Aerated concrete happens autoclave and non-autoclave, and many builders are wondering what the differences are between them.

Let's figure this out together, but looking ahead, let's say that autoclaved aerated concrete is a much higher quality material, and below we will tell you why.

What is autoclave processing of aerated concrete?

Autoclave processing – stage of processing aerated concrete with high temperature (190°C) under high pressure during 12 hours. Autoclaves are metal containers into which cut gas blocks are placed.

Autoclaving is done for the following purposes:

1. acceleration of aerated concrete hardening;
2. increased strength;
3. reduction of shrinkage;
4. improvement of structure homogeneity;
5. improvement of block geometry.

The autoclave also changes the structure of aerated concrete at the molecular level, forming new material – tobermoritis. This synthesized stone has properties that cannot be obtained under normal conditions at standard pressure and temperature.

We repeat that non-autoclaved aerated concrete hardens in natural conditions, and its production is expensive and modern equipment not required. In other words, many manufacturers stamp gas blocks in their garages, which does not inspire much confidence.

Now let’s take a closer look at the differences between aerated concrete, and we’ll start with strength.

Comparison of autoclaved and non-autoclaved aerated concrete

It is important to note that the video tests non-autoclaved aerated concrete, to which fiber fiber has been added; it significantly increases the strength of the blocks. But we note that in reality, not everyone uses fiber in the production of non-autoclaved aerated concrete, since it is quite expensive.

Strength

Aerated concrete without an autoclave is less durable, especially when it is fresh. After all, like ordinary concrete, it still needs time to gain strength, but autoclaved concrete has accelerated its hardening hundreds of times thanks to high-temperature steam treatment. But even with complete hardening of both materials, the strength of the autoclave is higher by half or more.

For example, autoclaved grades of aerated concrete D500 and D600 have a strength class of B2.5 - B3.5, while a non-autoclaved analogue of the same brand achieves, at best, class B2.

Shrinkage

Large shrinkage of blocks can create multiple cracks in the masonry; moreover, cracks can appear over the course of a year or more. To keep such processes to a minimum, block shrinkage should be minimal.

The shrinkage of non-autoclaved aerated concrete is from 3 to 5 mm per meter, while that of autoclaved aerated concrete is ten times less. That is, autoclaved aerated concrete practically does not produce shrinkage cracks when laid correctly.

Block geometry

The geometry of the blocks is also very important, and the smoother the blocks are to each other, the better. After all, if the blocks differ from each other by 5 mm, then the difference in level must be leveled with glue, and these are cold bridges that greatly worsen the thermal insulation characteristics of the masonry.

Moreover, thick seams cause greater shrinkage, which again can cause cracks. Experienced builders will tell you that the difference in levels can be leveled with a float on aerated concrete, but imagine how much time it will take.

Now let’s think about where the geometry of the blocks will be better, on high-tech factory equipment with autoclaves, or in garage conditions? The answer is obvious!

Most builders believe that the best and most even blocks are obtained from AEROC. average price per cube of their aerated concrete is 4000 rubles.

Uniformity of structure

Uniformity refers to the number of voids (bubbles) that are distributed in a certain way in aerated concrete, and the more uniform they are, the better. Autoclaved aerated concrete technology guarantees an ideal distribution of voids, due to the fact that bubbles form and harden immediately, and individual blocks are obtained after cutting one large block.

Non-autoclaved aerated concrete is made completely differently. IN concrete mixture foam and blowing agents are added. As a result, bubbles can rise closer to the surface, while heavier elements fall down. As a result, the distribution of bubbles will be uneven.

Now let's think about what this threatens. Firstly, where there are fewer bubbles, there is less strength, and where there are few bubbles, there is a cold bridge through which heat will escape faster. That is, the strength and thermal conductivity of non-autoclaved aerated concrete are very unstable.

Thermal conductivity

Smoothly moving from the topic of structure uniformity to thermal conductivity, we will say that the uneven structure of bubbles worsens the average thermal conductivity of the block, and naturally, in autoclaved aerated concrete, the uniformity of bubbles is better and, therefore, the thermal insulation is also better.

Conclusion

Autoclaved and non-autoclaved aerated concrete differ greatly from each other in a number of parameters, and it is safe to say that autoclaved material is superior to its counterpart in all respects, except one - price. Yes, non-autoclaved aerated blocks are cheaper, but if you count how many problems arise when laying them, how many additional materials, work and time will have to be done, we advise you to think carefully when making your choice.

