Many homeowners are interested in how to repair cracks in concrete, as this is a fairly common problem for cottages and country houses.

Concrete is used in different areas– for pouring floors of apartments and houses, production premises, roads, for the construction of the foundation.

This material is weak in tensile strength; during the drying process, concrete structures narrow, which can cause various defects and openings to appear.

This is especially true for concrete floors or foundations.

In addition, cracks often appear due to corrosion of metal reinforcement, temperature instability, and various negative influences.

This defect is very dangerous and common, and in order to solve the problem, you need to know why it occurs, what are the reasons for its disclosure.

Experts identify the following causes of cracks in concrete:

• Violation of the mixture production technology at the plant, when the ratio of water and cement is violated.
• Because of this, the brand of the composition does not correspond to the specified one. In addition, long-term transportation leads to “welding” of the concrete;
• Errors in calculations are also common causes of cracks. Insufficient reinforcement or heavy loads damage the integrity of the concrete pavement. It is very important to adhere to SNiP standards when making all calculations;
• Difficult geological conditions. The calculations do not always take into account the soil characteristics of the area;
• Incorrect mixture technology when laying. Often, in order to make the composition easier to lay, it is diluted with water, which prevents the concrete from gaining strength. In addition, improper compaction of concrete and dismantling of formwork, as well as neglect of the rules for laying reinforcement according to SNiP standards, will subsequently lead to concrete sagging and the formation of cracks;
• Violation of the rules for caring for freshly laid concrete, especially when laying in hot weather, when moisture evaporates from the coating too quickly;
• Construction of various objects that were not taken into account in advance in the calculations;
• It is not always possible to choose the right type of foundation according to SNiP rules, which is why deflections and cracks may also occur during the operation of the building;
• One more common cause The formation of cracks is the rusting of the reinforcement, as a result of which the volume of metal becomes larger and breaks the concrete coating from the inside.

To know how to repair cracks in concrete, you must first determine what type it belongs to:

• Through cracks occur due to tensile forces;
• Surface cracks appear after the concrete has dried due to a violation of the mortar formulation;
• Cracks in the tension zone appear during bending and are directed transversely to the reinforcing bars;
• Cracks located at an angle to the reinforcement, which occur under the influence of shear force;
• Shrinkage cracks parallel to the reinforcement, which arise due to soil heaving, uneven shrinkage or improper anchoring. Due to such cracks, shrinkage and deformation of the foundation and the entire building occurs. Shrinkage cracks can also appear if the load calculation was not made according to the rules of SNiP;
• Small cracks that appear due to temperature changes;
• Hairline cracks occur for the same reason as the previous ones, but usually their depth does not exceed a few millimeters.

Having determined the causes and types of cracks, the type of repair work is determined.

Repair with cement mortar and mixtures

This filling of cracks does not seal them, but protects them from contamination for a while and prevents their further opening for a short time.

Repairs begin according to SNiP rules with the preparation of the opening itself.

It should be checked for chips, as other cracks and openings may form in them in the future. Use a chisel to run along the entire length of the crack to make it wider.

Hidden chips that appear during work should be removed immediately.

Using a spatula, you should also deepen the crack to 5 mm so that the solution holds more firmly.

For repairs, make a solution of 3 parts sand and 1 part cement, to which you also need to add PVA glue. The solution should be thick enough.

Pour it into the crack with a trowel and moisten it on top. If you carry out repairs using a polymer mixture rather than using a concrete solution, you do not need to wet the composition.

Medium cracks usually show reinforcement and need to be cleaned and coated special means which will prevent corrosion. Next, you need to make grooves and place 4 mm pieces of reinforcement in them.

Now we apply the adhesive composition evenly over the entire surface so that the layer thickness is about 3 mm, and without waiting for it to dry, you need to fill it all with the solution.

The solution must be compacted so that it gets into all the recesses and irregularities, and the surface must be leveled with a wooden strip, which must be moved along the surface of the solution to the right and left and towards you.

If the gap is very deep, it is advisable to lay the solution in several passes. At each stage, the surface should be sprayed with a little water.

A special metal trowel will help make the concrete surface perfectly smooth. When the solution has hardened, the excess must be removed with a spatula.

If you paint or cover the concrete surface with a laminate, then such work can be done within a day after the repair is made, but you should wait longer to lay the tiles.

It is important to know that after drying the solution shrinks, so the filling compound is laid slightly above the floor level, and after drying it will fall into place.

If this still does not happen, use grinder the surface of the former crack is leveled to the required level.

If you are dealing with a crack whose width and length are quite large, you can treat it before repair with a circular saw with diamond blade, after which the repair is carried out according to the scheme described above.

This method of sealing is most often used as a temporary solution, since sealing does not occur during such repairs.

The method is relevant both for dry and for rooms with high humidity where good waterproofing is required.

Repair with elastic sealant

An elastic sealant can also help seal cracks.

Most popular in in this case is a silicone adhesive sealant. This sealant is used both for small cracks and for those whose width is quite large.

