Today builders are increasingly resorting to the use of modern, lightweight materials that are not inferior to traditional ones. These include aerated concrete. Blocks are obtained by two methods - non-autoclave and autoclave. What is the difference, how the materials differ, and most importantly - which one is better to prefer?

Which one is preferable?

Fake diamond

• cement;
• lime;
• quartz sand;
• aluminum powder (as a result of the reaction of its aqueous suspension with lime, hydrogen is released, due to which bubbles appear in aerated concrete).

A small amount of gypsum is also added to slow down the thickening of the mixture.

Technology

The composition is mixed automatically. Then it is poured into molds (up to about half). As the mass thickens itself, it rises to the brim, it takes about an hour or two. After that, aerated concrete is cut into blocks using special equipment, and sent to an autoclave oven for twelve hours. There, at an elevated pressure of 12 atmospheres, it is treated with water vapor heated to a temperature of 190 ° C, acquiring the required strength.

Features and benefits

Autoclave production of blocks gives them a number of special advantages. Among them:

• high thermal insulation properties (several times better than that of the usual brick);
• good sound insulation;
• resistance to moisture, mold;
• the correct shape, which allows you to make even masonry, decoration;
• ease of processing, quick installation;
• minimal shrinkage during construction.

disadvantages

The disadvantages of autoclave blocks include their certain fragility (you need to carefully handle the material during loading and unloading, transportation and directly laying). Even for work with such walls, special fasteners are required, ordinary dowels, screws, self-tapping screws - there are no helpers here.

Output. Aerated concrete that has been "hardened" in an autoclave installation is good and relatively inexpensive alternative traditional building materials. It is produced in the factory, which provides for quality control of finished blocks. However, as experts note, their laying should be done correctly, in compliance with the technology.

Natural hardening

Composition

The composition of non-autoclaved lightweight concrete includes:

• portland cement;
• sand (clean or with an additive in the form of fly ash remaining after combustion at thermal power plants of solid fuel);
• aluminum powder (as in autoclave production, it is used as a blowing agent);
• calcium chloride (accelerates the hardening process);
• various additives.

Technology

Non-autoclave manufacturing involves the same chemical reaction with the release of bubbles. The resulting mass with pores is also poured into molds, but left to solidify by itself, in natural conditions. To give the material greater strength, a steaming chamber is often used. For the same purposes, in the non-autoclave method of hardening, it is also practiced to "mix" additives with reinforcing properties (for example, polymer fiber, glass fiber).

disadvantages

The finished block has virtually the same properties as the autoclave one, only they differ not for the better. So, lower thermal insulation performance is inherent. It is not so strong, it gives a lot, so it is not used in load-bearing structures.

Unlike its "brother" in class, non-autoclave material does not stand out with ideal geometric shapes - when it is laid, the layer of mortar will be thicker, and the leveling of surfaces will be more difficult.

Initially, the technology for creating aerated concrete provided for its production only at a technological production. But over time, the demand for this material has increased so much that autoclaved aerated concrete began to be used in equal measure with a similar type of cellular material, produced without additional heat and moisture treatment. And if an unprepared beginner dives into the abyss of a huge selection of aerated concrete, he can easily drown in the flow of information provided about him. So what is the difference between autoclaved aerated concrete and non-autoclaved aerated concrete and which one is best to buy? You will find answers to these burning questions in our publication.

Aerated concrete production technology

Before talking about the significant differences in the properties and quality of autoclaved aerated concrete and natural aging blocks, consider their component composition, which is absolutely identical:

• no additive Portland cement grades M300, M400, sometimes M500 is used;
• clean sand of fine fractions - from 2.0 to 2.5 mm.
• water of medium hardness without chemical impurities;
• gasifier - aluminum powder or paste;
• a substance that triggers chemical swelling reactions - lime, the type, state and dispersion of which depends on the method of production;
• modifiers that improve the quality of the final product are added at will and are not required components.

Another similarity uniting autoclaved and non-autoclaved aerated concrete is the principle of mortar production.

At the first stage, in accordance with the technology, a conventional cement-sand mortar of the required consistency is prepared. The resulting mixture is distributed over the formwork. After that, aluminum powder and lime are introduced into it. It is the reaction of these components that ensures the formation of gas, the solution swells, forming pores.

Further, technologies diverge at the stage of exposure and processing of aerated concrete. With natural hardening, the ready-made mortar is poured into the formwork, which forms blocks of the desired size. After gaining strength, the products are unfolded and sent to the finished product warehouse.

