The concrete screed is crumbling under the tiles what to do. Strengthening a weak screed with a primer, liquid glass and silicate impregnations

The floor screed is crumbling what to do

Why is the cement screed crumbling, what to do?

arturio77

4 years ago

Basically, the reason is two factors - the wrong composition of the solution, that is, the proportions of cement were not observed and the solution turned out to be not strong and the second important factor is the rate of drying of the solution. If you arrange 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 finishing materials... Also, the cement mortar can simply be grabbed by a little frost, after thawing, that part of the solution into which the ice has made its way will necessarily peel off. If the question refers only to the screed, then a stronger one can be poured over, of course, if the height of the thresholds allows. If the screed completely crumbles into large pieces, then, of course, it is better to completely replace it.

the moderator chose this answer as the best

9 months ago

It is necessary to clarify, for clarity of the answer, where is your screed. It can be a street - a site 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, screed abrasion:

Substandard placeholders. Due to the abundance of dust in the aggregates or due to the large presence of fines, the brand indicators of the solution can drop many times. This leads to a decrease in strength, density and, in the wake of 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 else), cement in which the process of hydration began (soft cement pellets and grains were formed), the strength of the solution drops by 2, or even 3-4 times.
Too much plasticizer added. With a large inclusion of the plasticizer, stratification of the mixture may occur. When it hardens in a short time (literally 1-2 months later), chips, cracks appear, the screed peels off.
Similar, but only with water. With a large addition of water, the solution is porous, very soft. The finished screed will not be able to take serious loads. If the screed is in the open air, then it will "tear" in the autumn and spring.
Improper reinforcement. The absence of reinforcement or its insufficiency, lead to the fact that the screed cannot bear the load. Hence the cracks.
A 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. No wonder the screed is crumbling.
Poor base preparation - no tamping, screed construction on top of 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 cannot be stopped. It will continue. you need 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 make 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 and lay paving stones (as an example).

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

Aggregates must be clean: free of dust, impurities and large inclusions (if sand). Recommended fraction of crushed stone for screeds: 1-5 mm, 5-10 mm, 5-20 mm. It is recommended to use river sand, seeded - fractions of 0.1 - 3 mm.
Buy cement only in large stores or directly from the manufacturer. Look at the production date. Use the cement within 2-3 months after manufacture. Recommended cement grades are M400D20, M400D0, M500D0, M500D20.
Add the plasticizer to the solution no more than 2%. Read the manufacturer's instructions carefully. Typically, the plasticizer is added in the region of 0.5-1%. The recommended brand of mortar for screeds is at least M250, the classic version is better - M300.
Maintain the water-cement ratio. Recommended V / C - 0.5. For one part of cement, half part of water (by weight).
When pouring screeds up to 50 mm, it can be reinforced with reinforcing meshes with a diameter of 5-8 mm. You can do with one reinforcement plane. 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 planes of reinforcement (above and below), then reinforced meshes of 5 mm or 6 mm can be used. If the screed is more than 120 mm, it is recommended to use two reinforcement planes. The minimum diameters of reinforcement in meshes are 8 mm.
With an insignificant load on the screed, you can limit yourself to 50 mm of concrete (this is important for leveling the floor in apartments). When filling the blind area, yard, floor in the garage, the recommended screed thickness is 120-180 mm.
Before pouring the screed, remove the loose, vegetable soil... It is necessary to remove it to dense, clayey soils. Then, align the base. Make a sand embankment 40-150 mm thick. Tamp this thickness, vibrate it. Align to "level" the newly surfaced. Lay a waterproof film or geotextile and only after reinforcement start laying the mixture. This is for screeds outside the living area.
The 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. Protect from open sunlight.

favorite link thank Kim Jong-un

over a year ago

There are quite a few reasons for this behavior of the screed:

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

Incorrect proportions during mixing, the screed can burst with a small amount of cement in the solution and with a large one.

Screed too thin.

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

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

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

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

And actions must be taken based on a specific reason, cracks on 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 screed surface,

tap it with your knuckles, for sure there is 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 are not observed when drawing up the solution, there is a lot of sand;
poor quality cement;
the base for the screed is incorrectly prepared.

If the defective area is small, you can clean the screed, remove everything that crumbles, treat the surface with soil, dilute a new solution, slightly liquid, and make a new thin screed. If the entire floor is crumbling, it is necessary to completely remove the screed and fill in a new way.

3 years ago

This defect often happens if you mix sand with cement in advance, especially in warm weather, and do not seal it right away. We have already burned ourselves on this.

Do you know the answer?

How to strengthen a concrete screed that is crumbling

Screed coils - what to do?

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The concrete screed is crumbling - what to do?

