How to repair an old floor screed. Repairing a floor screed: do-it-yourself concrete, cracks and why it cracks, how to seal the warm one when it dries and repair it. Filling voids by injection

If, over time, you are depressed by the state of the once impeccable floor screed, seeing cracks, gouges and a large amount of cement dust on its surface, you should not immediately scold the builders (or yourself, if you did). First, remember what loads your screed was exposed to.

Types of ties: tied, floating, connected.

Under the influence of such a number and severity of loads, even a heavy-duty one perfectly made by a professional craftsman concrete screed will not stand the test of time and, having lost its original properties, will become unusable.

But if you notice in time that the screed has begun to deteriorate, then you can repair it, and it’s easy to do it yourself, saving your nerves and money. After all, there is no point in doing poor quality work on your own.

Strengthening a weak screed

In the event that the screed was performed poorly, the best solution It will be completely redesigned. But breaking the old screed to the ground and then filling it with a new one is long and hard work. Therefore, in cases where the destruction of the screed has not gone too far, repair of the floor screed can be performed using a special epoxy resin for concrete.

To do this you will need tools and materials:

a hammer drill with drills that have a small angle of inclination of the working groove (need as small as possible);
vacuum cleaner;
hacksaw or grinder;
quartz sand.

Using a hammer drill, we make holes with a diameter of 20 mm across the entire floor area at a distance of 25 cm from each other. It is necessary to drill through the entire thickness of the floor screed to the solid foundation. After completing this work, you need to go through each hole again and double their upper part. This expansion should be done up to half the thickness of the screed, but not less than 3 cm.

The holes made must be vacuumed to remove all dust. Then the steel reinforcement needs to be cut required quantity pins equal in length to depth drilled holes. The diameter of the reinforcement should be within 1.2 - 1.5 mm. All cut pins must be degreased.

After this, a special low-viscosity epoxy composition Rizopox-3500 is diluted. When repairing floor screeds in utility and utility rooms, such as a basement or garage, you can also use Rizopox -1605 to fill the holes, but the upper bowls still need to be filled with Rizopox -3500, so there is little point in diluting two epoxies at once.

To bring the composition of the rhizopox as close as possible to the composition of the screed, you need to add quartz sand to it as a filler. The size of sand grains is from 0.8 to 1.4 mm. Rizopox is poured into the drilled narrow hole, a metal pin is inserted into it, and the expanded upper part is poured. After the epoxy composition has completely hardened, you will have a screed surface reinforced with epoxy pins reinforced with steel reinforcement.

However, if the screed turns out to be severely damaged, then no reinforcement will help; you will need to completely dismantle the old one and make a new screed.

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Partial detachment of the floor screed

Partial peeling of the screed from the base occurs almost everywhere. The reason for this deformation is uneven loads on the floor surface. When the screed peels off, an empty space is formed between it and the base, which does not add any strength to the screed. The worst thing is that such a defect cannot be seen, it can only be heard.

To detect places of delamination, you need to tap the entire floor area with a hammer or metal rod. There is no need to hit hard to avoid damaging entire areas.

In the place of detachment, the sound from the impact will be noticeably muffled.

Detachment of the screed also often occurs along the edges and in places where cracks have appeared. If you hit with a hammer near a crack, and a small fountain of dust rises from it, then the screed in this place has 100% peeled off.

The repair of the floor screed itself is called the abstruse word “injection”, but in fact there is nothing complicated about it; in this case, without any special difficulties, you can repair the floor screed with your own hands. For execution repair work You will need the following tools and materials:

a hammer drill with drills that have a small angle of inclination of the working groove;
vacuum cleaner;
grinder with a special disc for working with stone;
putty knife;
construction syringe;
epoxy resin Rizopox - 3500;
special repair composition for floors.

All suspicious areas must be tapped a second time to determine the area of peeling. The contours of the suspected places of peeling are marked with chalk or a marker.

If the outlined contour small sizes, then it will be faster and more reliable to remove it along the outlined boundaries or to guarantee 0.5-1 cm more, and fill the resulting empty space with a special repair compound.

Such repair compositions are made on the basis of cement with the addition of various mineral and polymer additives. They are intended for filling voids up to 4 cm deep. If the depth is greater, then it will have to be sealed in two stages.