When using an autoclave for aerated concrete, this stage is a little more complicated. Namely, the mixture is poured into a monolithic formwork. After swelling and gaining minimum strength, the aerated concrete block is cut into products of the required dimensions and sent for additional firing to an autoclave, where the temperature is maintained within 200 0 C and a pressure of 10 bar. Such conditions activate the processes of cement hydration to the maximum and allow removing excess moisture from the concrete.

As a result, it turns out that naturally dried products are just a hardened expanded cement-sand mixture, when autoclave gas blocks in the process of firing, they form a new synthetic component - tobermorite, which qualitatively improves the characteristics of the final product.

Properties of non-autoclaved and autoclaved aerated concrete

The resulting blocks, made using two different technologies, are so different both in appearance and in their characteristics that even an inexperienced man in the street can distinguish between them.

External indicators

The first thing the buyer faces when choosing is the appearance of the materials. It would seem, what's the difference how the wall blocks look, which subsequently still need to be plastered. but appearance - the most accurate visual characteristic that will help weed out low-quality products.

Geometric dimensions

If we compare gas blocks by the criterion of geometry, then the products autoclave hardening are more accurate. This is partly due to the autoclaving and of course the cut technology. Even GOSTs regulate deviations linear dimensions from nominal in different ways, depending on the applied production method.

These data only underline the fact that autoclaved aerated concrete is characterized by precise geometry of finished products, which prevents:

• freezing of walls due to thickening of the masonry seam, which compensates for deficiencies in the form of blocks;
• overspending of masonry glue, leading to an increase in costs for it.

Color

When buying blocks, pay attention to their color. Of course, it will be gray in the case of naturally hardened products and almost white in autoclaved aerated concrete. Differences in block shades and color irregularities indicate changes in production process, which often lead to a decrease in performance.

Automated equipment for the production of autoclaved aerated concrete reduces any errors to zero, which is initially considered a guarantor of quality and durability. In addition, such large-scale workshops are supplemented by their own construction laboratory, the timely testing of which isolates inconsistencies in technology or recipes.

Physical and mechanical properties

Aerated concrete blocks differ not only in appearance and color, but also in physical and mechanical properties.

Strength

Aerated concrete is represented by a rich nomenclature of strength grades - from B1 to B7.5. They are widely used not only as a creation load-bearing structures, but also for wall insulation. If we compare aerated concrete produced using different technologies, then autoclave ones are distinguished by greater strength at the same density as non-autoclave ones.

For example, blocks with a density of D600 must have a strength class of B3.5. If for autoclaved products the indicator is observed, then with naturally aged products the strength class hardly reaches half the norm. The situation is even worse with the strength indicators of self-made aerated concrete. If you want to see for yourself, buy a block and test it in an independent construction laboratory. The results will be obvious.

Thermal conductivity

The thermal conductivity of aerated concrete directly depends on the density of this material. The lower the brand in terms of block density, the better its thermal capacity properties. It is wiser to purchase products of lower density, but with higher strength characteristics, thereby reducing the thermal conductivity of the walls.

Shrinkage

The weakest side of any aerated concrete is its shrinkage after the walls are erected. If the wrong construction technique is used, cracks may appear and the plaster layer will peel off. The processes of shrinkage of natural-aged aerated concrete can last up to several years, when autoclaved blocks are practically devoid of such a drawback, since during heat and moisture treatment they have already reached brand strength and complete drying.

Moreover, the aged aerated concrete blocks in natural conditions are far from ideal indicators, which is negatively manifested in the form of shrinkage. This not only leads to a violation of the linear dimensions, but also to the destruction of the structure.

Summing up, we can easily conclude that autoclaved aerated concrete blocks have undeniable advantages over naturally aged products. But in any case, when buying such a wall material, always ask for documents certifying its quality.

Autoclaving of aerated concrete

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

Recently, in connection with the growing popularity of building blocks made of aerated 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.

There are several common terms denoting building materials made of aerated concrete - aerated concrete, foam concrete, in addition, there are characteristics such as autoclaved and non-autoclaved. Let's figure out the definitions. Aerated concrete - this is the general name for 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.

By the method of pore formation, cellular concretes are divided into foam concreteand aerated concrete... As the name suggests, one material uses chemical foamand in the other gas.

