Concrete screed crumbles - what to do? Strengthening a weak screed with a primer, liquid glass and silicate impregnations Sand screed crumbles what to do

Violation of technology in the production of construction and repair work inevitably leads to large or small troubles, which subsequently have to be eliminated, spending great effort and considerable funds. This axiom fully applies to an incorrectly produced floor screed, as a result of which various defects may appear on the coating. It can crumble, crack and, as the builders say, swell.

If cracks appear in the floor after screed work, then the simplest, and most importantly, not expensive option is to make a regular repair.

What can be done to repair small cracks?

First, after detecting such a defect, it is necessary to carefully examine the floor and determine the root cause of the cracks. There are several reasons why this problem may occur. This is a poorly measured coating layer, rapid drying of the applied layer, problems with moisture in the solution - too much or, conversely, too little water. Forgetting to install the edge strip gasket, as well as the absence of expansion joints, also leads to cracks.

If it turned out that the cracks were due to unfinished seams, it is urgent to make seams for shrinkage. The depth of such a shrinkage seam should be buried no less than a third of the base. They should be done in increments of up to 5 meters. The seams must be sealed with a sealant based on polyurethane.

We will detect cracks, especially if they are very thin, they need to be expanded, for which they can be strobed. Remove the formed dust in the crack and prime it. It is necessary to close up such cracks with a non-shrinking material using a conventional staple. Some subtlety - if the floor is laid tile, and the cracks that appeared on the screed are very small, then nothing needs to be done with them. Larger cracks are sealed special composition which is easy to make with your own hands. It includes cement, PVA glue and water. The mixture that results from mixing must have a liquid consistency so that it can be poured into the cracks without problems. After the poured mortar has hardened in the cracks, all subsequent work can begin, for example, with a coating on the floor.

What to do if the screed is broken?

A broken screed is a serious defect that requires mandatory elimination. The cause of such a big trouble may be the unsatisfactory compaction of the mixture, as a result of which air cavities can form in it - caverns, leading to cracking on a large scale. In this case, the screed is removed to the detected unfilled cavity, and the cavity is filled with a solution. You can find a cavity by deepening the crack with a tool, such as a pickaxe. Accordingly, the test pit must subsequently be covered with soil and poured with mortar. The solution with which the cavity is poured should consist of sand and cement in a ratio of one to three. Before filling, the cavity is moistened with water. After the cavity is filled, it is necessary to verify the quality of the filling, for which try to seal the hole using an appropriate rod. The room temperature should not be too high. The screed must be moistened periodically using water.

The screed is bubbling - how to deal with it?

Experts use the word "buht" in cases where, when tapping the screed, there is a feeling that there is a void in the depth of the coating. Also, this term is used when a spring effect occurs under the foot, a kind of punching of the surface.
If the screed is bouncing, then there can be many reasons for this. The main reason is non-compliance with the process technology. If signs of coiling are found, it is necessary to break through this place, expand it and fill it with a liquid solution, which consists of cement and sand. The optimal solution will add PVA glue to the solution. There is a subtlety here - it is necessary to pour the solution in small portions, giving each of them the opportunity to freeze.
If this method did not help, then we go according to the “scorched earth” method - we break the screed and start all over again. To prevent this - do everything right and according to technology right away.

If cracks appear in the floor after screed work, then the simplest, and most importantly, not expensive option is to make a regular repair.

What can be done to repair small cracks?

We will detect cracks, especially if they are very thin, they need to be expanded, for which they can be strobed. Remove the formed dust in the crack and prime it. It is necessary to close up such cracks with a non-shrinking material using a conventional staple. Some subtlety - if tiles are laid on the floor, and the cracks that appear on the screed are very small, then nothing needs to be done with them. Larger cracks are sealed with a special compound that is easy to do with your own hands. It includes cement, PVA glue and water. The mixture that results from mixing must have a liquid consistency so that it can be poured into the cracks without problems. After the poured mortar has hardened in the cracks, all subsequent work can begin, for example, with a coating on the floor.

If the floor screed is made incorrectly, then over time it can collapse: crumble, crack, swell. In this case, you should not redo it.

You can promptly repair the screed, which will be more economical option.

How to fix cracks in the screed?

When cracks appear in the floor screed, it is necessary to initially determine the cause of their occurrence, and then proceed to eliminate them.

Causes of cracks in cement screed there may be an incorrect coating layer, rapid drying, excess or lack of water in the solution, lack of edge tape or expansion joints.

