The floor screed is crumbling, what should I do? Strengthening the concrete floor

The floor screed is crumbling, what should I do?

Why does cement screed crumble, what should I do?

arturio77

4 years ago

The main reason is two factors: the incorrect composition of the mortar, that is, the proportions of the cement are not met and the mortar is not strong, and the second important factor is the drying speed of the mortar. If you create large and constant drafts, then the moisture from the solution evaporates very quickly and the cement does not have time to show its adhesion properties and turns into ordinary dust, such a solution will constantly peel off and it is difficult and dangerous to finish it further with finishing materials. Also, the cement mortar may simply be stuck a little by frost; after thawing, that part of the mortar into which the ice has penetrated will definitely peel off. If the question relates only to the screed, then you can pour a stronger one on top, of course, if the height of the thresholds allows. If the screed completely crumbles into large pieces, then in this case it is of course better to replace it completely.

the moderator chose this answer as the best

9 months ago

It is necessary to clarify, for the clarity of the answer, where your screed is located. This could be a street - an area around a 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 or abrasion of the screed:

Poor quality fillers. Due to the abundance of dust in the aggregates or due to the large presence of fine fractions, the grade of the solution may drop many times over. This leads to a decrease in strength, density, and subsequently all other characteristics (moisture resistance, abrasion resistance, frost resistance, etc.). This is why cracks or chips can quickly appear.
Poor quality cement. When using stale, low-quality cement (purchased from someone else), 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 plasticizer, separation of the mixture may occur. When it hardens in short term(literally 1-2 months later), chips and cracks appear, the screed peels off.
Same thing, but only with water. With a large addition of water, the solution turns out to be porous and very soft. The finished screed will not be able to withstand heavy loads. If the screed is in the open air, 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 take 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. An 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 falls apart.
Poor preparation of the base - lack of compaction, erection of the screed on top of a soft base.
Rapid drying process, insufficient moisture after pouring the mixture or excessive exposure to sunlight.

What to do?

If cracks appear and the screed crumbles, then the destruction process cannot be stopped. This will continue. it is necessary to eradicate the cause, and this is only possible after dismantling the screed and erecting a new one. Of course, there are options where some decisions can be made. For example, if it is in the yard, then you can make a 20-30 mm mound of sand on top of the screed and lay paving stones (as an example).

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

Aggregates must be clean: free from dust, impurities and large inclusions (if sand). Recommended crushed stone fraction for screeds: 1-5 mm, 5-10 mm, 5-20 mm. It is recommended to use river sand, seeded sand - fractions 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 production. Recommended cement grades M400D20, M400D0, M500D0, M500D20.
Add no more than 2% plasticizer to the solution. Read the manufacturer's instructions carefully. Typically, 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 part water (by weight).
When pouring screeds up to 50 mm, it can be reinforced reinforcing mesh 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 you can use reinforced mesh 5 mm or 6 mm. When the screed size is more than 120 mm, it is recommended to use two planes of reinforcement. The minimum diameters of reinforcement in meshes are 8 mm.
If the load on the screed is insignificant, you can limit yourself to 50 mm of concrete (this is important for leveling floors in apartments). When pouring a blind area, yard, or garage floor, 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 it is tight, clay soils. Afterwards, level the base. Make an embankment of sand, 40-150 mm thick. Compact this thickness and vibrate it. Level the surface again. Lay a waterproof film or geotextile and only after reinforcement begin laying the mixture. This is for screeds outside the residential area.
Concrete should 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.

favorite link thank Kim Jong-un

more than a year ago

There are quite a few reasons for this screed behavior:

We bought cement by weight; the expiration date of the cement had expired (60 days after the date of manufacture).

The proportions when mixing are not correct; the screed can burst with both a small amount of cement in the solution and a large amount.

Screed too thin.

They did not give full time to dry and subjected the screed to stress.

There are warm floors under the screed, the screed is not dry, the heated floors are turned on.

The screed was dried additionally (forcibly) using heat guns, browsers, and so on.

We poured the screed in an unheated room, plus during the day, minus at night, as a result, instead of drying out, the screed froze (the water in it) the ice thaws and crumbles the screed.

But actions must be taken based on a specific reason; cracks in the screed can still be “cured,” but if the screed is crumbling everywhere, then only dismantling and pouring a new screed according to all the rules.

Crumbling means too many cracks on the surface of the screed,

tap it with your knuckles, there will probably be a dull sound everywhere, that is, it has moved away from the surface. add to favorites link thank SvetlanaSha

4 years ago

Cement screed crumbles for a number of reasons:

the proportions when preparing the solution are not met, there is a lot of sand;
low-quality cement;
the base for the screed is not prepared correctly.

If the defective area is small, you can clean the screed, remove everything that is crumbling, treat the surface with primer, dilute a new solution, slightly liquid, and make a new thin screed. If the entire floor crumbles, the screed must be completely removed and refilled.

3 years ago

This defect often occurs if sand and cement are mixed in advance, especially in warm weather, and not mixed immediately. We've already been burned by this.

Do you know the answer?

How to strengthen a concrete screed that is crumbling

The screed is leaking - what to do?

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Concrete screed is crumbling - what to do?

Concrete flooring is widely used in both industrial and civil construction. Its use is due to high strength, reliability and durability.