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

On 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 of 100 - 150 mm is poured onto it and compacted. Then the concrete is poured with a thickness of 40 - 50 mm. After gaining the necessary strength (about 7 days under normal conditions), a layer of roll vapor barrier and insulation is placed on it. Then the frame is mounted from metal mesh... After that, a layer of waterproofing is rolled out and a finishing concrete screed 50 mm thick is poured.

Screed on a separating waterproofing layer

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

Floating concrete screed

Suitable for repairing floors over 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 50 - 70 mm thick.

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

It will be difficult for an unprepared person to determine the presence of destruction 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, produced by an industrial method. 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 participates in chemical reaction hardening concrete mix... Some of the moisture simply freezes. The concrete screed collapses due to water trapped inside. Constant freezing and thawing leads to the destruction of bonds within the concrete and the formation of penetrating cracks.
Impact high temperatures... When the concrete floor cools sharply, for example during extinguishing a fire, steam is formed inside, which tears the concrete. Prolonged heating can lead to cracking. This is due to the different expansion coefficients for reinforcement and concrete. That is, at equal temperatures, their size does not change in the same way.

Important! Overheating cracks usually form in areas of the concrete floor adjacent to fireplaces or stoves. They are also prone to cracking meta, where non-insulated pipes of hot or cold water supply pass.

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

Excess water in concrete mortar can lead to cracking several months after the screed is poured.

Mechanical factors

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

Sex-disrupting factors are rarely found in their pure form. Usually, cracking or complete destruction of a concrete screed is associated with a complex effect of several reasons.

Ways to prevent the destruction of concrete floor screed

Choose the right concrete grade depending on the expected operational load. It is important to understand that the floor in the basement and garage will take different loads. For the basement, B10 grade concrete is suitable. In rooms with a more intense load, it is better to fill in the floors of the B12.5 or B15 brand.
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 of plasticizing or water-repellent additives into the solution. Additional chemicals can greatly increase the resistance of the concrete to moisture or mechanical stress. You can find such additives in hardware stores. The main thing is to carefully read the instructions and not be mistaken with the proportions.

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

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

Covering the entire floor surface with plastic wrap. Every knock opens and concrete is poured with warm water. The exposure period is 7 - 8 days. After that, the film is removed.
Protecting fresh concrete with sawdust. "Dedovsky", but very effective method... The compound 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 knead concrete in warm water. After pouring, the surface is covered with plastic wrap. It turns out a "hothouse", which will allow the concrete to gain the necessary strength. The aging period is 3-4 days.
Isolation of communications. If the heating and water supply pipes pass through the concrete screed, they are insulated. This is done to prevent the concrete floor from cracking where it touches the pipes.
Heat insulating pads between concrete floors and a fireplace or stove.
Protection against mechanical stress and abrasion with a topcoat in the form of ceramic tiles, laminate, linoleum.
The device of expansion joints. The concrete is poured in strips 1000 mm wide, between them a galvanized profile is laid. Thanks to this, the monolithic concrete surface does not break under the influence of thermal expansion.

Compliance with all technological features when laying and using a concrete floor, it will allow you to get a solid, reliable and durable base.

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 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 any special surface preparation work. It is enough to remove dust and debris.

Elimination of defects on old surface starts with removing the flooring and cleaning the floor of all paint and varnish or adhesives. For this, a spatula and a metal brush for metal are used.

Important! Cleaning can be accelerated by using special grinding attachments for 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 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:

Around each pothole, rectangular cuts are made using a grinder with a circle on concrete. The cutting depth is slightly deeper than the pothole.
Broken concrete is removed from the cut with a hammer and chisel. You can also use a rotary hammer with a spatula attachment.

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

The surface of the pothole is cleaned from dust and dirt with a regular flute brush.
The destroyed 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 of the soil is 45 - 60 minutes.

A primed pothole is filled with a special repair compound concrete surfaces... If it is not possible to purchase it, then prepare for small potholes cement-sand mortar.
The laid mixture is leveled with the old floor. For this, a plastering trowel of 100 - 150 mm is used.
After hardening, the repaired area is sanded.

Crack repair

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

Small cracks are cut with a grinder and a circle on concrete, or widened with a chisel and hammer. This process is called "crack patching". More serious areas are cut completely like potholes.
Remove dust and debris with a flute brush or vacuum cleaner.

Important! You can use a commercial or household hair dryer to clean up cracks.

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

Important! Shallow 1 - 2 cm cracks are filled at a time. More serious damaged areas are painted over in several layers. Layer thickness 1 - 2 cm.

After complete drying, the repaired floor surface is sanded.