It’s better to build a house correctly once, from quality material, and be sure that it will last for many years without problems.

To understand the difference between autoclaved concrete and non-autoclaved concrete, it is necessary to consider the main features of both types of aerated concrete. The popularity of aerated concrete in construction is growing every day, which is explained by its positive properties: good strength, low density, high quality, low weight (which generally reduces the cost of foundations and floors), the ability to lay thin, but warm and reliable walls.

Autoclaved and non-autoclaved concretes differ in their production method and, accordingly, in their performance characteristics. Initially created exclusively in conditions industrial production, but they soon found a way to produce cellular material without additional heat and moisture treatment.

Autoclaved aerated concrete is more stable, but non-autoclaved aerated concrete involves shrinkage. But if we consider their differences in more detail, it becomes clear: both types of aerated concrete are relevant for repair and construction work, it is important to know their characteristics and choose the right one for specific tasks.

Aerated concrete production technology

Autoclaved and non-autoclaved aerated concrete are produced using the same technology; the differences lie only in the accuracy of the technology and in the final stages of processing the material. The raw materials are used identically and in the same proportion.

• Fine sand 2-2.5 millimeters
• Portland cement grades M300 and M400
• Lime
• Aluminum powder or paste with an active metal content of 90-95%
• Various additives and modifiers (not necessarily introduced, but needed to improve various performance properties)
• Water

First, an ordinary cement-sand mortar is mixed, poured into a special mold, then aluminum powder is added. As a result of the reaction of powder and lime, carbon dioxide appears, due to which the mass increases in volume, swelling and forming a porous structure. The gas release reaction must be completed before the cement sets; to intensify the process, the mold is processed on a vibrating platform. But this process is only relevant for large factories.

In small workshops they create foam concrete, which is a type. After all, according to the method of foam formation, concrete is divided into gas and foam concrete. And if in the first case the foam is created by gas, then in the second - by chemicals.

The cellular structure is created by adding and whipping special chemical foaming agents. Shops are usually small, with a small number of employees, predominantly manual labor. The production of aerated concrete is more expensive, but such a material is also more stable and has better properties.

Further, the production technology of autoclaved and non-autoclaved aerated concrete suggests differences. If autoclaved aerated concrete is produced, after pouring the mixture into the mold and starting the reaction, wait a certain time, allowing the mixture to partially harden and gain sufficient strength to remove the mass from the formwork and cut it into blocks.

The cut blocks are sent to an autoclave and fired at a temperature of +190-200 degrees, the pressure is 8-10 Bar (so that moisture is completely removed from the material). Processing aerated concrete with an autoclave allows you to: accelerate the hardening of the material, increase its strength characteristics, reduce shrinkage in the future, make the structure homogeneous, and improve the geometry of the finished blocks.

Non-autoclaved aerated concrete gains strength not in the oven, but in natural environment– without exposure to temperature and pressure to evaporate moisture. Moreover, often for production of this type The material is not used in large molds with further cutting of gas blocks, but in molds for casting individual elements.

Autoclaved and non-autoclaved aerated concrete is produced in accordance with the following regulatory documents: GOST 21520 "", GOST 25485 "Cellular concrete", as well as GOST 31360 and GOST 32359.

Properties of non-autoclaved and autoclaved aerated concrete

Aerated concrete autoclave curing and non-autoclave - absolutely different materials at the exit. They differ as appearance(therefore you can immediately determine by eye what kind of concrete is in front of you), and performance characteristics.

External indicators

Blocks of a cellular structure, cut from solid wood, are usually distinguished by greater compliance with the design dimensions. They make masonry easier, less time, effort and materials are spent on sealing the seams, the thickness of the inter-masonry joints is much smaller (and cold bridges, respectively), and the finishing of the building is simpler.

Non-autoclaved aerated concrete turns out gray, while autoclaved aerated concrete turns out almost white. If the shade is uneven and various inclusions are visible in the structure, most likely the quality of such material is not very good.

The production of non-autoclaved aerated concrete is often carried out practically in artisanal conditions - the concrete is simply mixed, formwork is used for pouring, and after hardening in natural conditions, the material is supplied for construction. All this negatively affects the quality of the final material and its basic properties.

Physical and mechanical properties

Autoclaved aerated concrete shows a density of D400-800, the compressive strength is in the range of B1.5-B5, but non-autoclaved aerated concrete gives a maximum strength of B3. On walls made of fired blocks, you can attach shelves and cabinets, air conditioners, speakers and other devices that non-autoclaved aerated concrete is not always able to withstand.