On reinforced concrete slabs The floor screed is poured after cleaning and priming the surface. Layer thickness 50 – 100 mm. Typically, such flooring is installed in new apartments or houses. On the ground, concrete screed is laid on the floors in the basements. First of all, the soil base is compacted, a layer of sand of 100 - 150 mm is poured onto it and compacted. Then a footing with a thickness of 40 - 50 mm is poured. After gaining the required strength (about 7 days under normal conditions), a layer of rolled vapor barrier and insulation is placed on it. Then the frame is mounted from metal mesh. After this, 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 with floors 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 repairing floors above unheated rooms. A layer of insulation is laid ( mineral wool, Styrofoam). A layer of waterproofing is laid on it. Then a metal mesh frame is mounted and poured concrete base thickness 50 – 70 mm.

Causes of destruction of concrete screed

A seemingly strong foundation 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 damage associated with chemical reactions inside the concrete screed. This problem mainly concerns large industrial and public construction projects.

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

Physical factors

The cyclical process of freezing and thawing. Typical for winter concreting, when, if the pouring technology is violated, not all water is involved in chemical reaction hardening concrete mixture. Some of the moisture simply freezes. The concrete screed is destroyed due to water getting inside. Constant freezing and thawing leads to the destruction of bonds within the concrete and the formation of penetrating cracks.
Impact high temperatures. When a concrete floor cools suddenly, for example when putting out a fire, steam forms inside, which tears the concrete. Heating for a long time can lead to the formation of cracks. This is due to the different expansion coefficients of reinforcement and concrete. That is, at equal temperatures their size does not change equally.

Important! Typically, overheating cracks form in areas of the concrete floor adjacent to fireplaces or stoves. Also susceptible to cracking of the meta, where they pass through insulated pipes hot or cold water supply.

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.

Excess water in concrete mortar may lead to cracking several months after pouring the screed.

Mechanical factors

Abrasion. Intensive use of the floor surface leads to the destruction of the concrete surface. Characteristic feature Such destruction is caused by dips with rounded edges, so-called “scuffs.” The service life depends on the brand of the mixture.
Shock loads. Unlike abrasion, there is a sharp and rapid impact on the concrete surface. The result may be potholes with jagged edges and penetrating cracks.

Sex-destroying factors are rarely found in their pure form. Typically, cracking or complete destruction of a concrete screed is associated with the complex effects of several reasons.

Ways to prevent destruction of concrete floor screed

Choose the right grade of concrete depending on the expected operational load. It is important to understand that the floor in the basement and garage will be perceived different load. Concrete grade B10 is suitable for the basement. In rooms with more intense traffic, it is better to fill floors with grade B12.5 or B15.
Using durable filler. There are many types of gravel and crushed stone. Their strength characteristics greatly influence the quality of the concrete mixture.
Introduction of plasticizing or water-repellent additives into the solution. Additional chemicals can greatly increase the concrete's resistance to moisture or mechanical stress. You can find such additives in construction stores. The main thing is to read the instructions carefully and not make mistakes with the proportions.

Important! Excessive dilution of concrete with seven chemicals can cause the floor surface to weaken or completely fail.

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 absorb moisture and gradually collapse.
In hot weather, protecting the concrete screed from rapid evaporation of water. There are two ways:

Covering the entire floor surface plastic film. Once upon a knock, it opens and pours warm water onto the concrete. Exposure period is 7 – 8 days. After this, the film is removed.
Protection of fresh concrete sawdust. "Old-fashioned" but very effective way. The slurry is covered with sawdust and spilled with water twice a day. The aging period is 7 – 8 days.

Preventing freezing of the concrete screed until it reaches the required strength. To do this, you can mix concrete warm water. After pouring, the surface is covered with plastic film. It turns out to be a “warmhouse” that will allow the concrete to gain the necessary strength. Exposure period 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 where it comes into contact with the pipes.
Thermal insulating gaskets between concrete floors and fireplace or stove.
Protection against mechanical stress and abrasion using a finishing coating in the form of ceramic tiles, laminitis, linoleum.
Device expansion joints. Concrete is poured in strips 1000 mm wide, and 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 when laying and operating a concrete floor will allow you to obtain a strong, reliable and durable foundation.

Repairing potholes and cracks in concrete screed

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

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

Elimination of defects on an old surface begins with removing the floor covering and cleaning the floor of all paint and varnish or adhesive materials. To do this, use a spatula and metal brush on metal.

Important! You can speed up cleaning by using special grinding attachments 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 down using cement-sand mortar or repair mixture for concrete. Before grouting, the surface is dust-free and impregnated with soil. deep penetration(concrete contact) or mortar epoxy resin.

Pothole Repair

A pothole is a broken, bowl-shaped area of concrete with jagged and chipped edges. They are repaired to prevent further deterioration of the concrete surface. Repair stages:

Rectangular cuts are made around each pothole using a grinder with a circle on the concrete. The depth of the cut is slightly greater than that of the pothole.
Destroyed concrete is removed from the cut using a hammer and chisel. You can also use a hammer drill with a spatula attachment.

Important! If the pothole has exposed the reinforcement, then it must be painted over open area primer for metal.