Important! Wide and long cracks can be reinforced with 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 cobweb-like cracks

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

Repair of irregularities

During operation, "rubbed" areas may appear on concrete floor... They do not lead to the destruction of the entire coating, but they create inconvenience when moving on 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 an ordinary floor brush or broom.
The cleaned area is primed with concrete contact or epoxy glue 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 plastering 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, a complete overhaul of the concrete screed is 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 grinded with a grinder with a special attachment.

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

The base is impregnated with deep penetration soil. It is applied using paint roller 250 mm. 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 poured surface is rolled with a needle roller. If the need arises, then 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 the concrete screed in good condition, it is enough to notice the onset of destruction in time, determine the cause and quickly repair the destroyed section of the floor.

Video screed crack removal

How to strengthen the screed

03.04.2015

A loose, crumbling uneven screed should be knocked down to the ground in an amicable way. And pour a new one over the concrete slab.

However, the best is known to be 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 to strengthen the screed.

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 destructive for its engine. But if it's old and not a pity ...)

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 is the stage of reinforcement and preliminary leveling. The floor is putty 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 sufficiently strong material. In addition, thanks to the mesh, the floor becomes solid again, and not large pieces of screed separated by cracks.

We carry out the finishing alignment with a self-leveling pad. The dried layer of glue is prepared as well. Dedusting and soil. How to do this is described here.

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

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Overhaul of concrete floors: strengthening of the exfoliated 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 more than thirty percent destroyed, it makes sense to replace it with a new one.

The filling process itself is quite simple, but certain rules should 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, you should give preference to a primer with water-repellent properties.

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

After the screed has been poured, it must be given time to brew. It is not recommended to allow any impact on the coating throughout the month, because it is during this period of time that the poured 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 if high external loads are constantly acting on the floor surface (for example, in workshops and industrial premises). It is best to dismantle the low-quality base and fill in a new screed, rather than repair the coating on large damaged areas, but this does not always have enough time and money.

Strengthening technology

The first step in the renewed screed is to drill a number of holes 20 mm in diameter and 25 cm apart. Holes are drilled to the very bottom. 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 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 epoxy mortar (Rizopox 3500) and a filler is added, which acts as quartz sand. At the final stage, the surface is polished until a flat surface is obtained.

Repair of a peeling coating layer

Quite often, the screed, during operation, can peel off from the subfloor. This happens due to the effect of unevenly distributed loads on the concrete floor. It is not always possible to visually see the problem area. Peeling can be detected if the entire floor is gently tapped with a hammer. The exfoliation zone will indicate itself with a dull sound. In addition, it is not uncommon for delamination to occur on areas of the floor that have cracks, from which a cloud of cement dust flies out during tapping. After identifying all areas of the floor that require repair, you can begin to inject 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 have been found, holes are drilled at a distance of 250 mm, the diameter of which ranges 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 the voids formed by the peeling process are filled.

The undoubted plus of the described method lies in its speed, since the next day after the repair of 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 has burst or is bouncing - 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, flop. In this case, you should not redo it.

It is possible to repair the screed promsto. which would be a more economical option.

How to repair cracks in the screed?

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

The reasons for the appearance of cracks on cement screed there may be an incorrect coating layer, fast 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 the shrinkage joints must be cut.

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. The joints are sealed with a polyurethane-based sealant.

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

If the cracks on the floor screed are minor, and the floor covering will 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 that, the solution must be allowed to harden and start laying. 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.

In case of poor compaction of the concrete mixture, air cavities may appear in the screed, which cause cracks. In this case, it is necessary to remove the screed up 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 using a pickaxe, a solution is knocked out. The walls of the resulting fossa must be primed, and then repaired cement mortar.

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

After pouring, the seal of the mortar must be sealed by the piercing method. For this purpose, a metal bar is used.

After repairing the floor screed, it is necessary to ensure that the temperature in the room is not too 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.

Screed coils - what to do?

If the floor screed is coiled, then it is of poor quality. The reason for the coiling of the screed can be a poor-quality mixture for screed, the absence of a primer on the base, a dirty and dusty base that is used under the screed, etc.

In this case, it is necessary to hit the tie with a blunt edge of a hammer. If the mixture is of poor quality, then a dent will remain at the impact site. The screed can be coiled 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. For this it is necessary to widen the crack. Next, a very liquid solution is prepared from sand and cement.

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

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In the event that this method did 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 perform the screed according to strictly established rules.

Also watch a helpful 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 large or small troubles, which subsequently have to be eliminated, spending great efforts 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, a bay.

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

How can small cracks be repaired?

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 trouble 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 the installation of the edge strip, as well as the absence of expansion joints, also leads to cracks.

If it turns out that the cracks have gone due to unworked seams, it is necessary to urgently make seams for shrinkage. The depth of such a shrinkage joint should be deepened by no less than a third of the base. They should be done in increments of up to 5 meters. Seams should be sealed with a polyurethane based sealant.

