Causes of screed defects, repair. Examination of construction work on the screed device Elimination of defects in a semi-dry floor screed

The content of the article:

The cement screed is the outer layer of the subfloor. Over time, for many reasons, it wears out, but the floor covering laid on top does not give time to determine the defects that have arisen. In the process of its replacement, when the foundation is exposed, the hidden problems of the floor become apparent, and it becomes necessary to repair the cement screed. How it is done, you will learn from this article.

Assessment of the state of the cement screed

The floor screed is subjected to tremendous stress from the weight of the floor covering, furniture and equipment, as well as dynamic influences from falling objects and walking people. Therefore, the service life of an expensive floor repair largely depends on its condition. The money invested in this event can be wasted if a screed deprived of attention makes itself felt.

Reliable information about the state of its surface can be obtained only after the floor is completely cleaned of old coatings, debris and dust. To determine the degree of damage to the screed, there are such criteria:

The screed is even, but has small grooves, a grid of small cracks and is constantly dusty. To eliminate such damage, you do not need to invest significant funds, since such work can be done independently.
The surface of the base has delaminations and in some places is covered with deep transverse or longitudinal cracks, but their average size does not exceed? the length of the short wall of the room. Such a screed can also be repaired on its own, but for this you will need building mixtures that have a special composition.
The screed has a significant curvature, expressed in numerous depressions and humps. To level such a surface, a milling machine will be needed, which creates a lot of noise and dust during operation. Therefore, it is recommended to repair such a foundation only in non-residential premises or private households. In city apartments, neighbors may not be able to endure the discomfort from the operation of technology, complain or go in person.
The floor of the apartment, located in a high-rise building, is covered with large, deep and long cracks that intersect with each other or are located along the diagonals of the rooms. Such repairs are very complicated and are carried out only by specialists after studying the nature of the loads on the floor and the bearing capacity of the house structures.

Redecoration of a cement floor screed is carried out if no more than 30% of its area is damaged. In other cases, it is better to replace it completely.

Preparation of repair mortar for cement screed

Today, the construction market has a huge selection of mixtures designed to restore cement screeds. These formulations can have a variety of bases, including polyurethane and synthetic resins. Many of them are used to repair industrial floors. But in the conditions of an ordinary apartment, the use of such mixtures is not always rational, given their cost.

For a simple repair of the screed at home, a mixture that can be made independently from available and inexpensive materials is quite suitable. It consists of PVA glue, water, sand and cement. To prepare a repair mortar, you must first dilute the PVA glue in water in proportion to 1: 3, and then add a dry mixture of cement and sand 3: 1 to the resulting emulsion.

The composition should be mixed at minimum speed for 5 minutes using an electric drill with a mixer nozzle. After the process is completed, it is recommended to immediately immerse the mixer in water poured into a bucket and rinse well when the tool is in operation.

If the cracks in the screed are deep, this composition will not work. To repair it in this case, you will have to buy a special thixotropic liquid for concrete. Store-bought mixes are mainly mixed with water, and home-made formulations are mixed with glue suspension. Ready mixtures can be replaced with tile adhesive.

Cement screed repair technology

All screed defects, such as small and deep cracks, delamination and dust formation, potholes and depressions, are eliminated in various ways, which we will discuss below. In the meantime, it is necessary to prepare the following tools and materials for work: a puncher, a trowel and a rule, a brush, a grater and a paint roller, cement, a primer for concrete and a repair mixture.

Elimination of minor defects

These include small cracks, gouges and chips on the surface of the cement screed. The reason for these defects are errors made during its installation: the absence of expansion joints, poor-quality mortar for pouring or insufficient reinforcement of the base.

To repair a cement-sand screed with minor defects, first you need to mark all problem areas with chalk, and then cut each crack and recess with a hammer and chisel a few millimeters deep and 1-2 cm wide along the edges. After that, you need to remove construction debris from the surface of the screed with a broom, and from the cracks - with a vacuum cleaner.

Cleaned cracks and recesses should be treated with a penetrating primer several times until it no longer soaks into the concrete. This procedure is necessary to increase the adhesion of the base with the repair mixture.

