How to patch up a hole in a concrete floor. How and how to repair cracks and holes in concrete

Tsugunov Anton Valerievich

Reading time: 5 minutes

When replacing the floor covering, apartment owners often have to face the need to repair the concrete floor, which can be either concrete or the floor slab itself. Despite the fact that concrete is a durable and reliable material, under the influence of various factors, potholes and cracks can appear on it. To prevent further destruction, timely measures are necessary, because the service life of the finished floor depends on the condition of the concrete base. We will find out how to repair a concrete pavement using special concrete floor repair mixes.

Reasons for the appearance of defects on concrete

Defects on the concrete floor can form for various reasons, which are primarily associated with violations in the process of its arrangement.

Cracks often appear due to missing, untimely cutting or incorrect calculation of the thickness of the joints in concrete floors, designed to prevent the stress of concrete during thermal expansion and shrinkage. A properly made shrinkage joint will avoid many problems.

Other reasons for the appearance of cracks include:

a large amount of water in the solution when pouring a concrete screed or its lack;
poor quality reinforcement;
lack of waterproofing of the base.

Defects can form even with quality work done. Any coating is subject to natural wear and tear, excess moisture negatively affects it. Potholes appear due to physical influences. The influence of external factors on the concrete floor cannot be ruled out. The weak point is the junction of the wall and the floor, cracks often appear there.

It is necessary to determine the type of damage. This will allow you to draw up a work plan and select the desired material. The following varieties are often encountered:

small depressions, potholes;
cracks of various sizes;
the finest cracks and chips.

Repair is not worth postponing for a long time. The size of the defects may gradually increase, the concrete will begin to crumble and come off in pieces, which will complicate the repair of problem areas.

Choosing a mixture for repairing a concrete surface

Before you start repairing the floor in an apartment with your own hands, you need to prepare a mixture for restoring concrete surfaces and structures. In hardware stores, they are presented in large quantities. In order to choose the right mixture grade, you need to determine the degree of damage to the concrete surface:

The first degree - there are shells, shrinkage cracks.
Second degree - peeling of the surface, small chips.
Third degree - cracks within 2 mm with a depth of no more than 40 mm.
Fourth degree - cracks more than 2 mm, depth up to 10 cm.
Fifth degree - large potholes and cracks, more than 20 cm deep.

The purpose of the repair mix must be indicated on the packaging. Such manufacturers of mixes for the restoration of concrete surfaces as Emaco, Birss, Ceresit, Bars deserve attention.

You can use general purpose repair mixes such as Ivsil Render.

Since the price of special thixotropic compounds containing reinforcing microfibers and polymers is quite high, the mixture can be prepared independently for a small amount of work. To do this, take 1 part of PVA glue and mix with 4 parts of water. On this solution, using a construction mixer or a special nozzle on a drill, a sand-cement mixture is kneaded in a ratio of 1: 3.

Preparatory work

After choosing the material for repairing concrete floors, you should proceed with the repair. First, there is a preparatory stage:

All foreign objects are removed from the room.
Existing debris, concrete chips and dust are swept out. Potholes and cracks are thoroughly cleaned with a vacuum cleaner.
Any dirt, rust, mold or old soil is removed with a stiff metal brush.
To remove greasy stains, you need to use a special solution.
The concrete floor is swept with a wet broom, then it must be dried.
If the reinforcement is visible, then it should be cleaned with sandpaper and primed with a compound with anti-corrosion properties.

Areas of the concrete surface that have lost strength are best tapped with a hammer and cleaned. The rule applies to the edges of problem areas.

Sealing potholes in concrete floor

Repairing concrete floors begins by expanding and deepening the pothole around the perimeter. It is better to use a grinder with a diamond disc for this.

The cut is made 1 cm deeper than the defect. The pothole expands to the sides by 2–3 cm. If necessary, these indicators are increased.
Using a hammer drill or a hammer with a chisel, a notch is made at the place of the pothole, a rectangular depression should be obtained. If a puncher is used, then it is better for outsiders to move away.
The recess is thoroughly cleaned with a vacuum cleaner and primed.
The pothole can be repaired after the soil has dried. The mixture is carefully leveled, it is pierced several times to remove air. You can use a metal pin or a trowel. Level the surface using a rule.

The depth of the pothole matters. If it is more than 5–6 cm, then the composition is poured into several layers. The maximum layer thickness is 2 cm.

After hardening, they proceed to grinding. The building level will help to achieve an even concrete base.

It is recommended to carry out work in a respirator, goggles and gloves. The windows must be open during the renovation process. The floor can be painted over concrete for additional protection. It is selected specifically for residential premises. The floor repaired in this way will serve for a long time.

Crack repair rules

The process of repairing cracks in a concrete floor differs depending on the size of the cracks.

Small slots widen in depth and width by 2–5 cm. For this, you can use a chisel or grinder.
The recess is cleaned of pieces of concrete and dust, then processed.
To repair cracks in the concrete floor, a homemade mixture based on PVA is used. The crack is filled with it and shrinkage is expected.
The second layer is coated, dried and sanded.

In cases where the sawing is accompanied by strong dusting, which indicates that the concrete is weakened, it is necessary to use only special thixotropic compounds.