Foam concrete is a cement-sand mortar solidified in a porous state. The cellular structure in it is formed due to the introduction and "whipping" of chemical foaming agents. As a rule, the workshop for the production of foam concrete (it is extremely difficult to call this factory a "plant"), small in area with a predominance manual labor and unqualified personnel. The volume of production is extremely small, the turnover of funds is low, therefore, it is necessary to save in such production on literally everything that 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 complicated process and requires careful control over the dosage of these components. This can only be ensured in large factories with high-quality automated equipment, and until recently the term "aerated concrete" already by default meant the presence of autoclaving. So gradually a stable and quite objective opinion was formed in the consciousness of the consumer: foam concrete is cheap and with mediocre characteristics; aerated concrete - slightly more expensive, but much better quality and stable properties.

In the competition for the buyer, the producers of foam concrete, instead of reducing the price or improving the quality of their products, decided to simply leave the completely discredited term "foam concrete", replacing it with a more euphonic one - non-autoclave aerated concrete. In essence, the material has not changed, now a little gas generator is added to the same chemical foam, then everything is also poured into the formwork and the solution is gaining strength in the open air. For the end consumer, except for an increase in the price of the product, this renaming does not mean anything.

What is autoclaving and what is it for?

Autoclaving - steaming in metal capsules (autoclaves) at high pressure (12 atm.) And high temperature (191 o C) - allows you to obtain a material with such properties that cannot be obtained in normal conditions... Autoclaving of aerated concrete is performed not only in order to accelerate the hardening process of the mixture. The main point is that changes in the structure of aerated concrete occur in the autoclave at the molecular level, and a new mineral with unique performance characteristics is formed - tobermorite. therefore autoclaved aerated concrete - this is artificially synthesized stone, and non-autoclaved concrete - actually frozen in a porous state cement-sand mortar.

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

Let's consider the main indicators:

1. Quality stability of autoclaved aerated concrete

Autoclaved aerated concrete is manufactured only in large-scale 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 the manufacture it is necessary to simultaneously control several dozen processes and parameters. Modern plants of autoclaved aerated concrete have a high degree of automation (about 95%) and practically exclude the influence of the human factor on the production process.

Autoclaved aerated concrete is produced in accordance with the 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 aerated concrete and non-autoclaved aerated concrete does not require a large plant and huge capital investments, which provides a low threshold for entering this business. In practice, this means that with a small concrete batching plant, formwork and a couple of low-skilled workers, it is possible to organize handicraft production with unstable quality indicators, proudly calling it a plant or a factory for the production of building materials. It is practically impossible to ensure the stability of the characteristics of the product under such conditions, since the components are dosed manually and, as a rule, "by eye", and the old GOST, which is more than a quarter of a century old, allows the production of such products.

2. Strength

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

Non-autoclaved 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-autoclaved materials simply cannot produce building blocks with a density lower than D600, because these blocks have no strength at all, and it is unacceptable to use them in construction.

3. Mountable

Autoclaving significantly increases the strength characteristics of aerated concrete. At the base of autoclaved aerated concrete you can fix not only cabinets and shelves, but also boilers, air conditioners, ventilated facades. Moreover, curtain facades can be made of both light composite and heavy porcelain stoneware. For this, anchors with polyamide expandable elements are used. For example, one 10x100 anchor can withstand a pull-out load along the axis of up to 700 kg, which is quite comparable to the indicators of solid brick or heavy concrete.

There is simply no need to talk about fixing in 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. It can be used to attach non-heavy items, such as mirrors or clothes hooks, an expensive two-component chemical anchor, which gives at least some illusion of reliability. But when hanging on the wall kitchen set even the use of "chemistry" will not help, because under the weight of the cabinet with the dishes, the non-autoclave material will be destroyed 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. Curing occurs in parallel with gassing. As the array grows, an impulse is periodically applied to the formwork from special vibrators fixed on it, which "shakes" the array, expelling large gas bubbles from it and excluding the presence of shells and air bags in the finished blocks. As a result, the pores are of the same size and evenly distributed throughout the volume of the material. Building blocks from autoclaved aerated concrete are obtained as a result of cutting a large block, which guarantees the perfect and uniform quality of all blocks.

Non-autoclaved aerated concrete and foam concrete are obtained by introducing foam, blowing agents into the concrete mass and mixing it. As a result, it often happens that bubbles, as 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, there is no way to achieve uniform characteristics on different blocks. The technology for the production of non-autoclaved aerated concrete excludes the possibility of shaking the massif, therefore the presence of bubbles with a diameter of 50-70 mm is a common thing. In such a 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

Strength gain of non-autoclaved aerated concrete is accompanied by its significant shrinkage, which, in turn, leads to cracking of the finished masonry. Very often you see 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 for several years - the same period while the "strength gain" is taking place.