In the process of drying the primer, you can prepare the mixture according to the recipe described above. The resulting solution should fill the cut damage to the screed just above the general level of the rest of the surface, and after the mixture has hardened, sand the repaired areas.

Advice! If the thickness of the screed is small, it is better to cut the damage to its entire depth. In this case, the adhesion of the putty to the base will be better, and the further development of cracks will become impossible.

Filling deep cracks

Such damage to the screed must be cut to the full depth. For this purpose, it is recommended to use a circular saw and a puncher; it will be unproductive to work with a hammer and a chisel.

After the crack is cut, several strobes must be made across it, the ends of which will extend beyond the resulting cavity by 5-6 cm on each of its sides. Then, holes 2-3 cm deep should be drilled at the two ends of each strobe, and then debris should be removed and the cut cracks should be cleaned with a vacuum cleaner. Prepared recesses must be treated with a primer and left to dry.

Now it is necessary to prepare a mortar of sand and cement in a ratio of 3:1. Filling the crack should be done gradually in several stages. The first of them uses a liquid mixture, which needs to fill part of the cavity in depth so that it penetrates into the most inaccessible places of the excavation.

Then you need to prepare a solution of medium density and fill it with a crack flush with the bottom of the transverse strobes. When it hardens, it is necessary to make staples tightening the crack from thick wire or reinforcement and mount them in the strobes so that the bent ends of the rods go into the drilled holes.

After that, a little plasticizer should be added to the solution and filled to the end of the cavity along with the staples. Then the surface in the area of the former crack must be leveled, and after the mortar has dried, it must be sanded. Now the repair of the crack in the cement screed can be considered complete.

Restoration of delaminations of the screed

Delamination and even swelling of the screed occurs when laying it on a dirty and unprimed floor. Such defects can be found using a light hammer or a piece of rebar. To do this, it is enough to tap the surface of the screed with this tool and determine the place of the defect by the dull sound of impact. When the screed is peeled off, gaps may appear through which, with this diagnostic method, dust clouds will fly into the air.

Repair of delaminations can be done in two ways. In the first case, the entire damaged area must be cut out, and a new screed should be laid in its place. In the second, the exfoliated area is subjected to injections, during which a special binder composition on an epoxy or adhesive basis is introduced under it. The second method is less time consuming and faster. It makes sense to use it if the problem area is even and does not have through cracks.

After determining the places of delamination of the screed, they need to be outlined with a marker or chalk, then take a perforator or drill and install a drill or drill for concrete with a diameter of 16 mm in any of these tools. Drilling in places of delamination should be carried out for the entire thickness of the screed, keeping the distance between them 0.2-0.3 m.

When this work is completed, a primer must be poured into the holes obtained. It should moisten the entire internal cavity between the base and the screed layer. To speed up the drying process of concrete, you can use a building hair dryer.

It is important to correctly determine the material for screed injection. It must have good fluidity, because the repair mixture will have to be pumped under the screed using a plunger pump or a construction syringe. The cement-adhesive mixture will cost less, more expensive, but more reliable - low-viscosity epoxy.

Injections through the holes in the screed should be done gradually, allowing time for the repair compound to fill the entire space of the cavity. This procedure should be continued until the mixture appears on the surface of all drilled holes and its level does not stop dropping.

The screed must dry for 24 hours. After that, you can work with it further: primer, glue linoleum, lay tiles, and so on.

How to repair screed potholes

These damages occur due to a violation of the technology of the screed device and significant loads on the base. In the presence of such factors, voids appear in the screed during the operation of the floor. They are more dangerous for flooring than cracks. In the areas of potholes, the floor suffers subsidence and deforms, which leads it to complete destruction in the future.

In this case, for repair, it is first necessary to cut through the pothole with a “grinder” equipped with a diamond disk along the damage perimeter to the entire thickness of the screed. Then, using a perforator or a chisel and a hammer, the concrete should be removed from the pothole. After that, the cavity must be cleaned of screed residues and dust, and then treated with a penetrating primer.