Repairing cracks in concrete floors should not be delayed for long. If they are deformational, then they need to be treated with special attention. You can determine their appearance using strips of paper. A few months before renovation, they are glued to cracks in the concrete floor. With shrinkage gaps, the paper will remain intact, with deformation strips, they will break, which indicates their expansion.

Such a crack is sawn 5 cm deep and 3 cm wide.
The edges of the cut are knocked off, a triangular notch is formed.
After thorough cleaning, the recess is primed.
Markers are inserted into the crack in 3 m increments.

Thin smooth metal rods serve as markers. You can make them yourself from the spokes from a bicycle wheel.

The crack is filled with a thixotropic compound, the use of homemade mixtures in such cases is not recommended
The concreted area is sanded after drying.
The marker rods are removed, and a new expansion joint is cut through the holes left after them.
Dust is removed from the seam, and a Vilotherm cord or its analogue is placed in it.
The joint is finally sealed with a silicone or polyurethane based sealant.

Some people notice small cobweb cracks on the floor, as in the following photo. They can get wider over time. When the concrete weakens in this part, they are cleaned, covered with soil. For sealing, you can prepare your own composition or use a store one.

To seal the gaps in the floor between the boards, there are many options, you need to study them and choose the most suitable A wooden house is the most environmentally friendly and modern construction for housing. It is pleasant and cozy to be in it, however, there are a number of problems faced by the owners of this building, for example, cracks in the wooden flooring.

Good to know: how to seal the cracks in the wooden floor

Cracks can occur due to drying out of the wood. The tree dries up within 10 years. Deformations of wood are possible in the off-season. In winter, the wood swells, and in summer it dries and decreases in size. Visually, you will not find it, however, in the microcosm, under a microscope you can see how the fibers in the tree change over time.

Other possible reasons:

Incorrect calculations by builders or incorrect installation of floorboards.
Incorrectly prepared wood for use - low-quality paints and varnishes.
Poor ventilation.
Insufficient floor adhesion.
The appearance of mice and termites.

Making your own grout for gaps in the floor is a very economical method, however, it is not aesthetically pleasing and is used mainly in dilapidated housing or in the country

All cracks, depending on the size and location, are eliminated, you just need to choose the right solution. There are many methods for fixing gaps in wood floors. Filling gaps up to 15 cm is done with a sealant. In this case, 2 types of sealant can be used, this is a silicone or acrylic sealant for wood. Special sealants for wood differ in color, which allows you to eliminate joints and cracks as invisibly as possible.

Sealants have a number of advantages: resistance to dampness, profitable consumption in the process of filling the gap and long operation after removing defects in the floor.

You can fill the gap with wood putty. The choice can be applied to acrylic-based, solvent-based, oil-based or polymer-based, water-based fillers. You can putty not only cracks and holes, but also irregularities on plywood or wood, as well as cracks. You can seal the gap with polyurethane foam. However, it is necessary to eliminate the cracks very carefully, without splashing the foam. Excess foam can be removed only after it has hardened.

Close up the gaps and polyester paste. There can be both one and two-component options. Suitable for filling gaps and seams up to 5 cm. Sealing gaps with improvised materials such as slats, tow with paint, glass wool, paste and paper grout, sawdust and your own preparation of putty is also relevant.

High-quality sealing of cracks in the wooden floor

Regardless of the size of the gap between the boards in the floor or in the parquet, before removing it, it is necessary to do dry and wet cleaning, remove dust and clean the place of the gap, let it dry.

Termination options:

If the gap in the wooden floor is up to 1 cm in size, then it can be sealed with a tourniquet, grout or filled with sealant.
If from 1 cm to 3 cm, then a special putty is well suited.
If the slots are very large, then foam, wedges or slats are well suited.

The most common filling of large gaps in a wooden floor is polyurethane foam.

The field of operations performed, it is better to cover the floor with sheets of plywood, the joints of which are also processed and leveled with putty. Small cracks or joints can be covered with the actually prepared putty from glue and sawdust.

Sawdust is selected in small fraction, poured with boiling water and mixed until smooth.

After the solution with sawdust has cooled down, add PVA glue and apply with a spatula in the localization of the gap cleared of dirt and dust. After the surface of the sealed gap has been leveled to floor level, then it must be left for a couple of days for the mixture to take and dry. After everything has dried out, the irregularities must be treated with an abrasive, and applied fire protection, and only then the selected paints and varnishes.

You need to know: how to fix a hole from mice

There are mice in both rural and urban areas. If there are any cracks in the houses, then the mice can easily enter the living quarters, they will not only harm human health, as they are carriers of leptospirosis, toxocariasis, streptobacillosis and many others, which can be fatal, but also harm the room, its decoration, can penetrate into food.

The hole from the mice, so that they do not gnaw a new passage in the wooden floor at all, can be sealed with concrete mortar, after putting metal shavings there

The most proven options for sealing holes in the wall from mice are:

Glass wool filling;
Elimination of the defect with cement;
Polyurethane foam also helps well, mice do not gnaw it, and tightly seals the hole.

The advice of experts comes down to broken glass, which are placed in the holes of the mice.