One of the main differences between the materials is shrinkage - unfired aerated concrete contains moisture, which causes cracks to appear on the walls. And density plays an important role - as it decreases, the shrinkage coefficient during residual strength increases. The process lasts about 5-10 years. Autoclaved aerated concrete shrinks by approximately 0.5 mm/mm, unburnt - by 2-3 mm/m.

Thermal conductivity indicators also vary - the property depends on the density: the lower the density, the more heat-intensive the material. To reduce the thermal conductivity of walls, it is best to choose aerated concrete with high strength and lower density.

Differences: pros and cons of materials

Autoclave aerated concrete blocks differ quite noticeably in various indicators from material that has not been fired. Due to their different properties, blocks are used to perform different tasks; they are relevant for certain types construction. Before using a particular material in your work, you first need to study all the specifications, advantages and disadvantages.

Strength

Naturally hardened aerated concrete is less durable, especially if it is completely fresh. It takes a lot of time to gain strength. But an autoclave for aerated concrete helps speed up the process of strength gain (it speeds up hundreds of times), so after steam treatment at high temperatures, the strength of autoclaved concrete is one and a half to two times higher than its counterpart without firing.

So, for example, autoclave brands D500 and D600 demonstrate a strength indicator at the level of B2.0-B3.5, a non-autoclave of a similar brand will, at best, give class B2.

Block geometry

During the construction process, the evenness of the blocks and their compliance with the specified parameters are very important. Regardless of what kind of object is being built (a bathhouse, a garage or a residential building), the quality of the masonry is higher, the more accurately the blocks are made. Indeed, if something happens, the difference in level is leveled out with glue or solution, cold bridges are created, and the thermal insulation properties.

Thick seams negatively affect shrinkage during the process and cracks may appear. To avoid this, the difference in levels is removed and a regular hand saw can be used. But the time and labor costs in this case are simply enormous. It is much easier and cheaper to immediately buy smooth autoclaved aerated concrete and build a building from it.

Uniformity of structure

The uniformity of the structure is determined by the number of bubbles in the material and the uniformity of their distribution. The more homogeneous the material, the better it is - this has a positive effect on quality. Autoclaved aerated concrete blocks have a more uniform structure, since they are created quickly, harden immediately, and then the masses are cut into individual blocks.

Non-autoclaved aerated concrete is produced differently - foam and gas-forming agents may not be distributed evenly: often bubbles float up, heavy elements fall down. This has a bad effect on construction - strength decreases in places large cluster bubbles, cold bridges appear in places with a small number of bubbles. Characteristics are unstable.

Possibility of fastening

Autoclaved aerated concrete is a durable material onto which even very heavy devices and elements can be attached. It is possible to mount facades made of light expanded clay or even heavy porcelain stoneware. Thus, a 10x100 anchor can easily withstand an axle pullout load of about 700 kilograms. That is, you can attach shelves, cabinets, boilers, air conditioners, without fear that all this will fall with a piece of the wall and fasteners.

Non-autoclaved aerated concrete is much less durable - sometimes you can even press screws or nails into it by hand. No mechanical fasteners are used; lightweight objects are secured with an expensive two-component chemical anchor.

Drying shrinkage

When choosing autoclaved blocks for masonry, you can hope for minimal shrinkage during the process. Under firing conditions, concrete has already gained strength and gives a shrinkage rate of a maximum of 0.5 mm/m, while non-autoclaved aerated concrete gives about 5 mm/m - the difference is significant.

Severe shrinkage of buildings made of non-autoclaved aerated concrete can cause a lot of troubles - cracking of masonry, appearance of cracks, peeling of finishing and plaster. This can continue for several years until the concrete takes on all its strength.

Environmental friendliness

Autoclaved aerated concrete is absolutely environmentally friendly, allows air to pass through well, allows the building to breathe and helps create an optimal microclimate. Aerated concrete is created from mineral raw materials, so it is not afraid of rotting, moisture and mold.

In the case of the production of non-autoclaved aerated concrete, chemical additives are used to form foam, which already reduces the level of safety of its operation. Often, chemical components are introduced into a block with fiber impregnated with special thiocyanates, chlorides and acids, which is even more dangerous, since these substances can be released and accumulate in the air of the home over time.