After the primer has dried, it is necessary to prepare a repair mixture and fill the pothole with it using a spatula. Without waiting for the mixture to dry, use a wide spatula and a rail to level it with the floor and leave it until the final polymerization. Grinding the problem area should be done so that the pothole filled with the mixture does not stand out against the background of the floor.

Important! At a depth of damage of more than 5 cm, the repair mortar should be applied gradually in several steps.

Dusty screed repair

Over time, cement-sand dust begins to appear on the screed. This is especially clearly seen in those rooms on the floors of which the screeds act as a finishing coating, for example, in the basement, garage or some other utility room.

Gradually, the amount of dust increases, and it becomes impossible to simply sweep it away. Often it is a consequence of significant mechanical loads on the surface of such a floor and its "old age". In other cases, dust appears immediately after a month or two after the start of using a new screed. The reason for this is the low quality of the cement mixture and violations in the technology of its laying. If it is not possible to replace the screed, it can be repaired in the following way.

First you need to thoroughly clean its entire surface with a vacuum cleaner. If potholes and cracks are found at the same time, they must be repaired using the technology described above. After that, the screed must be sanded and cleaned again in the same way. Then the floor surface should be treated with a penetrating primer and allowed to dry. At the final stage of work, the entire screed must be covered in two layers with a polymer composition. If the room has high humidity, special water emulsifiers should be used for this purpose.

There is another way to eliminate dusting of the screed - this is its painting. In this case, the coating must be sufficiently wear-resistant, according to this parameter, the finishing material should be selected.

The cardinal method of such a defect in the screed is its reinforcement with fiberglass and subsequent pouring with a special self-leveling building mixture. To implement this method, the floor surface must first be cleaned with a vacuum cleaner, treated with a primer and allowed to dry.

After that, glue should be applied to the surface of the screed and the fiberglass should be laid with overlapping sheets. When the first layer of glue dries, the second layer must be applied to the resulting coating and allowed to dry completely. The floor can then be sanded or poured over the fiberglass with a self-levelling compound.

How to make a cement screed - look at the video:

Any do-it-yourself work on repairing a cement floor screed is not particularly difficult and does not require professional knowledge. Some tools for their implementation, such as a hammer drill, can be rented, while others can be purchased for the future for personal use. High-quality floor repair is more profitable, since it can last only a few days, and a complete replacement of the screed will take up to a month. Good luck with your work!

People who are not privy to the lexical intricacies of apartment renovation often have difficulty understanding the phrase "screed bubchit". In reality, this means that when the surface of the screed is tapped, a sound is produced, as if the blows were applied to an object that has voids inside. In such places, it is also possible to push through the screed layer with your foot (with some "springing"). If the leveling of the floor surface was carried out using the “bonded screed” method (the mortar was applied directly to the upper side of the ceiling; there is no separating or soundproofing layer), then this phenomenon, as a rule, is defect(in most cases caused by violation). It tells what happened detachment leveling layer from the base (for example, the top side of the floor).

The reason for the onset of such consequences, as a rule, is the poor quality of work. In any case, the violations committed must be eliminated - screed repair. Up to this point, it is not allowed to lay the floor covering. A complete replacement of the screed is carried out if the area of the areas with delamination is 30%. Otherwise, you can limit yourself to a partial repair of the leveling layer.

In addition, non-compliance with the prescribed water-cement ratio (the optimal indicator for a cement-sand screed should be considered a value of 1.33), as well as a violation of the technology for caring for it during the period of curing, can lead to the formation cracks in the screed. The main mistakes resulting in such cracking should include the rapid loss of moisture by the screed, exposure to direct sunlight, and drafts in the room. All this unfavorably accelerates shrinkage processes and leads to a sharp reduction in the volume of the hardening solution.

When carrying out work on the device, the laying of the floor covering is carried out only after the removal of the patina - a thin, poorly bonded, fragile surface layer formed during the drying of the mortar.

Floating screed defect.

With the arrival in Russia (European technologies for the repair of interior spaces), more and more often the manufacture of the base for laying flooring is carried out using the method. Its essence lies in the fact that a leveling layer, prepared from a solution based on, for example, a cement binder, is placed on top of a layer of noise and heat insulation covered with a film. The lack of fastening of the screed with the floor surface and vertical structural elements (due to the laying of damper tapes around their entire perimeter) allows us to call it floating.