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

Important! Drying time for 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 prepare a cement-sand mortar for small potholes.
The laid mixture is leveled with the old floor. For this purpose, a plaster spatula of 100 - 150 mm is used.
After hardening, the repaired area is sanded.

Crack repair

Conducted immediately after detection. Otherwise, water may get into the cracks and the process of destruction of the concrete screed will continue. Elimination steps:

Small cracks cut using a grinder and a circle on concrete or expanded using a chisel and hammer. This process is called “crack bridging”. More serious areas are cut out completely, like potholes.
Dust and construction debris are removed using a 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. Drying time is given for 45 - 60 minutes.
Cracks are filled with a special repair solution based on polymer or epoxy filler.

Important! Cracks that are not deep, 1–2 cm, are filled at a time. More severely damaged areas are covered with several layers. Layer thickness 1 – 2 cm.

After complete drying, the repaired floor surface is sanded.

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

Repair of small spider-like cracks

This type of destruction is not dangerous for bearing capacity concrete floor. To fix it, just make a liquid cement-sand mortar and rub over the cracked area.

Repair of irregularities

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

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

Major repairs of concrete screed

The methods described above are suitable when no more than 15% of the surface is destroyed. In other cases it is required major renovation 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 deposits.
The screed is sanded using a grinder with a special attachment.

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

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

To maintain a concrete screed in good condition, it is enough to notice the beginning of destruction in time, determine the cause and quickly repair the damaged area of the floor.

Video removing cracks in screed

How to strengthen a screed

03.04.2015

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

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

We remove dust from the loose base (necessarily construction vacuum cleaner, a broom will not be enough. You can also use regular household vacuum cleaner, but keep in mind that concrete dust is harmful to its engine. But if you’re old, you don’t mind...)

We prime with deep penetration soil. 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 comes the stage of reinforcement and preliminary leveling. The floor is puttied with a layer of tile adhesive. A plastic facade mesh with a 5x5 mm cell is embedded in the glue.

As a result, our crumbling screed is covered with a layer of fairly durable material. In addition, thanks to the mesh, the floor becomes solid again, rather than large pieces of screed separated by cracks.

We carry out the final leveling using a self-leveling method. The dried layer of glue is also prepared. Dust removal and soil. How to do this is described here.

The presence of tile adhesive will not allow the hardening self-leveling material to tear off the weak and loose upper layer screeds. The glue also covers the deepest irregularities, which helps the self-leveling product to spread. thin layer(as practice shows, 3-5 mm - optimal height layer of self-leveling mixture. If somewhere the layer thickness turns out to be 10-15 mm, cracks, as a rule, also appear there.)

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Major repairs of concrete floors: strengthening the peeling screed

Popular methods for repairing concrete floors work effectively provided that the floor surface has retained at least seventy percent of its integrity. 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 when performing it you should follow certain rules. The surface on which the screed will be poured must be absolutely clean. For better adhesion of the mixture to the rough surface, it is necessary to use a primer mixture. If there is high humidity in the room, preference should be given to a primer with water-repellent properties.

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

After the screed has been poured, it needs to be given time to settle. It is not recommended to allow any impact on the coating for a month, because... It is during this period of time that the filled layer finally hardens and acquires all its inherent properties. However, despite compliance technical rules pouring concrete floors, after a while there is a need to repair them. Let's look at the types of damage and repair methods.

Steps to strengthen a weak concrete floor

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

Strengthening technology

The first step is to drill a series of holes in the screed to be renewed, 20 mm in diameter and located at a distance of 25 cm from each other. The holes are drilled all the way to the base. Professional hammer drills, 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) you should drill a support bowl, 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 undergo a priming process, after which grease-free reinforcement is inserted into them, the diameter of which is ~ 12 mm, and the length is equal to the depth of the hole.

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

Repair of peeled coating layer

Quite often, during operation, the screed can peel off from the subfloor. This happens due to the impact of unevenly distributed loads on the concrete floor. Visually see problem area It does not always work. You can detect peeling by lightly tapping the entire floor with a hammer. The peeling zone will indicate itself with a dull sound. In addition, it is not uncommon for peeling to occur in areas of the floor that have cracks, from which a cloud of cement dust flies out when tapped. Once all areas of the floor requiring repair have been identified, you can begin injecting 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 from 12 to 20 mm. Then, using a construction syringe, an epoxy-based composition is poured into them. The mixture is poured several times as it is absorbed into the concrete and fills the voids created by the peeling process.

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

vest-beton.ru

How to strengthen a screed that is crumbling, and how to repair cracks? The floor screed bursts or buckles - what to do?

How to strengthen a screed that is crumbling?

If the floor screed is not done correctly, it may collapse over time. crumble, crack, buckle. In this case, there is no need to redo it.

You can simply repair the screed. what will happen more economical option.

How to repair cracks in screed?

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

The reasons for the appearance of cracks on 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 is cracked due to the lack of expansion joints, then it is necessary to cut through the shrinkage joints.

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

When cracks appear in them, you can make a groove, thus expanding it. It is necessary to remove dust from the walls of the groove 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 insignificant, and the floor covering will tile, then they can be ignored.

Cracks in the floor screed must be sealed with a mixture of PVA glue, cement and water. All these components are mixed so that the mixture can be poured into the gap. After this, the solution must be allowed to harden and installation can begin. flooring.