If the floor screed has cracked due to the lack of expansion joints, it is necessary to cut the shrinkage joints.

In this case, the depth of the cut must be at least one third of the thickness of the base. The distance between the seams should be within 5 meters. Joints are sealed with a polyurethane-based sealant.

If cracks appear in them, you can make a strobe, thus expanding it. It is necessary to remove dust from the walls of the strobe and prime them. To seal cracks in the floor screed, it is necessary to use a non-shrinking substance, which is applied with a spatula.

If the cracks on the floor screed are minor, and the flooring is tile, then they can be ignored.

Cracks in the floor screed must be sealed with a composition of PVA glue, cement and water. All these components are mixed in such a way that the mixture can be poured into the slot. After this, the solution must be allowed to harden and proceed with laying the flooring.

Floor screed burst - what to do?

If the floor screed has burst, then in without fail it is necessary to correct this defect before laying the flooring.

For poor sealing concrete mix air pockets can appear in the screed, which cause cracks. In this case, it is necessary to remove the screed to the cavity and fill it with mortar.

In order to see the caverns, it is necessary to widen the crack. If you find it, then the solution is knocked out with the help of a pick. The walls of the resulting hole must be primed, and then sealed with cement mortar.

Part cement mixture, which is being prepared for sealing the cavity, should include one part of sand and three cement. Before pouring the mixture, the concrete must be wetted with water.

Compaction of the mortar after pouring must be compacted by piercing. For this purpose, a metal rod is used.

After repairing the floor screed, it is necessary to ensure that the temperature in the room is not very high. In order to prevent cracks from appearing on it, it is necessary to periodically moisten the place of laying the cement mixture with water.

The screed is bubbling - what to do?

If the floor screed coils, then it is of poor quality. The reason for the screed buckling may be a poor-quality mixture for screeding, lack of a primer on the base, dirty and dusty base, which is used under the screed, etc.

In this case, it is necessary to hit the screed with the blunt edge of the hammer. If the mixture is of poor quality, then a dent will remain at the site of impact. The screed may swell in the presence of cracks or in their absence.

If the screed coils in the presence of cracks, then you can try to eliminate it. To do this, it is necessary to widen the crack. Next, a very liquid solution of sand and cement is prepared.

It is best to add PVA glue to this solution. Next, the resulting solution is slowly poured into the expanded mixture. It is necessary to fill the solution in small quantities, allowing it to dry in parts.

Concrete screed crumbles - what to do?

The concrete floor base is widely used in both industrial and civil construction. Its use is due to its high strength, reliability and durability.

On the reinforced concrete slabs floor screed is poured after cleaning and priming the surface. Layer thickness 50 - 100 mm. Typically, such flooring is arranged in new apartments or houses. On the ground, a concrete screed is laid on the floors in the basement. First of all, the soil base is rammed, a layer of sand 100 - 150 mm is poured on it and compacted. Then the footing is poured with a thickness of 40 - 50 mm. After gaining the required strength (about 7 days under normal conditions), a layer of rolled vapor barrier and insulation is placed on it. Then a metal mesh frame is mounted. After that, a layer of waterproofing is rolled out and the finishing layer is poured. concrete screed 50 mm thick.

Screed on the separating layer of waterproofing

Suitable for repairing floors in garages, workshops and other premises contaminated with grease and oil. A layer is laid on the surface roll waterproofing. A concrete screed with a thickness of 50 - 70 mm is poured over it.

floating concrete screed

Suitable for floor repairs unheated premises. A layer of insulation is laid (mineral wool, polystyrene). A layer of waterproofing is laid on it. Then a metal mesh frame is mounted and poured concrete base thickness 50 - 70 mm.

Reasons for the destruction of the concrete screed

A solid-looking base can crack or completely collapse under the influence of a number of external and internal factors.

Chemical Factors

For an untrained person, it will be difficult to determine the presence of destruction associated with chemical reactions inside the concrete screed. This problem mainly concerns large industrial and public building objects.

Important! During construction, it is better to use concrete that has a quality certificate produced industrial way. Or mix directly at the work site, but from proven and high-quality components.

Physical factors

Cyclic process of freezing and thawing. It is typical for winter concreting, when, in case of violation of the pouring technology, not all water is involved in the chemical reaction of concrete mixture hardening. Part of the moisture simply freezes. The concrete screed collapses due to water getting inside. Constant freezing and thawing leads to the destruction of the bonds within the concrete and the formation of penetrating cracks.
Exposure to high temperatures. When the concrete floor is suddenly cooled, for example, during fire extinguishing, steam is formed inside, which tears the concrete. Prolonged heating may cause cracking. This is due to the different coefficient of expansion for reinforcement and concrete. That is, at equal temperatures, their size does not change equally.