The main defects in the manufacture of such a screed are associated with deformation of its layer in the form of bulges or concavities.

The screed takes shape concavity(its edges rise) due to the fact that the surface layer dries faster than the bottom layer. The separating layer prevents the removal of moisture from the bottom layer of the screed facing it. At the same time, drafts, unnatural exposure to heat, sunlight accelerate the drying process of the upper layers. Covering with a film, moistening the screed slows down such processes, reduces internal stresses.

convex the screed is formed as a result of premature laying of the floor covering, when, for example, tiling is carried out even before the residual moisture indicators correspond to the normative ones. As a result, not only the internal structure of the floor is damaged, but also the floor covering.

Screed getting wet

Simultaneously with the spread of floating screed technology, cases of wetting of the heat or sound insulation layer began to occur as a result of emergency situations on water or heat supply lines. The main problem from the point of view of the operational properties of such a design is the lack of access to the underlying insulating layer and the impossibility of drying it. In Germany, an effective dehumidification technology has been developed and is being used. On the video you can see an example of its practical use.

There are currently no references to this topic in the article.

Particular attention to the strict observance of the recipe and external conditions (temperature, humidity) should be paid during the manufacture. The effectiveness of the use of such mixtures, the absence of defects even depend on the grain size of the aggregate and its type.
In some cases, mechanization of manual labor is used to carry out work on the installation of monolithic floors. This technology has both positive and negative aspects. All (or almost all) we present in our article at this link. In preparing the materials, we used our own experience in conducting this kind of work on the territory of Moscow - in conditions where we have to comply with the requirements of management companies, engineering services, as well as other conditions that are important for the area.

Notes

No footnotes found for this article. We regularly edit dictionary entries. Perhaps soon additional materials will be posted at this place.

All concrete floor defects are conditionally combined into the following groups:

operational damage;
damage resulting from chemical and climatic influences.

Mechanical damage

This type of damage is the most common. Mechanical damage occurs due to a variety of factors and is conventionally divided into internal and external. The latter can be found on the floor surface on their own, and to find the internal ones you will need a special device - a concrete flaw detector.

The most common mechanical damage and their causes:

chipped. They are formed as a result of mechanical impact on the floor areas, under which there are zones of low density. The reason for the appearance of chips may be a violation of the ratio of water and cement in the concrete solution during pouring, the absence of temperature-shrinkage joints, insufficient reinforcement, movements in the base;
potholes. Usually caused by shock loads. Potholes can also be formed as a result of the impact of a large mass, for example, in areas where heavy equipment is located;
delamination of the top layer of concrete. It occurs most often due to poor-quality drying of the concrete surface and finishing it until the solution is completely hydrated;
swelling. They appear when the surface layer of concrete has been compacted until air bubbles are completely removed from the mortar mass. Blisters also appear after treatment with impregnations or paints of an undried concrete surface;
cracks. Over time, they can expand and connect with each other, which can cause large potholes to form.

As you can see, the appearance of some defects could have been avoided. But chips, potholes and cracks are formed during the operation of the concrete floor, so they need to be repaired periodically.

Prevention of mechanical defects

To minimize the possibility of mechanical damage, it is necessary, first of all, to comply with the technology for arranging the concrete floor.

When arranging a concrete floor, the following rules must be observed:

the class of concrete must necessarily correspond to the design loads. Saving on materials can cause the life of the floor to be reduced significantly and you will have to spend money and effort on its repair much more often;
it is impossible to violate the technology of pouring concrete mortar and its further drying. Concrete requires high-quality compaction, and when hydrated, it should not lack moisture;
attention should be paid to deadlines. If concrete without special additives-modifiers was used to fill the screed, then it is possible to start finishing the surface no earlier than a month after the installation work;
the concrete floor during operation should be protected from excessively intense impacts. Loads, of course, will be present, but you can reduce the harm from them. For example, simply limiting the speed of traffic on an industrial floor causes damage to the coating to occur much less frequently.