If the peeling area is too large to use repair compounds, then holes with a diameter of 20 mm are drilled in the marked contour along its entire area every 25 cm. As in the case of reinforcing the screed, Rizopox is diluted, only without sand and with a more liquid consistency.

Diluted Rizopox is poured into the holes using a construction syringe. To completely eliminate the detachment, the hole must be completely filled with Rizopox. However, this is unlikely to succeed the first time, since Rizopox needs time to displace the air from the cavity, and the concrete will absorb some of it. Therefore, you need to be prepared for the fact that the described procedure will have to be repeated several times.

But this can only be done if the total area of delamination does not exceed a third of the total area of the screed. If the area of delamination is larger, then the screed will have to be completely redone.

Repairing concrete floors with your own hands is by no means a simple “greasing” with cement mortar. Such a “blame” will not stop the destruction of concrete, will not level the floor and will not block the access of vapors through it.

The thing is that concrete, even if it has gained structural strength, lives its complex physical and chemical life for decades: it changes its structure, gains strength, and then weakens a little until it stabilizes. Fresh concrete has a number of indicators, including shrinkage rate and coefficient of thermal expansion, that differ significantly from cured concrete. For the repair of an old floor to be successful, you need to somehow coordinate the properties of the old and new concrete. One of the optimal methods for minor DIY repairs is giving a fresh cement mortar thixotropic and rheological properties.

Thixotropy and rheology

Thixotropy is the ability of a medium to yield, to reduce its viscosity under even small but constant influence. Good example thixotropic substance - ordinary construction bitumen. If you move your finger along it with pressure, you will first feel roughness, and then the movement becomes easier and a hollow remains behind your finger. By the way, continental plates move across the face of the Earth due to the fact that the material in the upper mantle is thixotropic.

Rheology is nothing more than superfluidity. The phenomenon is not at all a privilege of ultra-low temperature physics. Any housewife who forgot to tightly close a container with sunflower oil has encountered rheology. However, if liquid helium-II is 100% superfluid, then vegetable oils- by units and fractions of percent. But this is enough for the vessel to end up all sticky after a while, and the kitchen furniture to be damaged.

Under normal conditions, thixotropy and rheology are inextricably linked. When builders say “thixotropy,” they immediately mean rheology. When repairing a concrete floor, rheology ensures that the smallest irregularities are filled with the repair composition, and thanks to thixotropy, the new concrete mass, figuratively speaking, does not rest against the old one, but plays along with it.

Construction stores have a wide range of thixotropic-rheological mixtures for repairing concrete floors based on epoxy resin and polyurethane. However, to repair an apartment floor that is in relatively stable conditions and lightly loaded, a cheap thixotropic composition can be prepared independently:

To do this, PVA glue or bustylate is diluted three to five times with water, and mixed with the resulting suspension. cement-sand mortar in a ratio of 1:3. If the amount of work is large enough, you can immediately buy PVA putty. This is the same highly diluted glue, but the minimum packaging is 5 liters.

PVA suspension is not suitable for sealing deep deformation cracks; here you will have to buy a branded thixotropic primer for concrete and a repair compound. In this case, you should focus solely on price: an apartment floor is a lightweight object, and exclusive quality compounds are not required.

Mixer and rule

All repair compounds for concrete must be mixed: ready-made with water; homemade - with PVA suspension. It is impossible to knead manually: the finished solution must be as “dry” as possible, i.e. water or suspension is added in a minimal amount. A very viscous mixture will have to be “pounded” for too long to achieve the desired homogeneity, and irreversible changes will begin in it, deteriorating the quality of work.

For mixing small volumes of repair construction compounds I use an electric drill or hammer drill at low speeds with a special attachment - a mixer. The principle of its operation is no different from a cocktail mixer.

In tool stores you can find a wide selection of different mixers, sometimes in completely bizarre configurations. But a mixer, in no way inferior to them, is made from an even rod 8-10 mm in diameter and half a meter long, the end of which is bent into a ring or simply folded in half.

The kneading lasts 3-5 minutes. When kneading in a bucket, move the tool in a circular motion; in the trough - transverse zigzag. You should have a bucket of water at hand - after kneading, the mixer should be rinsed immediately by immersing it in water and turning it up to high speed. When mixing with a hammer drill, you should never turn on the impact mechanism: the entire room and you will immediately find yourself covered in a thin layer of concrete.