We will find cracks, especially if they are very thin, they need to be widened, for which you can grind. Remove the formed dust in the crack and prime it. It is necessary to close such cracks with non-shrinking material using an ordinary staple. Some subtlety - if tiles are laid on the floor, and the cracks that appeared 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 make with my own hands... It includes cement, PVA glue and water. The mixture resulting from mixing must have a liquid consistency so that it can be poured into the cracks formed without problems. After the poured mortar has hardened in the cracks, all subsequent work can be started, for example, with a coating on the floor.

What to do if the screed is broken?

Broken screed, a serious defect that must be eliminated. The reason for the occurrence of such a big trouble may be the 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 to the detected unfilled cavity, and the cavity is filled with mortar. The cavity can be found by deepening the crack with the help of a tool, for example, a pickaxe. Accordingly, the test hole must subsequently be covered with soil and filled with mortar. The solution with which the cavity is poured should consist of sand and cement in a ratio of one to three. Before pouring, the cavity is moistened with water. After the cavity is filled in, it is necessary to make sure of the quality of the filling, for which 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 is bunching - how to deal with it?

Experts use the word "bukhtit" in cases when, 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 bunching, then there can be many reasons for this. The main reason is non-compliance with the process technology. If signs of swelling 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 best solution would be to add PVA glue to the solution. There is a subtlety here - the solution must be poured in small portions, making it possible for each of them to solidify. If this method did not help, then we go according to the "scorched earth" method - we break the tie and start all over again. To prevent this, do everything right and according to technology at once.

fortstroi.com.ua

Floor screed repair: do-it-yourself production

Read in this publication: Repair of a floor screed: about its expediency

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 moment, then with the second, things are a little different - excessive loads on floors, despite the fact that they have a fair amount of safety, can be catastrophic, especially when it comes to old houses. The screed must be kept in order - in the event of a major overhaul, change or at least repair. In this article from the site stroisovety.org we will deal with the question of how to repair a floor screed with our own hands?

Repair of cement screed floor photo

Floor screed repair: on its feasibility

Before proceeding with the direct solution of the question of how to repair the floor screed with your own hands, first you need to understand its expediency - perhaps things are so that there is no point in it, and it is not the restoration of the surface that is needed, but its complete replacement. In what situations does it become necessary to install a new floor screed? There are not so many signs that the screed has already become obsolete.

By and large, there are no specific criteria according to which it is necessary to completely change the floor screed. There are just prescriptions and common sense that the new surface is better than the old one. It can serve for a long time, and if you intend to live in an apartment or house for a long time, then it would be best to completely replace this surface - naturally, when it comes to major repairs. It is better to spend money on a new screed once than to make repairs with enviable regularity. old screed floor. Recovery is primarily a temporary measure that solves the issue for a short period of time.

Floor cement screed repair: preparatory work

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

There is no need to wait for the second layer of primer to dry - while you prepare the solution, it will be absorbed into the old screed and this will be 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 serve at least another ten years.

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

This stage (as, in general, the preparatory one) can be conditionally divided into two substages - fastening the split fragments of the floor and the final leveling of the base. These are two different technologies that should be dealt with separately.

In principle, this is the whole 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 almost all subtleties are individual. For example, depending on the degree of destruction of the old floor screed, reinforcement may be needed - naturally, it is better to change such a floor covering as a whole, but situations are different and even with large destruction, repairs may be advisable.

stroisovety.org

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

How to strengthen a screed that is crumbling?

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

It is possible to repair the screed industrially, which will be a more economical option.

How to repair cracks in the screed?

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

The reasons for the appearance of cracks in the cement screed can be an incorrect coating layer, rapid drying, excess or lack of water in the solution, the absence of an edge tape or expansion joints.

If the floor screed is cracked due to the lack of expansion joints, then the shrinkage joints must be cut.

When cracks appear in them, you can make a strobe, 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 that is applied with a trowel.

If the cracks on the floor screed are insignificant, 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 of sand and three cements. Before pouring the mixture, concrete is necessarily wetted with water.

After pouring, the seal of the mortar must be sealed by the piercing method. For this purpose, a metal bar is used.

Screed coils - what to do?

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

You will also be interested in:

Also see useful with expert advice on screed repair:

http://glavspec.ru

legkoe-delo.ru

Floor screed what to do if crumbling

Articles

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

If the floor screed is cracked due to the lack of expansion joints, then the shrinkage joints must be cut.

FLOOR REPAIR (BURNED, BROKEN, ROLLING SCREED)

cement screed after treatment with liquid glass

If the cracks on the floor screed are insignificant, 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.