Operational damage

All of the following defects occur either as a result of improper operation of the concrete floor, or as a result of a violation of the technology for its arrangement.

Operational damage includes:

tie deformation. This defect is expressed by a change in the level of the concrete floor. The coating most often sags in the center and rises at the edges. The reason may be the uneven density of concrete during pouring due to insufficient compaction, as well as insufficient reinforcement thickness and different humidity of the lower and upper layers of concrete;
screed cracking. Cracks can occur both during mechanical influences on the floor, and during its deformation, which can be provoked either by thermal expansion, or by excessive loads that significantly exceed the calculated ones;
peeling. Peeling of small scales is observed on the concrete surface. It usually begins with the appearance of a network of small cracks. The cause of this defect is too rapid evaporation of moisture from the top layer of concrete;
dusting the concrete surface. It is expressed in the appearance of fine cement dust on the floor surface. May be due to several reasons. This is a lack of cement in the solution, and an excess of moisture when pouring the floor, and the impact of various abrasives on concrete.

Operational damage is eliminated somewhat more difficult than mechanical damage.

To minimize the risk of defects during the operation of the concrete floor, the following recommendations should be considered:

the solution should be processed and poured in accordance with all the rules of technology, preventing it from peeling and delamination during drying;
to prevent cracking of concrete, it is necessary to lay a damper tape along the perimeter of the room to compensate for deformations. On large-area screeds, expansion joints with polymer filling are required;
it is also necessary to qualitatively prepare the base for the screed: the denser the soil is compacted, the less likely it is to subside, deform and crack the concrete structure;
to avoid surface damage, a polymer-based reinforcing impregnation or iron-hardening of the concrete should be applied to the concrete surface.

Climatic and chemical impact

A separate group consists of defects resulting from a reaction to any chemical substance or climatic influence.

This may include:

the appearance of light spots and streaks on the surface of the concrete floor, the so-called efflorescence. The reason for the formation of salt deposits is a violation of the humidity regime or the ingress of calcium chlorides and alkalis into the composition of the concrete solution. It is for this reason that experts recommend using imported water for the preparation of a concrete mixture in areas with highly carbonate soils;
destruction of the concrete floor surface under the influence of low temperatures. Water that has entered the pores of the upper layer of concrete, when frozen, increases in volume by 10-15%. Therefore, microscopic pores gradually expand. The more often the process of freezing / thawing occurs, the more intensively the concrete is destroyed. To combat this phenomenon, special anti-frost impregnations or compounds are used that reduce the porosity of the material;
Corrosion of reinforcement is also included in this group of damages. Metal mortgages become rusty where they are exposed. This leads to a decrease in the strength of the reinforcement and the entire concrete structure. To prevent this process, the reinforcement must be treated with an anti-corrosion compound.

All the defects described above can manifest themselves in a variety of forms. The first signs of many of them may look quite harmless, but nevertheless, when they are detected, appropriate measures should be taken. Otherwise, the situation may worsen over time.

The main technologies for eliminating defects are described in this article, and about repairs using epoxy mastic

Screed- this is an intermediate layer in the construction of floors between the base and the finishing floor of the room.

Leveling screed

Leveling ties serve to level the base, to give a given height (or slope) to the floor plane. For the screed device, they use: cement-sand mortar, lightweight and cellular concrete, ready-made dry mixes for self-leveling floors, self-leveling mixes.

The minimum thickness of the cement-sand mortar screed is 30mm. For screeds with a thickness of less than 20 mm, ready-made dry mixes are used. For a layer less than 5 mm, self-leveling compounds are used.

Thermal insulation screed

Thermal insulation screeds serve to provide thermal insulation of the room from the base. Thermal insulation is carried out with a density of about 170 kg/m³ or foam plastic with a density of at least 30 kg/m³.

In the case of underfloor heating, a heat-insulating layer is necessary to prevent the spread of heat into the room below.

Dry floor screed

Dry floor screed is made of special gypsum-fiber or cement-fiber boards. Such slabs are laid on a dry backfill (sand, expanded clay fraction 1-5mm, perlite) or polystyrene (expanded polystyrene), which perform a leveling function.