How and what to seal the seams between plywood on the floor

Plywood flooring often has seams and joints that need to be repaired. You need to know that the most important thing in choosing a putty is elasticity, since plywood consists of wood veneer, and the tree is subject to seasonal deformations. Over time, the plywood dries up and the joints become more visible. It is also worth choosing a putty according to the color of the wood, as well as a special one, that is, for wood material.

For sealing seams, the following are used:

Acrylic putty;
Elastic sealant;
Hot melt glue;
Sawdust with PVA and gypsum;
Epoxy adhesive.

To seal the seams between the plywood on the floor, it is necessary to choose a filler for wooden floors, since the other simply will not withstand the load

It is worth considering that chipboard, plywood should be well fixed so that they do not walk or vibrate, then the selected putty (putty for wooden floors) will not crack and will hold tightly, closing the gap.

These works are also being done for plywood, on which linoleum will subsequently be laid.

You should also cover up with putty or better with silicone sealant, dents in the plywood and all joints, cracks. The plywood needs to be coated with an antiseptic. Before laying linoleum, you need to pay attention to the evenness of the plywood and its cleanliness.

Types of floor fillers from boards

Today there is a fairly wide selection of wood putties. Before choosing a putty, you need to decide on the price, scope, type and brand.

Elastic floor putty does not require careful preparation of the surface, it is easily applied and covered with other paints and putties

Putties are divided into types:

Water-based polymer putty therefore does not emit chemicals into the atmosphere. It dries quickly enough, holds well and does not crack.
Oily putty based on water, chalk and oils. It is one of the most reliable, however, after processing the gap, it takes a lot of time for it to dry completely.
Acrylic putty is environmentally friendly and non-flammable, which is very important for wood.
Solvent-based filler is ideal for parquet flooring, but is not the most sustainable option.
Elastic putty, ideal for floating crevices and joints. It holds its shape perfectly, has good adhesion to the surface.
Pigmented wood putty, that is, various colors (white-birch, teak-red wood, wenge-dark oak, beech-oak). It should be noted that often the color does not coincide with the color stated on the package; a demonstration of the product or a stand with these putties should be required.
Putty for wooden floors, which is used to smooth out irregularities, various defects and cracks.

The main brands of putty manufacturers are Dulux, Parade, Semin, Varathane, Axton, Neomid, Forwood, Rainbow, Tytan, Master's Choice. We must not forget that putties differ in basic types: finishing, leveling, filling, universal, sealing. Putty is applied with a spatula of the selected size, by pressing it into the depth of the gap. After the putty dries, it is necessary to level the surface using abrasive wood products.

How to seal cracks in a wooden floor (video)

When gaps appear, it does not matter, any gap can be repaired with your own hands, and the wooden floor is easy to install and repair.

Concrete coatings are used in a wide variety of areas: when installing floors, concreting surfaces both in industrial and residential buildings, in the construction of highways and much more. However, concrete has a low tensile strength, therefore, during the hardening process, the mixture shrinks a little and the structures shrink. Because of this, small and more serious defects appear on the surface. In this case, filling of cracks in concrete is required, which is carried out using different technologies, depending on the type of damage and the reason for its occurrence.

Types of cracks in concrete

Some beginners or unscrupulous builders prefer to simply cover up a hole or any other defect with putty or mortar. However, before repairing a hole or crack in a concrete wall and other foundations, it is worthwhile to figure out what exactly caused such troubles.

There are several types of defects:

Superficial. Such cracks often appear after the foundation is poured in the process of drying out the sand-cement mortar, if the mixture was prepared without observing the required proportions of the components, poor-quality components were used, or there was not enough water in the mixture.
Shrinkage (also called hairline cracks). Defects of this type are considered the most dangerous, since they cause not only deformation of the fundamental foundation, but of the entire building as a whole. This leads to a decrease in strength. Flaws of this type appear when the load on the foundation is uneven and when the cement composition is incorrectly selected.

Temperature shrinkage. Slots of this type appear during the hardening of the concrete base due to the exothermic reaction that occurs between cement and water. Very often, when erecting walls and floors, novice builders do not take into account the freedom of deformation, as a result of which temperature stress occurs in the concrete mass and defects appear on the surface.
Cracks and holes that appear due to poor-quality reinforcement. If the frame for strengthening the structure is too weak, then it will bend under loads, which will also lead to the formation of defects. In addition, the reinforcing rods can begin to oxidize. Due to the appearance of corrosion, the material increases in size, tearing apart the concrete mass from the inside.

Outdoor concrete surfaces are also susceptible to cracking. The environment contains chemically active substances that create a fertile ground for the appearance of defects.

In addition, sharp temperature drops, which can occur both on the surface and in the concrete thickness itself, have a destructive effect. At the same time, not only cold air, but also ultraviolet light has a detrimental effect.

It is also worth paying attention to the width of the cracks, since in some cases such defects are not critical.

Acceptable crack sizes

In the construction industry, there is such a definition as the permissible crack opening width, which is determined according to DBN V.2.6-98: 2009 based on the operating conditions:

The crack size should not exceed 0.5 mm if the concrete surface is not exposed to weather conditions. That is, it is not affected by moisture, low temperatures and ultraviolet light.
The permissible crack opening width cannot be more than 0.4 mm, provided that the structure is exposed to weather conditions.
The crack width should not exceed 0.3 mm if the concrete base is in an aggressive environment.
It is not recommended to allow the formation of gaps of more than 0.2 mm when it comes to reinforced structures characterized by a reduced resistance to corrosion.