Important! Usually cracks from overheating are formed in areas of the concrete floor adjacent to fireplaces or stoves. Also subject to cracking are meth, where non-insulated pipes of hot or cold water supply pass.

Shrinkage of concrete screed. Associated with the rapid release of moisture. In hot weather, water evaporates quickly from concrete. This leads to the formation of microcracks and small dips on the floor surface.

Too much water in concrete mortar may lead to cracking a few months after pouring the screed.

Mechanical factors

Abrasion. Intensive use of the floor surface leads to destruction concrete surface. characteristic feature such destruction are dips with rounded edges, the so-called "abrasions" The service life depends on the brand of the mixture.
Impact loads. Unlike abrasion, here a sharp and rapid impact is exerted on the concrete surface. As a result, potholes with jagged edges and penetrating cracks may appear.

Sex-destroying factors are rare in pure form. Usually, cracking or complete destruction of a concrete screed is associated with the combined effect of several causes.

Ways to prevent the destruction of the concrete floor screed

Choose the right brand of concrete depending on the expected operational load. It is important to understand that the floor in the basement and garage will take different loads. For basement suitable concrete grade B10. In rooms with a more intense load, it is better to fill in floors of grade B12.5 or B15.
Use of durable filler. There are many types of gravel and crushed stone. Their strength characteristics greatly affect the quality of the concrete mix.
Introduction to the solution of plasticizing or water-repellent additives. Additional chemicals can greatly increase the resistance of concrete to moisture or mechanical stress. In hardware stores you can find such additives. The main thing is to carefully read the instructions and not make a mistake with the proportions.

Important! Excessive dilution of concrete with seven chemicals can cause weakening or complete destruction of the floor surface.

Impregnation of the poured concrete mixture with a special composition for hydrophobic protection.
Mandatory waterproofing of the base before laying concrete on the earthen surface. Otherwise, it will suck in moisture and gradually collapse.
In hot weather, protection of the concrete screed from the rapid evaporation of water. There are two ways:

Covering the entire floor surface polyethylene film. Once in a knock, concrete opens and spills warm water. The exposure period is 7 - 8 days. After that, the film is removed.
Protection of fresh concrete with sawdust. "Grandfather", but a very effective way. The syazhka is covered with sawdust and spilled with water twice a day. The exposure period is 7 - 8 days.

Prevention of freezing of the concrete screed until it reaches the required strength. To do this, you can knead concrete in warm water. After pouring, the surface is covered with a plastic film. It turns out "teplyak", which will allow concrete to gain the necessary strength. The exposure time is 3-4 days.
Isolation of communications. If heating and water supply pipes pass through a concrete screed, they are insulated. This is done to prevent cracking of the concrete floor at the points of contact with the pipes.
Heat insulating pads between concrete floors and a fireplace or stove.
Protection against mechanical impacts and abrasion with finish coat in the form of ceramic tiles, laminate, linoleum.
Device expansion joints. Concrete is poured in strips 1000 mm wide, a galvanized profile is laid between them. Thanks to this, the monolithic concrete surface does not tear under the influence of thermal expansion.

Compliance with all technological features during the laying and operation of the concrete floor will allow you to get a solid, reliable and durable foundation.

Repair of potholes and cracks in concrete screed

Even observing all the rules for pouring and operating a concrete screed, cracks, chips and potholes are likely to appear. The technology of repairing a concrete surface depends on the type and degree of destruction. But any work begins with preparation.

Preparatory stage. Repair of a new screed does not require special work on surface preparation. It is enough to remove dust and debris.

Troubleshooting old surface begins with the removal of the flooring and cleaning the floor of all paint and varnish or adhesive materials. To do this, use a spatula and a metal brush for metal.

Important! You can speed up cleaning by using special grinding nozzles on a drill or hammer drill. They are sold at any hardware store.

Repair of formwork marks

Often, after dismantling the formwork, uneven areas remain on the floor surface. They are rubbed with a cement-sand mortar or repair mix for concrete. Before grouting, the surface is dedusted and impregnated with deep penetration soil (betonokontakt) or mortar epoxy resin.

Pothole repair

A pothole is a broken piece of concrete that is bowl-shaped and has jagged and chipped edges. They are repaired to prevent further deterioration of the concrete surface. Repair steps:

Around each pothole, rectangular cuts are made using a grinder with a circle on concrete. The depth of cut is slightly greater than that of the pothole.
Destroyed concrete is removed from the cut with a hammer and chisel. You can also use a puncher with a spatula nozzle.

