Elimination of cracks in aerated concrete walls. Cracks in aerated concrete walls Shrinkage cracks in gas silicate blocks

Popular today building material- aerated concrete, there are several disadvantages. One of them is the appearance of cracks. Let's talk about possible reasons the occurrence of this problem, preventive measures and methods of combating cracks that have already appeared in walls and partitions made of aerated concrete.

We described in detail the properties, pros and cons of aerated concrete, specifically mentioning that approximately 20% of all blocks used in building a house crack. Of course, most often the cracks are very small, not critical, and you don’t need to do anything special with them.

External small cracks are perfectly hidden, for example, under plaster or siding, without compromising the thermal insulation of the house and the load-bearing capabilities of the walls. From the inside, such small flaws in aerated concrete blocks are also usually hidden finishing and do not lead to serious problems.

What if the crack runs through several blocks and is noticeable even from afar? If it was formed in fact important area walls, for example, on a corner and threaten to expand over time?

There are two types of cracks: those caused by shrinkage of the house, exposure to moisture and temperature, and mechanical cracks associated with the applied load.

The reasons for the appearance of cracks in aerated concrete masonry can be:

Poor quality aerated concrete. Simply defective material that has no chance of calmly “surviving” the coming winter. We strongly advise you to purchase aerated concrete blocks exclusively from trusted suppliers, from manufacturers already known on the market, and not from “bushes”;
Incorrect choice block class. Let us recall that for load-bearing walls you should choose aerated concrete modification D500, or better yet D600, with a density of B2.5, B3.5-5. Otherwise, the material will simply not be adapted to high loads and will begin to crack;
Foundation problems. Yes, aerated concrete is a relatively lightweight material, especially in comparison with hyper-pressed brick or good old cinder blocks. However, you cannot save on the foundation! It needs to be reinforced, hydro- and thermally insulated, otherwise frost heaving and uneven subsidence will lead to the appearance of very serious cracks;
Laying aerated concrete on poor quality solution or adhesive mixture. It is better to purchase special glue recommended by manufacturers of aerated concrete blocks to prevent problems from occurring.

So, in order to prevent the appearance of cracks in aerated concrete as much as possible, it is necessary:

Choose quality material.
Use material of the required grade and density.
Purchase high-quality adhesive.
Take care of reliable foundation, its heat and waterproofing.

That is, in fact, to follow the technology of building houses from aerated concrete blocks, paying attention to all the details. There is no guarantee that even in this case there will be no cracks at all, but serious problems certainly will not appear.

Based on the causes of cracks in aerated concrete blocks, there are several options for eliminating them. For example, in case of problems with the foundation, most often it is necessary to first strengthen it, insulate it, waterproof it, and only then deal with the cracks themselves.

The crack itself should be dealt with as follows:

clean the area from dust, rinse with water;
prime;
cover the cracks with putty;
use a reinforcing material on top, for example, fiberglass, which will then be hidden under the finish.

Important! Most of the cracks in aerated concrete form during the cold season. There is a high risk of large cracks appearing if the house has already been built, but is not finished and no one lives in it, that is, there is no heating.

Aerated concrete is an excellent building material, the main advantage of which is heat preservation. But at the same time, aerated concrete is quite fragile, which makes it less versatile.

A house made of aerated concrete must be built exactly according to technology, and then it will be warm, comfortable and will last 100 years. But if some stages of the construction technology are violated, cracks will appear in the aerated concrete.

And it is precisely about cracks in aerated concrete that we will talk about in this article. So, the cracks can be small shrinkage cracks, which in principle is not scary, but they can be fundamental.

Causes of cracks in aerated concrete:

Laying blocks on mortar.
Do not level the surface of the aerated concrete with a float.
Absence or improper reinforcement of masonry.
Incorrect or missing jumpers.
Lack of armored belt.
Poor quality aerated concrete.
Savings on foundation, cushion, drainage.
Application of low density aerated concrete.

Laying an aerated block on a mortar is not allowed, since the mortar joint will not be able to properly fasten the aerated blocks. The thing is that aerated concrete very quickly draws water out of an ordinary solution, and as a result, the cement does not have time to react with water. That is cement mortar It does not hold gas blocks together very well, so glue is needed.

The only place where gas blocks need to be laid on mortar is the first row for waterproofing.

Between themselves, the blocks must be laid with a special glue, which provides a thin seam and excellent bonding of the blocks.