In addition to a mixer, to repair a concrete floor you will need a rule - a wide, one meter, spatula. A plaster float will not work: it will not smooth out the concrete properly, and will wear off on it itself. The rule, on the contrary, is to purchase a factory one, and you should not skimp on it, especially since it is inexpensive. Concrete is a good abrasive, and if the middle of the rule turns out to be “eaten away,” then the floor will turn out humpbacked.

Types of concrete floor repairs

There are four different types of concrete floor repairs:

Elimination of defects - bulges, potholes, seams from markers and formwork, cracks in the screed.
Sealing gaping cracks.
Major renovation floor screeds for polishing concrete, laying a finishing coating or underfloor heating with insulation and waterproofing.
Dust removal.

Each type of repair is carried out using a special technology. Repairing the screed under a clean floor is the most labor-intensive and expensive. To overhaul it, you will additionally need a metal rolling roller with a width of at least 0.5 m and a weight of at least 10 kg with a carrier handle.

After all types of repairs, except for dust removal, the floor must be left for at least 20 days before continuing work, sprayed with water every day or wiped with a generously dampened rag. It is impossible to pour or wet the floor more often: set concrete absorbs a certain amount of water and slowly. "Binge drinking" will harm him.

Recommendations about mandatory curing for 40 days or more, covering concrete with wet burlap, etc. are intended for concreting on outdoors. In relatively stable conditions of a residential or commercial premises, 20 days of exposure is more than enough.

Preparing the premises

Preparing to repair a concrete floor comes down to emptying the room and thoroughly cleaning it. Large debris is raked with a shovel, then the floor is thoroughly swept two or three times with a wet broom and spraying. After each sweep, potholes and cracks are blown out with a household vacuum cleaner after the floor has dried.

If you have the opportunity to use an industrial vacuum cleaner, preparing the floor can be done in an hour: suck the floor, blow out potholes with cracks, suck again - and that’s it, the preparation is complete.

Procedure for repairing a concrete floor

Repairing the floor in an apartment begins with its inspection and assessment of its condition. Before dismantling the old finishing flooring and cleaning it is impossible to correctly assess the required degree of repair. The following cases are possible:

The floor is generally level, but dusty, and in places there are potholes, clearly defined small ledges or thin, snaking cracks. DIY repair possible and inexpensive.
There are gaping cracks no longer than half the short side of the floor, gravitating towards the perimeter or longitudinally and transversely. Self-repair is possible using proprietary thixotropic compounds.
The floor is “all humped”: small bulges and depressions alternate relatively regularly. Self-repair “on concrete” is possible in a private house or outbuildings.
In a multi-apartment building, there are long gaping cracks on the floor of the floor screed, generally located diagonally or crosswise. Only major repairs of the screed are possible with a preliminary professional assessment of the condition of the ceiling.

Note to point 3: Leveling a carelessly poured screed is possible either with a milling machine or with a liquid leveler after sealing the cracks. Leveling the floor with a hardening compound is a subject for a separate discussion, but milling machine V apartment building cannot be used: it generates a lot of dust, and the presence of cement dust in the air of residential premises is strictly prohibited sanitary standards. In addition to the “gratitude” of your neighbors, you can also fall under serious legislative sanctions, including imprisonment. For example, if during or after your work one of the residents is hospitalized with an exacerbation of asthma or a pulmonary disease, this is a moderate or severe harm to health. Deadlines - see the Criminal Code.

Minor pothole repair

The potholes are sawed off using a grinder with a diamond wheel along a rectangle with at least 20 mm of sticking to the sides. The cutting depth is to the depth of the pothole plus 10-20 mm. Less - if the floor is dense; more - if dusty. The protrusions are knocked down with a hammer drill or manually to the depression.
Using a hammer drill with a concrete chisel, select a rectangular depression at the site of the pothole. Small potholes can be picked out by hand with a 200g hammer and carbide-tipped chisel. You can’t hit a dull chisel with all your might: it could cause a crack.
The recess is blown out with a vacuum cleaner, then the remaining dust is sucked out with it.
Coat the recess with one layer of any concrete primer. Choice - by price; the case is not responsible.
After the primer has dried, fill the recess with a thixotropic compound, homemade or purchased, level it using a rule and leave it to cure - sealed.

Notes:

Branded repair compounds are mixed only with sifted quartz sand. It can be purchased at the same store. Proportion - according to the instructions on the package. Thixotropic mixtures in small packaging are sometimes sold as a set with a package of sand in the required quantity.