Horizontal cracks with a small opening, which often appear in reinforced concrete columns, are also considered harmless.

However, it is important to take into account that there are certain operating conditions under which cracking is not allowed at all:

when it comes to reinforced concrete structures that constantly interact with liquids and gases (that is, they must be impervious and sealed);
when using structures that are subject to more stringent requirements for their durability.

Having determined the type of defect and the need to fix it, it is much easier to choose than to repair holes in a wall or any other concrete surface.

Cement mortars

These compositions are very popular due to their low cost and the ability to repair minor shrinkage cracks in concrete.

Crack sealing

Before proceeding with the repair, it is necessary to check the crack itself for chips around it. If there are any, then in the near future they can turn into holes, so it is imperative to eliminate all flaking pieces of concrete. After that it is necessary:

Perform jointing. To do this, using a chisel and a hammer, you need to walk along the entire length of the crack so that its depth is at least 5 mm. If necessary, you can use a spatula to create a depression.

remove dust with a vacuum cleaner and rinse the formed cavity with water.
Remove excess water and cover the crack with cement mortar (3 parts of sand to 1 part of cement with the addition of PVA). In this case, you need to ensure that the composition covers the entire space of the groove.
Moisten the poured cement with water.

Sealing the hole

If a hole has formed in the concrete surface, in which the reinforcement is visible, then the defect can be repaired as follows:

Clean the hole in the concrete and treat its surface with an anti-corrosion compound.
Place pieces of steel wire with a diameter of about 4 mm in the recess.
After that, the recess is covered with a primer, evenly applying it to the entire surface. In this case, the thickness of the mixture layer should be about 3 mm.
Without waiting for the mixture to dry, fill the cavity with a cementitious compound to seal the cracks in the concrete and make sure it fills the entire cavity. If the hole is too deep, then the cement is poured in several stages. In this case, each subsequent layer must be moistened with water from a spray bottle.
Level the surface with a rail (metal or wood) moving the tool from right to left.

After the mixture has hardened, the excess cement composition must be removed with a spatula and the surface must be plastered. If the crack was too deep, then leveling is carried out with a grinder.

Healthy! The cement composition must be poured with a margin so that it is slightly above the floor surface. In the process of hardening, the mixture will shrink.

After 24 hours, the concrete floor can be painted or any finishing material can be laid on it.

However, it should be borne in mind that such filling of cracks in concrete will not give a sealing effect and is not suitable for surfaces that have increased requirements for waterproofing. In addition, the cement composition can be considered as a temporary solution to problems. Sooner or later, defects will appear again. If you want to "overhaul" the holes and avoid their appearance in the future, then in this case you can seal the defects with resins, specialized repair compounds based on them, or sealant.

Long-term sealing of defects

When deciding how to repair cracks in concrete for a long time, you should pay attention to this method of processing defects. Resin and resin-based embedding mixtures are suitable for the restoration of screeds, blind areas and various concreted areas or horizontal surfaces.

Repairing cracks in concrete using such compositions has a number of advantages. First of all, this is the cheapness of the mixtures, as well as their quick drying. On the other hand, the resin allows the seams to be held securely in place and to keep them from enlarging later.

So, to eliminate defects, you will need to prepare:

angle grinder and diamond-coated discs;
vacuum cleaner;
spatulas and trough for diluting the composition;
primer for concrete;
Epoxy (base A and hardener B);
Fine-grained sifted sand.

Before sealing the crack, you need to clean it of dust and dirt. After that, we carry out the embedding in the following sequence:

We make the jointing of the crack. In this case, the width of the resulting recess must be at least 5 mm.
With the help of a grinding machine, we cut transverse seams in concrete with a pitch of 400 mm (the length of the grooves is about 100-150 mm).
We remove the loose concrete layer and dust the surface with a vacuum cleaner.
We treat the surface of the defect with a primer, and fix the transverse grooves with repair brackets.
We prepare a solution from resin (base), hardener and sand according to the instructions on the package with the composition.
We close the defect with the resulting mixture and quickly level the surface, since the setting time of the resin is only 10 minutes.

The best epoxies

If we talk about the best materials for repairing cracks in concrete walls and other surfaces, then the most effective today are:

Epoxy resin of domestic production ED-16 and ED-20 costing about 2,000 per 3 kg. The hardener will have to be bought separately (it costs about 300-500 rubles).
Epoxy 520 resin from the Czech manufacturer Spolchemie costing 3,500 rubles per 5 kg.
The German composition UZIN KR 416, which will cost 2,700 rubles for 0.75 kg.

Also, formulations from the Italian manufacturer Sika are very popular.

However, it should be borne in mind that this method of correcting defects is not suitable for treating holes that form in concrete foundations experiencing strong pressure from water. In this case, it is worth using a sealant.

Use of sealants and self-expanding tapes

It should be said right away that this method of sealing defects is very expensive, therefore it is most often used when repairing concrete bowls of country pools. However, despite its high cost, the use of sealant and self-expanding cords has its own advantages:

the ability to handle any type of defect;
complete tightness;
the ability to carry out installation work in cold weather.