You can read more about the composition of adhesive for aerated concrete in our previous article - composition of adhesive for aerated concrete.

also in Lately a special one appeared polyurethane foam for masonry, which is also an excellent material.

Although aerated concrete blocks are geometrically accurate, there is still an error of 1-2 mm. And during laying, this error must be removed using a grater. The plane of the gas blocks must be perfectly flat.

The thing is that aerated concrete adhesive has a very strong shrinkage, about 1.5 times. It follows from this that if the difference between the blocks is several millimeters, a void will form under one of the blocks, and as the walls grow, tension will be created in this place, which will create a crack along the entire wall.

It is necessary to level the plane of the blocks with a float. It is strictly forbidden to use the thickness of the glue to level the blocks.

Reinforcement aerated concrete masonry is also important part technology, without which a crack in the wall is ensured. The reinforcement works in tension, and ensures the rigidity of the walls and resistance to cracks.

The first and every fourth row are reinforced. Two reinforcement rods with a diameter of 8 mm are used per row, although 10 mm can be used. The overlap of the reinforcement must be at least 200 mm, with mandatory bends at the corners. The distance from the edges of the block to the reinforcement must be at least 690 mm. Places under need to be reinforced window openings, under the jumpers.

We described reinforcement in more detail in the article at the link, be sure to read it, it contains very important information!

Lintels over windows and doorways should be rigid, they should not bend. For such rigidity, there are two solutions: buy ready-made aerated concrete lintels, or pour the lintel yourself. In order for a homemade lintel to be of high quality, you need to use four reinforcement bars with a diameter of 8-10 mm for reinforcement, and also use grade 300 concrete.

The lintels must rest on blocks of at least 300 mm on each side. Also, do not forget about insulating the jumpers with polystyrene foam to avoid cold bridges.

Armored belt required reinforced concrete structure, which creates a monolithic ring around the perimeter of the walls. The armored belt significantly strengthens the walls of the house, and also evenly distributes the load from the floors and rafter system.

Low-quality (garage) aerated concrete has different densities and sizes, which affects the overall quality of the masonry. Moreover, the garage gas block shrinks differently, which can cause cracks.

Other causes of cracks

A house made of aerated concrete requires a reliable and rigid foundation. We also note that the lower the density of aerated blocks, the more likely occurrence of cracks in the walls.

It is also advisable to protect aerated concrete from getting wet, because if frost hits, microcracks in the blocks are possible, although in most cases, aerated concrete does not collapse in the cold.

As a result of this article, we will say that aerated concrete is a good building material, but it requires full compliance with technology. Build wisely and don't skimp on quality.

During the construction work, various unpleasant situations, from which no one is safe. One of them is a crack in.

There are several reasons why cracks may appear in This usually occurs due to subsidence of the foundation or due to a violation of the block production technology.

There is another reason that arises when creating a ventilated facade, when wind load through the frame it is transmitted to the walls of the house.

Violation of manufacturing technology

Some manufacturers, when creating blocks, may experiment with the composition of the mixture and violate their manufacturing technology.

This may be the use of inappropriate additives, when they begin to set earlier and the gas-forming processes do not have time to complete; there may be no hardening accelerators or additives that ensure uniformity of the structure.

Violations of foam block production technology lead to deterioration performance characteristics material.

In this case, cracks usually appear almost immediately or 1-2 weeks after.
This deficiency cannot be corrected., since the structure of the building material has been changed, so the way out of the situation is to dismantle the walls and use normal foam blocks.

It is imperative to carry out high-quality waterproofing, since foam concrete absorbs moisture well and this can cause cracks.

If you plan to install a ventilated facade with additional insulation, then you must use blocks of grade D600 and higher, otherwise they may not withstand the wind load that is transmitted from the cladding to the walls.

If the rafter system is created incorrectly, the load is unevenly distributed, which can cause damage to the walls made of foam blocks.

To compensate for the forces created by the rafter system, it is necessary to install tie rods (a beam connecting the rafters at the level of the mauerlat) and use an installation scheme with inclined legs.

Errors during construction

Often, the cause of cracks is associated with a violation of the technology for creating both the foundation and the walls of the building:

during foundation installation, the characteristics of the soil were not taken into account and as a result of the action of heaving forces, there is a displacement of soil layers that destroy concrete base Houses;
was not fulfilled, this must be done every 3-4 rows, due to which the rigidity of the wall decreases and cracks may appear on it;
homemade solution is used, in which the recommended proportions are not met or there are impurities that reduce the strength of the seams.