Thermal insulation properties

Heat retention characteristics directly depend on density. There it is best performance demonstrates foam concrete, the disadvantage of using it in construction is its low strength. For laying walls they use more dense materials– the density kg/m3 must be at least 700 kilograms per cubic meter. And if you use non-autoclaved aerated concrete of such a density, then due to the cold bridges of thick joints, the characteristics are further reduced.

Autoclaved aerated concrete provides the same properties, but with a smaller wall thickness and with smaller cold bridges, which ultimately provides better performance.

We can conclude that autoclaved aerated concrete is superior to non-autoclaved blocks in many areas and indicators. It's about both about geometry and physical and mechanical properties. Autoclave units are created in a factory environment, with strict adherence to regulations and compliance with standards. It is easier and simpler to build from such concrete, the buildings are more durable and of higher quality. Completely safe and environmentally friendly material withstands any load and guarantees the best performance properties of the structure.

Autoclaving of aerated concrete

What is the difference between autoclaved aerated concrete and non-autoclaved aerated concrete?

IN Lately In connection with the growing popularity of building blocks made of cellular concrete, the question often arises: what is the difference between autoclaved aerated concrete and non-autoclaved materials (foam concrete and non-autoclaved aerated concrete)? We will try to answer this question in this article.

Several terms are common for building materials made of cellular concrete - aerated concrete, foam concrete, in addition there are characteristics such as autoclave and non-autoclave. Let's look at the definitions. Cellular concrete - This common name all lightweight concretes, which are characterized by the presence of many pores (cells) in their structure, which impart improved physical and mechanical properties to the material.

According to the method of pore formation, cellular concretes are divided into foam concrete And aerated concrete. As the name suggests, one material uses chemical foam, and in the other gas.

Foam concrete is a cement-sand mortar frozen in a porous state. The cellular structure in it is formed by introducing and “beating” chemical foaming agents. As a rule, a workshop for the production of foam concrete (“a factory” is extremely difficult to call this factory), small in area with a predominance of manual labor and unqualified personnel. The production volume is extremely small, the turnover of funds is low, so in such production you have to save on literally everything, which clearly does not contribute to improving the quality of the finished product.

Saturation of concrete with gas released during the reaction of lime and aluminum paste is a rather complex process and requires careful control over the dosage of these components. This can only be achieved in large factories with high-quality automated equipment, and until recently the term “aerated concrete” already by default meant the presence of autoclave processing. Thus, gradually a stable and completely objective opinion: foam concrete is cheap and has mediocre characteristics; aerated concrete – a little more expensive, but significantly better quality and stable properties.

IN competition for the buyer, foam concrete manufacturers, instead of reducing prices or improving the quality of their products, decided to simply move away from the completely discredited term “foam concrete”, replacing it with a more euphonious one - NON-autoclaved aerated concrete. In essence, the material has not changed, now a little gas-forming agent is added to the same chemical foam, then everything is also poured into the formwork and the solution gains strength under open air. For the end consumer, apart from increasing the price of the product, this renaming does not bring anything.

What is autoclaving and why is it needed?

Autoclave processing - steaming in metal capsules (autoclaves) at high blood pressure(12 atm.) and high temperature (191 o C) - allows you to obtain a material with properties that cannot be obtained under normal conditions. Autoclaving of aerated concrete is carried out not only to speed up the hardening process of the mixture. The main idea is that in an autoclave, changes occur at the molecular level in the structure of aerated concrete, and a new mineral with unique performance characteristics is formed - tobermorite. That's why autoclaved aerated concrete- This artificially synthesized stone, A non-autoclaved concrete– virtually frozen in a porous state cement-sand mortar.

Autoclaved aerated concrete and non-autoclaved materials differ fundamentally in a number of parameters, ranging from composition to physical, technical and operational characteristics. And to be more precise, autoclaved aerated concrete surpasses them in everyone indicators.

Let's look at the main indicators:

1. Stability of the quality of autoclaved aerated concrete

Autoclaved aerated concrete manufactured only in large production and arrives at the construction site in the form of finished blocks. The production of autoclaved aerated concrete in artisanal conditions is impossible, since during production it is necessary to simultaneously control several dozen processes and parameters. Modern autoclaved aerated concrete plants have a high degree of automation (about 95%) and practically eliminate the influence of the human factor on the production process.

Autoclaved aerated concrete is produced in accordance with modern GOST 2007, which is confirmed by test reports, the products have a quality certificate, and the client can be sure of the proper quality.