After pouring, the seal of the mortar must be sealed by the piercing method. For this purpose, a metal bar is used.

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

You will also be interested in:

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How does the construction of any object begin? Naturally, with the laying of the foundation. Concrete is needed to create a good solid foundation. It is he who is one of the most popular and inexpensive building materials... But the quality of the components of the concrete mixture is currently not always high, therefore, to extend its service life, additional components are needed.

In order to increase the strength of concrete, steel reinforcement is laid in the structure, that is, they create the basis of reinforced concrete.

There are many ways to strengthen concrete. There are several quite decent tools on the construction market.

These are special impregnations from various foreign and domestic manufacturers.

Moreover, in terms of quality, they are almost the same. The main function of impregnations is to strengthen the concrete mix for the floor, blind area, foundation. Without such mixtures, the concrete base has low wear resistance, and if the coating is applied outdoors, then cracks appear from the constant temperature drop or vibration. The composition is gradually crumbling, and it is almost impossible to save the coating. Such a disintegration of the concrete coating also occurs if the cement itself is of poor quality or when filling the solution the correct proportions of the constituents of the concrete material are not observed.

The most effective are polymer or polyurethane impregnating mixtures for hardening concrete composition. When filling the top layer of the screed with polymer impregnation, a new, higher-quality layer of concrete polymer is formed on its surface. The quality of the expected strength of the floor will depend entirely on how deeply the reinforcing compound penetrates. The surface becomes stronger, and, accordingly, the service life of the coating increases. One of the main advantages of reinforcing impregnations is the ability to apply them to the surface at an air temperature of up to -30 degrees.

Application of additives

Diagram of a pilot plant for impregnation of porous concrete with liquid radioactive waste: 1-container with porous concrete; 2-probe; 3-pump; 4-pressure gauge; 5-storage tank for liquid radioactive waste; 6-protective box; 7-pipeline.

after you have purchased a reinforcing screed, you need to prepare the surface. Concrete already applied in a standard way must be even and always damp. Application of impregnation to a frozen dry screed is not permissible;
the dry reinforcing mixture is applied to the wet screed in an even layer. After that, it immediately begins to interact with the surface layer of the floor. The result of the actions taken will be a floor covering that is resistant to chemical and mechanical stress. If the screed is outside, the impregnation will protect it from exposure to sunlight. In terms of aesthetic qualities, appearance the floor becomes much more attractive;
when concrete is strengthened in production and industrial premises, where the area of the processed surface is large, additional construction tools are used: a grinder, a distribution trolley and a seam cutter. They are necessary for faster processing of a wet concrete layer;
using a hardening mixture, you can create a room decor. Modern manufacturers take this fact into account and release strengthening compounds of various colors. At the same time, the main technological qualities of impregnations do not decrease, but increase. Colored compounds protect any concrete coating not only from mechanical stress, but also reduce dust formation. Such mixtures are used in sales areas and warehouses.

Types of impregnations

Currently, the most popular are impregnations made with the use of polyurethane materials. Modern technologies allow to produce them for concrete pavement located in any room or outdoors.

If the basis of the future surface is soil, then the concrete and floor screed can be carried out using impregnation for concrete grade M150-M350. This composition allows impregnation of a layer with a depth of 3 mm. In this case, the concrete itself in the upper layer becomes similar in strength to the M600 brand. The surface will be more resistant to dust and the base will be more airtight.

Scheme of repairing concrete defects with bare reinforcement: a - concrete defect with bare reinforcement; b - removal of destroyed concrete, applying a protective layer to the reinforcement; в - the restored section of the structure. 1 - building structure; 2 - fittings; 3 - material "KTtron-primer"; 4 - KTtron repair material is thixotropic (depending on the project).

The biggest advantage when using polyurethane reinforcements is their ability to increase the chemical resistance of the concrete pavement. For example, a floor with such an impregnation serves for many decades and does not require additional cleaning efforts. They are easy to clean with common detergents.

There is another impregnation option with deeper penetration. It is intended for concrete grade M300. The composition used penetrates the floor to a depth of 5 mm. When applying this mixture, it is necessary that the ambient temperature is from +5 degrees. Deep penetration reinforcing mortar, as a rule, is used for floors with a weak concrete layer M150. When working with this composition, for maximum hardening, the floor with the already applied impregnation should be covered with a polyethylene film. In this case, the impregnation will penetrate the floors much deeper. The technology of manufacturing impregnation with deep penetration allows it to be used for high-strength concrete substrates and damp substrates.

In addition to polymer impregnations, there are other varieties that are more modest in cost. This is a fluate impregnation. Despite the low cost of the material, its qualities are no different from their polymer counterparts. The strength of the concrete pavement is increased up to 50%, and the appearance of the floor does not change and pleases the eye. In addition, after applying this impregnation, a film does not form on the floor surface. All types of reinforcing mixtures are able to reduce dust formation in the room.

