials used in repairs of this type are divided into two categories:
Bulk mixtures are used to restore the surface in case of large-scale damage or if it is necessary to eliminate irregularities in large areas. The composition of these products includes non-shrink types of cements, as well as polymer additives. The manufacture of bulk compositions is a complex technological process and it is better to purchase them in specialized stores.
Thixotropic repair materials are used to restore local areas of the coating. They have high viscosity and excellent adhesion to concrete. There are many varieties of these solutions, which may include cement, polymers, and epoxies. You can make a simple thixotropic solution yourself. To do this, use the following components:
- A solution of PVA glue in water in a ratio of 1 to 3,
- 1 part cement
- Fine river sand - 4 parts.
First, a cement-sand mixture is prepared, into which, with constant stirring, a water-glue suspension is added. For mixing, it is better to use the mixer nozzle on the drill - this will significantly speed up the process and prepare a bucket of the solution in less than 5 minutes. Состав не следует делать слишком жидким – идеальная консистенция его должна быть как у средней густоты сметаны.
Перед тем как приступить к ремонту, нужно подготовить бетонную поверхность. Для этого из трещин извлекают мусор, пыль и осколки материала. A stiff brush and a powerful vacuum cleaner can help in this matter. When cleaning, you need to monitor the edges of cracks and chips and, if you suspect their low strength, broaden the edges with a grinder and a diamond wheel. If the defect depth is more than 50 mm, it is necessary to perform additional reinforcement using a rust-free steel wire. In the manufacture of frames, it must be remembered that the protective layer of the solution above the reinforcement should be at least 20 mm.
To seal cracks and chips, the thixotropic composition is put on a grater or putty knife and pressed into the recess. Do not try to fill the crack immediately, as this is fraught with the appearance of voids in the recess. It is better to lay the solution in several penetrations, 15-25 mm at a time. The polymerization time of an industrial compound is usually indicated on the package. When working with self-created compounds, you will have to determine the degree of setting visually or tactilely. After the repair mortar has set, it is carefully leveled with a spatula.
After completion of work, care must be taken to ensure that the restored surface retains moisture for 2–3 days. This is especially important in the summer heat and neglecting this rule, you can get a lot of thin cracks on the surface, which will again turn into defects over time.
3. Restoring a concrete countertop
Concrete worktops are rarely found in the homes and apartments of our fellow citizens. But very often such products can be found on garden tables and market stalls. Small damage to the surface does not affect its operational properties too seriously, but, unfortunately, under the influence of external factors, they can turn into deep defects and cracks. In addition, damage makes the product unattractive and contributes to delays on its surface of dirt and the growth of microorganisms.
The easiest way to restore concrete worktops is to carefully grind them using an electric hand grinder. This work must be done with goggles, a respirator, gloves and protective clothing. Grinding begins with the processing of the largest abrasive nozzles, gradually reducing the grain size to achieve a perfectly smooth surface. This procedure is quite “dirty”, therefore, if possible, it is better to produce it away from home.
After the surface has acquired the proper smoothness, it can be polished using mastics designed for working with natural and artificial stone.
4. We restore expansion (deformation) seams
Professional builders are well aware of how important expansion joints are in the construction of roads and concrete malls. The task of these structural elements is to compensate for the stresses that occur during the thermal expansion of the material. Over time, the edges of the seams begin to collapse and this process can only be stopped by radical intervention. The best way to avoid breaking the joint is to seal it. Since these coating elements must fulfill their functions, materials with sufficient elasticity are used for sealing. For such work, polyurethane sealants are ideally suited, which are commercially available in a tube form for use with a construction gun.
Before starting work, expansion joints must be thoroughly cleaned of contaminants to the entire available depth and must be removed from dust. Polyurethane sealant is placed in the gaps at a temperature of +10 to +25 degrees Celsius, while the air humidity should not exceed 80%, and the humidity of the concrete surface - 4%. Since polyurethane compounds have a strong odor, ventilation must be taken into account if work is carried out indoors or respiratory protection if sealing is performed outdoors.
In some cases, the linear dimensions of the joints and their number may require the use of a large amount of sealant, which leads to serious financial costs. Avoid significant cost increases by using special sealing cords, such as Vilaterm. These products are produced specifically for laying in expansion joints and can be purchased at many hardware stores. The cord is selected so that it is in the seam compressed, about 25%. When using this technology of filling the seam, it is allowed to apply sealant with a thickness of only 5 mm, which contributes to significant savings.
5. Basement Wall Repair
Many residential buildings and industrial premises have basement floors and basements, the walls of which are made of monolithic concrete or concrete blocks. Under the influence of external soil pressure, aggressive chemicals and other factors, these critical building envelopes begin to become cracked. If you do not pay attention to this phenomenon, then the destruction process may go too far and the help of professional builders will be required, therefore it is easier to eliminate defects as soon as they were noticed.
Repair of concrete walls located indoors is carried out using building mixtures, which include cement, fine aggregate, polymer additives and fiber. It is not difficult to purchase such materials, but it is more profitable to make them yourself. The simplest solution for repairing concrete structures at home is to include the following ingredients:
- Quartz sand,
- Ground limestone
- Fine gravel
- Polypropylene fiber
The preparation of the mixture begins by mixing the dry components and only then gradually add water to the resulting composition with continuous stirring. As always, the best assistant in this matter will be a mixer nozzle for a drill or perforator.
Before closing the cracks, the base is prepared by cleaning the voids from splinters, debris and dust. Before applying the solution, the damaged areas are primed using primers with high adhesive characteristics. The repair mixture is applied with trowels making sure that it penetrates into the cracks as deep as possible. After 20-40 minutes after filling the cracks, the solution needs to be smoothed with a grater. If an angle is located at the restoration site, then it must be formed at the same time as smoothing the surface.
The above methods for repairing concrete products are far from the only ones. But, despite this, owning these five technologies, you can effectively repair concrete surfaces at home, in the country or in a production workshop.