The repair process that requires the use of a sealant is no different from a repair that uses a concrete compound.

First you need to clean the crack from dirt, make grooves for better bonding of the material to the surface. When applying glue/sealant to the surface, it must also be moistened.

The sealant, unlike the cement mixture, dries in short terms, which makes this material much more convenient.

However, the sealant is noticeably more expensive, so not everyone can afford such repairs.

Repair with epoxy resin

Epoxy resin and epoxy repair compound are also used to seal cracks in concrete.

First you need to open up the opening and remove loose concrete and chips. The width of the groove should be no more than 25 mm and no less than 4 mm.

Every 400 mm along the crack you need to make transverse grooves 150 mm long. Using a vacuum cleaner, collect all debris and dust and treat the seams with a primer.

Metal brackets for reinforcement are placed in the transverse grooves that were made earlier. Next, according to the instructions, dilute the epoxy solution and add a hardener to it.

Sand is also poured into the epoxy solution and the mixture is poured into the furrows.

The epoxy solution is sprinkled with sand on top, and after an hour the sand is removed with a vacuum cleaner.

Repairing a crack in concrete with epoxy resin is quite economical and takes very little time to dry. In addition, this treatment of cracks prevents their further movement.

It can be used for dry screed.

If you need to apply an epoxy resin coating to a liquid environment, you do not need to add sand to the mixture. You should also not sprinkle sand on top.

Repair with cords and tapes

If you need to cover up cracks in a swimming pool or water tank, in an underground section of the foundation or on the external walls of a building where high-quality waterproofing is required, then the methods described above will not be enough to ensure the strength of the structure.

To process openings in such places, they usually use special composition. The cost of such repairs is much higher usual ways, but in a humid environment it fully justifies itself.

For each task there is a special material on sale, you just have to make the right choice.

These materials ensure complete sealing of the crack, so the coating will last for many years.

Repairs are possible both indoors and outdoors, at any time of the year.

Repairs must begin, as in previous cases, by processing the opening. After all excess has been removed and the surface of the furrow has been cleaned with a vacuum cleaner, the width and depth are measured.

This is done in order to choose the right self-expanding cord for repair.

A cord is placed in the cut, which should lie without coercion, freely.

There should be 20-30 mm left to the bottom and top of the furrow so that the cord will expand further. Whatever type of cord you choose, you cannot force it.

Now polyurethane sealant is applied on top of the cord, the surface of which is smoothed with a spatula. The glue that has come out of the seam is removed with a sponge.

Usually it is written on the packaging which material is preferable for a given type of cord or tape; strictly follow the recommendations.

If you will be using this material in relatively dry areas where the waterproofing is only for insurance purposes, finishing can be produced using cement mortar.

In order to choose a material for concrete repair, you should familiarize yourself with what these materials are and how they differ from each other.

Today the range of such products is quite wide.

This material consists of polymer resins and modified clay, and also contains bentonite material or its analogue, which binds the surfaces together and seals them.

As for the release form, they are as follows:

1. Cord - the material is used for repairing shallow cracks of 30 - 50 mm;
2. Tape - the material is placed in cracks 20 - 50 mm wide and up to 150 mm wide;
3. Paste - sealant is used to treat small furrows;
4. Mats – hold layers together concrete screed, and when the old coating is applied, a new layer is laid.

Crack repair by injection

The name of this method speaks for itself - injection involves introducing special materials into the voids formed in concrete by “injection”.

Injection allows you to repair concrete pavement without replacing the entire concrete pavement.

This is one of the most effective ways to repair these defects, which is also quite economical.

Injection involves introducing a cement, epoxy or polymer mixture into a crack under pressure, so that the mixture fills any small voids or cracks.

This makes the structure very strong and reliable.

This method is also used to waterproof concrete, for which different compositions are used.

Prevention of cracks

Even at the stage of pouring concrete, it is very important to ensure that the concrete composition of the floor and foundation is high quality, in compliance with all proportions.

When laying concrete, you need to carefully compact it not only manually, but also using a special tool.

To prevent moisture from freshly poured concrete from evaporating at high speed, it can be covered with a damp cloth on top.

In addition, today there are special drugs on sale that will protect concrete covering from the appearance of cracks and chips upon contact with water.

These means should not be neglected, since waterproofing is very important for the integrity of the concrete coating.

Waterproofing walls and foundations using such means will help prevent further cracks from opening.

Concrete is often used to lay paths, sidewalks and garage driveways. Over time, cracks appear in the concrete sheet, into which water gets in and even grass begins to grow. If the damage is large and there are many small cracks on the path, then most likely you will have to completely change the surface. But in case of isolated damage, the cracks can be repaired with fresh mortar and such repairs will last for several years of operation.

The first and very important stage work consists of thoroughly cleaning the crack from debris, dirt, mold and grass. If possible, use a pressurized water jet to flush the entire depth of the crack.

To prepare the solution you will need a container in the form of a tray or wide bucket. Stirring the solution by hand is not very convenient; it is better to use a drill with a special mixing attachment for this purpose.