Important! If the pothole has exposed the reinforcement, then it is necessary to paint over open area metal primer.

The surface of the pothole is cleaned from dust and dirt with an ordinary flute brush.
The destroyed area is treated with concrete contact or epoxy primer. This will allow you to get a better adhesion of the repair mixture to the concrete.

Important! The drying time of the soil is 45 - 60 minutes.

The primed pothole is filled with a special compound for repairing concrete surfaces. If it is not possible to purchase it, then a cement-sand mortar is prepared for small potholes.
The laid mixture is leveled with the old floor. For this, a plaster spatula 100 - 150 mm is used.
After hardening, the repaired area is polished.

Crack repair

Take place immediately upon discovery. Otherwise, water can get into the cracks and the process of destruction of the concrete screed will continue. Elimination steps:

small cracks cut with a grinder and a circle on concrete or expand with a chisel and hammer. This process is called "crack jointing". More serious areas are cut out completely, like potholes.
Remove dust and construction garbage with a flute brush or vacuum cleaner.

Important! To clean cracks, you can use industrial or home hair dryer.

The surface of the cracks is impregnated with concrete contact or epoxy primer. The drying time is 45-60 minutes.
Cracks are filled with a special repair mortar based on polymer or epoxy filler.

Important! Not deep 1 - 2 cm cracks are filled at a time. More serious destroyed areas are smeared in several layers. Layer thickness 1 - 2 cm.

After complete drying, the repaired floor surface is polished.

Important! Wide and long cracks can be reinforced with rebar inserts. Every 300 - 350 mm cuts are made perpendicular to the crack. Then a piece of reinforcing wire is inserted into each and smeared with repair mortar.

Repair of small spider cracks

This type of destruction is not dangerous for bearing capacity concrete floor. To eliminate it, it is enough to make a liquid cement-sand mortar and wipe the cracked area.

Rough repair

During operation, “wiped” areas may appear on the concrete floor. They do not lead to the destruction of the entire coating, but create inconvenience when moving on it. Elimination steps:

Using a milling machine, an uneven area is cut to a depth of 10 - 15 mm.
The repaired surface is cleaned of dust and dirt. To do this, use a regular floor brush or broom.
The cleaned area is primed with concrete contact or epoxy adhesive, diluted with a solvent in a ratio of 1 to 10. Drying time 45 - 60 minutes.
The impregnated surface is filled with mortar and smoothed with a plaster rule.
After drying, the entire repaired surface is sanded.

Overhaul of concrete screed

The methods described above are suitable when no more than 15% of the surface is destroyed. In other cases, you need overhaul concrete screed. For these purposes, there are self-leveling compounds. Stages of work:

The surface of the concrete floor is cleaned of dirt, dust and mortar sagging.
The screed is polished with a grinder with a special nozzle.

Important! Sanding the floor does not level the level relative to the horizon, but only removes all small bumps and bulges.

The base is impregnated with deep penetration soil. It is applied with a 250 mm paint roller. Drying time 45 - 60 min. After that, re-priming is carried out.
Self-leveling mortar is poured. The layer thickness ranges from 50 to 100 mm. For removing air bubbles the filled surface is rolled with a spiked roller. If necessary, the mixture is applied in several layers. The drying time of the new screed is written on each bag of dry mix. But it must be at least 7 days.

To maintain a concrete screed in good condition, it is enough to notice the destruction that has begun in time, determine the cause and quickly repair the destroyed section of the floor.

Video removal of cracks in the screed

meot.ru

How to strengthen the screed

03.04.2018

A loose, crumbling uneven screed in a good way needs to be knocked down to the ground. And pour over concrete slab new.

However, the best, as you know, is the enemy of the good. And far away there is a financial opportunity and time for a major renovation. In this case, I suggest using the following method of strengthening the screed.

We dedust the loose base (necessarily construction vacuum cleaner, a broom will not be enough. You can also use normal household vacuum cleaner, but keep in mind that concrete dust is detrimental to its engine. But if the old one is not a pity ...)

Primed with deep penetration primer. Let it dry for at least 3-4 hours. It is also not worth tightening too much, so that dust does not appear again. Next is the stage of reinforcement and preliminary alignment. The floor is puttied with a layer of tile adhesive. A plastic facade mesh with a cell of 5x5 mm is recessed into the glue.