The production of foam concrete and non-autoclaved aerated concrete does not require a large plant and huge capital investments, which ensures a low barrier to entry into this business. In practice, this means that having a small concrete-mortar plant, formwork and a couple of low-skilled workers, you can organize a handicraft production with unstable quality indicators, proudly calling it a plant or factory for the production of building materials. It is almost impossible to ensure the stability of product characteristics under such conditions, since the dosing of components is done manually and, as a rule, “by eye”, and old GOST, which is already more than a quarter of a century old, allows the production of such products.

2. Strength

Cellular concrete is produced in various densities: from 400 to 800 kg/m3 with a compressive strength class from B1.5 to B7.5. The most popular densities are D500 and D600, while autoclaved aerated concrete at these densities has a compressive strength class of B2.5 and B3.5, respectively.

Non-autoclave materials are significantly inferior autoclaved aerated concrete By physical properties and strength at the same density. For example, with a density of D600, they have a compressive strength two times lower than that of autoclaved aerated concrete! In addition, manufacturers of non-autoclave materials simply cannot produce building blocks with a density below D600, because These blocks have no strength at all, and their use in construction is unacceptable.

3. Possibility of fastening

Autoclaving significantly increases the strength characteristics of aerated concrete. To the base of autoclaved aerated concrete You can fix not only cabinets and shelves, but also boilers, air conditioners, and ventilated facades. Moreover curtain facades can be made from either light composite or heavy porcelain stoneware. For this purpose, anchors with polyamide expanding elements are used. For example, one 10x100 anchor can withstand an axial pullout load of up to 700 kg, which is quite comparable with the performance solid brick or heavy concrete.

There is simply no need to talk about fastening into foam concrete or non-autoclaved aerated concrete. The nail or screw is simply pressed into the wall by hand, so the use of conventional mechanical fasteners is not possible here. An expensive two-component chemical anchor can be used to attach non-heavy objects, such as mirrors or coat hooks, which gives at least some illusion of reliability. But when hung on the wall kitchen set Even the use of “chemistry” will not help, because... under the weight of the cabinet with dishes, the non-autoclave material will collapse at the attachment point and a piece of the block will simply fall out of the wall.

4. Uniformity

In production autoclaved aerated concrete gas formation occurs simultaneously throughout the entire volume of the material. In parallel with gas formation, curing occurs. As the mass grows, a pulse is periodically applied to the formwork from special vibrators attached to it, which “shakes” the mass, expelling large gas bubbles from it and eliminating the presence of shells and air bags in ready-made blocks. As a result, the pores are of the same size and evenly distributed throughout the entire volume of the material. Building blocks from autoclaved aerated concrete obtained as a result of cutting a large array, which guarantees ideal and identical quality of all blocks.

Non-autoclaved aerated concrete and foam concrete obtained by introducing foam and gas-forming agents into the concrete mass and mixing it. As a result, it often happens that bubbles, like lighter components of the mixture, float up, and heavier fillers settle down. It turns out uneven distribution of pores in the block, and due to this it is not possible to achieve uniform characteristics on different blocks. The technology for producing non-autoclaved aerated concrete eliminates the possibility of shaking the mass, so the presence of bubbles with a diameter of 50-70 mm is common. In such material, colder sections of the wall often appear with condensation on the surface, as well as cracks in places where the masonry is weakened by large air bubbles.

5. Drying shrinkage

The strength gain of non-autoclaved cellular concrete is accompanied by significant shrinkage, which, in turn, leads to cracking of the finished masonry. Very often we see how multiple cracks appear on a newly built and finished building, the finishing layer peels off, and the plaster falls off. These processes can take place over several years - the same period while the “strength is gaining.”

Moreover, the blocks are riddled with cracks even before they are laid into the masonry. You can only get rid of shrinkage and cracks by autoclaving, but in artisanal production this is impossible. Therefore, sellers of foam concrete and non-autoclaved aerated concrete go to marketing gimmicks, adding fiber (paper impregnated with a solution of sulfuric acid and calcium thiocyanate) and calling it "reinforced foam concrete" resistant to cracking. For the end consumer, again, apart from increasing the cost, fiber does not give anything, because any person, even not associated with construction industry, understands that if you add paper to concrete, then the material will not have any miraculous properties promised by foam concrete sellers.

It should be noted that the lighter (and as a result, warmer) the material, the more shrinkage. Construction experience shows that walls made of non-autoclaved cellular concrete cannot simply be puttied and painted - they have to be covered inside with plasterboard, and to exterior finishing use suspended facades with fastening into the ceiling or brick.

