Minor defects on the screed how to fix. Floor screed repair: how to repair cracks, potholes and stop delamination? Preparation of repair mortar for cement screed

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, an 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 soundproofing and for compensating for the linear expansion of the laid slabs.

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 floor installation on wooden floors who 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 floor covering already 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 cleared of debris and dust, beacon rails are laid through 1.5-2 m with a height equal to the specified screed thickness (usually 3-5 cm).

Used as a beacon rail wooden blocks of appropriate thickness, galvanized profiles UD, CD, intended for installation or steel pipes the desired diameter, which are used repeatedly.

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 temperature(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.

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Every day, the floor screed is exposed to various loads: heavy furniture, flooring, people walking, as well as falling objects. As a result, the screed wears out, cracks, deep cracks and chips form, in addition to everything, flaking appears.

Defects also appear from non-compliance with the technology when creating a screed: a solution of the wrong consistency, bubbles formed during pouring, a poorly cleaned base, the use of low-grade cement.

If defects occur, the floor screed needs to be repaired. Experts in this field recommend not to delay this process and make repairs, the sooner the better, in order to avoid large physical and financial costs.

To determine the defects of the screed, it is necessary to completely remove the old coating. There are several types of screed damage:

the formation of cracks - occurs as a result of the deflection of the main plate;
stratification - occurs during the production of pouring the solution on a poorly cleaned surface;
surface abrasion - the screed solution was made from low-quality material;
the formation of voids - the floors were filled with a solution of disturbed density.

If, with these damages, the screed is broken by 30%, then the repair will not make sense and the pouring must be done again.

Repair of small and large cracks

Cracks in the subfloor should be repaired immediately. A delay in this procedure can lead to a lot of negative consequences: an increase in the size of cracks, the penetration of debris and moisture, scattering of edges, damage to expensive flooring.

If the depth of the crack corresponds to a reading of no more than two centimeters, it is necessary to make cuts along the crack to a depth of several millimeters and 2 cm in breadth. Then remove dust and debris with a vacuum cleaner. These cracks are treated with a primer until it is no longer absorbed. This procedure is performed to improve the adhesion of the concrete solution to the surface.

To repair small cracks, a repair compound is prepared, which includes PVA glue - 1 part, water - 3 parts, cement - 3 parts and sand - 1 part. The glue is carefully diluted in water, then pre-mixed sand with cement is added to the resulting solution.

This solution is not suitable for repairing deep cracks. Treated cracks just above the floor level are filled with freshly prepared mortar. After drying, the excess concrete is removed by means of a grinder.

Repair of large cracks begins with cutting the latter to their full depth. For the production of this process, you must use a puncher or a construction saw. It must also be remembered that the solution is poured onto a surface thoroughly cleaned of dust and debris and treated with a special primer.

If the cracks are wide enough, they should be reinforced with metal staples to avoid further development. To do this, every 25-30 cm, transverse two-centimeter cuts are made to a width of 1.5 cm.

At the next stage, a solution is prepared, which includes a mixture of sand and cement 3: 1. Such cracks are filled in several stages.

On early stage production uses a liquid solution to shed a crack in hard-to-reach places.

Next, a solution of medium density is mixed, and concrete is poured flush with the bottom of the cuts made. After the new layer has hardened, metal staples are made from reinforcement or wire and inserted into the strobes made.

Next, you need to mix a little plasticizer into the repair solution and fill the cracks with it, pouring it along with the staples to the brim. When all layers are thoroughly dry, it is necessary to perform grinding work.

Repair of potholes and defects

If the cement screed installation technology is not followed, potholes form. In order to avoid subsequent destruction, it is urgent to start repairing the screed. Before repair, it is necessary to first cut a pothole by 2-3 cm. through a diamond disc.

The recess is treated with a special primer, and then with a concrete solution. The repair composition is poured flush with the entire floor using the rule. On final stage the floor is being sanded. If the recess exceeds 5 cm, then the solution is laid in two stages in layers.