As a result, our loose screed is covered with a layer of sufficiently durable material. In addition, thanks to the grid, the floor becomes solid again, and not large pieces of screed, separated by cracks.

We carry out the final alignment with a self-spreader. The dried layer of glue is also prepared. Dedusting and soil. How to do this is described here.

The presence of tile adhesive will not allow the hardening self-flowing to tear off the weak and loose upper layer screeds. Also, the glue closes the deepest irregularities, which helps the self-spreading spread with a thin layer (as practice shows, 3-5 mm is the optimal layer height of the self-leveling mixture. If somewhere the layer thickness is 10-15 mm, cracks usually appear in the same place .)

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Overhaul of concrete floors: strengthening the peeled screed

Popular methods of repairing concrete floors work effectively, provided that the floor surface has retained its integrity by at least seventy percent. If the concrete screed is destroyed by more than thirty percent, it makes sense to replace it with a new one.

The pouring process itself is quite simple, but certain rules must be followed when performing it. The surface on which the screed will be poured must be absolutely clean. For better adhesion of the mixture with the rough surface, it is necessary to use a soil mixture. If there is high humidity in the room, a primer with water-repellent properties should be preferred.

After the above steps, the starting floor is poured with a small layer (5-10 cm) of a self-leveling compound, from which air bubbles formed during the filling process are removed using a special spiked roller. It is acceptable to apply a second layer of the composition if necessary.

After the screed has been poured, it needs to be given time to brew. For a month, it is not recommended to allow any impact on the coating, because. it is during this period of time that the filled layer finally solidifies and acquires all its inherent properties. However, despite the observance of the technical rules for pouring concrete floors, after a while it becomes necessary to repair them. Consider the types of damage and repair methods.

Stages of strengthening a weak concrete floor

Strengthening the screed may become necessary if low-quality cement was used during its pouring or high external loads constantly act on the floor surface (for example, in workshops and in industrial-type premises). It is best to dismantle a poor-quality base and pour a new screed than to repair the coating on large damaged areas, but this is not always enough time and money.

Strengthening Technology

First of all, in the renewed screed, it is necessary to drill a series of holes with a diameter of 20 mm and located at a distance of 25 cm from each other. Holes are drilled to the very base. Professional rotary hammers, equipped with a special drill with a small angle of inclination of the working groove, cope well with this task.

Next, in each hole (in its upper part), a support bowl should be drilled, the depth of which is 30 mm, and the diameter is twice the size of the hole itself. The drilled holes are cleaned of dust and go through the priming process, after which degreased reinforcement is inserted into them, the diameter of which is ~ 12 mm, and the length is equal to the depth of the hole.

After that, each hole is filled with an epoxy mortar (Rizopox 3500) and a filler is added, which is quartz sand. At the final stage, the surface is polished until a flat plane is obtained.

Repair of a peeled coating layer

Quite often, the screed, during operation, can peel off from the subfloor. This happens due to the impact on the concrete floor of unevenly distributed loads. It is not always possible to visually see the problem area. Peeling can be detected by lightly tapping the entire floor with a hammer. The detachment zone will indicate itself with a dull sound. In addition, it is not uncommon for delamination to occur in areas of the floor that have cracks, from which a cloud of cement dust flies out during tapping. After all areas of the floor that require repair have been identified, you can proceed with the injection of the screed.

The essence of the method is quite simple and does not take much time. In those parts of the floor where signs of delamination were found, holes are drilled at a distance of 250 mm, the diameter of which varies in the range from 12 to 20 mm. Then using building syringe, they are filled with an epoxy-based composition. The mixture is poured several times as it soaks into the concrete and fills the voids formed by the peeling process.

The undoubted advantage of the described method is its speed, tk. the next day after the repair of concrete floors, a protective layer can be applied to the screed.

It is necessary to clarify, for clarity of the answer, where your screed is located. It can be a street - a plot around the house or a vestibule in a bathhouse, a screed in a garage or a screed in a bathroom, etc.