The floor screed has burst - what to do?

If the floor screed has burst, then it is imperative to correct this defect before laying the floor covering.

If the concrete mixture is poorly compacted, air cavities may appear in the screed, which cause cracks to appear. In this case, it is necessary to remove the screed to the cavity and fill it with solution.

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

Part cement mixture, which is 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.

The compaction of the mortar after pouring must be compacted using the piercing method. A metal rod is used for this purpose.

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

The screed is leaking - what to do?

If the floor screed coils, then it is made poorly. The reason for the coiling of the screed may be a poor-quality mixture for the screed, a lack of primer on the base, a dirty and dusty base that is used for the screed, etc.

In this case, it is necessary to hit the screed with the blunt edge of a hammer. If the mixture is of poor quality, then a dent will remain at the impact site. The screed may buckle 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 would be best to add PVA glue to this solution. Next, the resulting solution is slowly poured into the expanded mixture. It is necessary to pour the solution in small quantities, allowing it to dry in parts.

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If this method does not remove the coiling of the screed, then it must be completely removed and refilled. This is a rather expensive option. That is why it is necessary to carry out the screed strictly established rules.

Also watch a useful video with expert advice on screed repair:

Based on materials from the site: http://glavspec.ru

fix-builder.ru

The screed is crumbling, how to strengthen it?

The content of the article:

Violation of technology in the production of construction and repair work inevitably leads to big or small troubles, which subsequently have to be eliminated, spending a lot of effort and considerable money. This axiom fully applies to incorrectly performed floor screed, as a result of which various defects. It can crumble, crack and, as builders say, buckle.

If cracks appear in the floor after screed work, then the simplest, and most importantly, inexpensive option would be to make regular repairs.

How can you repair small cracks?

Firstly, 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 can 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 gasket also leads to cracks. edge tape, as well as the absence of expansion joints.

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

We will find cracks, especially if they are very thin, they need to be widened, for which we can drill them. Remove any dust that has formed in the crack and prime it. Such cracks must be sealed with non-shrinking material using a regular staple. Some subtlety - if tiles are laid on the floor, and the cracks that appear on the screed are very small, then you don’t need to do anything with them. Larger cracks are sealed with a special compound that is easy to make with my own hands. It includes cement, PVA glue and water. The resulting mixture must have a liquid consistency so that it can be poured into the cracks formed without any problems. After the poured mortar has hardened in the cracks, you can begin all subsequent work, for example, covering the floor.

What to do if the tie breaks?

A broken screed is a serious defect that requires mandatory elimination. The reason for such a big problem may be unsatisfactory compaction of the mixture, as a result of which air cavities can form in it - cavities, leading to cracking on a large scale. In this case, the screed is removed until an unfilled cavity is discovered, and the cavity is filled with solution. You can find a cavity by deepening the crack using a tool, such as a pick. Accordingly, the test pit must subsequently be covered with soil and filled with solution. The solution used to fill the cavern 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, you need to make sure that the filling is of good quality, for which you try to seal the hole using the appropriate rod. The room temperature should not be too high. The screed must be periodically moistened using water.

The screed buckles - how to deal with it?

Experts use the word “bukhtit” in cases where, when tapping the screed, there is a feeling that there is a void in the depths of the coating. Also, this term is used when a spring effect occurs under the foot, a certain pressing of the surface. If the screed buckles, there can be many reasons for this. The main reason is non-compliance with process technology. If signs of bubbling are detected, you need 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 - you need to fill the solution in small portions, giving each of them the opportunity to freeze. If this method does not help, then we follow the “scorched earth” method - we break the screed and start all over again. To prevent this, do everything correctly and according to technology right away.

fortstroi.com.ua

Floor screed repair: do-it-yourself production

Read in this publication:Repair of floor screed: about its feasibilityRepair of cement floor screed: preparatory work How to repair a floor screed: the main stage of work

A cracked or crumbled screed is not only an uneven and uncomfortable floor, but also an undistributed load on the floor slabs in the house. If you can more or less put up with the first point, then with the second things are a little different - excessive loads on the floors, despite the fact that they have a fair margin of safety, can be catastrophic, especially when it comes to old houses. The screed must be kept in order - in case of major repairs, it must be changed or at least repaired. In this article from the site stroisovety.org we will deal with the question of how to repair a floor screed with your own hands?

Repair of cement floor screed photo

Floor screed repair: its feasibility

Before you begin directly solving the question of how to repair a floor screed with your own hands, you first need to understand its feasibility - perhaps things are such that there is no point in it, and what is needed is not restoration of the surface, but its complete replacement. In what situations does it become necessary to install a new floor screed? There are not many signs indicating that the screed has already outlived its usefulness.

By and large, there are no specific criteria according to which it is necessary to completely change the floor screed. There are simply regulations and common sense that dictate that the new surface is better than the old one. It can last a long time, and if you intend to live in an apartment or house for a long time, then the best option would be to completely replace this surface - of course, if we are talking about major repairs. It’s better to spend money on a new screed once than to carry out repairs with enviable regularity old screed floor. Restoration is primarily a temporary measure that resolves the issue for a short period of time.

Repair of cement floor screed: preparatory work

Preparing an old screed for repair is not a difficult task, and in most cases it comes down to just two steps.