To work, in addition to the standard set of tools, you will need:

assembly gun;
self-expanding tape or cord;
chisel and brushes;
concrete sealant.

However, before covering up the flaw, it is necessary to measure the dimensions of the slots and purchase the required type of sealant and tapes, depending on this. For example, if the hole is 60 mm deep, an 18 x 23 mm cord will work.

The next step is necessary:

Expand cracks and remove dust.
Install the cord into the groove.
Fill the rest of the space with sealant.
Smooth out the composition that has come out with a spatula.

After completing the work, you do not have to guess how to putty the surface or caulk it. It is enough just to apply the composition and smooth it out.

If we talk about the best compositions of this type, then the most popular are:

Domestic ELASTOSIL PU 20 worth 280 rubles for 600 ml.
Composition from the French manufacturer Rubberflex, which today is sold at a price of 300 rubles for 310 ml.
Russian-made PLUG tape costing about 260 rubles per running meter.

Injecting

Also, when deciding how to seal holes in a concrete wall in the most effective way, especially if not only a crack has appeared, but water also flows through it, you should pay attention to this method.

The injection technology involves the introduction of a special composition (polyurethane or epoxy resin, microcement or waterproofing mixture) into the concrete using special injection pumps that create strong pressure.

To perform such a restoration of defects, it is necessary:

Make staggered holes on both sides of the gap.
Install packers in them (special tubes through which the solution is fed, resemble a dowel) at an angle.

Pour in the solution.
Pull out the tubes and coat the surface with the building compound.

So, we looked at how to independently repair a hole in a concrete wall, but what if we are talking about aerated concrete?

Features of sealing cracks in aerated concrete

Cracks in aerated concrete are formed as often as in conventional cement-sand monoliths. To seal them, work is performed in the following sequence:

A layer of collapsed building material is removed from the wall or any other aerated concrete surface and dust and dirt are removed.
The gap is primed. For this, it is recommended to use a 50% aqueous dispersion of PVA and water (ratio 1: 3).
Cracks are filled in depending on their dimensions. If the damage is single and its width does not exceed 0.4 mm, then the gap is expanded to 10 mm and any building compound is poured into it (you can use cement or special glue for aerated concrete). If the width of the defect is up to 10 mm, then it is better to use a porous adhesive for sealing and widen the gap to 20 mm. In the event of a defect with a width of up to 20 mm, it is recommended to apply an adhesive or cement composition, having previously added coarse-graded crushed stone from aerated concrete to it.

After completing the work, it is necessary to close the treated surface with a sheet of plywood (secure with self-tapping screws) for 3-5 hours.

Do-it-yourself concrete floor repair is by no means a simple "grease" with cement mortar. Such a "plaque" 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 having gained structural strength, lives for decades its complex physical and chemical life: 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, significantly differ from aged concrete. For the renovation of the old floor to be successful, it is necessary to somehow reconcile the properties of the old and new concrete. One of the ways that is optimal for small self-repair is to impart thixotropic and rheological properties to the fresh cement slurry.

Thixotropy and rheology

Thixotropy is the ability of a medium to succumb, to reduce its viscosity with a small but constant impact. A good example of a thixotropic substance is common construction bitumen. If you run your finger over it with pressure, then at first you feel roughness, and then the movement is facilitated and a hollow remains behind the finger. By the way, continental plates move across the face of the Earth due to the fact that the material of the upper mantle is thixotropic.

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

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

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

To do this, PVA glue or bustilate is diluted with water three to five times, and a cement-sand mortar is kneaded on the resulting suspension in a ratio of 1: 3. If the volume 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.

For sealing deep deformation cracks, PVA-suspension is not suitable; here you will have to buy a proprietary thixotropic primer for concrete and a repair compound. In this case, you should focus solely on the price: the apartment floor is a light object, and the exclusive quality of the compositions is not required.

Mixer and rule

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

To mix small volumes of repair building materials, I use an electric drill or a perforator at low speeds with a special attachment - a mixer. Its principle of operation is no different from that of a cocktail mixer.

In tool stores you can find a wide selection of different mixers, sometimes in completely fancy configurations. But the mixer, which is in no way inferior to them, is obtained from an even rod of 8-10 mm in diameter and half a meter in length, 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, the tool is driven in a circular motion; in the trough - transverse zigzag. There should be a bucket of water at hand - after kneading, the mixer must be rinsed immediately, dipping it into the water and giving more speed. When mixing with a perforator, in no case should the percussion mechanism be turned on: the whole room and you will immediately find yourself concreted with a thin layer.

In addition to a mixer, for repairing a concrete floor, you will need a rule - a wide, meter-wide, spatula. A plastering trowel will not work: it will not smooth out the concrete properly, but will rub off on it itself. The rule, on the contrary, must be purchased from the factory, and one should not save on it, especially since it is inexpensive. Concrete is a good abrasive, and if the middle of the rule is "eaten up", then the floor will turn out to be humped.

Types of concrete floor repair

There are four different types of concrete floor repairs:

Elimination of defects - bulges, potholes, seams from markers and formwork, cracks on the screed.
Sealing gaping cracks.
Overhaul of the floor screed for polishing concrete, laying a finishing coating or underfloor heating with insulation and waterproofing.
Dedusting.