There are several main reasons for the appearance of cracks or delamination, erasing the screed:

Poor quality fillers. Due to the abundance of dust in aggregates or due to the large presence of a fine fraction, the grade indicators of the solution can fall many times over. This leads to a decrease in strength, density and, after them, all other characteristics (moisture resistance, abrasion, frost resistance, etc.). This is why cracks or chips can quickly appear.
Poor quality cement. When using stale cement, low-quality (bought from someone with hands), cement in which the process of hydration has begun (soft cement pellets and grains have formed), the strength of the solution drops by 2, or even 3-4 times.
Added too much plasticizer. With a large inclusion of a plasticizer, separation of the mixture may occur. When it hardens in a short time (literally 1-2 months later), chips, cracks appear, the screed peels off.
Likewise, but only with water. With a large addition of water, the solution is porous, very soft. The finished screed will not be able to withstand serious loads. If the screed is on outdoors, then it will "tear" in the autumn and spring periods.
Incorrect reinforcement. The absence of reinforcement or its insufficiency leads to the fact that the screed cannot perceive the load. Hence the cracks.
thin layer of concrete. With a small thickness of the screed and significant loads, it will simply begin to crack. The example is simple: when 30 mm of concrete is poured in garages and then a dump truck is driven there. It is not surprising that the screed crumbles.
Poor preparation of the base - lack of compaction, erection of a screed over a soft base.
Fast drying process, lack of moisture after pouring the mixture or excessive exposure to sunlight.

What to do?

If cracks appear, the screed crumbles, then the process of destruction can no longer be stopped. This will continue. it is necessary to eradicate the cause, and this is possible only after dismantling the screed and erecting a new one. Of course, there are options where you can take some decisions. For example, if it is in the yard, then on top of the screed, you can make a sand embankment of 20-30 mm to lay paving stones (as an example).

To avoid the appearance of cracks, consider the possibilities of eliminating each of the 8 causes at the stages of screed erection.

Aggregates must be clean: free of dust, impurities and large inclusions (if sand). Recommended crushed stone fraction for screeds: 1-5 mm, 5-10 mm, 5-20 mm. Sand is recommended to use river, seeded - fractions of 0.1 - 3 mm.
Buy cement only in large stores or directly from the manufacturer. Look at the production date. Use cement within 2-3 months after manufacturing. Recommended brands of cement M400D20, M400D0, M500D0, M500D20.
Add a plasticizer to the solution no more than 2%. Read the manufacturer's instructions carefully. Usually, a plasticizer is added in the region of 0.5-1%. The recommended brand of mortar for screeds is at least M250, better classic version- M300.
Maintain the water-cement ratio. Recommended W / C - 0.5. One part cement, half a part water (by weight).
When pouring screeds up to 50 mm, it is possible to reinforce reinforcing meshes with a diameter of 5-8 mm. You can get by with one plane of reinforcement. It must be located at the bottom of the screed. With a screed thickness of 50-120 mm, it is necessary to increase the cross section of the reinforcement. When using one plane of reinforcement, use reinforcement with a diameter of 8-14 mm. If there are two reinforcement planes (top and bottom), then reinforced meshes of 5 mm or 6 mm can be used. For screeds larger than 120 mm, it is recommended to use two reinforcement planes. Minimum diameters reinforcement in grids - 8 mm.
With a slight load on the screed, you can limit yourself to 50 mm of concrete (this is true for leveling the floor in apartments). When pouring a blind area, a yard, a floor in a garage, the recommended screed thickness is 120-180 mm.
Before pouring the screed, remove loose, vegetable soil from the surface. It is necessary to remove it until dense, clay soils. After that, level the base. Make a mound of sand, 40-150 mm thick. Tamp this thickness, vibrate. Level the surface again. Lay a waterproof film or geotextile and only after reinforcement start laying the mixture. This is for screeds outside the residential area.
Concrete must dry slowly. 2-4 hours after laying the mixture, cover the surface of the screed with a dark film. Water the concrete for 3-5 days. Keep away from open sunlight.

Concrete floors are characterized by high strength, durability, unpretentiousness, affordable price. But at the same time they have weaknesses. The most obvious of these is the tendency to destroy the top layer. Over time, cracks, potholes and chips appear on the surface of the concrete floor. To prevent this process, various concrete strengthening technologies are used.

The main ways to strengthen the concrete floor

Strengthening concrete floors prevents their further destruction and restores their former performance properties. Exists different technologies reinforcement of concrete. The specific method is chosen depending on the condition and age of the sex.

Currently, to strengthen the concrete floor, the most commonly used:

grinding;
topping;
special impregnations.

If the concrete screed is made with the addition of granite or marble chips, then after grinding the floor will also acquire a beautiful, textured pattern.

Topping is a relatively simple and economical technology, allowing you to get high-strength, dust-free floors. The surface of concrete after applying the topping becomes 5 times more wear-resistant and 2-4 times more impact-resistant. Topping floors are recommended for use in production halls where heavy loading equipment operates, in shopping malls, in garages and parking lots. But such floors are not suitable for rooms where spills of chemicals are possible.