Moreover, blocks are covered with cracks even before they are laid in the masonry. You can get rid of shrinkage and cracks only by autoclaving, but in the conditions of handicraft production this is impossible. Therefore, the 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 the construction industry, understands that if you add paper to concrete, then no miraculous properties, promised by the sellers of foam concrete, the material will not appear.

It should be noted that the lighter (and as a result, warmer) the material, the greater the shrinkage. Construction experience shows that walls made of non-autoclaved aerated concrete cannot be simply putty and painted - inside they have to be covered with plasterboard, and for exterior decoration, hinged facades with fastening to the ceiling or brick must be used.

Autoclaved aerated concrete fully gained strength already in the process of production and autoclaving, therefore, shrinkage deformations do not threaten it.

For example, for autoclaved aerated concreteshrinkage index does not exceed 0.4 mm / m, while for non-autoclave materials it is 10 times more - up to 5 mm / m.

6. Sustainability

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 wooden house... Aerated concrete is made from mineral raw materials, therefore it is not at all susceptible to decay, and due to the ability to regulate the humidity of the air in the room, the likelihood of the appearance of fungi and mold on it is completely excluded.

Foam concrete can be made from the cheapest local raw materials: sand, crushed stone waste, in addition, chemical additives are used as foaming agents, which undoubtedly reduces the environmental performance of a foam concrete house. Also, chemical components are introduced into a 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 living quarters.

7. Geometry

Accuracy of geometric dimensions of blocks of autoclaved aerated concrete regulated by modern GOST, permissible deviations are up to 3 mm in length, up to 2 mm in width, and up to 1 mm in thickness. 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. In view of the same savings, the formwork is used several times longer than its standard service life, and since the formwork is collapsible, due to its deformations and wear, it becomes more and more difficult to assemble it correctly every time - hence the deviations in the geometry of the blocks. For non-autoclaved aerated concrete and foam concrete, deviations of geometric dimensions are allowed much more - in thickness they can reach 5 mm (old GOST 1989).

A large run-up in the geometric dimensions of blocks made of non-autoclaved materials entails 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 the blocks, thick mortar joints also shrink
• - cold bridges are formed due to thick mortar joints
• - laborious leveling of the vertical surface of the walls is required
• - consumption of cement-sand mortar is 5-6 times higher than that of masonry glue
• - thickness and labor intensity increase 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 an excellent thermal insulation material, but its strength is extremely low and cannot be used for masonry walls. As constructive, especially for load-bearing walls, a higher density is required, which means that the material will be "colder". For example, for the Irkutsk region, when using non-autoclave materials, the density of aerated concrete should be at least 700 kg / m3. meter. The already not outstanding thermal insulation properties are significantly deteriorated by masonry maintenance on a cement-sand mortar with thick joints. 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 strength at thickness only 40 cm, while the density of D400-D500 is sufficient. Objectively autoclaved aerated concrete has better strength and thermal insulation indicators than non-autoclave materials with less weight.

Let's sum up

• - Autoclaved aerated concrete surpasses non-autoclave materials in physical and technical properties due to autoclave processing.
• - Autoclaved aerated concreteproduced only on modern factories with stable guaranteed quality at the level of world standards.
• - Autoclaved aerated concrete differs from non-autoclaved materials in higher strength with less weight.
• - Autoclaved aerated concrete does not shrink during operation.
• - Blocks from autoclaved aerated concrete are distinguished by precise dimensions and uniform density of the array.
• - 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 a heat-efficient house with a homogeneous wall of 400 mm, which does not require insulation.

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

Gas blocks obtained by processing in autoclave ovens gained popularity and took a worthy place in industrial and residential construction. The material has many advantages over traditional ones, including natural ones, building materials... Automation of the technology for the production of gas blocks allows you to obtain products with specified controllable characteristics. First of all, we are talking about the high strength of the product and its low thermal conductivity, which is especially important against the background of the constant rise in the cost of energy resources.

Composition

Aerated concrete gets its amazing properties thanks to: limestone, Portland cement, calcium silicate, aluminum pastes (suspensions), calcium chlorides, water, etc., which are included in its composition in a strictly defined percentage with each other (to form products with given density characteristics etc.). The calculation of the components is in kilograms to obtain 1 m3 of the finished mixture. The binder can be lime, cement, slag, gypsum, both by themselves and in various mixtures. The most common base is cement with lime pieces. Additional additives allow the production of blocks different color and give the product specific properties.