Sawing work should be carried out wearing a respirator, safety glasses, ear muffs, gloves and tightly buttoned clothing, with the open windows, tight closed door and as quickly as possible. Unlike your hypothetical asthmatic neighbor, you will certainly find yourself in the very center of a cloud of cement dust. In this case, headphones protect more from it than from noise.

Repair of small cracks

Small cracks are first sawed through with a grinder along the length to a depth of 20-50 mm and a width of 10-20 mm. As in the previous case, the minimum/maximum depth and width of the cut are determined based on the condition of the floor. The cut is also blown and sucked.

How to repair cracks in the floor? If the floor itself is not dusty, but the circle is a little tight, then a homemade repair mixture will do just fine. If sawing is easy, and the grinder even slips at times, you definitely need a good branded primer and thixotrope. But if the dust during sawing is so thick that the tool is hard to see in your hands, and/or streams of sand are thrown out from under the wheel, you need to seal it in full, like gaping cracks.

Repairing small cracks comes down to coating them with a primer and filling them with thixotrope, just like the recesses.

Advice: If possible, two to six months before repair, stick paper strips on the cracks every half meter. If the paper is not torn before repair, the crack is a shrinkage one, it will not go any further, and can be repaired at a quick fix as described. If at least one piece of paper is torn, the crack is deformation and must be repaired according to the complete scheme.

Repairing gaping cracks

A crack with a width of more than 2 mm is considered gaping, but this criterion is very relative. Greater value has the dynamics of the process: whether the crack will continue or not. You can independently evaluate the dynamics, without having construction experience, using the “paper” method described above or turning on a laser level for several days with a sensor or reflector on the opposite wall. If, for example, the light spot has decreased on average by 0.01 mm per day, then in a year it will be 3.65 mm - the situation is emergency, and you need to think about overhauling the entire building.

If the condition of the building as a whole does not cause concern, then repair of gaping cracks is carried out as follows (see figure):

The crack is sawed 50-60 mm deep and 20-30 mm wide.
The edges of the cut are knocked together to form a triangular hollow.
The cut is thoroughly blown and sucked out.
The hollow is treated with a primer.
Once the primer has dried, markers are inserted into the cut one by one. Holding the next marker vertically with your hand, cover the hollow with a thixotropic compound, leveling it with the rule. Homemade thixotrope cannot be used in this case!
Once the thixotrope has set, the markers are removed, and using the holes from them, the seam is cut to the previous width.
A damper cord of the Viloterm type or similar is placed in the seam. Clotheslines, synthetic ropes, etc. no good.
The seam is finally sealed with silicone or polyurethane sealant; under no circumstances polyurethane foam, epoxy or other fully curing compounds.

Note: markers are thin, smooth metal rods. Excellent markers are made from bicycle spokes. To make it easier to remove later, the markers can be lubricated with grease before installation.

Overhaul of screed

Overhauling a screed means actually replacing it. This is a last resort, costly and time consuming. They go for it if it is intended to be finished, but the moisture test gave an unfavorable result.

More information about the formation various types Floor screeds from scratch can be read using the links below:

Calculation of screed thickness

If the renovation is carried out in a room adjacent to others, then the floors should be on the same level. And in any case, the finished floor should not be higher than the door threshold. Therefore, the calculation of the thickness of the screed is carried out from the bottom up with a margin to the larger side. In this case, the level of the base floor will be lower, but this can be compensated by increasing the thickness of the plywood underlay or the height of the joists. The thickness of the mortar layer above the reinforcing mesh must be at least 8 mm.

Calculation example: from the bare floor to the door threshold 80 mm. Initial data:

Waterproofing – 1 mm.
Expanded clay bedding in one layer - 25 mm.
Reinforcing mesh – 6 mm.
The concrete layer above the mesh is 8 mm.
Mastic layer – 1 mm.
Plywood – 8 mm.
Adhesive layer – 1 mm.
Laminate – 16 mm.

The total is 66 mm. You can improve thermal insulation by adding one and a half layers of expanded clay or taking thicker plywood. However, laying the floor on joists will not work, unless you abandon expanded clay insulation, but such a floor will be colder and more sensitive to dampness.