Strengthening large volumes of concrete

If the task is to strengthen a more powerful volume of concrete for large areas, then a complex of different modifier additives should be used. They are mainly used in the construction of large, high-strength structures for concrete reinforcement. Additives are added to the ready-mix concrete mass. They help the concrete mass to achieve a strength grade of M700 and higher. At the same time, the technical composition of the bulk does not change.

So, with the help of reinforcing impregnations, you will not only achieve the strength of the floor covering, but also create unique interior in your room.

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

How can small cracks be repaired?

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

What to do if the screed is broken?

The screed is bunching - how to deal with it?

Experts use the word "bukhtit" in cases when, 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 bunching, then there can be many reasons for this. The main reason is non-compliance with the process technology. If signs of swelling 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 best solution would be to add PVA glue to the solution. There is a subtlety here - the solution must be poured in small portions, making it possible for each of them to solidify.
If this method did not help, then we go according to the "scorched earth" method - we break the tie and start all over again. To prevent this, do everything right and according to technology at once.

The reasons why the screed will turn out to be weak are different:

Failure to comply with the proportions of water and cement.
Old cement (with lumps).
Increased clay content in the sand.
Improper preparation and care after installation when conditions of rapid dehydration occur.

But if this happened, then something needs to be done with it - because with further finishing, difficulties are possible.

It is also impossible to leave it unchanged. Dust is constantly generated on such a floor. The weak layer is easily destroyed by feet.

The first way. Strengthening with a primer.

The first thing most people come to is to strengthen it with a primer. The option is real, accessible and on everyone's lips. But rarely gives the result:

A short commentary on the video.

Judging by the nail test, the screed is quite suitable for tiling indoors. There are examples of a more deplorable state of the foundation, which they tried to strengthen with a primer:

Why did the tile bounce off the screed?

They tried to strengthen the loose screed with a primer. But primer, primer strife. Judging by the color and the resulting film, the primer-concentrate was used in shock proportion. Or primed several times, with each layer completely dry (as written on the canister). This gave a film on the surface. A tile with glue was fixed to it. But the same weak layer remained under the film. A tile came off along it.

Alternatively, you need a deep penetration primer and pour it in buckets in one go. To fix a weak layer to a greater depth. The deep penetration primer (according to the manufacturers) has smaller particles and therefore, can penetrate deeper without creating a film on the surface.

Strengthening the cement screed with silicates (water glass).

The idea of using liquid glass to repair weak surfaces did not appear out of nowhere. Liquid glass in construction for a long time:

Additives to concrete and mortars to accelerate the setting (1-15% by weight of cement).
Manufacturing of refractory paints, putties and putties with the addition of fillers (talc, marble dust, fine sand).
Waterproofing concrete and timber structures.
Fighting mold and mildew.
In metallurgy, the arch of furnaces is laid out of fireclay bricks on a sodium silicate binder.

There are three main types (depending on the composition) of liquid glass: potassium, sodium and lithium. They have different properties, which gives different benefits and different prices.

Sodium is more common. They are trying to strengthen the screeds in garages and basements:

You can experiment with this method. It is useful to have at least some other people's experience.

Below are the most interesting details of the use of liquid glass. It is difficult to call this qualitative material for conclusions. But still:

It would be possible to call all this fuss with liquid glass a collective farm and forget it, if it were not for such a detail as recommendations for strengthening loose screeds with silicates from many manufacturers of mixtures. One of them from “MAPEY”:

Important points in the video:

Viscosity impregnation is more similar to a primer than to liquid glass in cans, which is used to strengthen floors in garages.
The impregnation must be applied continuously, preventing the top layer from forming a crust.
Consumption can be significant, and 3-4 liters per meter.

It is clear that Prosfas hardening primer does not consist of silicate alone. Therefore, its price differs from the price of liquid glass. If we compare the cost of strengthening a loose screed with silicate from "MAPEY" and ordinary liquid glass, taking into account its consumption and a similar consumption of liquid glass, then the discrepancy will be significant:

Prosfas and liquid glass.

But Mapei is not the only company that prepares impregnations for concrete and screeds.

An entire industry has been created on this problem. Millions of businesses have been built on a simple chemical reaction (Ca (OH) 2 is converted to C-S-H) between silicate in the impregnation and calcium hydroxide in concrete. The composition of the impregnations is not disclosed, except for the name of one of the silicates, on the basis of which it was created.

Like different types For liquid glass, various strengthening impregnations based on potassium, sodium, magnesium and lithium have been created. An important difference between the two is the size of the molecule. How deeply the silicate can soak the screed depends on this:

Impregnants based on sodium silicates.