You don’t have to wait for the second layer of primer to dry - while you prepare the solution, it will be absorbed into the old screed and that will be quite enough. Such repair of cracks in the floor screed (or rather, the preparatory work associated with its implementation) will give you a guarantee that the base of the floor will last at least another ten years.

How to repair a floor screed: the main stage of work

This stage (as, in general, the preparatory stage) can be divided into two substages - fastening the broken floor fragments and finishing leveling the base. These are two different technologies, which should be dealt with separately.

In principle, this is the entire repair of the floor screed. It seems to be not difficult, but there are plenty of nuances - they are not obvious. We can say that the subtleties are almost all individual. For example, depending on the degree of destruction of the old floor screed, reinforcement may be needed - naturally, it is better to replace such a floor covering entirely, but situations are different and even with large damage, repairs may be advisable.

stroisovety.org

How to strengthen a screed that is crumbling, and how to repair cracks? The floor screed bursts or buckles - what to do?

How to strengthen a screed that is crumbling?

If the floor screed is not made correctly, then over time it can collapse: crumble, crack, buckle. In this case, there is no need to redo it.

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

How to repair cracks in screed?

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

The reasons for the appearance of cracks in a cement screed 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 is cracked due to the lack of expansion joints, then it is necessary to cut through the shrinkage joints.

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

The floor screed has burst - what to do?

If the floor screed has burst, then it is imperative to correct this defect before laying the floor covering.

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

The compaction of the mortar after pouring must be compacted using the piercing method. A metal rod is used for this purpose.

The screed is leaking - what to do?

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.

You might also be interested in:

Also look at this useful article with expert advice on screed repair:

http://glavspec.ru

legkoe-delo.ru

Floor screed what to do if it crumbles

Articles

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

The reasons for the appearance of cracks in a cement screed 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 is cracked due to the lack of expansion joints, then it is necessary to cut through the shrinkage joints.

FLOOR REPAIR (BROKEN, BROKEN, FLAWING SCREED)

cement screed after treatment with liquid glass

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

If the floor screed has burst, then it is imperative to correct this defect before laying the floor covering.

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

The compaction of the mortar after pouring must be compacted using the piercing method. A metal rod is used for this purpose.

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.

You might also be interested in:

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A flat floor is a prerequisite when renovating an apartment. It is important to keep it in good condition even after repairs. If the floor has undergone deformation, it is necessary to find out and eliminate its cause and repair the floor screed.

Peculiarities

The floor screed, even if it was made exactly in accordance with the correct instructions, becomes unusable over time. This is not surprising, because it experiences enormous loads from the weight of flooring, furniture, people’s movement and other dynamic influences. Therefore, to avoid complete loss of it operational properties Periodically it is necessary to repair the floor screed.

To get an idea of the degree of surface deformation, you must first completely remove the old coating and clean the floor of debris, dust and dirt. Next, you need to decide on the type of deformation and repair that will need to be done.

One of the following may happen:

The smooth surface has small pits and a few cracks, and the level of dust formation is increased. These damages are not terrible; they can be easily repaired with minimal loss of time and money.
The screed is peeling off, the surface is cracked quite deeply in some places. This type of deformation can be repaired, but it will be necessary to use special building mixtures.
The surface is significantly curved, the floor is covered with deep cracks. Repairing damage of this magnitude can only be done by professionals with the appropriate skills and techniques.

Before you begin repairs, you should pay attention to some procedures that will tell you which method of eliminating defects is suitable in each specific case. Necessary:

identify the cause of deformation;
identify the presence or absence of expansion joints (if there are none, then it is necessary to start laying);
determine the method of pouring the cement mixture and the type of base on which the floor was laid;
find out whether concrete is peeling by tapping the surface with a hammer.

Types of damage

Before starting floor screed repairs, it is necessary to determine the type of damage. This can be done by removing the floor covering. A visual assessment of defects will help identify specific type damage, which will allow you to quickly select the necessary means and begin repairs.

The main types of damage include:

detachment of the screed (in whole or in part) from the base of the floor;
unevenness, potholes, cracks and holes on the surface;
excessive dust formation, which means weakening of the screed material.

The reasons for the appearance of defects can be very diverse. It is necessary to pay special attention to them in order to avoid similar mistakes and further destruction of the screed in the future.

The most common reasons are:

Violation of mixing technology. Most often this happens when using a ready-made mixture. It is recommended to strictly follow the manufacturer's instructions, as incorrect proportions will lead to deterioration in the quality of the mixture. Also, you should not mix the solution by hand - for this purpose it is better to use a special attachment on electric drill or a construction mixer so that the existing substances are mixed evenly.
Fast drying. When working with concrete, you should always remember that its durability and strength directly depend on contact with water. The cement floor should not dry too quickly; periodically it should be sprinkled with a small amount of water and covered with polyethylene so that the top layer does not become dry before the concrete has completely hardened.
Excessive amount of water in solution. Excess water in the concrete mixture, firstly, deforms the concrete itself and reduces the strength of the screed. Too much a large number of water ultimately leads to the screed cracking and the surface becoming loose. To avoid this, after the concrete has dried, the screed must be covered with deep penetration soil, which will entail new costs and increase the repair period.