Before backfilling, the base is covered with a film with an overlap between pieces of film of at least 20 cm to protect the screed from moisture. The film should go on the walls 20 cm above the level of the future floor. Along the walls around the entire perimeter, an insulating tape made of polyethylene foam is laid. The tape is used for sound insulation and to compensate for the linear expansion of the laid boards.

The thickness of the backfill must be at least 2 cm. Level the backfill along the guides using the rule.

Then the plates are mounted. The plates are stacked on top of each other with an overlap and fixed in special grooves with self-tapping screws. Before this, the joints are coated with glue.

After laying the plates, cut off the protruding parts of the film and insulating tape.

Dry screed is used to repair old floors or flooring on wooden floors, which are afraid of a lot of moisture.

The advantage of a dry screed is the simplicity and speed of its installation, the possibility of laying the flooring within a day after the installation of the screed plates.

Video: dry floor screed device

A screed is satisfied if:

it is necessary to level any element of the floor under the coating;

give the floor a given slope;

form a durable layer along non-rigid (or fragile) floor elements.

Floor screed device

Before pouring the cement screed, it is necessary to check and close the gaps and joints between the floor and walls, between the floor slabs. After that, the floor surface is dedusted. It is necessary to remove oil stains, paint residues.

For the installation of a cement-sand mortar screed on a concrete underlying layer, reinforced concrete floor or waterproofing layer on a surface cleaned of debris and dust, beacon rails are laid through 1.5-2 m with a height equal to the specified thickness of the screed (usually 3-5 cm).

As a beacon rail, wooden bars of the appropriate thickness, galvanized UD, CD profiles intended for installation or steel pipes of the required diameter, which are used repeatedly, are used.

The level of the top of the lighthouse hreek is determined by the marks that are made on the walls using a level or a simple water level. Then, the marks of the top of the lighthouse are set using a tape measure or a measuring ruler and, if necessary, the underlying layer is leveled.

In accordance with the marks applied to the wall, beacon rails are installed, which are laid on the fixing marks from the solution, embedding them to the required level. To maintain a predetermined level, dry cement is poured onto the marks, which accelerates the hardening of the marks. To create screed slopes, beacon rails are installed with a slope.

With the help of the rule, the correct laying of the beacons is checked.

The surface of the underlying layer is moistened immediately before laying the cement-sand mortar. Humidification prevents excessive suction of moisture from the solution and increases the strength of the screed.

The solution is laid between two lighthouse rails in strips through one and leveled with a rail-rule, which is supported on two lighthouse rails, and after removing the lighthouse rails, on the edges of the previously laid screed strips that have hardened. In the missed strips, the solution is placed 24 hours after the laying of the first strips.

A freshly laid screed is protected from moisture loss by covering it with matting, film, shields, etc. and watered for 7 days at least once a day. At high temperatures (above 15 ° C), the screed is watered twice a day, this will avoid the appearance of cracks.

You can usually walk on a freshly laid screed after 24 hours. The screed gains full strength after 28 days.

Screed requirements (SNiP 3.04.01-87)

The clearance between the 2-meter control rail and the surface of the screed to be checked must not exceed:

2mm for screeds for coverings from parquet, linoleum and other rolled synthetic materials;

6mm for screeds for other coatings.

The deviation of the screed plane from the horizontal or the specified slope is 0.2 of the corresponding room size, the maximum deviation is not more than 50 mm.

Floor screed defects and how to eliminate them.

Irregularities on the surface of the screed. Large irregularities are knocked down (or hollowed out with subsequent embedding), small ones are ground with an abrasive tool.

Cracks in the screed. Occur as a result of the drying of the screed (very fast drying) or the use of poor-quality mortar. Cracks are embroidered, primed and sealed with mortar.

Detachment of the screed from the base. Cut out a "bubbling" area, remove dust and moisten the base, re-fill with a solution.

There are no comments for this article.

Only registered users can leave comments on articles!

Floor screed repair is a fairly common type of repair work. The rough floor experiences significant loads, as a result of which it gradually wears out and weakens. You can strengthen the concrete base and eliminate defects yourself.