Sodium impregnation.

Here are some examples of sodium impregnations. This is not all. New ones may appear, cheaper and more efficient. Some cut production and leave the market:

Ashford Formula- Brand Ashford Formula. Produced by Curecrete Chemical Co (USA). The country of origin may be different.
Lithurin.
Diamond Hard(Diamond Hard). Product of the American chemical concern "EUCLID CHEMICAL".
Liquid-Hard from W.R. Meadows (USA). The manufacturer may be Czech Republic.

All impregnations are similar in the method of application:

Apply so that the entire surface remains wet for 30-60 minutes. No puddles and drying out in some areas. This is achieved with the help of a soft panicle, redistributing the liquid over the screed. The surplus is moved to adjacent areas and removed with a water vacuum cleaner.

Some impregnations are diluted with water (Lithurin I). Some have features - Ashford Formula is not effective on concrete below M 300 and on cement-sand screeds:

Reinforcing impregnations based on lithium.

According to the American Concrete Institute, lithium-based impregnations have a number of advantages:

Increases the strength of concrete by more than 45% (for sodium - 37%).
Seals concrete and completes the chemical reaction within 7-14 days (operation after 2 hours). Sodium has 6-12 months.
There is no need to rinse it with water.
Penetrates 1-5 mm, forming a chemical reaction with the top layer.

Lithium based impregnations.

ULTRALIT HARD (1)

If you believe the prices and consumption (for 20 squares - 1 one liter), then impregnation of one square of concrete surface costs $ 0.05. Country of origin - Czech Republic (technology, most likely, USA).

The release of three varieties of Ultralit Hard Standard, Ultralit Hard Premium, Ultralit Hard Extra has been launched.

Mapecrete LI Hardener (2)

Lithium based liquid for new and old concrete floors from MAPEI.

5.8 $ - impregnation of one square meter, with a consumption of 0.4 kg / m2 (the real price can be found only at the time of purchase).

Concria Super Hard and Concria Hard (5)

Country of origin USA. Based on the consumption of 1 liter per 10-20m2, we get the cost of one square meter: $ 1.2-2.2. C2 Hard can be used on floors that have already been treated with other silicate impregnations and which have begun to dust and flake off.

In addition to these two impregnations for strengthening, the production of others has been established, for coloring, giving gloss ....

SPEKTRIN LITHIUM(4) - made in Sweden / Ukraine. Lithium impregnation for concrete and stone (marble). The depth of penetration is about 7 mm. Strength increase up to 16%. Decrease in water absorption by 3.3 times. The impregnation can be used in the food and pharmaceutical industries. Costs (cost of impregnation) per 1 square meter -1.5 $. It is used for interior and exterior work on strong and dense concrete (M 300 and above):

The first impregnations on the American market appeared about 50 years ago. The search for new trains does not stop. The competition is growing. Without experience, it is difficult to understand the features of each and the veracity of the declared properties. Alarming is the indication in some of those cards of reinforcing impregnations: "Do not apply on dusty, crumbling and fragile substrates." The marketing wars lead to even more confusion:

A good warning was posted before purchasing one of the impregnations:

As a way out - you need a test area 1.5m x 1.5m. If there are different surfaces, then there is a separate area for each type of surface. After doing everything according to the instructions, let it dry for 3-7 days. Then make a conclusion on consumption, costs, obtained and expected surface strength.

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

It is possible to repair the screed industrially, which will be a more economical option.

How to repair cracks in the screed?

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

If the floor screed is cracked due to the lack of expansion joints, then the shrinkage joints must be cut.

If the cracks on the floor screed are insignificant, 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.

After pouring, the seal of the mortar must be sealed by the piercing method. For this purpose, a metal bar is used.

Screed coils - what to do?

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

You will also be interested in:

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

glavspec.ru

The concrete screed is crumbling - what to do?

The base of the concrete floor 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 the reinforced concrete floor slabs 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 of 100 - 150 mm is poured onto it and compacted. Then the concrete is poured with a thickness of 40 - 50 mm. After gaining the necessary strength (about 7 days under normal conditions), a layer of roll 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 a finishing concrete screed 50 mm thick is poured.

Screed on a separating waterproofing layer

Floating concrete screed

Suitable for repairing floors over unheated rooms. 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 a concrete base 50 - 70 mm thick is poured.

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

Physical factors

Cyclic process of freezing and thawing. It is typical for winter concreting, when, if the pouring technology is violated, not all of the water participates in the chemical reaction of the concrete mixture hardening. Some of the moisture simply freezes. The concrete screed collapses due to water trapped 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 the concrete floor cools sharply, for example during extinguishing a fire, steam is formed inside, which tears the concrete. Prolonged heating can lead to cracking. This is due to the different expansion coefficients for reinforcement and concrete. That is, at equal temperatures, their size does not change in the same way.