For rooms with high humidity special impregnations that seal the structure of concrete are more suitable. They penetrate deep into the concrete, thus creating the effect of sealing and compacting the material. Impregnations are widely used to strengthen old and weak screeds, as they allow several times to increase their strength and resistance to abrasive loads.

concrete grinding

The surface layer of the concrete floor is not very durable, therefore, when exposed to mechanical loads, temperature and humidity changes, it begins to crumble, which leads to a reduction in the life of the floor. In addition, the process of concrete maturation is always accompanied by the release of cement laitance to the surface. This milk forms an extremely fragile layer during solidification, which often becomes the main source of cement dust formation. To prevent dust formation, the top weak layer of concrete must be removed and a stronger surface exposed. To do this, use the grinding of the concrete floor.

Polished floors have a number of positive qualities:

high strength and wear resistance. Floors after grinding well tolerate any increased loads;
chemical inertness. Polished floors acquire resistance to various technical fluids and chemical solutions;
dust-free, hygienic. The concrete floor after grinding ceases to dust, so it is easier to care for it;
decorative. After grinding and subsequent polishing, concrete floors become aesthetically attractive and can be used not only in industrial premises, but also in residential premises.

There are different technologies for polished concrete pavement, so they can consist of a different number of stages. The number of these stages depends on many factors, including the initial state of the concrete floor, the conditions for this process, and the type of tool used.

In any case, the process includes the following main steps:

preparatory work. At this stage, the concrete base is cleaned of debris and dust. If there is any floor covering, it must be dismantled and the surface leveled as much as possible. Next, all existing cracks and chips should be repaired;
after preparatory work perform rough grinding of the concrete surface. To do this, use a diamond tool with a grain size of 80 Grit;
after rough grinding, impregnation is applied to the concrete to harden its surface;
after the impregnation dries, perform fine grinding using a tool with a grit of 150 to 400 Grit
The next step is polishing the floor. Its surface is brought to perfection by successive application of fine-grained tools, from 1000 to 3000 Grit;
floor surface after polishing cleaned of dust and covered with several layers of polyurethane varnish.

Grinding can act as a stand-alone procedure to reinforce a concrete floor or as a preparatory stage before applying reinforcing compounds, since it increases the adhesion of the concrete surface to any building mixtures and solutions.

Grinding is used both for freshly laid floors and for old bases.

The first pass on the freshly laid floor is done no earlier than 6-7 days after pouring the concrete mix. This is necessary in order to remove the layer of cement laitance and open a stronger layer for better maturation. Finishing grinding is performed no earlier than a month later, that is, after the concrete has fully matured.

Before grinding the old concrete base, first evaluate its readiness for this procedure. "Weak" areas are unacceptable - looseness, delamination, crumbling. In the presence of such defects, it is necessary to carry out repair work using epoxy compounds.

For more information about repairing with epoxy mastic, see the article Eliminating defects in a concrete floor using epoxy mastic

In the event that damages occupy more than 30% of the floor area, a new screed is poured.

Other ways to repair a concrete floor are described in the article Basic methods of repairing a concrete floor.

Benefits of Topping Strengthening

The technology of strengthening the concrete floor with the help of special dry mixes (toppings) has proven itself well when used on various objects, therefore it is now very popular. Topping can be used to strengthen the concrete surface, which will later be used independently or to strengthen the base for any other flooring. This technology involves applying a special dry mixture to a freshly poured concrete concrete and its subsequent grouting with a trowel. The smoothing blades of this machine press the topping into the hardening concrete. This forms a hardened surface layer.

Concrete floors after strengthening with topping acquire the following advantages:

high strength. After topping, concrete grade M400 acquires strength equal to grade M800;
reinforced surface acquires the best performance characteristics , and care for her becomes easier;
topped concrete floors stop dusting and acquire high resistance to abrasives;
treated concrete acquires antistatic properties;
with topping you can improve the decorativeness of the concrete floor, giving it a varied texture: grainy, smooth, mirror.

The main technical parameters of floors with topping are determined by the components of the rubbed mixture. The composition of this mixture includes cement, mineral pigments and fillers.

The size of the filler fractions is chosen depending on the type of concrete used to fill the floor. When choosing, it must be remembered that any fine fraction filler has the least adhesion to the concrete base, so the likelihood of such a topping peeling off is much higher.

The use of a larger fraction gives the floor increased strength, but greatly reduces the plasticity of the mixture.