Malfunctions and their causes

The most common subfloor damages are:

general loosening of the screed. It is characterized by the appearance of a large amount of cement dust as a result of a violation of the mortar preparation technology or low quality cement;
potholes and cracks. Formed due to excessive point load on the floor surface. The presence of voids in the upper layer of the concrete base also causes the screed to crack and deform. This defect is considered the most dangerous for decorative flooring: the area located above the damage and devoid of solid support quickly becomes unusable and collapses;

exfoliation. Diagnosis of this malfunction is made by tapping the floor surface with a hammer. In the exfoliated areas, the sound from the impact will be deaf, and dust will begin to come out through the cracks formed. Delamination can be expressed in visual swelling of the top layer and raising the corners after the mortar dries. The reasons are often the uneven drying of concrete, the lack of a primer layer under the base and the use of low-quality cement;
excessive dusting. Due to excessive loads and general aging of the screed, a large amount of cement dust is formed on its surface. Sometimes floor dusting is associated with poor quality cement and violation of pouring technology.

Repair composition

Mixtures for the restoration of cement screeds are widely represented in the modern construction market. They include polyurethane components and synthetic resins and are more intended for industrial use. When carrying out repair work in an apartment, the purchase of expensive compounds is not always rational, therefore for minor repairs, the mixture can be prepared by hand.

For this it is necessary mix PVA glue with water at a ratio of 1: 3, then add one part sand and three parts cement. The resulting composition should be carefully moved using a construction mixer or a drill with a paddle nozzle.

A homemade cement mixture can repair shallow cracks and small potholes. For large-scale repair and restoration work, you need to purchase professional tools.

How to strengthen?

To strengthen the subfloor screed, it is necessary to drill a series of holes with a puncher, equidistant from each other at a distance of 25 cm and having a diameter of 20 mm. The depth of the channels made should be equal to the thickness of the screed. Work should be carried out using a drill with a small angle of inclination of the working groove. Openings should be cleaned of dirt and, if possible, dust-free. Next, you need to prepare trimmings of reinforcement, equal in length to the depth of the channels and having a diameter of 12 mm.

Then, a mixture of epoxy for concrete "Rizopox-350" and quartz sand should be poured into the holes, then iron rods should be inserted. Reinforcement must be pre-degreased b. The upper, widest part of the channel is also carefully poured until it is level with the base. The installation of a decorative coating can be started after complete drying, subsequent dedusting and priming of the screed.

If there is a “warm floor” system, this method of strengthening the screed is not suitable: drilling channels can damage the cable and thermomat, as well as pierce the water heating pipeline.

How to repair?

After diagnosing the delaminations that have appeared, as well as in cases where the screed is swollen and “swollen”, it is possible to start repairing it only if the damaged surface is no more than 30% of the total area of the self-leveling floor. There are two ways to repair delaminations. The first is to carry out point injections using a liquid repair mixture. and consists of several steps. Initially, problem areas should be identified by tapping and outlined with chalk. Then, channels with a diameter of 15 to 20 mm are drilled in places of delamination. The distances between the holes should be 25-30 cm.

Next, the channels should be dedusted and poured into them with a primer mixture, trying to evenly moisten the entire surface of the inner cavity. At the end of the pouring, you need to dry the treated surface with a building hair dryer. As a material for injection, cement-adhesive mixtures or epoxy resins can be used..

An important condition for the maintainability of the solution is good fluidity. To fill the channels, you can use a construction syringe or a plunger pump.

Injections should be carried out slowly, allowing the solution to be evenly distributed throughout the entire internal cavity. The procedure should be carried out until the upper part of the channels is filled with the mixture to the floor level.. The repaired screed should dry for at least a day, after which you can proceed to priming and subsequent installation of the finish coating.

The second way to repair a delaminated screed is to completely dismantle the problem area, dedusting and priming the surface, followed by concrete pouring. The method is used in cases of impossibility of spot repair with a large area of the damaged area.