Elimination of peeling screed

This defect occurs as a result of the production of a screed on a dirty and unprimed surface. Damage to the screed is detected when voids and cracks form, and a large amount of dust is released from under the floor covering.

Repair of such damage is carried out in several ways. In the first case, repairs are carried out by applying patches. That is, the deformed area is completely removed, at the same time dust and debris are removed, the surface is treated with a soil solution, and filled with a new solution.

The next method is less laborious, reproduced by injection and filling the resulting voids. In places of delamination, holes with a diameter of 16 mm are made with a drill. for the entire thickness of the screed, with a distance of 30-40 cm from each other.

With this method, you need to correctly calculate the consistency of the solution, it must be fluid in order to completely penetrate into hard-to-reach places with a construction syringe. The repair composition for this type of work is made on an adhesive or epoxy basis.

Screed alignment

As a result of the use of the screed, irregularities are formed, the impact of which adversely affects the finish coating. To eliminate this defect, the floor should be leveled with a milling machine. This device is deepened by 1 cm and the floor is sanded.

The dust is then removed and treated with a polyurethane or epoxy primer. A solution is laid on the treated surface and leveled using the rule. After the concrete mortar has hardened, the floor is re-sanded.

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 you will need special device- 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 observe the technology of 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 impacts 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 around 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 that have arisen as a result of 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 in areas with highly carbonate soils to use for cooking concrete mix imported water;
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 the different form. 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

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 generated, 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 errors 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 drying of the surface layer is faster compared to 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, Sun rays accelerate the drying process 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 flooring, 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 a layer of heat or sound insulation began to arise as a result of emergencies on water or heat supply lines. The main problem in terms 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.

When performing capital repair work in a room of any purpose, the technical condition of the floors requires special attention. After long-term operation, the coating may have a number of defects, which can only be corrected by overhaul floor screeds.

After a long use of the concrete floor, it can receive both minor damage and become covered with large cracks, which can be corrected only by a complete replacement of the screed.

Defect classification

The easiest way is to completely dismantle the existing coating to the very base and arrange a new screed. Such actions justify themselves if there are no more ways to restore the old screed. Under normal circumstances, this is unacceptable for a number of reasons:

Most often, the old flooring can be repaired and updated without resorting to such drastic methods.
Dismantling of old screeds in a residential area is a very noisy and extremely polluting event; during the work, cement dust will spread throughout the entire volume of the apartment.
It is necessary to dismantle the existing screed to the very foundation, otherwise the procedure loses its meaning. However, it is not known what state the foundation itself is in. The case may end with the repair of bearing reinforced concrete structures which is very expensive. Ideally, applying a scrupulous approach to the issue, it is necessary to do so in order to ensure the safe and durable operation of the premises. But in the short term, this approach may not be justified.
Repair the floor screed by complete replacement- the most expensive method of all available.

It would be more correct to remove the finished top flooring, clean the surface of the existing screed and visually examine it, determining the number and size of defects. In the process of studying the entire area of the concrete surface, it is recommended to gently tap with a hammer for the presence of hidden voids in the thickness of the screed as a result of delamination. A dull sound will accurately indicate the location of such a defect. After all damages and their number are determined, you can start choosing a way to eliminate them.

There are several types of wear on old concrete floor coverings:

Delaminations occur due to temperature changes and the effect of moisture on concrete.

Cracks of various depths and degrees of opening occur over time in the thickness of the coating as a result of loads and temperature effects.
Potholes and depressions appear during operation after constant mechanical impacts on the concrete layer. This may be moving heavy pieces of furniture or musical instruments(e.g. piano) or vibration load from washing machine. In industrial premises, the range of loads on floors is very wide.
Delamination of concrete in a certain area is formed with the simultaneous effect of moisture and temperature changes.
The low strength of the surface layer of the screed is the result of an initially low grade of cement-sand mortar or concrete. On such a surface, dust of cement and sand from the slightest mechanical impact is constantly present.