Material advantages

Autoclaved aerated concrete has a number of technological, operational and production advantages. The blocks are lightweight, which is convenient when erecting walls. One piece of product can replace up to 20 masonry bricks, which speeds up construction. Factory products have a high manufacturing accuracy, which reduces the consumption of solutions, ensures the formation of flat surfaces.

Low provides heat retention in buildings without additional thermal insulation. Provides sound insulation and has the required degree of gas permeability (similar to wood). When heated, the material does not emit gases hazardous to health, and has a high fire resistance. It is also a neutral medium for microorganisms. Blocks are easily drilled and sawn even with a hand hacksaw.

Material processing is carried out with any tool. Products with a structural and thermal insulation density of the substance (from 500 kg / m3) are intended for the construction of walls of buildings from 3 floors and above. The durability of the products is tens of years. The construction cost is lower than that of other materials.

disadvantages

High-tech material (blocks) has the ability to absorb moisture from the environment and direct precipitation, so it needs additional waterproofing. After installation, the construction of walls made of gas blocks already has lower thermal insulation due to cold bridges, which are created by fastening mortars, armored belts, metal embedded, masonry seams, lintels, etc. Out-of-factory blocks do not have standard characteristics for this material.

Areas of use

Autoclaved aerated concrete is widely used in the construction of industrial buildings, residential and commercial real estate. From autoclaved gas blocks, external walls are erected, which can be single-layer, combined and two-layer. Such interior walls are designed to take on the load of the upper floors.

It is important to lay the first row perfectly straight.

Autoclave blocks can form partitions and walls of fire-fighting rooms, as well as fill steel or concrete frames. A separate area of \u200b\u200buse is the formation of floor slabs (density of autoclaved aerated concrete 800-1000 kg / m3) in structures. A material with a lower density (slabs) is used for thermal insulation of basements, attics, etc.

Autoclaved aerated concrete has been used in the production of wall panels for residential, public and industrial buildings. This applies to reinforced strip cut panels. For typical projects of large-panel buildings, such panels consist of several typical sections.

Production

High-quality autoclaved aerated concrete is manufactured in industrial conditions. All processes at the production sites are automated, which makes it possible to form aerated concrete products of different formulations with the required characteristics. The production is easily readjusted for the manufacture of products at the request of customers.

Preparation of components

For the production of autoclaved aerated concrete, not the quartz sand itself is used, but the product of its processing, obtained by wet grinding in ball mills. Further, the sand slurry is additionally processed to the desired consistency in the slurry tanks. The compacted material is pumped into the units, which form the required weight proportions of the components.

Dosage and mixing

For this, special automated modules are used with a capacity of up to 40 cubic meters of products per shift. Sufficiently wide range of mixing proportions raw materials allows to form autoclaved aerated concrete with specified characteristics. The dosed components of future products are mixed with water, aluminum suspension and lime (Portland cement, etc.) in a mixer according to a given program.

The molds with the mixture are transported to the maturing and pre-hardening chamber.

The addition of gypsum slows down the thickening process. After the mixture reaches the density of the pouring sour cream, it is poured into molds to half the level. Regulation of the amount and ratio of aluminum and lime determines the amount of hydrogen gas released and, as a result, different density aerated concrete. Impact loads on forms accelerate chemical processes replacement of hydrogen in voids with air in aerated concrete, increasing the volume of material and filling forms with it. Primary aging and hardening of the material takes place.

Currently, the demand for building blocks made from aerated concrete is growing rapidly and one often hears the question: "What is the difference between autoclaved and non-autoclaved aerated concrete?" Within the framework of this article, we will discuss the main differences and performance of these products.

Material characteristics

First you need to clarify the terminology. Cellular concretes are understood as all lightweight concretes during the manufacture of which cells (pores) are formed in the structure. In turn, it is divided into aerated concrete and aerated concrete, depending on the technology for creating pores. The next stage of division arises depending on the hardening process - autoclave or non-autoclave.

Autoclaving

When steaming the mixture necessary for the production of aerated concrete at a pressure above 12 atmospheric and a temperature above 190 degrees Celsius in devices called autoclaves, one obtains new material with characteristics that cannot be obtained under normal conditions - this process is called autoclaving. As a result, the structure of concrete changes at the molecular level and a new material with completely unique characteristics is obtained, called tobermorite.