Getting rid of cracks

Cracking of the screed surface can occur from uneven loading on the finish coating, impacts and poor wetting of the concrete base during drying. If the floor surface is cracked, burst or crumbles badly, emergency measures must be taken, because cracks are the most serious defect in screeds. To fix the problem, you need to deepen and widen the crack with a grinder until strong edges are obtained, while using a stone working disc. Then, grooves perpendicular to the direction of the crack should be cut with a depth of 2 and a width of 15 cm. The surface of the recesses is carefully dusted and primed.

Next, the crack must be filled with a repair compound to half its depth and a metal bracket should be installed. To increase the strength of the solution, you can add quartz sand to it. After filling the main crevice, it is required to fill the transverse grooves with mortar and remove excess mortar. Then you need to wait for the complete drying of the repaired surface and proceed with its grinding.

When repairing deep cracks, their cavity must be drilled to the entire depth of the screed. When forming transverse grooves at the ends, it is necessary to drill holes 2-3 cm deep. It is necessary to fill a deep crack in several stages, giving each layer time to harden as much as possible.. The first batch of the mixture should be made a little more liquid. This will allow her to penetrate into the most inaccessible places at the base of the floor and fill them evenly. The next batch should be of medium density, it should be poured into the crevice to the level of the transverse grooves.

After the second layer has set, you need to install the tightening metal brackets, fixing their ends in the drilled holes. Then a plasticizer is added to the solution and a final pour is made, which will hide the bracket underneath. After the solution has completely dried, the repaired area is polished and the screed is prepared for the installation of a self-leveling floor or the installation of a floor covering.

Elimination of potholes

Repair of potholes and chips should begin with their expansion and deepening, which must be carried out until the edges of the recess stop crumbling. To do this, use a grinder equipped with diamond discs designed for working with stone. For serious potholes, the depth of which exceeds five centimeters, you need to drill through the entire thickness of the screed. Then, construction debris should be removed from the crevice and carefully dusted. Next, you need to apply a primer mixture and let it soak.

Filling the pothole with mortar should be done in several stages., applying each subsequent layer only as the previous one dries. This will ensure uniform drying of the solution throughout the depth and prevent the appearance of cracks.

If, after drying, the screed cracked again, you should increase the opening area of the concrete layer and repeat the procedure. A day after the repair work, it is possible to grind the site and prepare a screed for laying the turnkey coating.

Dust removal

Very often, an old screed, especially one that does not have a decorative coating on top, begins to dust. This problem is most typical for the floors of garages, warehouses and industrial premises. Constant weight loads, combined with vibration and regular temperature fluctuations, contribute to the rapid destruction of the coating and the appearance of cement-sand dust. Over time, the dust becomes so much that it is impossible to sweep it away. If it is impossible to completely change the concrete screed, you must immediately strengthen the old base..

Initially, the floor should be cleaned of mechanical debris and dirt. Then the surface is dedusted and examined for cracks and potholes. When they are detected, problem areas are repaired, and after the solution dries, they are polished. Then you need to cover the entire surface of the screed with an all-penetrating primer mixture and wait until it is completely absorbed. In rooms with high humidity, special water emulsifiers should be used.. Next, the surface is painted with wear and frost-resistant enamel for concrete surfaces.

It is possible to cover a dusty floor with a specialized compound having a polymer base. The solution is able to penetrate deep into the concrete screed by 5 mm, completely preventing the formation of dust. The treated surface acquires excellent vapor-permeable properties, and is also characterized by high resistance to chemicals, sudden temperature changes and abrasion.

To increase the anti-slip effect of the floor, quartz sand is applied to the uncured composition., which, after drying, forms a rough surface.

More reliable is the method of reinforcing a dusty floor with special fiberglass.

To do this, the surface of the screed is dedusted and primed. After the primer mixture has dried, tile adhesive is applied to the screed and the fabric is laid. Cloths should be laid with an overlap, leaving no open areas.

After the first layer of glue has dried, a second layer should be applied over the fabric. This will securely fix the dusty base and increase adhesion. Then, along the perimeter of the room, it is necessary to install a damper tape, which will act as a compensator. The last step will be the installation of beacons and the installation of a self-leveling mixture.