Cleaning the surface and washing out cracks.

For narrow cracks, the solution is mixed from sand and cement in a ratio of 3/1. For wide ones, it is better to use a cement-gravel mixture, but with small fractions. If the crack is deep, reinforcement made of thick wire can be laid inside.
But it’s better to find kits for sealing cracks in concrete in stores. The set consists of a polymer primer composition, which is used to treat the edges of cracks, and a ready-made dry mixture of sand, cement and astringent polymer additives.

The solution, brought to the consistency of sour cream, is poured into the crack and leveled along the entire length. Then the mixture is pierced inward with a spatula so that the solution fills the entire volume.

If you do not have the opportunity to sand the surface using special power tools, then at the end of laying the mortar, the surface is leveled with a simple brush. This method not only helps squeeze out the air, but also makes the surface rough. Ultimately, the sidewalk won't have too slippery patches. Still close to the topic, article.

Leave the concrete alone for at least a day until it sets. In hot weather, you need to try to prevent the seal from drying out too quickly. To do this, it is better to lay rags and sackcloth moistened with water over the cracks and, if necessary, add water with a spray bottle.

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Often, the occurrence of cracks in the foundation of a house is an inevitable event. But there's no need to panic. You should carefully understand what caused this process and quickly solve this problem. This article will discuss how to repair a crack in the foundation.

Causes of cracks and their main types

The most common causes of cracks include:

• poor-quality soil preparation for the foundation;
• savings on the purchase of materials for construction;
• natural soil shifts;
• non-compliance with house construction technology;
• construction of a new facility nearby.

There are two main types of cracks on the foundation surface:

• horizontal;
• vertical.

Horizontal cracks do not pose such a danger. They can occur for various reasons. The main ones are:

• impact low temperatures(concrete dries out);
• increased pressure from wet soil.

Long cracks and horizontal faults with bulges present on external wall houses, indicate a possible displacement of the foundation or pressure exerted on load-bearing walls. To determine the specifics of faults, you should use a level. If there is a bulge of more than 1 cm or a ridge has formed on the edge of the wall, major repairs to the base are necessary.

What to do when the crack in the foundation is vertical? Such breaks in the walls do not bode well. If there is only one crack at the base of the building, its parameters need to be determined. If there is a fault with smooth edges and a small thickness (about a hair's breadth), repairing a crack in the foundation will not be difficult.

More difficult work occurs when the vertical edges of the fault are uneven and the gap expands in any direction. It should also be taken into account that the crack can be located underground. In this case, you need to excavate the entire area near it.

Technology for sealing faults in the foundation

Depending on the complexity of the job, various materials will be required to seal cracks in the foundation. When the faults are small, they are sealed using a regular repair mixture or sealant. More complex areas are treated with special materials. These include epoxy resin and quick-hardening cement.

In most cases, sealing faults in the foundation involves choosing one of two options:

• pouring into it concrete mortar;
• treating cracks with epoxy resin.

Using concrete to fill cracks

Fixing a crack in the foundation begins with its preparation. Using a chisel, old concrete chips are removed from the crack. If there is a small crack, it should be widened at the bottom. Using a construction trowel, the crack is filled with mortar. After this, the entire surface to be treated is smoothed and leveled.

This method is also used in cases where there is too much damage in concrete structures. The work begins with cleaning the surface of the crack in the foundation with a chisel. Having cleared the fault, it is thoroughly washed with water under pressure. While the gap dries, you should start preparing the solution.

The cement material is sold in finished form. You just need to dilute it with water and mix the mixture to form a paste. Shouldn't cook large number solution because it hardens quickly. The solution can also be prepared from ordinary Portland cement with the addition of sand and water.

Filling cracks in the foundation is carried out in such a way that the concrete mixture protrudes above the surface. When the concrete begins to set, it is thoroughly smoothed using a trowel. After filling the crack in the foundation, the entire surface is covered thick fabric and left for several days. Moreover, it is necessary to maintain the moist condition of the finished area. To do this, lightly wet the fabric.

Repairing defects with epoxy resin

The second method of sealing cracks in the foundation of a house involves using epoxy resin. Maximum efficiency its application is achieved for sealing small cracks (up to 5 mm) in monolithic concrete.

The embedding process itself consists of the following main stages:

• removal of old concrete chips;
• drying the surface;
• application of epoxy resin.

Using a metal brush, the entire area with defects and the surface near it are cleaned. To completely clean the concrete chips, the crack is blown out. The inside of the fracture is dried with a hair dryer.

The components of the epoxy resin design are a nozzle and liquid resin, which is placed in a tube. Installation of nozzles into the fault occurs at intervals of 30 cm. The first nozzle is inserted 30 cm from the ground surface. Epoxy resin is mixed with a hardener. The prepared solution is applied to bottom part all attachments. They are glued to the base of the crack. The resin should harden.

After this, the entire damaged area is sealed with epoxy resin. The mixture is also rubbed around the fracture. After the solution has set, liquid resin is injected into all nozzles, starting from the bottom. If there is a crack with a width of more than 3 mm, each nozzle is equipped with several tubes. After 5 days, when the epoxy resin has completely set, the nozzles can be cut down.