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

An excess of water in the concrete solution can lead to cracking several months after the screed is poured.

Mechanical factors

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

Sex-disrupting factors are rarely found in their pure form. Usually, cracking or complete destruction of a concrete screed is associated with a complex effect of several reasons.

Ways to prevent the destruction of concrete floor screed

Choose the right concrete grade depending on the expected operational load. It is important to understand that the floor in the basement and garage will take different loads. For the basement, B10 grade concrete is suitable. In rooms with a more intense load, it is better to fill in the floors of the B12.5 or B15 brand.
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 of plasticizing or water-repellent additives into the solution. Additional chemicals can greatly increase the resistance of the concrete to moisture or mechanical stress. You can find such additives in hardware stores. The main thing is to carefully read the instructions and not be mistaken with the proportions.

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

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

Covering the entire floor surface with plastic wrap. Every knock opens and concrete is poured with warm water. The exposure period is 7 - 8 days. After that, the film is removed.
Protecting fresh concrete with sawdust. "Dedovsky", but a very effective way. The compound 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 knead concrete in warm water. After pouring, the surface is covered with plastic wrap. It turns out a "hothouse", which will allow the concrete to gain the necessary strength. The aging period is 3-4 days.
Isolation of communications. If the heating and water supply pipes pass through the concrete screed, they are insulated. This is done to prevent the concrete floor from cracking where it touches the pipes.
Heat insulating pads between concrete floors and a fireplace or stove.
Protection against mechanical stress and abrasion with a topcoat in the form of ceramic tiles, laminate, linoleum.
The device of expansion joints. The concrete is poured in strips 1000 mm wide, between them a galvanized profile is laid. Thanks to this, the monolithic concrete surface does not break under the influence of thermal expansion.

Compliance with all technological features when laying and operating a concrete floor will allow you to get a strong, reliable and durable base.

Repair of potholes and cracks in concrete screed

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

Elimination of defects on the old surface begins with removing the flooring and cleaning the floor from all paint and varnish or adhesives. For this, a spatula and a metal brush for metal are used.

Important! Cleaning can be accelerated by using special grinding attachments for a drill or hammer drill. They are sold at any hardware store.

Repair of formwork marks

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:

Around each pothole, rectangular cuts are made using a grinder with a circle on concrete. The cutting depth is slightly deeper than the pothole.
Broken concrete is removed from the cut with a hammer and chisel. You can also use a rotary hammer with a spatula attachment.

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

The surface of the pothole is cleaned from dust and dirt with a regular flute brush.
The destroyed 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 of the soil is 45 - 60 minutes.

A 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 should be prepared for small potholes.
The laid mixture is leveled with the old floor. For this, a plastering trowel of 100 - 150 mm is used.
After hardening, the repaired area is sanded.

Crack repair

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

Small cracks are cut with a grinder and a circle on concrete, or widened with a chisel and hammer. This process is called "crack patching". More serious areas are cut completely like potholes.
Remove dust and debris with a flute brush or vacuum cleaner.

Important! You can use a commercial or household hair dryer to clean up cracks.

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

Important! Shallow 1 - 2 cm cracks are filled at a time. More serious damaged areas are painted over in several layers. Layer thickness 1 - 2 cm.

After complete drying, the repaired floor surface is sanded.

Repair of small cobweb-like cracks

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

Repair of irregularities

During operation, "rubbed" areas may appear on the concrete floor. They do not lead to the destruction of the entire coating, but they create inconvenience when moving on 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 an ordinary floor brush or broom.
The cleaned area is primed with concrete contact or epoxy glue 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 plastering rule.
After drying, the entire repaired surface is sanded.

Overhaul of concrete screed

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

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

The base is impregnated with deep penetration soil. It is applied with 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 poured surface is rolled with a needle roller. If the need arises, then 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 the concrete screed in good condition, it is enough to notice the onset of destruction in time, determine the cause and quickly repair the destroyed section of the floor.

Video screed crack removal

meot.ru

How to strengthen the screed

03.04.2018

A loose, crumbling uneven screed should be knocked down to the ground in an amicable way. And pour a new one over the concrete slab.

We carry out the finishing alignment with a self-leveling pad. The dried layer of glue is prepared as well. Dedusting and soil. How to do this is described here.

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

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Overhaul of concrete floors: strengthening of the exfoliated screed

Stages of strengthening a weak concrete floor

Strengthening technology

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

Repair of a peeling coating layer

The undoubted plus of the described method lies in its speed, since the next day after the repair of concrete floors, a protective layer can be applied to the screed.

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