Most often, defects appear in the cement screed; when using semi-dry mixtures and gypsum compositions, the likelihood of cracking is significantly reduced.

No expansion joints. Incorrectly laid expansion joints or their complete absence most often cause the surface to crack. It is recommended to fill the wall seam with an elastic material like polypropylene foam. It is located along the thickness of the screed, and this reduces the influence of the wall load on it. Intermediate seams divide the screed into equal parts, running along half of its thickness.
Lack of damper tape. It is especially important to have an edge tape when pouring screed for heated floors. When heated, concrete tends to expand, thereby creating additional pressure on the walls. Thus, the absence of a pressure-compensating tape can cause the destruction of not only the screed, but also the walls themselves.
Poor quality reinforcement. The main rule when installing reinforcement is its location in the concrete, and not under the screed.

There are many other factors that lead to the destruction of the screed. Most often, this is poor quality of the solution, poor-quality cement mixture used in construction, or violation of the pouring stages. Detachment of the screed can be caused by local impact loads or improper preparation of the surface for pouring concrete.

Whatever the error, you should not ignore the detected deformation of the screed. Minor repairs on initial stage destruction will keep the floor intact and save a significant amount on its subsequent restoration.

How to repair cracks?

The types of deformation described above lead to the screed starting to crack. This is bad because over time, even the smallest recesses expand, and because of them, major repairs of the floor will have to be done. Cracks are one of the most severe types of destruction, requiring emergency removal, so they must be eliminated in a timely manner. Cracks can be small or deep.

You can repair the screed yourself as follows:

Use a grinder to widen and deepen the crack. Special attention It should be noted that after expansion, the edges of the crack should not crumble, but should be absolutely solid. If you can’t use a grinder, you need to stock up on a hammer and chisel.
After expansion, the cracks need to be cleaned. Only a construction vacuum cleaner is used for this purpose.
The cleaned areas are coated with epoxy primer. This must be done several times until the mixture is completely absorbed into the concrete.
After the primer has completely dried, the damaged areas are filled with a mixture of Rizopox 3500 and quartz sand. The mixture should fill the crack just above the surface level.
After the mixture has hardened, the repaired areas are sanded and cleaned.

To seal very small cracks, you can stop buying ready-made mixtures and use regular tile adhesive or a mixture for self-leveling floors. However, it must be taken into account that this method is unacceptable when repairing screeds in rooms with high humidity.

Repairing minor damage takes little time and allows you to do without special tools.

If large cracks have formed in the screed - more than 2 mm in width - the repair process will proceed according to the following scheme:

As in the first case, the cracks must be cut to their full depth.
After expanding the crack across it, it is necessary to make several grooves.
Small grooves are made along the grooves repair seams(1.5 cm long) at 2 cm intervals.
The prepared recesses should be cleaned using a construction vacuum cleaner, treated with a primer and left to dry.
After the primer has dried, the repair joints will need to be filled with pieces of reinforcement, metal staples or wire.
Next, the cavities are filled with liquid mortar from a mixture of sand and cement. The surface is leveled with a lath and sanded after drying.

Reinforcing the screed helps protect it from stress and extends its service life. There is also a little trick that will help you find out whether the cracks are expanding over time or not. To do this, you need to glue a paper strip to the edges; if it breaks after a while, then the forecasts are disappointing. If the piece of paper remains the same as it was, then everything is in order. But this method requires a lot of time.

Elimination of peeling

As mentioned above, the reason for concrete peeling in some places is the uneven distribution of loads. You can identify exactly where the areas affected by mechanical stress are located by hearing. To do this, it is best to arm yourself with a small hammer and gently tap the entire surface. Repair work is needed in those places where the sound will be dull, especially if they are marked with cracks and the concrete begins to crumble.

Elimination of peeling occurs as follows:

After identifying areas in need of repair, you need to highlight their boundaries using chalk or a marker.
Inside the damaged area, holes with a diameter of no more than 20 mm must be made in the screed. The distance between the holes should be 25-30 cm.
The epoxy solution is brought to a liquid consistency, after which it is poured into a construction syringe.

Using a syringe, the solution must be poured into the holes. The essence of this method is that the composition will displace the air mass accumulated between the concrete and the base, fill the space and adhere the screed and the ceiling to each other.

If the air does not come out of the cavity completely the first time, the procedure must be repeated.

A day after it is carried out, you should make sure that the entire surface has been reanimated. If this operation was successful, you can begin laying the floor covering. Make sure the solution is completely dry. To speed things up, you can use a hair dryer.

It is very important to remember: if at the diagnostic stage it was revealed that more than 1/3 of the area has peeled off, then the screed will have to be completely dismantled, since similar works strengthening will not help in this case.

How to strengthen?

Strengthening a weak screed is a method of preventive repair. Carrying out some simple manipulations will eliminate the need to remove the screed to the base, and will also protect it from destruction and delay the need for urgent repairs.

If the floor screed is not made correctly, then over time it can collapse: crumble, crack, buckle. In this case, there is no need to redo it.

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

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

The reasons for the appearance of cracks in a cement screed 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 is cracked due to the lack of expansion joints, then it is necessary to cut through the shrinkage joints.

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

The floor screed has burst - what to do?

If the floor screed has burst, then it is imperative to correct this defect before laying the floor covering.