You can reduce the likelihood of cracks in the foundation by taking preventive measures. As is known, main problem for the foundation is excess moisture. Therefore, it is necessary to constantly ensure that water does not accumulate near the house.

Video on sealing cracks in the foundation:

Concrete is the most popular building material, characterized by high durability and strength, wide application, absolute non-combustibility and low cost. However, violations of the technology of its preparation and installation lead to rapid wear of products and structures. Accelerated destruction of concrete is also facilitated by operation in aggressive environments and increased mechanical loads. As a result, the material loses its design strength and becomes covered with cracks and cavities.

For restoration, a traditional solution is not used, but a specially created repair mixture for concrete with suitable technical characteristics. Such compositions are produced and packaged in the form of a dry powder, which is diluted with water in a certain proportion. To give them special properties(frost resistance, moisture resistance, hardening speed) various ingredients are added (plasticizers, modifying additives, fractional fillers).

Ready-made compositions for concrete repair are conventionally divided into groups.

By area of ​​application:

• For the restoration of structures and products experiencing increased mechanical loads (beams, columns, floor slabs, load-bearing walls).
• For strengthening reinforced concrete elements susceptible to corrosion.
• For repair road surfaces and floors.

According to the complexity of the composition:

• Single-component (cement with large and small fractions).
• Two-component (epoxy with different degrees of fluidity).
• Multicomponent (liquid polyurethane).

There are also repair compounds for concrete with special conditions Applications:

• Thixotropic - for vertical surfaces.
• Casting - for horizontal planes.
• Fast-hardening - for urgent repairs and eliminating leaks.
• Frost-resistant - for use at low temperatures.
• Industrial and domestic use.

Self-leveling mixtures are used when the thickness of the working layer is no more than 100 mm, and quick-hardening mixtures, which gain the necessary strength after 6 hours, are used up to 40 mm.

Selection method

Correctly selected repair dry mixture for concrete and strict adherence to the technology of its use will ensure the strength and durability of the product or structure. When purchasing a composition, you should take into account the nature of the damage, the size of the affected area and the operating conditions of the concrete. After hardening, the repair mortar should not shrink or delaminate. Its compatibility with the surface being restored and the required level of adhesion to it are extremely important. Almost every manufacturer of repair compounds additionally offers branded deep penetration primers that bind concrete and ensure high adhesion to the solution.

When choosing the type of mixture, the extent of surface damage must be taken into account. Significant potholes, cracks and differences in floor levels are eliminated with solutions with large fractions. To seal small sinks and cracks, it is enough to buy a fine-grained concrete repair mixture with increased plasticity. If the product or structure is used in extreme conditions, then the restorative composition must contain additional ingredients that give it special qualities, for example, frost and water resistance.

Technology of use

Floor repair

To eliminate large damage on horizontal surfaces and differences in concrete floors, inexpensive dry cement-sand mixtures are usually used. Before application ready solution The work area should be cleaned of debris and dust, degreased, and then treated with a deep penetration primer recommended by the manufacturer. After assessing the extent of damage, the required amount of repair mixture for concrete is determined. The recommended thickness of the cement-sand screed does not exceed 40 mm. Control beacons are set and the solution is drawn out, which will gain strength within 2 weeks. All this time, the surface of the screed, covered plastic film, should be periodically moistened with water to prevent cracking. To eliminate small defects For floors, it is advisable to use self-leveling, finely dispersed self-leveling compounds with increased plasticity.

Crack repair

Before using the crevice solution on concrete surface usually expand. To do this, grooves up to 50 mm deep are cut around them with a diamond wheel or grinder, and then the destroyed material is selected with a hammer drill or chisel. Work area cleanse compressed air from debris and dust, treated with impregnation, after which a repair solution is applied. Cracks on horizontal and inclined surfaces are eliminated using the saturation method without overpressure. To fill vertical cracks, inexpensive and practical repair mixtures MBR 300 and MBR 500 for concrete are often used, which differ in strength characteristics and hardening speed. In some cases, to fill internal voids and deep cracks, they resort to the injection method using a special device - a packer. The repair compound that has come out on the surface under pressure is removed with a lath, and after hardening it is ground.

• Repairing foundation cracks cement mortar
• Repairing foundation cracks with epoxy resin
• Features of working with resin
• Elimination of defects of an incorrectly executed base
• Base plastering technology

The foundation is the main part of any structure. This is an important and main structural element. The strength, reliability and durability of structures or buildings will depend on how it is executed. Over time, cracks may form on it. Repairing cracks in the foundation is not a difficult task, you just need to know some features and choose the right building materials.

The durability of the building depends on how the foundation was built.

Experts say that cracks can often occur if the building shrinks unevenly.

It happens that everything is fixed, but they appear again. This indicates that settlement is still ongoing and in this case it is necessary to use special concrete. You can do this kind of work yourself. To repair cracks, you will need either polymer or cement materials.