Markers for screeds

The screed is leveled using pin or plaster rack markers. Both of them are immured with a small amount of cement-sand mortar (see figure below):

Pins - in the corners and along the walls every half meter or less.
Plaster markers - parallel to the short wall. The first is 25-30 cm from it; further - half the width of the rule from each other.

The pins can be made from scrap materials, but you will have to buy plaster markers, and you will need to roll out the expanded clay very carefully. But even an experienced craftsman will hardly be able to maintain a horizontal surface better than 3 mm/m using pins, since he will usually have to work without additional support.

The height marks on the pins are made with a tightly stretched cord and a bubble level, starting from the corner closest to the door diagonally. Then a second diagonal is beaten along the primary cord, the cords are pulled around the perimeter and marks are made on wall markers. To speed up the tapping of heights, you can use a laser level, but this will not improve the accuracy and smoothness of the floor, see above.

The procedure for overhauling the screed

Lay waterproofing ( plastic film) with an overlap of 0.5 m and an overlap of 10-15 cm on the walls. The joints along the entire length are taped.
Expanded clay is poured in and leveled with a rolling roller. It is permissible to use a manual tamper, wooden or metal, under the subfloor.
Lay the reinforcing mesh with an overlap of 1-2 cells and a distance of 30-40 mm from the walls.
The markers are lined up.
If pin markers are used, the heights are marked after the underlining has hardened.
Mix viscous cement-sand mortar (1:3) in 10-20 liter portions; Thixotropic additives are not necessary. At the end of kneading, the next portion is dumped between the markers next to the previous one.
Each portion of the solution is leveled using a rule, starting from the far wall: along a cord or with the rule resting on two adjacent markers. The rule is held obliquely so that excess solution falls into the empty cell.
Kneading the next portion begins after leveling the previous one.
Once the solution has hardened, the markers are removed and the grooves are sealed with the solution.
Excess waterproofing is not touched; they are cut after installing the baseboard.

Note: under the subfloor, instead of plaster markers, you can use wooden beams, even and of the same height.

Video: example of pouring screed

Dust removal

A concrete floor that is in good working order, but dusty due to surface wear, can be quickly repaired with special compounds:

Subfloor and floors in outbuildings - domestic Neomer-LP, Elakor-PU or imported Ashford-formula, etc. They give a layer of 150 microns.
Finish concrete floor in residential premises, garage, workshop - GruntElast-PU, Elakor-ED, Retroplate. Layer – 250 microns.

In terms of quality and cost, these compositions are approximately equivalent.

Bottom line

Repairing concrete floors yourself can be simple, quick and cheap, or complex, difficult and expensive. The need for some degree of repair, other than the presence of gaping cracks, can be determined independently. In any case, it is definitely beneficial to do it yourself by removing dust from the worn-out floor surface.

What to do if the screed is cracked and there is movement (movement) of the screed along these cracks?

There are at least two options - completely dismantle the screed and make a new one, or repair and bind these cracks, stopping their further growth.

Repairing cracks is a less labor-intensive and expensive process than dismantling and installing the screed all over again. Therefore, if you do it correctly, you can save a lot of time and money.

It is highly advisable to tie up the cracks before leveling the floor, because... all of which can show up over time on a new finished floor.

Like most people do.

Basically, everyone does this in one way - they open (widen) the cracks and fill these cavities with mortar or repair mixtures.

It's not effective.

When there is tension in the screed or the slightest movement along these embroidered cracks, additional cracks may appear and their number will only increase.
Those. the likelihood of delamination at the junction of the screed and fresh mortar is very high.

How to do this much more efficiently.

It will be much more effective if you tie this crack across its direction with a strong “patch”.
In this way, the cracks are better bonded and immobilized, and movement of the screed is prevented.

Naturally, not always and not the entire screed can be saved. If it has crumbled into many unrelated fragments, then nothing will help. Only dismantling.

Procedure for repairing cracks:

First, we mark with a pencil the locations of future repair seams.

The width of the groove should be about 2-3cm, length 15-25cm. Grooves are made every 30-50cm, depending on the number of cracks.

Then we cut the grooves using a wall cutter or a regular grinder with a vacuum cleaner along the intended lines.

Then we use a puncher or a hammer and a chisel to knock out the grooves between the cut lines.

Then we remove dust using a vacuum cleaner and prime the grooves.

This is a very important point; it determines how well our “patch” will adhere to the screed.