Depending on the type of filler, the mixtures are divided into:

quartz;
corundum;
metallized.

Quartz mixtures

Operational and technical properties quartz hardeners allow them to be used for floors subjected to moderate wear loads. With the help of quartz toppings, floors are strengthened in shops, office buildings, warehouses and garages with low loads.

Concrete floors at various objects are described in the articles below.

Polished concrete floors in parking lots and garages

The use of quartz sand as a filler allows you to increase the strength of the concrete floor by one and a half times. The main advantage of quartz topping is its affordable price.

Corundum topping

Corundum hardeners are used when it is necessary to create a particularly stable concrete floor subjected to high loads. Floors reinforced with corundum can be subjected to increased daily abrasive and impact loads, but they still will not show cracks and other damage.

Corundum chips, used as one of the components of the hardening mixture, give special strength to the floors. With the help of corundum topping, the strength of a concrete floor can be increased by 1.7 times. But compared to the quartz mixture, corundum is more expensive. The difference in price is approximately 20-30%.

metallic topping

As a filler for this topping use metal shavings which gives it special strength. Metallized topping is recommended for floors that are subject to increased loads. It can be floors in the workshops of those industrial enterprises where heavy loaders are used or in garages designed for heavy equipment.

But it should be borne in mind that metallized mixtures cannot be used in rooms with high humidity, since a floor with such a topping will quickly become unusable due to a rusted metal component. The floor screed for metal topping must be cast from concrete with a grade of at least M300. Otherwise, the concrete base will quickly crack.

For more information about the technology of applying topping, see the article Technology of applying topping.

Strengthening concrete with impregnation

Impregnation for concrete is one of the most common ways to strengthen concrete floors. They are a liquid composition on an organic or inorganic basis. Inorganic impregnations are called fluates. After application, they enter into a chemical reaction with the components of the concrete. As a result of this reaction, a strong protective film of chemically inactive compounds is formed on the concrete surface.

Organic (polymeric) impregnations are considered more effective material to reinforce concrete. When using them, the pores of the top layer of concrete are filled with a polymer, so it is modified into a concrete polymer with improved strength characteristics. Moreover, the degree of strength obtained will largely depend on how deeply the polymer composition has penetrated into the concrete thickness.

Unlike topping, impregnations should be applied to concrete no earlier than 10-15 days after pouring. The surface of the floor must be thoroughly cleaned and sanded before applying the impregnation in order to remove the layer of cement laitance.

The main types of impregnation for concrete

All strengthening impregnations available today are divided into:

impregnating compositions-fluates;
polyurethane;
deep penetration.

On the this moment The most popular are polyurethane impregnations. The high demand for impregnations of this type is explained by the fact that they allow not only to strengthen concrete, but also to create additional tightness, protection from dust, increase immunity to temperature extremes and various chemicals. The depth of the reinforcing layer in this case reaches about 3 mm.

The main restriction on the use of polyurethane impregnation is imposed by the moisture content of concrete: it should be no more than 5%.

When it is required to maximize concrete pavement, use impregnations of deep penetration. These compounds give concrete floors specifications, identical to those that they acquire using the materials of the first group, but only the latter can also be used in rooms with high humidity.

As a result of treatment with deep penetration impregnations, the reinforcing layer is 5 mm.

Fluate impregnating compounds are the cheapest materials for strengthening concrete. With their help, you can strengthen the concrete base by at least 50%. The main advantage of using fluates is their low cost.

Depending on the method of action, film and penetrating impregnations are distinguished.

The former form a protective layer on the floor surface, but do not strengthen loose foundations.
Penetrating, on the contrary, react with concrete and fasten unstable surfaces.

Penetrating compounds can be used at low temperatures. Their main advantage is relative savings: film impregnations must be periodically updated, and penetrating ones are applied once.

But it should be noted that the use of penetrating impregnations is useless on screeds made of low grades of concrete and on cement-sand bases. These hardeners in this situation will not give the desired effect. For this reason, film compositions are more in demand.

Film strengthening compositions are divided into:

acrylic film coatings that are used to protect concrete floors operated with light to medium loads. floors impregnated acrylic compounds, can be operated without repair for no more than 3 years. After this period, the layer must be updated. Key Benefits acrylic impregnation– relative cheapness and ease of application;
epoxy impregnations allow you to protect the concrete floor from strong abrasive and chemical loads, as well as seal a fairly loose surface;
polyurethane mixtures are used for maximum loads on the concrete floor. These compounds provide optimal protection in wet areas and allow you to extend the life of the floor by 4-5 times.