Autoclaved aerated concrete It has fully gained strength already during the production and autoclaving process, so it is not threatened by shrinkage deformations.

For example, for autoclaved aerated concrete the shrinkage rate does not exceed 0.4 mm/m, while for non-autoclave materials it is 10 times greater - up to 5 mm/m.

6. Environmental friendliness

Autoclaved aerated concrete is an absolutely environmentally friendly and air-permeable material. Therefore, in a house made of autoclaved aerated concrete there is always a favorable microclimate for living, similar to the climate of a wooden house. Aerated concrete is made from mineral raw materials, therefore it is not at all susceptible to rotting, and due to the ability to regulate air humidity in the room, the likelihood of fungi and mold appearing on it is completely eliminated.

Foam concrete can be made from the cheapest local raw materials: sand, waste from crushed stone production, in addition, chemical additives are used as foaming agents, which undoubtedly reduces the environmental friendliness of a house made of foam concrete. Also, chemical components are introduced into the block with fiber impregnated with acids, chlorides and thiocyanates. Even present in small quantities, these substances can be released and accumulate in the air of residential premises.

7. Geometry

Accuracy of block geometric dimensions from autoclaved aerated concrete regulated by modern GOST, permissible deviations– length up to 3 mm, width up to 2 mm, thickness – up to 1 mm. The blocks are obtained by cutting a large mass of autoclaved aerated concrete with strings, and it is simply impossible to cut unevenly with such equipment.

Non-autoclaved aerated concrete and foam concrete are poured into formwork with limited cycles of use. Due to the same savings, the formwork is used several times longer than its standard service life, and since the formwork is dismountable, due to its deformation and wear, it becomes more and more difficult to assemble it correctly each time - hence the deviations in the geometry of the blocks. For non-autoclaved aerated concrete and foam concrete, deviations in geometric dimensions are allowed significantly more - the thickness can reach 5 mm (old GOST of 1989).

A large variation in the geometric dimensions of blocks made of non-autoclave materials leads to a deterioration in all masonry parameters:

• - the thickness of the mortar layer increases, leading to an increase in the cost of masonry
• - shrinkage of the masonry increases, because In addition to blocks, thick mortar joints are also shrinked
• - cold bridges are formed due to thick mortar joints
• - labor-intensive alignment required vertical surface walls
• - consumption of cement-sand mortar is 5-6 times higher than masonry adhesive
• - thickness and labor intensity increases finishing works
• - the strength of the masonry decreases

8. Thermal insulation properties

The density of foam concrete or aerated concrete directly affects their thermal insulation properties and the denser the material, the lower the thermal insulation. Foam concrete or non-autoclaved aerated concrete with low density is excellent thermal insulation material, but its strength is extremely low and cannot be used for laying walls. As a constructive, especially for load-bearing walls, a higher density is required, which means the material will be “cooler”. For example, for the Irkutsk region, when using non-autoclave materials, the density of cellular concrete should be at least 700 kg/cubic. meter. The already outstanding thermal insulation properties are significantly worsened by laying the masonry on cement-sand mortar with thick seams. This means that the thickness of a wall made of foam concrete or non-autoclaved aerated concrete with a density of D700 for normal thermal insulation without the use of insulation should be about 65-70 cm.

wall of autoclaved aerated concrete provides the same performance thermal protection and durability with thicknessonly 40 cm, while the density D400-D500 is sufficient. Objectively autoclaved aerated concrete has better strength and thermal insulation characteristics than non-autoclave materials and is lighter in weight.

Let's sum it up

• - Autoclaved aerated concrete surpasses non-autoclave materials in physical and technical properties due to autoclave processing.
• - Autoclaved aerated concrete produced only on modern factories with stable guaranteed quality at the level of world standards.
• - Autoclaved aerated concrete differs from non-autoclave materials in higher strength with less weight.
• - Autoclaved aerated concrete does not shrink during use.
• - Blocks from autoclaved aerated concrete differ in precise dimensions and uniform mass density.
• - Autoclaved aerated concrete is an artificial natural mineral, which determines the highest level of its environmental friendliness.
• - Application autoclaved aerated concrete allows you to build thermally efficient house with a homogeneous 400 mm wall that does not require insulation.

Building houses from non-autoclave materials is cheaper only at first glance. If we take into account the poor geometry of non-autoclave materials, worse thermal insulation and strength indicators compared to autoclaved aerated concrete, and the need for greater consumption of masonry and leveling materials, then there is no benefit in building from non-autoclave materials.