We put reinforcement or a couple of rods of metal wire (no thinner than 3mm) into the repair seams.

Filling the grooves repair mixture.

In my opinion, the most suitable composition for these purposes is self-leveling floor/leveling compound (it hardens quite quickly, and after hardening it becomes very durable) or good repair mixtures (such as Mapei, etc.).

Cement-sand mortars or tile adhesives are much weaker. Their use is not advisable.

In order for the floor to be level and flooring served for a long time, a high-quality, even screed is required. It can be done by different technologies(there are single-layer screeds, which are laid in one layer over the entire thickness, there are multi-layer screeds, which consist of several layers, there are prefabricated or dry screeds, which consist of elements ready for installation). But under any floor covering (laminate, parquet, tiles, linoleum or others) you need a smooth screed without cracks.

Screed tasks:

ensure the durability of the floor covering;
improving heat and sound insulation, which is important in apartment buildings;
alignment of the horizontal plane of the load-bearing base (SNiP 3.03.01-87 allows for “Deviation horizontal planes for the entire length of the verified section - 20 mm")
hide utilities (electrical wiring, heated floors, etc.)

There is no point in saving on the screed; it is better to do it right away with high quality and cost-effective long years. However, everything tends to age and deteriorate; an old screed may develop cracks and chips. When starting a repair, you need to start from the base of the floor: check the old screed for voids or cracks. If a third of the old screed requires repair, then it is better to replace it completely. However, if the flaws are minor, you can repair the screed - this will significantly save repair time.

In our apartment, the old screed was initially made poorly. When we first crossed the threshold of our future apartment, where a modest renovation had been done, neat linoleum lay everywhere on the floor. After the move, we discovered that large and small irregularities began to appear through the thin linoleum. As soon as you lifted it, small pebbles, cracks, and irregularities appeared. Although in general the screed fulfilled its role. Therefore, it was decided to repair the screed with minimal costs time and money.

Tools and materials for screed repair

Hammer;
Rule;
Master OK;
Grater;
Brush or roller for priming;
Cement;
Penetrating primer;
Mixture for screed “Self-leveling floor” (2 in 1: screed and self-leveling floor).

Repairing screeds with your own farts

Using a level and a rule, we find the unevenness of the floor. “Pits” will be filled later, “hills” and “elevations” will be knocked down using a hammer drill.

The floor level along the entire wall under the window was higher than in the entire room, so the layer was completely knocked down.

The defects in the floor slab were simply foamed over: before the repair, we could not find sources of cold winter air coming from under the floor.

Mix the cement mortar.

Fill the areas with broken screed with the solution and level them using the following rule:

Let the new layer dry

For better adhesion to the leveling layer, prime the old screed with a penetrating primer.

The finishing layer is quite liquid and is much easier to install than the base layer, but control using the rule is mandatory.

Before drying finishing layer rubbed with a grater.

The self-leveling floor dries quickly enough, so it needs to be applied in small areas. A new screed, made with your own hands and for yourself, turns out smooth and without cracks, even if there is not enough construction experience.

After drying, the finishing layer is primed again. This will prevent cracks and other troubles.

Agree, the new screed even looks better than the old one.

Now you can lay almost any floor covering. We are planning carpet, naturally, with a backing.

Often, construction technology requires concrete floors. This is due to high technical characteristics components of the mixture. The finished coating is affordable, durable and practical. It stands out perfectly on its own and serves as the basis for subsequent finishing with any floor materials. However, for a number of reasons, the base becomes deformed and becomes unusable - cracks appear and dust formation increases. The resulting defects reduce the strength and reliability of the screed. Therefore, repairs carried out in time will help prevent further destruction. The article will discuss the technology for repairing concrete floors.

conduct a visual inspection to assess the condition;
identify the reasons that led to the result obtained.

Based on the data obtained, an elimination technology is selected. For minor damage (potholes, isolated cracks), it will be enough to carry out local repairs. If the area of the area to be repaired is more than 30-35% of the area of the entire premises, then we will talk about capital work.

Causes of concrete floor destruction

There are several main reasons that negatively affect concrete covering. Conventionally, they are classified into 3 groups: soil influence; external influence; internal factors.