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

The compaction of the mortar after pouring must be compacted using the piercing method. A metal rod is used for this purpose.

The screed is leaking - what to do?

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.

Also watch a useful video with expert advice on screed repair:

If the floor screed is not made correctly, then over time it can collapse: crumble, crack, buckle. In this case, there is no need to redo it.

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

How to repair cracks in screed?

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

The reasons for the appearance of cracks in a cement screed 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 is cracked due to the lack of expansion joints, then it is necessary to cut through the shrinkage joints.

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

The floor screed has burst - what to do?

If the floor screed has burst, then it is imperative to correct this defect before laying the floor covering.

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

The compaction of the mortar after pouring must be compacted using the piercing method. A metal rod is used for this purpose.

The screed is leaking - what to do?

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.

You might also be interested in:

Also watch a useful video with expert advice on screed repair:

glavspec.ru

Concrete screed is crumbling - what to do?

Concrete flooring is widely used in both industrial and civil construction. Its use is due to its high strength, reliability and durability.

The screed is poured onto reinforced concrete floor slabs after cleaning and priming the surface. Layer thickness 50 – 100 mm. Typically, such flooring is installed in new apartments or houses. On the ground, concrete screed is laid on the floors in the basements. First of all, the soil base is compacted, a layer of sand of 100 - 150 mm is poured onto it and compacted. Then a footing with a thickness of 40 - 50 mm is poured. 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 this, a layer of waterproofing is rolled out and a finishing concrete screed 50 mm thick is poured.

Screed on the separating layer of waterproofing

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

Floating concrete screed

Suitable for repairing floors above unheated rooms. A layer of insulation (mineral wool, polystyrene foam) is laid. A layer of waterproofing is laid on it. Then a metal mesh frame is mounted and a concrete base 50–70 mm thick is poured.

Causes of destruction of concrete screed

A seemingly strong foundation can crack or completely collapse under the influence of a number of external and internal factors.

Chemical factors

Physical factors

The cyclical process of freezing and thawing. It is typical for winter concreting, when, if the pouring technology is violated, not all the water participates in the chemical reaction of hardening the concrete mixture. Some of the moisture simply freezes. The concrete screed is destroyed due to water getting inside. Constant freezing and thawing leads to the destruction of bonds within the concrete and the formation of penetrating cracks.
Exposure to high temperatures. When a concrete floor cools suddenly, for example when putting out a fire, steam forms inside, which tears the concrete. Heating for a long time can lead to the formation of cracks. This is due to the different expansion coefficients of reinforcement and concrete. That is, at equal temperatures their size does not change equally.

Important! Typically, overheating cracks form in areas of the concrete floor adjacent to fireplaces or stoves. Metas where uninsulated hot or cold water supply pipes pass are also susceptible to cracking.

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.

Excess water in the concrete solution can lead to cracking several months after pouring the screed.

Mechanical factors

Abrasion. Intensive use of the floor surface leads to the destruction of the concrete surface. A characteristic feature of such destruction are dips with rounded edges, so-called “scuffs.” The service life depends on the brand of the mixture.
Shock loads. Unlike abrasion, there is a sharp and rapid impact on the concrete surface. The result may be potholes with jagged edges and penetrating cracks.

Sex-destroying factors are rarely found in their pure form. Typically, cracking or complete destruction of a concrete screed is associated with the complex effects of several reasons.

Ways to prevent destruction of concrete floor screed

Choose the right grade of concrete depending on the expected operational load. It is important to understand that the floors in the basement and garage will bear different loads. Concrete grade B10 is suitable for the basement. In rooms with more intense traffic, it is better to fill floors with grade B12.5 or B15.
Using durable filler. There are many types of gravel and crushed stone. Their strength characteristics greatly influence the quality of the concrete mixture.
Introduction of plasticizing or water-repellent additives into the solution. Additional chemicals can greatly increase the concrete's resistance to moisture or mechanical stress. You can find such additives in construction stores. The main thing is to read the instructions carefully and not make mistakes with the proportions.

Important! Excessive dilution of concrete with seven chemicals can cause the floor surface to weaken or completely fail.

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 absorb moisture and gradually collapse.
In hot weather, protecting the concrete screed from rapid evaporation of water. There are two ways:

Covering the entire floor surface with plastic film. Once upon a knock, it opens and pours warm water onto the concrete. Exposure period is 7 – 8 days. After this, the film is removed.
Protecting freshly laid concrete with sawdust. "Old-fashioned" but very effective way. The slurry is covered with sawdust and spilled with water twice a day. The aging period is 7 – 8 days.

Preventing freezing of the concrete screed until it reaches the required strength. To do this, you can mix concrete in warm water. After pouring, the surface is covered with plastic film. It turns out to be a “warmhouse” that will allow the concrete to gain the necessary strength. Exposure period 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 where it comes into contact with the pipes.
Thermal insulating gaskets between concrete floors and fireplace or stove.
Protection from mechanical stress and abrasion using a finishing coating in the form of ceramic tiles, laminite, linoleum.
Construction of expansion joints. Concrete is poured in strips 1000 mm wide, and 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 when laying and operating a concrete floor will allow you to obtain a strong, reliable and durable foundation.