Unlike brick walls, foam blocks must be efficiently and reliably protected from atmospheric precipitation, wind, sun rays, this is best done by creating a wet facade.

What to do if a block bursts

It is necessary to ensure that cracks that appear on the foam blocks are not transmitted to the finishing surface; this can be achieved in several ways:

cracks are sealed with putty, in this case the facade is leveled, and only then the finishing coating is installed;
at , It is recommended to use fiberglass mesh, due to which the surface is reinforced, this helps prevent the appearance of cracks in the finishing material;
usage decorative plaster , having wear-resistant fillers, for example basalt or granite chips.

These methods do not eliminate the formation of cracks, they allow them to be hidden and prevent their appearance on the façade cladding.

Strengthening

To prevent further formation of cracks on walls made of foam blocks, it is necessary:

strengthen the foundation;
install an additional armored belt;
change the layout of the rafter system in order to reduce horizontal loads on the walls.

For additional protection of a foam concrete house, experts recommend making it around its perimeter drainage system and blind area.

Storm drainage or will allow ground, flood and melt water to be drained away from the walls, which will not increase soil moisture, so the foundation and walls will not absorb it.

How to repair a crack

To fix a crack you will need:

vacuum cleaner;
glue;
water;
cement;
grout;
putty knife;
primer;
iron mesh.

First, the place where the crack appears is thoroughly cleaned and the destroyed material is removed, then it is washed with water or cleaned with a vacuum cleaner.

Dry and clean surface Apply primer and seal the crack. Depending on the size of the crack, it can be sealed with a solution of crushed stone or glue.

The crack is filled with the selected composition, they do this using a spatula and grout, after which it is covered with a sheet of plywood, which is attached to the wall with self-tapping screws.

If a large crack or hole has formed, it is reinforced with iron mesh, which is secured with self-tapping screws and then filled with solution.

Conclusion

To avoid cracks in walls made of foam concrete, it is necessary to buy high-quality building material, make the foundation correctly, avoid violations and create a rafter system.
If everything is done correctly, you can build a reliable, durable and comfortable home yourself.

Useful video

How to repair a wall crack in an apartment with your own hands, video:

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The popular building material today, aerated concrete, has several disadvantages. One of them is the appearance of cracks. Let's talk about the possible causes of this problem, preventive measures and ways to combat cracks.

What if the crack runs through several blocks and is noticeable even from afar? What if it formed on the most important part of the wall, for example, on a corner and threatens to expand over time?

There are two types of cracks: those caused by shrinkage of the house, exposure to moisture and temperature, and mechanical cracks associated with the applied load.

The reasons for the appearance of cracks in aerated concrete masonry can be:

Poor quality aerated concrete. Simply defective material that has no chance of calmly “surviving” the coming winter. We strongly advise you to purchase aerated concrete blocks exclusively from trusted suppliers, from manufacturers already known on the market, and not from “bushes”;
Incorrect choice of block class. Let us remind you that for load-bearing walls you should choose aerated concrete of the D500 modification, or better yet D600, with a density of B2.5, B3.5–5. Otherwise, the material will simply not be adapted to high loads and will begin to crack;
Foundation problems. Yes, aerated concrete is a relatively lightweight material, especially in comparison with hyper-pressed brick or good old cinder blocks. However, you cannot save on the foundation! It needs to be reinforced, hydro- and thermally insulated, otherwise frost heaving and uneven subsidence will lead to the appearance of very serious cracks;
Laying aerated concrete with a low-quality mortar or adhesive mixture. It is better to purchase special glue recommended by manufacturers of aerated concrete blocks to prevent problems from occurring.

So, in order to prevent the appearance of cracks in aerated concrete as much as possible, it is necessary:

Choose quality material.
Use material of the required grade and density.
Purchase high-quality adhesive.
Take care of a reliable foundation, its heat and waterproofing.

The crack itself should be dealt with as follows:

clean the area from dust, rinse with water;
prime;
cover the cracks with putty;
use a reinforcing material on top, for example, fiberglass, which will then be hidden under the finish.

Important! Most of the cracks in aerated concrete form during the cold season. There is a high risk of large cracks appearing if the house has already been built, but is not finished and no one lives in it, that is, there is no heating.

We advise that if the crack is very deep and the reasons for its occurrence are unclear, contact a specialist. In this case do-it-yourself repair walls can only make the situation worse.published

If you have any questions on this topic, ask them to the experts and readers of our project.