Each type of repair is carried out using a special technology. The most time-consuming and costly repair of a screed under a clean floor. For its overhaul, you will additionally need a metal stitching 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 kept for at least 20 days before continuing work, sprinkling with water every day or wiping with a generously moistened cloth. Pouring the floor or moistening more often is impossible: the set concrete absorbs a certain amount of water and slowly. A break will hurt him.

Recommendations on mandatory exposure of 40 days or more, covering the concrete with wet burlap, etc. are intended for outdoor concreting. In relatively stable conditions of a residential or utility room, 20 days of exposure is more than enough.

Room preparation

Preparation for the repair of a concrete floor is reduced to emptying the premises and thorough cleaning. Large debris is raked with a shovel, then the floor is thoroughly swept two or three times with a wet broom with spraying. Potholes and cracks after drying the floor after each sweeping are blown out with a household vacuum cleaner.

If it is possible to use an industrial vacuum cleaner, the preparation of the floor can be completed within an hour: they suck the floor, blow through the cracked potholes, suck in again - and that's it, the preparation is over.

Concrete floor repair procedure

Repair of the floor in the apartment begins with its examination 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 flat, but dusty, and occasionally has potholes, well-defined small protrusions, or fine serpentine cracks. Self-repair is possible and inexpensive.
There are gaping cracks no more than half the length of the short side of the floor, gravitating towards the perimeter or longitudinal-transverse. Self-repair is possible using proprietary thixotropic compounds.
The floor is “all humpbacked”: small bumps and depressions alternate relatively regularly. Self-repair "on concrete" is possible in a private house or outbuildings.
In a single-family house on the floor there are long gaping cracks on the floor screed, generally located diagonally or crosswise. Only a major overhaul of the screed is possible with a preliminary professional assessment of the condition of the ceiling.

Note to point 3: leveling of a carelessly poured screed is possible either with a milling machine or with a liquid leveler after filling the cracks. Leveling the floor with a hardening compound is a subject for a separate conversation, and a milling machine in an apartment building cannot be used: it is very dusty, and the presence of cement dust in the air of residential premises is strictly prohibited by sanitary standards. In addition to the "gratitude" of neighbors, one can also fall under serious legislative sanctions, up to and including imprisonment. For example, if during or after your work one of the residents is hospitalized with an exacerbation of asthma or pulmonary disease, this is a moderate or serious harm to health. Terms - see UK.

Minor patching

The potholes are cut off with a grinder with a diamond wheel in a rectangle with a grip of at least 20 mm to the sides. Cutting depth - 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 puncher or manually to the depression.
Using a perforator with a chisel for concrete, a rectangular depression is selected at the place of the pothole. Small potholes can be picked by hand with 200g hammer and carbide chisel. You cannot pound with all your might on a dull metal chisel: a crack may go.
The recess is blown out with a vacuum cleaner, then the remaining dust is sucked out with it.
The recess is coated with one layer of any primer on concrete. Choice - by price; the case is not responsible.
After drying, the primer is filled with a thixotropic compound, homemade or purchased, leveled with a rule and left to stand - sealed.

Notes:

Proprietary repair compounds are kneaded only on sifted quartz sand. It can be purchased at the same store. Proportion - according to the instructions on the package. Thixotropic mixes in small packages are sometimes sold in a set with a package of sand in the right amount.

Sawing work should be done in a respirator, goggles, ear muffs, gloves and tightly buttoned clothes, with wide open windows, tightly closed doors and as quickly as possible. Unlike a hypothetical asthmatic neighbor, you will surely find yourself in the very center of a cloud of cement dust. Headphones in this case protect more from it than from noise.

Repair of small cracks

Small cracks are first sawn 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 by the condition of the floor. The kerf is also blown through and sucked out.

How to repair cracks in the floor? If the floor itself is not dusty, and the circle is taut, then a homemade repair mixture will do. If the sawing is easy, and the grinder even slips from time to time, you definitely need a good branded primer and thixotrope. But if the dust during sawing is so thick that the tool is poorly visible in the hands, and / or streams of sand are thrown out from under the circle, you need to close it up in full, like gaping cracks.

Sealing small cracks is reduced to coating with a primer and filling with thixotrope, like recesses.

Advice: if possible, two to six months before the repair, stick paper strips on the cracks half a meter apart. If the paper is not torn for repair, the crack is shrinking, it will not go further, and you can whip up it as described. If at least one piece of paper is torn, the crack is deformation and must be repaired according to the full scheme.

Sealing gaping cracks

A gaping crack is considered to be more than 2 mm wide, but this criterion is very relative. The dynamics of the process is of greater importance: will the crack go further or not. You can independently assess the dynamics without having any construction experience using the "paper" method described above or a laser level with a sensor or reflector on the opposite wall turned on for several days. If, for example, a light spot has gone on average by 0.01 mm per day, then in a year it will be 3.65 mm - an emergency situation, and you need to think about overhauling the entire building.