To the first point include poor soil compaction, winter swelling of the earth and close proximity groundwater. Such factors lead to formation movements, and as a result, destruction of the concrete floor.
Second point assumes a negative impact on the base due to the use of low-quality mortar, as well as pouring carried out in violation of technology. Here it is necessary to note such a common reason as shrinkage of the house, which creates some movement.
In the third point There are factors such as: natural wear and tear of the coating, mechanical impact (falling heavy objects) and prolonged exposure to moisture, for example during flooding.

After analyzing this information, you can move on to eliminating the causes. Only after this can we talk about the benefits of repair work, otherwise all the restorations carried out will be useless.

Preparing to repair an old concrete floor

Work begins with clearing the room of furniture and other interior items. If there is a floor covering on the screed, it is dismantled. All debris and dust are removed. Much attention applied to damaged areas. This is where a large number of flaking elements accumulate.
Use a wire brush to remove old layers of primer, rust and other contaminants. Then it is necessary to make notches on the repaired area, which will increase adhesion between the material and the new concrete.
Chips and dust formed during the process are swept away with a broom. Good results in cleaning will show construction vacuum cleaner. The surface must be treated with a degreasing impregnation or primer.

The degree of damage to the coating determines the complexity and type of subsequent work. If financial resources allow, a major overhaul can be carried out. concrete surface, in order to significantly extend the service life of the floor.

Preparation of working mixture for repairing concrete floors

To eliminate shallow potholes and cracks, you can use a solution containing PVA, prepared at home. First, dilute 1 part glue with 4 parts water. Then into the prepared dry cement-sand mixture(1:3) add diluted PVA until the optimal consistency is achieved.
More serious problems are solved by using building mixtures. In such compositions for repairing concrete floors, specially selected components guarantee ultimate strength and high resistance to mechanical damage.
The mixed powder composition is thoroughly mixed with a mixer. The use of such equipment will allow the process to be performed more efficiently. The finished solution penetrates deeply into the concrete structure and forms a single monolith with the original surface.

Partial renovation

For damaged areas of small areas, local work can be done. Cosmetic repairs are exposed to:

recesses;
cracks, various depths and width;
hair gaps (web);
minor irregularities.

Despite minor defects, work must begin immediately. The smaller their size, the easier it is to tidy up the surface. An increase in existing cracks will lead to their growth, and as a result, to deformation of the floor covering.

Filling Potholes

They usually appear as a result of furniture or bulky equipment being left in one place for a long time. Often the reason for the appearance is a mechanical impact, for example, an object falling from a height.

Elimination technology

With the help of a tool, the defect expands and deepens. This is done in order to eliminate the possibility of leaving weakened pieces of concrete on the site. The recess is cleaned and primed. Filling is done with an epoxy mixture or adhesive.

The solution is pierced several times with a metal pin. It is important to remove air voids and distribute the mixture evenly in the resulting recess. Horizontal leveling is done with a wide trowel or building rule. After drying, the area is sanded.
If the depth of the pothole is more than 5 cm, the technology for laying the solution is slightly different. Here the mixture should be poured in several stages to avoid the formation of cavities.

Repairing cracks in concrete floors

These types of defects appear due to shrinkage of the structure or foundation. Temperature changes, incorrect proportions of the concrete composition, and lack of reinforcing elements can lead to deformation.

Elimination technology

Using a hammer drill or a hammer with a chisel, the gap expands both in width and depth. Carefully inspect the surrounding area for hidden defects, which after some time will lead to repeated repair of the surface.
The groove clears concrete debris and dust. A polyurethane primer is used for processing. The mixture is poured into the crack and then leveled with a spatula or level.

If there are large cracks on both sides, use a grinder to make auxiliary grooves. They will serve for laying metal grips, the distance between which should be 25-30 cm. All recesses are filled with mortar.

Closing the cobweb

This kind of deformation cracks can appear during excessive quick drying solution. They are not fraught with danger, but they are quite capable of expanding over time. The web is almost invisible. Its detection is possible by wetting the surface.

Elimination technology

It is enough to treat the so-called hairline cracks with a primer and seal them with an elastic sealant. If weakened areas are observed along the edges of the crack, it is recommended to clean up the delamination.
The resulting groove is cleaned of foreign inclusions and treated with primer solutions. For sealing, you can use your own composition or purchase ready-made mixtures of various grain sizes.

Minor unevenness

As a result of pouring, it is not always possible to obtain a perfectly flat floor. This is due to non-compliance with the technology of these works. Defects appear due to neglect of the installation of beacons, incorrectly mixed cement mass (too liquid or thick). Therefore, after drying, “waves” are formed.