Repairing cracks in the foundation with cement mortar

Today in many stores you can buy ready-made cement mixture. To use, you just need to add water and mix well. Such mixtures consist of fast-hardening cements. Since the mortar hardens very quickly, repairing cracks in the foundation must be done at a rapid pace. There is no need to prepare a large amount of solution at once. Better later stir again for an additional portion.

1. First you need to prepare the faulty base for work. Use a chisel to remove any remaining crumbs. If the foundation is severely cracked, then the cavity needs to be widened towards the bottom, and then everything will need to be sealed with a “lock”.
2. When everything is prepared, we begin filling with the solution. To do this we need to take a trowel. It's easier for her to fill out free space. Next, the surface must be smoothed thoroughly. Cement mixtures are also good for repairing large damage to any reinforced concrete structures. Any similar work begins with cleaning the damaged area.

When working, you must follow safety precautions and be sure to wear gloves and, preferably, safety glasses. Before applying the mixture to depressions and cracks, rinse with water from a hose. You can continue working when the surface is dry.

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Repairing foundation cracks with epoxy resin

The appearance of depressions can be eliminated using epoxy resin. It is especially suitable for small and minor cracks (approximately 3-5 mm) if the concrete was cast in place.

1. The surface must be thoroughly cleaned. It is advisable that it be dry. If there is moisture or water seeps in, it must be dried first. For this suitable for work regular hair dryer. If after this the surface seems dry, you still need to wait another 30 minutes to be sure that moisture does not reappear. When everything is dry, you can start sealing the creases.
2. Epoxy resin is sold in many hardware stores. Often this is a kit that contains 2 parts: a nozzle and liquid resin. Everything is packed tightly in a tube, and a device for filling seams should also be included.

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Features of working with resin

Before starting work, you must carefully study the instructions.

1. The crack in the foundation must be thoroughly cleaned: it is better to use a wire brush. You need to make sure that there are no crumbs left. Next, you need to blow it out with compressed air. Everything is dried with a hair dryer.
2. Then glue the nozzles, bring them to the crack and insert. Start from 30 cm above the floor level and then continue at a distance of 30 cm.
3. Mix the epoxy resin with a spatula while adding a hardener: it is better to use a piece of cardboard for this purpose. The resin is applied from below to the surface of the nozzle and glued over the depression or crack. Next you need to wait for everything to dry.
4. Mix the second portion of the paste from 2 components and continue to cover the surface. The paste is pressed into the cracks, thus creating a coating about 3 mm thick. Carefully rub the remaining paste around. Everything needs to be left for a while, that is, until the paste has completely hardened.
5. Then we inject the liquid resin mixture, which must be prepared strictly according to the instructions. You need to start working with the nozzle, which is located below. This operation must be done with each nozzle until the entire crack is completely filled. In order to fill a depression more than 3 mm wide with a liquid resin mixture, you will need more than 1 tube.
6. The liquid resin should harden after 5 days, and only then can the nozzles be removed if desired.

It often happens that simple sealing with solutions and resin does not give a positive result. Then it is necessary to clarify the cause of the crack formation. It is possible that the foundation was originally designed and calculated incorrectly. Or the technology for its production was violated. If this is the reason, then you will need to do slightly different work.

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Elimination of defects of an incorrectly executed base

The reason for the appearance of cracks in the foundation may be the small depth of its laying, or an incorrectly calculated load. In such cases, experts recommend conducting a small test. After a very small crack has been removed, you need to stick a piece of paper on which the date of work will be indicated. If the paper does not tear within 20 days or a month, then the problem can be fixed with cement mortar. If it breaks, then it will be necessary to remove part of the brickwork thoroughly. Repairing the foundation after unexpected damage It is necessary to begin work with careful preparation. It is better to consult with professionals. If it is decided that a major restoration is needed, then it is better not to delay the repair.

1. In places where cracks increase, several rows of masonry will need to be removed. The walls will need to be reinforced with supports for a while.
2. Next damaged part the foundation will need to be removed and the surface thoroughly cleaned of debris. If possible, install reinforcement.
3. Fill everything with cement mixture and level it. When the solution sets, the surface is leveled. The brickwork will need to be made with reinforcement. This will give additional strength and stability.

The ideal option for eliminating any problems, including the appearance of cracks, is timely preventive maintenance. A good way to do this would be to create a blind area with a good slope. Those places where cracks appear must be thoroughly plastered with good cement mortar.

Concrete is one of the most durable building materials, but, unfortunately, it is also susceptible to destruction. Cracks and damage that appear must be repaired, but this must be done competently, otherwise the repair will be of no use.

Preparing a concrete solution is not a complicated operation, but, nevertheless, builders often make mistakes in the recipe and also violate the concrete laying technology, as a result of which, after some time, cracks appear on its surface. If they are not eliminated, the concrete structure will collapse without serving its intended life.

There are three types of concrete corrosion:

physical – when, as a result of a violation of concreting technology, water gets inside the concrete structure and, freezing, breaks it;
biological – caused by the activity of fungi and bacteria;
chemical - its cause is aggressive chemical elements, located in the air or in the very concrete mixture.