If the condition of the building as a whole does not cause concern, then the gaping cracks should be repaired as follows (see figure):

The crack is sawn 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 through and sucked in.
The hollow is treated with a primer.
As the primer dries, markers are inserted into the cut one by one. Holding the next marker with the hand vertically, the hollow is covered with a thixotropic composition, leveling it with the rule. Homemade thixotrope cannot be used in this case!
When the thixotrope is seized, the markers are removed, and the seam is cut through the holes from them to the same width.
A damper cord like "Vilotherm" or similar is placed in the seam. Clotheslines, synthetic ropes, etc. do not work.
The seam is finally sealed with silicone or polyurethane sealant; never with polyurethane foam, epoxy or other fully curing compounds.

Note: markers - thin smooth metal rods. Great markers come from bicycle spokes. To make it easier to remove later, markers can be lubricated with grease before installation.

Screed overhaul

Overhaul of the screed means actually replacing it. This is a last resort, costly and time consuming. They go to it if it is supposed to be laid or finished, and the moisture test gave an unfavorable result.

You can read more about the formation of various types of floor screeds from scratch by following the links below:

Screed thickness calculation

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 threshold of the door. Therefore, the calculation of the thickness of the screed is carried out from the bottom up with a margin in the big direction. In this case, the level of the base floor will be lower, but this can be compensated for by increasing the thickness of the plywood underlayment or the height of the logs. The thickness of the mortar layer above the reinforcing mesh must be taken at least 8 mm.

Calculation example: from a "bare" floor to a door threshold of 80 mm. Initial data:

Waterproofing - 1 mm.
Expanded clay bedding in one layer - 25 mm.
Reinforcing mesh - 6 mm.
Concrete layer over the mesh - 8 mm.
The layer of mastic is 1 mm.
Plywood - 8 mm.
The adhesive layer is 1 mm.
Laminate - 16 mm.

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

Screed markers

The screed is leveled with pin or plaster lath markers. Both are lined up with a small amount of cement-sand mortar (see figure below):

Pins - in corners and along walls every half a 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.

Pins can be made from scrap materials, but plaster markers will have to be bought, and expanded clay will need to be rolled very carefully. But even an experienced craftsman will hardly be able to maintain the horizontal surface of the surface better than 3 mm / m on the pins, since the rule will have to work without additional support.

The height marks on the pins are made with a tight cord and a bubble level, starting from the corner closest to the door diagonally. Then they beat off the second diagonal along the primary cord, pull the cords around the perimeter and make marks on the wall markers. You can use a laser level to speed up the heights, but this will not improve the accuracy and smoothness of the floor, see above.

Screed overhaul procedure

Lay the 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 glued with tape.
Expanded clay is poured and leveled with a stitching roller. It is permissible to use a manual rammer, wood or metal, under the subfloor.
Reinforcing mesh is laid with an overlap of 1-2 cells and an indent from the walls of 30-40 mm.
Wall markers.
If pin markers are used, the heights are skimmed when the sub-bricking has solidified.
Mix in portions of 10-20 liters viscous cement-sand mortar (1: 3); thixotropic additives are optional. At the end of the batch, the next portion is dumped between the markers next to the previous one.
Each portion of the solution is leveled with a rule, starting from the far wall: along a cord or with the support of the rule for two adjacent markers. The rule is kept obliquely so that the excess solution falls into the empty cell.
The next portion is kneaded after leveling the previous one.
When the solution hardens, the markers are removed and the grooves are sealed with a solution.
Excess waterproofing does not touch; they are cut off after installing the plinth.

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

Video: an example of pouring a screed

Dedusting

Completely serviceable, but dusty due to surface wear, the concrete floor can be quickly repaired with special compounds:

Sub-floor 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 living quarters, garage, workshop - GruntElast-PU, Elakor-ED, Retroplate. Layer - 250 microns.

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

Outcome

Do-it-yourself concrete floor repair can be as simple, fast and cheap as it can be difficult, hard and expensive. The need for repairs of one degree or another, in addition to the presence of gaping cracks, can be determined independently. In any case, only dedusting of the floor worn out from the surface is definitely beneficial for self-execution.

Despite the strength and durability of concrete floors, even they need regular repairs. Violations of the technology of laying such a floor, the peculiarities of its operation, improper care can lead to problems in the form of cracks, chips, potholes, swelling and other surface defects. Repair of concrete floors allows you to return the coating to its original appearance and high performance characteristics. In some cases, repairs can be done by hand, and to eliminate complex defects, you will need to involve specialists.

Causes of Concrete Floor Defects

Even if the concrete flooring technology is strictly followed, cracks and other defects may appear on the surface. Among the main causes of problems with concrete floors are the following:

Swelling and unevenness of the surface of the concrete floor can lead to the destructive effect of the subgrade. At the same time, the front layer of the floor remains absolutely smooth and free of cracks. Its unevenness can be caused by swelling of the soil in the cold season in a warehouse without heating, shrinkage of the structure, exposure to groundwater or insufficient tamping of the base during flooring.
Cracks on the floor surface can be caused by improper maintenance of the concrete surface immediately after installation. Internal factors cause shrinkage of the floor and peeling of the top layer. As a result, the floor begins to crumble, potholes and chips form on it.
The negative influence of external factors leads to "dusting" of the surface. Due to the significant regular loads on the floor from heavy objects and vehicles, potholes can occur.