Elimination technology

Wave crests are removed using a grinder with a trowel disc. This is a dusty job, so personal protective equipment must be used. If the area to be treated is large, it makes sense to contact specialized companies. They have equipment in their arsenal that, along with sanding, sucks up dust.
The depressions are cleaned out and deepened. They are treated with primers or diluted solvent. The recesses are filled construction mixtures, you can also use self-leveling solutions.

Do-it-yourself overhaul of a concrete floor

Major work will be needed if:

there is extensive damage (over a third of the entire area);
the “warm floor” system is being installed;
There is a desire to completely renew the old concrete screed.

Such work can be carried out using the following technologies:

laying wet screed using standard cement-sand mortar;
pouring a self-leveling mixture, which includes plasticizers, stabilizers and fiber fibers;
installation of a dry screed, including backfill, followed by laying gypsum fiber sheets (GVL).

In each case it is required different set materials for repairing concrete floors.

Laying wet screed

Repair work begins with removal construction waste and dust removal of the surface. It is necessary to remove all peeling areas, which can subsequently significantly affect the strength characteristics of the new floor.
Next, the flooring of waterproofing materials is made. A huge selection will allow you to purchase products with the maximum suitable properties By affordable price. The next stage is to place the beacons. Their step should be slightly less length the rule being used.
Kneading concrete mortar carried out in accordance with the current proportions. The ratios used depend entirely on the brand of cement used and the desired strength of the finished mixture. Water is added until the required viscosity is achieved.

Filling is carried out in small portions. This will help distribute the mixture evenly without creating voids. It takes about 30 days to completely dry, during which time it is advisable to avoid any mechanical impact on the surface.

Pouring self-leveling mixture

Special compounds allow for leveling with minimal labor costs. After inspecting the surface, all existing peelings are removed. If there is contamination, treatment is carried out with a solution of copper sulfate.
Seams and cracks are sealed with a repair mixture. It is mandatory to spread out waterproofing materials. If the pouring is done on an old coating in fairly good condition, then the waterproofing step can be skipped.
If you plan to pour a mixture with a thickness of more than 10 mm, it is recommended to pre-install profile beacons. Work begins from the far corner of the room. The solution is fed in parts and leveled with a needle tool.

After just 8 hours, small impacts can be applied to the surface. The floor will be ready for full use after 5 days. Then they move on to finishing(laying decorative flooring).

Installation of dry screed

Such a device has some advantages over “wet” work. For example, there is no need for drying time; installation can be carried out regardless of temperature regime. In addition, the floor is characterized by high levels of noise and heat insulation.

First, the floor is marked. Spread polyethylene film or any vapor barrier material. Then lighthouse slats are installed, which allow you to maintain the desired level. Horizontalness is checked with special tools.
Expanded clay, vermiculite, perlite or compavite are poured between the profiles. Starting from the doors, sheet material is mounted from right to left. It is spread out at intervals (at least 25-30 cm). Move along the laid sheets with caution.

Fastening is done with special self-tapping screws; the screw pitch must be at least 30 cm. For additional fixation, mastic is used. If necessary, you can lay a second layer sheet material without matching joints in any direction.

The final stage of repairing a concrete floor in an apartment

The concrete surface, while monolithic, has the property of dust formation, which occurs due to various mechanical loads. Invisible particles negatively affect human health. Wet cleaning will not solve this problem.

To avoid harmful effects the following will help:

clean the surface as much as possible;
treat with a primer;
paint with a material that will prevent the concrete from peeling off.

Here you can use polymer-based products that form a protective layer of varying thickness. For rooms with minimal loads, thin-layer materials (up to 150 microns) are used: Neomer-LP or Elakor-PU.

IN living rooms with intensive traffic, Elakor-ED, Retroplate or GruntElast-PU are used. Protective layer of such products is over 250 microns, which allows them to withstand high loads.

Thanks to deep penetration concrete screed is characterized by:

resistance to temperature changes;
moisture resistance;
lack of dust formation;
high wear resistance.

Defects noticed in a timely manner and their immediate elimination will help increase the service life of the surface. In addition, this will avoid more expensive and time-consuming work to restore the concrete floor. Accurate adherence to all stages of repair work will lead to an impeccable result.