Poor quality concrete

Different types of structures require an appropriate composition of the concrete mixture. If the proportions of all components are not maintained, then subsequently concrete element will be destroyed. The cause of destruction can also be uncleaned gravel or crushed stone introduced into the concrete mixture as filler. Often the problem is old expired cement, water with inappropriate chemical composition or violation of the mixing rules, namely too much quick cooking, which does not ensure homogeneity of the mixture. If the mixture, on the contrary, is kept in a concrete mixer, then its components may separate, which will also affect the performance of the concrete product.

During laying, it is necessary to carefully monitor the compaction of concrete, otherwise the remaining voids (shells) will cause fractures in the supporting structures. Compliance with concreting technology is not only about correctly prepared mixture and high-quality styling, but also care for hardening concrete. During hardening, it must be watered and avoid overdrying, overheating, or freezing.

Cause of destruction iron concrete structures The fittings may become rusty or poorly degreased. To provide it with reliable protection against corrosion, it is necessary to lay it to a depth where moisture does not penetrate through concrete of a given density.

Damage to high-grade concrete

Even the highest quality concrete can fail from strong impacts, or when the load on it exceeds the design load. Acid rain can affect the integrity of concrete. sea ​​water, gases and aggressive substances falling on it from environment(e.g. de-icing agents). The reason for the destruction of initially high-quality concrete can be substances formed in it as a result of the entry of some components into a reaction with carbon dioxide and air. Corrosive substances are also produced by bacteria that settle in the thickness of concrete. Mainly sulfuric acid, hydrogen sulfide and carbon dioxide. Mechanically, concrete is often destroyed by tree roots that pass under monolithic structures.

Signs of concrete deterioration

If mistakes were made during the concrete removal process, its surface may delaminate. As a rule, this happens when hardening concrete overheats, when it is exposed to bright colors for a long time. sun rays. Acid rain can also cause a similar effect.

Very noticeable efflorescence on the surface of concrete structures indicates that water penetrates into its thickness and gradually washes away salts that crystallize. The crystals themselves are not as dangerous as demineralization of concrete, which can cause it to crack.

When a concrete structure is subjected to a load greater than the design load, the concrete will certainly crack. Often, violations of its integrity are caused by shrinkage of the building by initial stage operation. Main danger cracks is that moisture entering deep through them, freezing, tears apart the concrete until it completely collapses.

Unhealthy signs are also rusty stains and streaks on the surface of concrete structures. If they are not caused by external factors, then most likely they are a consequence of corrosion of the reinforcement. This means that there are cracks in the area that will progress, causing gravel to fall out and even entire concrete fragments to break off.

Troubleshooting

The modern materials market offers a lot of means for repairing cracks, peeling and other damage to concrete. The simplest and most affordable are repair mixtures based on the same cement, which can only be prepared by mixing with water. A solution with similar characteristics can be prepared independently. To do this, it is necessary to introduce special polymer additives into the sand-cement mixture, which impart elastic properties to the frozen mass, as well as making it more durable. If the amount of polymer turns out to be more or less than required, the repair mixture will be ineffective, so if you lack experience, it is better to use ready-made mixtures, among which there are two main modifications:

Dry mixtures that are mixed only with water (they already contain powder polymer);
dry mixtures that must be diluted with both water and polymer in a strictly defined amount.

There is also a third modification, which requires the addition of a mixture of polymer and hardener, which is prepared immediately before use.

When performing minor repairs, it is necessary to give preference to quick-hardening mixtures and leveling putties. Elimination of plaque and efflorescence is carried out with special cleaning agents. Manufacturers of concrete repair materials also produce anti-corrosion agents to protect reinforcement and special primers for screeds.

Selection repair mortar

An important factor influencing the choice of mixture is the location of the problem area. If these are horizontal cracks or potholes that will be sealed from above, then any mixtures will do, but for vertical and steep places special mixtures with enhanced adhesion are needed. When choosing a mixture, you also need to consider its strength, since what is suitable for repairing a crack in a wall will not be suitable for repairing a crack in a garage floor screed, since the cured mixture will need to support the weight of the car. The properties and purpose of the mixture are indicated on the packaging, and before purchasing this or that repair composition, you must study the manufacturer’s recommendations for its use.

Some solutions are designed to be applied in layers up to 10 mm, others up to 100 mm, and this must be taken into account in each specific case. Dry repair mixtures are mainly sold in 25 kg bags. The mixture that will not be used must be stored in a dry place. Some of its species are afraid of low temperatures, as the manufacturer informs about on the packaging.

Preparing a damaged concrete surface for restoration

First, it is necessary to chip off all exfoliated elements, after which the surface is thoroughly cleaned until cracks in the base concrete are permanently sealed. It is better to do this manually, so as not to damage the whole concrete and not create problems for yourself. extra work. The prepared surface must retain some roughness in order for its adhesion to be higher. Small cracks must be widened to 5 mm so that the repair solution can penetrate into them to a sufficient depth.