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Elimination of minor damage

Repair of small cracks begins with opening them in width and depth. For this, an angular Grinder with cutting wheel for stone and concrete. On both sides of the defect, the screed is cut in a circle to a depth of up to 5 cm so that after removing pieces of the old mortar, a rectangular groove 2-3 cm wide is obtained. It is cleaned and dust is removed to assess the sufficiency of the cut depth. If it turns out that the crack goes to the very base, then you will have to do the same work as in the case of through wide cracks.

The cut groove is sealed after applying a primer to its walls, which will lead to dust removal and hardening of the existing concrete layer. It may be necessary to primer several times, especially when it is noticeable that the surface strongly absorbs the applied composition. To complete the last stage of the repair, you need to prepare a special cement-sand mortar on PVA glue. The recipe is as follows: the glue is mixed with water in a ratio of 1:3, after which the mortar itself is mixed on this basis, the ratio of cement and sand is 1:3. Since the amount of work is small, it is best to do the mixing in a plastic bucket (possible from under the paint) with an electric drill with a mixing nozzle. If the latter is absent, you can use a piece of wire with a diameter of 6 mm, one end of which is bent up or in the form of a ring, and the other is fixed in the chuck of a power tool.

With the help of a trowel and a rule, the cut crack is filled, and the surface is smoothed, removing the remnants of the solution. Subsequent work can be carried out no earlier than 20 days after the end of the repair, this applies to all types of work to restore the screed. The same method can be used to repair potholes and other mechanical damage in the surface of a concrete screed.

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Deep Crack Filling Technology

Through wide cracks are expanded to the very base with a perforator, broken pieces of old mortar and dust are removed. For this purpose, it is best to use compressed air to blow out any excess debris. If a crushed stone pillow is found as a base, it will need to be compacted and filled with liquid cement milk at the cutting site, if possible. In this case, the milk should fall under the cut edges of the screed, after which you need to give time to solidify. base in the form reinforced concrete slab must be primed together with the edges of the resulting groove.

Further repair of the screed consists in filling the groove with a special compound. You can do this work by preparing the same solution as in the previous case, and smoothing it out with a rule. But it should be understood that cracks of this size do not occur in the screed just like that and can reappear, so it is recommended to withstand the technology. In this case, you should not save on self-cooking, it is better to purchase a ready-made thixotropic mixture for repairing the floor in the distribution network, at the same time buy a special damper cord-seal, this is used for the construction of expansion joints.

After stirring, the entire cut-out niche is filled with the mixture, while vertical markers made of thin steel wire are installed along the entire crack. When the thixotropic mixture sets, the markers can be pulled out so that they come out more easily, they should first be lubricated with grease.

The next stage is the laying of a damper cord, under which a narrow groove 5 cm deep is cut. After this operation, the groove is sealed with a plastic sealant based on silicone or polyurethane. As can be understood from the technology, the result of such a repair is the construction of an expansion joint at the site of a large floor crack. Whatever the reasons for its occurrence, new defects will not appear in this place.

Layering of concrete in the thickness of the screed can be eliminated by injection. As soon as all places with this defect are found, it is necessary to drill holes in the screed within these areas using a perforator and a drill with a diameter of 12 to 20 mm, the distance between the holes is 250 mm. Next, they should carefully pour a special composition based on epoxy resins. If possible, it is better to use a syringe. Pouring should be carried out until all the voids and pores are filled, the process should be done intermittently, allowing the composition to soak into the concrete. Repairing a floor screed with this method is not difficult work, but it requires attention and patience. After the epoxy glue hardens, which will occur within a day, you can proceed to further work.

The weakened surface layer of the screed can be made stronger with modern building deep-penetrating compositions based on polyurethane. Such impregnations allow you to raise the grade of the screed solution from M50 to M300 to the required depth. After the floor is treated with polyurethane compounds, the formation of cement dust will stop, and a protective film up to 200 microns thick will appear on the concrete surface.

Carrying out restoration work concrete pavement floors, you can save a lot cash, which will inevitably be spent during the dismantling and installation of a new screed.