Non-autoclaved concrete is cured naturally or with steam, but under normal atmospheric pressure mortar with pores, while autoclaved aerated concrete is an artificial stone. They are fundamentally different in many respects. They have a different composition and different physical and technical parameters, which are an order of magnitude higher for autoclaved aerated concrete.

Main characteristics of materials:

Quality

The quality of autoclaved aerated concrete is always, without a doubt, since its production is extremely difficult and impracticable in artisanal conditions technological process... During production, it is necessary to simultaneously control many processes and parameters; for this, in modern factories, the degree of automation reaches 95 percent and practically excludes the possibility of non-compliance with the technology due to human fault. Manufacturing usually takes place in large factories and the material is brought to the construction site already in the form of finished building blocks. The technology is described in the modern GOST of 2007 and must be confirmed by test reports and product certificates. For the manufacture of foam blocks and aerated concrete, such capacities are not required and at first glance it seems like a plus. After all, the products are cheaper. But can you eliminate the risk of low-quality production or even handicraft production? When buying autoclaved aerated concrete, this question will not arise, because you can always be 100% sure of its quality.

Uniformity

Non-autoclaved aerated concrete is produced by adding a gas generator to the concrete mass and mixing it. As a result, there are cases in which the bubbles, having less weight, float up, and the fillers, on the contrary, settle down. As a result, finished products in the form of building blocks are heterogeneous and may even have different parameters. In the case of the production of autoclaved aerated concrete, everything is completely different. The process of gas formation and hardening occurs simultaneously and proceeds uniformly throughout the volume of the material produced. As a result, the pores in the finished material are evenly distributed and after the completion of the stage of cutting the finished material into building blocks, they are obtained with an ideal quality and a homogeneous structure.

Mountings

Since aerated concrete is very strong, it is possible to fix heavy materials and equipment on it. For example, ventilated facades made not only of light materials, but also heavy ones of porcelain stoneware. In order for the fastening to be reliable, anchor bolts with polyamide expandable elements are used. As a result, when using, for example, a 10x100 anchor, a pull-out load along the axis of up to 700 kg is maintained, which is very close to the values \u200b\u200bof a solid brick.

Shrinkage

During the gaining of strength, significant shrinkage of non-autoclaved aerated concrete occurs, as a result of which cracks appear in the finished masonry, plaster falls off or the finishing layer peels off. All this lasts for 3-5 years until the material reaches its strength. Often, when using such materials, it is impossible to just putty and paint the walls, as a rule, more complex work is required. Inside, you have to finish plasterboard, and outside use bricks or curtain facades. Such problems do not arise when using autoclaved aerated concrete, since it gains its strength even during the production process. For comparison, the shrinkage rate of autoclaved aerated concrete is 0.5 mm / m, but non-autoclaved from 1 to 3 mm / m.

Manufacturing precision

In the production process for non-autoclaved materials, they rely on indicators of permissible values \u200b\u200bfrom the old GOST, as a result, the finished building blocks have a large difference in geometric characteristics. For autoclaved aerated concrete blocks, such problems do not exist, since all production is carried out according to modern GOST and the discrepancies in the parameters of the finished product are minimal. Due to the large error in geometric dimensions, a number of problems arise when using non-autoclaved aerated concrete:

• Increases required amount solution and, as a consequence, the cost of construction.
• Cold bridges are formed due to thick seams.
• Leveling the surface of the walls becomes a rather laborious process.

Thermal insulation

The thermal insulation level of both materials is very good. But you can consider this issue from the side of efficiency of use different materials and costs to achieve the same effect. The level of thermal insulation, among others, is influenced by such an indicator as the density of the material. The higher the density level, the lower the thermal insulation values \u200b\u200bof the building blocks will be. For example, to use the material as a structural one, and even more so for load-bearing walls, high strength is required. To achieve the required performance using non-autoclaved aerated concrete, a density of at least 700 kg / m3 is required. This means that for high-quality thermal insulation, the wall thickness should be about 65 cm.Under the same conditions, to achieve the required level of strength, autoclaved aerated concrete with a density of 500 kg / m3 can be used and the wall thickness will already be about 40 cm.

Outcome

At first glance, when building houses, it seems obvious that the price advantage is not in favor of autoclaved aerated concrete. But in the end, taking into account all the shortcomings of non-autoclave materials and the amount required to eliminate them, this plus comes to naught. Autoclaved aerated concrete is superior to non-autoclaved aerated concrete in almost all respects.