Autoclaved aerated concrete is a type of porous concrete processed in a special way. Manufacturing technology provides such positive traits such as lightness, high vapor permeability, dimensional accuracy and excellent thermal insulation. The scope of application is practically not limited by the climatic characteristics of the regions and the size of the structure: it is used both in private construction and in industrial construction. But when choosing, it is important to take into account some requirements for masonry and subsequent finishing, due to fragility and hygroscopicity.

The blocks are made of concrete, filler and water. A mandatory component is a foaming agent – ​​aluminum powder. Reacting with lime, it forms many bubbles distributed throughout the mass. The size of the cavities varies from 1 to 3 mm, they communicate with each other, but are closed. Finished elements - solid cement mixture, consisting of ⅔ pores. This makes the material very light and significantly reduces the cost of raw materials. Weight depending on density – from 300 to 700 kg/m3.

The composition of autoclaved and non-autoclaved aerated concrete is identical:

• wet-crushed quartz sand or washed natural fine sand – 30-40%;
• Portland cement M400, M500 – from 15 to 50%;
• lime – 12-26%;
• aluminum powder or paste as a gas-forming agent – ​​0.1-1%;
• chemical additives that regulate foaming and hardening speed (caustic soda, sodium sulfate, calcium chloride) - 0.05-0.45%;
• water – 45-70% of the total weight of all dry ingredients.

Each manufacturer selects its own recipe and ratio of components; fillers are often replaced with industrial waste and aerated concrete.

Production technology

Autoclave blocks are manufactured in accordance with GOST 31360-2007.

• In a ball mill, sand is mixed with water and ground to form sand slurry.
• Sand with all other components is placed in an airtight container.
• A homogeneous mixture with an introduced blowing agent is poured into large molds up to half the volume.
• After foaming is completed, it is sent for pre-hardening.
• Solid large blocks are cut into standard elements and form a tongue and groove.
• Placed in a special installation - an autoclave. In it they are treated with hot steam and high pressure.

It is the production process that distinguishes autoclaved aerated concrete from non-autoclaved aerated concrete. The latter is immediately poured into molds the right size and dries naturally, therefore it has large discrepancies from the standard dimensions, less clear corners and is inferior in strength. Its production does not require the purchase of an expensive autoclave, and therefore such a product is less expensive.

Autoclaving removes remaining moisture and changes the characteristics of the material particles. They are converted into an artificial mineral - tobermorite. Products obtained by this method are much stronger, withstand more freezing cycles and have an extended service life. The block is in the autoclave chamber for at least 10 hours.

Advantages and disadvantages of aerated concrete

Autoclave elements have improved performance characteristics, but the whole group is united by big row advantages over other types of products for the construction of walls, ceilings and partitions:

1. The dimensions are standardized, the maximum deviation of the geometry does not exceed 2-3 mm - this allows you to make a thin seam, devoid of cold bridges.
2. Aerated concrete is easy to process, cut and drill.
3. Not included harmful substances. The aluminum content is minimal, and it is in a bound state, so the material is considered environmentally friendly. Even exposure to open fire does not lead to the release of toxic fumes.
4. Complete fire safety. The blocks not only do not burn, but are also able to withstand prolonged exposure high temperatures without destruction.
5. The breathable structure creates a favorable microclimate in the room with optimal humidity.
6. Not susceptible to any biological effects and decay.

A building made of aerated concrete can have thin walls and still be warmer than a standard one brickwork. This reduces heating costs by 25-30%. Soundproofing properties are several times better compared to concrete, wood and brick.

The light weight of the blocks ensures savings on the construction of the foundation. This also allows you to make elements big size, while lifting for one person. Construction proceeds much faster and without the use of special equipment.

The main drawback is hygroscopicity, but it can be easily eliminated: it is enough to cover the walls under the finishing immediately after completion of the work. Care is required, as the products are fragile and can break if struck. There are strict restrictions on the number of storeys for elements of different densities and requirements for strengthening window and doorways. Autoclaved aerated concrete has a high cost compared to non-autoclaved aerated concrete.

Scope of application

By changing the number and size of pores (density) and the ratio of the main components, manufacturers obtain blocks with different properties:

1. Thermal insulation with a density of up to 400 kg/m3. It is worth purchasing for the construction of small buildings or insulation of walls made of other materials.
2. Structural and thermal insulation – 500 kg/m3. They can be purchased for a private or low-rise home.
3. Structural, the most dense - 700 kg/m3. Suitable for load-bearing walls, but with load restrictions. The structure must be no higher than 3 floors.