Immediately before applying the repair solution, the base must be moistened so that it does not attract water from the fresh mixture. For the same purpose, the base can be primed, which will improve its adhesion.

Wide cracks require additional strengthening. To do this, along the gap, every 20-25 cm, a transverse cut is made with a grinder, into which reinforcement with a diameter of 3-4 mm is inserted. If chipped concrete exposes rusty reinforcement, it must be stripped down to intact metal and treated with an anti-corrosion agent. In cases of severe damage to the reinforcement, welding may be necessary.

Since the repair mortar cannot become a monolith with the base, the place where it is applied must have the best possible adhesion. Where there is a high probability of failure of the repair layer, it is necessary to create a contact layer on the surface to be repaired before applying it. For this, there are special primers based on cement and polymers in a 1:1 ratio or based on liquid resins mixed with fine-grained sand.

After creating the contact layer, you must immediately proceed to applying the repair mortar, otherwise the connecting effect will not be achieved. The mixture for the contact adhesive layer is not intended to serve as a repair composition.

In conclusion, it should be noted that before undertaking repair of cracks in concrete, it is necessary to find out the real reason their appearance. Wide cracks are usually formed due to improper distribution of loads on the concrete element. And sealing the gap alone is not enough - after some time it will appear again. In order to relieve the stress where the concrete is cracking, it may be necessary to reconstruct some load-bearing elements buildings.

depth, removing all crumbs from it before embedding.

Epoxy resin is most effective for small cracks (3 to 5 mm) in cast-in-place concrete. The surface of the crack must be dry. If the surface is damp or water is leaking through a crack, it should first be dried, which can be done using a hair dryer. When the surface appears dry, wait another 30 minutes to see if it becomes damp again. If it remains dry, seal the cracks.

Epoxy resin for this purpose can be purchased at a hardware store in the form of a kit containing two-part epoxy paste, nozzles and liquid resin packaged in a tube suitable for use with a standard joint caulking tool. Wear gloves and safety glasses.

Clean the crack and the area around it with a wire brush. Make sure there are no crumbs left in it. Blow out the crack with compressed air. Dry the surface of the crack using a hair dryer.

2. Glue the nozzles by inserting them into the crack, starting from 30 cm above the floor and then every 30 cm.

3. Using a spatula, mix the epoxy resin and hardener on a piece of cardboard, apply the resin to the bottom surface of each nozzle and glue it over the crack. Wear rubber gloves. Allow the resin to harden.

4. Mix another portion of two-component paste and cover the surface of the crack with it. Press the paste into the crack, creating a 3mm coating by rubbing the paste around the crack. Leave this coating overnight to allow the paste to harden.
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5. Now inject liquid epoxy resin into the cracks according to the manufacturer's instructions. Start injecting resin from the lowest nozzle. Having finished injecting through the nozzle, close the hole with the cap and begin injecting into the next nozzle located above. Continue until the crack is completely filled. If you are filling a crack that is more than 3mm wide with liquid resin, you will need several tubes for each nozzle.

Allow the liquid resin to cure for five days, then cut off the nozzles if desired.

Cracks in concrete can also be repaired using other materials. One of them is presented in the form of tubes, from which the cleaned crack is filled. Then the surface is cleaned with a trowel. Excess of this substance can be wiped off the surface with a wet cloth before the filler sets.

Cracks in concrete

If small cracks appear after pouring concrete, they must be repaired as quickly as possible to stop the destruction process.

Why do cracks appear in concrete after pouring?

• shrinkage after drying,
• chemical and mechanical damage,
• sudden changes in ambient temperature,
• excessively rapid evaporation of water in hot weather,
• reinforcement corrosion,
• incorrect calculations during construction and, as a result, excessive load,
• incorrect composition of the concrete mixture, technology of its production or mixing.

Repair methods

If small cracks appear immediately after pouring the concrete, you can simply and quickly eliminate them by re-compacting the mixture that has not yet hardened. If the surface has already hardened, use one of the methods below.

• Shotcrete - applying a layer of the same concrete mixture to the cracks.
• Injection is the introduction of a polymer or repair composition under pressure into the cracks.

Having decided how to repair cracks in concrete after pouring, you need to choose the right product for this.

Types of compositions

You can fill cracks in concrete after pouring with different materials:

• cement-sand mortar with a polymer additive (this can be sulfanol and furyl alcohol). The hardened solution is covered with polyurethane sealant.
• elastic sealant. Silicone is especially popular.
• liquid cement “dough” (for cracks less than 3 mm).
• repair mixture (for voids larger than 3 mm). It contains Portland cement and water in a ratio of 1:3, PVA glue.
• special ready-made solutions.

Work process

Regardless of the chosen composition, sealing shrinkage cracks in concrete is carried out almost the same way.