Types of concrete floor repair

Concrete floor repair technology involves four types of work:

Repair of minor surface defects formed after removal of markers, removal of the formwork, due to traffic. These include small cracks, bulges, and potholes on the top layer of the floor.
Repair of deep damage to the surface. In the course of the work, it will be necessary to close up deep deformation and shrinkage holes and cracks, and eliminate chips.
Major overhaul concrete surface is done if it is planned to polish the front layer, lay a new floor covering or perform waterproofing and floor insulation in a warehouse or in another room.
Dedusting. If the floor begins to crumble and become dusty, it is necessary to carry out repair work to remove dust from the floor.

Important: after the repair work, in addition to dust removal, the floor cannot be used for three weeks. During this time, the concrete will fully set and gain the required strength. At the same time, during the first week, the surface of the repaired floor must be regularly moistened with water to prevent shrinkage and cracking.

Preparatory work

Repair of concrete floors can only be started after careful preparation of the warehouse or other premises. To do this, do the following:

All furniture and work equipment must be removed from the room.
Large debris is collected with a shovel, and the surface of the floor is sprayed with water and swept.
All holes and cracks are well blown with a vacuum cleaner.
After blowing them out, the floor is swept again.

Tip: It is much faster and more efficient to clean the floor with an industrial vacuum cleaner. With such equipment, you can blow well and clean all floor defects.

Damage assessment and choice of repair tactics

Before starting repairs, the floor must be carefully inspected in order to assess the degree of its damage and choose the appropriate tactics for further actions. The floor in a warehouse or in another production area may look like this:

In general, the floor surface is flat, but in some places there are small holes and a thin network of cracks. Repair of this floor is easy to do with your own hands.
If large holes and deep longitudinal or transverse cracks are visible on the surface, then the repair is best done using thixotropic compounds.
If the floor crumbles heavily, depressions and protuberances are visible on its surface, then it will not be enough to just patch up the holes. A thorough repair of the floor screed with the use of special mixtures will be required.
The floor is crumbling, it is all covered with deep cracks, potholes, in some places delamination of the upper layer is noticeable. In this case, a major overhaul will be required.

Repair of small holes

Do-it-yourself concrete floor repair can be done if there are small holes on a relatively flat surface. The sequence of repair work is as follows:

To close small holes, you need to expand the pothole with a diamond wheel tool, grabbing 2 cm of the floor on each side. The hole also needs to be cut 1-2 cm deep in depth. If the floor is hard enough, then the amount of grip on all sides can be slightly reduced. On dusty floors, on the other hand, it is worth making a deeper and wider cut.
Then, using a perforator or chisel, concrete is knocked out of the expanded hole. This must be done very carefully so that a crack does not go.
Use a vacuum cleaner to blow through the pothole well and clean the floor around it of debris.
Further, all surfaces in the hole are lubricated with a concrete primer. One coat of primer is enough.
When the primer is dry, a thixotropic mixture is placed in the hole. It can be bought or prepared locally.

Repair of shallow cracks

The technology for repairing small cracks involves several stages:

Small cracks are expanded with a grinder. To do this, it is enough to grab 1-2 cm of the floor in width, and 2-5 cm in depth. Depending on the strength of the floor, the cut can be reduced or increased.
Sealing cracks on non-dusty floors can be done using a homemade repair compound. Dusty fragile floors with cracks are repaired with proprietary primers and a thixotropic mixture. It is applied after the primer has dried on the walls of the expanded crack.

Advice: in order to understand the nature of the crack, you need to glue it with paper strips with a step of 50 cm two months before the start of the repair.If during this time the strips do not break, it means that the crack was formed due to concrete shrinkage and will not expand anymore. It can be repaired with ordinary mortar. In the event that at least one strip of paper breaks, the crack is considered deformation, it must be repaired as described below.

Repair of deep cracks

A crack is considered deep if its width is more than 2 mm, but this parameter is relative. The nature of the crack is important. Deformation defects can increase over time and can only be repaired thoroughly. Deep cracks should be repaired in the following order:

With a grinder, the crack opens in width and depth by 2-5 cm, depending on the condition of the concrete floor.
The edges of the recess must be knocked down so that the cut expands upward.
The crack is cleaned of debris and dust.
The recess is treated with a primer.
Next, the crack must be covered with a thixotropic mixture, placing markers in the recess. When the composition is set, the markers are removed.
Through the holes from the markers, a crack is cut again.
A damper cord is placed in the resulting seam.
From above, the seam is closed with a polyurethane or silicone sealant.

Important: for sealing the joint, it is forbidden to use hardening mixtures, such as polyurethane foam or epoxy resin.

Floor overhaul

This type of repair involves a complete replacement of the top layer of the screed. It takes place in several stages:

After complete dismantling of the old screed, a viscous cement-sand mixture is prepared in a ratio of 1: 3 and laid on the floor according to pre-set markers.
The stacked portion of the solution is leveled with a rule. The next portion can be stacked after the previous one has been completely leveled.
When the concrete has hardened, the markers can be removed, and the holes can be repaired with mortar.

Dedusting floors

For dedusting rough concrete floors, you can use mixtures of domestic production Ashford, Elakor-PU or Neomer. They are suitable for floors in outbuildings and utility rooms in industrial plants.