Repairing potholes and cracks in concrete screed

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

Eliminating defects on an old surface begins with removing the flooring and cleaning the floor of all paint and adhesive materials. To do this, use a spatula and a metal brush for metal.

Important! You can speed up cleaning by using special grinding attachments 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 down using cement-sand mortar or concrete repair mixture. Before grouting, the surface is dust-free and impregnated with deep penetration soil (concrete contact) or epoxy resin solution.

Pothole Repair

A pothole is a broken, bowl-shaped area of concrete with jagged and chipped edges. They are repaired to prevent further deterioration of the concrete surface. Repair stages:

Rectangular cuts are made around each pothole using a grinder with a circle on the concrete. The depth of the cut is slightly greater than that of the pothole.
Destroyed concrete is removed from the cut using a hammer and chisel. You can also use a hammer drill with a spatula attachment.

Important! If the pothole has exposed the reinforcement, then you need to paint over the exposed area with metal primer.

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

Important! Drying time for 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 prepare a cement-sand mortar for small potholes.
The laid mixture is leveled with the old floor. For this purpose, a plaster spatula of 100 - 150 mm is used.
After hardening, the repaired area is sanded.

Crack repair

Conducted immediately after detection. Otherwise, water may get into the cracks and the process of destruction of the concrete screed will continue. Elimination steps:

Small cracks are cut using a grinder and a concrete circle or widened using a chisel and hammer. This process is called “crack bridging.” More serious areas are cut out completely, like potholes.
Dust and construction debris are removed using a brush or vacuum cleaner.

Important! You can use an industrial or home hair dryer to clean cracks.

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

Important! Cracks that are not deep, 1–2 cm, are filled at a time. More severely damaged areas are covered with several layers. Layer thickness 1 – 2 cm.

After complete drying, the repaired floor surface is sanded.

Repair of small spider-like cracks

This type of destruction is not dangerous for the load-bearing capacity of the concrete floor. To fix it, just make a liquid cement-sand mortar and rub over the cracked area.

Repair of irregularities

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

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

Major repairs of concrete screed

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

The surface of the concrete floor is cleaned of dirt, dust and mortar deposits.
The screed is sanded using a grinder with a special attachment.

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

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

To maintain a concrete screed in good condition, it is enough to notice the beginning of destruction in time, determine the cause and quickly repair the damaged area of the floor.

Video removing cracks in screed

meot.ru

How to strengthen a screed

03.04.2018

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

We remove dust from the loose base (be sure to use a construction vacuum cleaner, a broom will not be enough. You can also use a regular household vacuum cleaner, but keep in mind that concrete dust is detrimental to its engine. But if it’s old, you don’t mind...)

We carry out the final leveling using a self-leveling method. The dried layer of glue is also prepared. Dust removal and soil. How to do this is described here.

The presence of tile adhesive will not allow the hardening self-leveling compound to tear off the weak and loose top layer of the screed. The glue also covers the deepest unevenness, which helps the self-leveling mixture to spread in 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, as a rule, also appear there .)

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pro.batyanya.ru

Major repairs of concrete floors: strengthening the peeling screed

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 to the rough surface, it is necessary to use a primer mixture. If there is high humidity in the room, preference should be given to a primer with water-repellent properties.

After the screed has been poured, it needs to be given time to settle. It is not recommended to allow any impact on the coating for a month, because... It is during this period of time that the filled layer finally hardens and acquires all its inherent properties. However, despite observing the technical rules for pouring concrete floors, after some time it becomes necessary to repair them. Let's look at the types of damage and repair methods.

Steps to strengthen a weak concrete floor

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

Strengthening technology

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

Repair of peeled coating layer

Quite often, during operation, the screed can peel off from the subfloor. This happens due to the impact of unevenly distributed loads on the concrete floor. It is not always possible to visually see the problem area. You can detect peeling by lightly tapping the entire floor with a hammer. The peeling zone will indicate itself with a dull sound. In addition, it is not uncommon for peeling to occur in areas of the floor that have cracks, from which a cloud of cement dust flies out when tapped. Once all areas of the floor requiring repair have been identified, you can begin injecting the screed.

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

Violation of technology during construction and repair work inevitably leads to large or small troubles, which subsequently have to be eliminated, spending a lot of effort and considerable money. This axiom fully applies to incorrectly performed floor screed, as a result of which various defects may appear on the coating. It can crumble, crack and, as builders say, buckle.

If cracks appear in the floor after screed work, then the simplest, and most importantly, inexpensive option would be to make regular repairs.

How can you repair small cracks?

Firstly, 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 can 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. Cracks can also be caused by forgetting to install the edge strip gasket, as well as by the lack of expansion joints.

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

We will find cracks, especially if they are very thin, they need to be widened, for which we can drill them. Remove any dust that has formed in the crack and prime it. Such cracks must be sealed with non-shrinking material using a regular staple. Some subtlety - if tiles are laid on the floor, and the cracks that appear on the screed are very small, then you don’t need to do anything with them. Larger cracks are sealed with a special compound, which is easy to do with your own hands. It includes cement, PVA glue and water. The resulting mixture must have a liquid consistency so that it can be poured into the cracks formed without any problems. After the poured mortar has hardened in the cracks, you can begin all subsequent work, for example, covering the floor.

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