1. If there are chips around the defect, remove the broken concrete pieces immediately.
2. Expand the crack along its entire length with a chisel and hammer, and then deepen it to 5 mm with a spatula. This will help the solution not fall out and reliably fill the entire space.
3. Clean the surface first with a vacuum cleaner, and then with a brush, water and any other detergent. Remove any remaining moisture with a sponge.
4. If the cracks in the concrete after pouring are wide enough, make transverse grooves along them and place pieces of wire with a diameter of approximately 4 mm in them. These staples will help the compound stick inside.
5. If reinforcement is visible in the crack, it must not only be cleaned, but also treated with an anti-corrosion compound.
6. Fill the crack with your chosen compound, doing it slowly so that it settles as tightly as possible. Level the surface. Take into account drying shrinkage and make the fill layer slightly above the surface. If it is a sand-cement mortar, lightly moisten it with water after pouring.
7. When the solution has hardened, remove the excess with a spatula. A grinding machine will help achieve a smooth surface.

Prevention of defects

• Observe the proportions when making the concrete composition,
• Compact it carefully when laying it,
• After pouring, cover the concrete with a damp cloth to prevent rapid evaporation of moisture.
• Use special protective waterproofing preparations.

Concrete is widely used in construction. Foundations, floors, and walls of industrial and residential buildings are made from it. This is a very durable material. However, it has one unpleasant feature. It is very prone to the formation of defects such as cracks. This is especially true for concrete that has been poured recently.

There are several types of cracks:

Before you begin to repair cracks in concrete, you need to find the cause of their occurrence. Used to seal cracks in concrete special sealants. They are tough and elastic.

If defects arose at the final stage of construction, then they will be suitable for elimination epoxy resins or other hard materials. Required condition for such repairs - the immobility of the foundation.

Thin cracks are sealed with more elastic sealants. Care must be taken in the selection of materials to eliminate voids in tanks. drinking water. The sealant must be non-toxic, bioresistant and harmless. If there are many defects or they appeared in the first 2 hours after laying the concrete, then best way their elimination is injection.

This method does not require replacing part of the structure. Cracks in concrete are sealed by injecting special materials or solutions into the voids under pressure. A small number of voids can be filled manually.

If damaged vertical surfaces, then they are eliminated by applying sand-cement mixture. It is necessary to add a polymer to it: 0.35% furyl alcohol or 0.02% sulfanol. The percentage of additive is calculated based on the mass of cement.

When the applied repair mixture hardens, a layer is applied to it polyurethane sealant. To seal cracks in concrete no larger than 3 mm in size, cement “dough” is used. It is prepared from cement, water and glue. You can use special solutions.

If there are too many voids, a decision may be made to remove the damaged concrete. A layer of the same material is applied on top. This method is not used often, as it is very labor-intensive and impractical. It is necessary to take into account that the new layer also shrinks, and this leads to cracks.

There are several ways to repair cracks in concrete yourself. The most economical and simplest is to seal voids with cement mortar or repair mixture.

To work you will need:

• grinding machine;
• vacuum cleaner;
• spatula;
• chisel;
• trowel;
• metal brush;
• hammer;
• mixing containers;
• wooden slats;
• brush;
• cement;
• sand;
• water;
• metal smoother;
• PVA glue;
• wire.

Stages of work on sealing cracks in concrete:

This method does not provide a sealing effect. It is used as a temporary and partial solution to the problem. Suitable for use in both dry and damp areas.

Repair with epoxy resin

Repairs to seal cracks in concrete can be made using epoxy resin and epoxy repair compounds:

To work you will need:

• Bulgarian;
• primer for concrete;
• vacuum cleaner;
• epoxy composition for repair or resin with hardener;
• packaging of fine sand;
• spatulas;
• repair brackets;
• mixing containers.

Work progress:

1. Joining the crack. At this stage, the edges are leveled with a grinder and loose concrete is removed. The width should be no more than 25 mm and no less than 4 mm. Every 400 mm along the entire length of the crack it is necessary to cut transverse grooves 150 mm long.
2. Use a vacuum cleaner to remove small debris and dust.
3. Treating seams with primer.
4. Staples should be placed in the transverse grooves.
5. Following the instructions, you need to prepare a solution and add a hardener.
6. Sand is poured into the solution and the seams are filled with the resulting mixture.
7. The surface should be sprinkled with sand.
8. After an hour, remove the sand with a vacuum cleaner.

This method is economical high speed drying, and also prevents further movement of cracks. It is suitable for eliminating defects in dry screeds.

If the concrete will come into contact with water, then there is no need to use sand. Repairing water tanks, such as swimming pools, requires a more serious approach.

To work you will need:

• Bulgarian;
• vacuum cleaner;
• primer for concrete;
• cord or tape for sealing stone cracks;
• construction gun;
• polyurethane sealant for concrete;
• brushes;
• chisel;
• brushes;
• foam rubber

Work progress:

Cracks in concrete are not unexpected, but positive emotions they don't call either. More often defects arise when reducing work time or saving on materials. But even with full compliance with the technology, it is not possible to avoid concrete cracking, but it can significantly reduce the number and depth of voids.

Small voids do not cause serious damage to the building, and repairing them yourself will not be difficult.