Autoclaved aerated concrete is used mainly in private construction for the construction of cottages, country houses, garages, outbuildings. But it is also suitable for load-bearing walls of low-rise buildings, as well as for masonry in frame structures without restrictions on the number of floors. It is successfully used to create insulated attics.

4.5 / 5 ( 2 voices)

Aerated concrete is classified as cellular concrete and consists of evenly closed air pores, equally distributed throughout the material. Aerated concrete blocks are an environmentally friendly and high-quality product. They are released in exact dimensions and have correct form, can be easily processed and are ideal for finishing.

Aerated concrete is distinguished by the type of binder composition and type of hardening. The product, processed at high pressure and temperature in a specialized oven - an autoclave, is called autoclaved aerated concrete. He has many positive characteristics, and the use of this material improves the quality of construction, and, importantly, significantly reduces the cost of constructing the structure.

Such cellular concrete is made from crushed quartz sand, gypsum, cement, lime (quicklime), andrigid and water. At the exit, autoclaved aerated concrete is 2/3 filled with air pores. Proportions aerated concrete solution for an autoclave oven according to the standard:

• cement - 20%;
• quartz sand - 60%;
• quicklime - maximum 20%;
• aluminum residues - no more than 1%.

Manufacturing process of autoclaved aerated concrete

It is manufactured using the following technology:

• Sand and water are combined and ground into sand slurry.
• The resulting mass is poured into a mold for a chemical reaction between an alkali solution and highly dispersed aluminum. This process promotes hydrogen formation to produce bubbles.
• Hydrogen bubbles foam the solution and create a porosity structure. It is at this stage that the concrete is distributed into molds and left to mature and harden for 2-3 hours.
• The hardened material is cut with industrial strings into blocks of a given size.
• The blanks are sent to the final stage - steaming in an autoclave, where the blocks are processed in temperature conditions 180-200 degrees under pressure for 12 hours. An autoclave is a sealed chamber where a product that requires heating under pressure exceeding atmospheric pressure is processed.

Autoclaving removes excess moisture from the product, completing the hardening process, after which cellular concrete acquires its final properties.

Advantages of porous autoclaved concrete

The uniqueness of this material lies in:

• low thermal conductivity;
• increased fire resistance, it is able to hold fire for up to 7 hours or more;
• breathability due to increased breathability;
• mechanical strength;
• lightness due to low density;
• immunity to pest attack;
• resistance to rotting and moisture;
• ensuring the correct microclimate in any season.

Gas blocks can hold fire for up to 7 hours or more

The fact that autoclaved aerated concrete blocks combine the main qualities of wood and brick makes it a unique product. And if we take into account the high frost resistance of the material (it can withstand up to hundreds of freezes and defrosts), it becomes clear that this construction material can be used regardless of regional climate, without exception.

It is also worth noting the flexible indicators of such a block. Its flexibility allows you to create structures of various shapes, embodying various architectural ideas.

The scope of application for the autoclave block is very wide: construction of cottages, low-rise and high-rise buildings, industrial and commercial construction, reconstruction work, construction of foundations. Autoclaved aerated concrete does not require a large set of tools for work. Quite enough:

• notched trowel (for working with mortar);
• large-toothed hacksaw (for sawing non-standard);
• coarse sandpaper (for leveling);
• rubberized mallet (for laying blocks);
• containers for the solution (any convenient one, a bucket is also possible).

Features of autoclaved aerated concrete

Porous concrete is special due to its low weight. Thanks to this, production allows the production of increased sizes, namely: length - 62.5 cm, height - 20 (up to 25) cm, width - 10 (up to 40) cm. Cellular concrete is very lightweight material. Its lightness and increased size make construction from it easier and speed up the process several times. It makes installation so easy that not only a specialist, but also an ordinary consumer can handle it.

The advantage of aerated blocks is perfectly even corners and plane

Almost all batches in the production of such products provide units of the same size. The maximum error is from 1.5 to 3 mm for any direction. Such forms increase the corner and rib standards for release. The result is clear geometric proportions due to the autoclave firebox. It is in it that surfaces acquire smoothness and corners become clear.

For laying concrete bricks it is recommended to use glue solution. Such a layer will not only be more economical option, but will also ensure the solidity of the building. This means it will maintain and increase its thermal insulation performance. If you choose a solution, add some glue to it, and also ensure that the mixture is more soft. This will help avoid “cold bridges” on the seam.