What is autoclaved aerated concrete? The main differences between autoclaved and non-autoclaved aerated concrete blocks: properties, characteristics, application Autoclaved aerated concrete characteristics.

• Preparation of components. Some components come to production ready-made, while others undergo preparation. Quartz sand combined with water is ground to form sludge, and then constantly mixed in sludge basins and brought to the desired level. Aluminum powder also undergoes pre-production preparation.
• Dosage and mixing. Dosing and preparation of the mixture is performed automatically. All components, prepared in advance, are accurately weighed and filled into a large mixer. The prepared mixture is poured into metal molds - baths ½ of the volume. As a result, a chemical reaction of the components occurs with the formation of hydrogen and the block fills the entire mold and becomes porous. Hydrogen bubbles can be up to 3 mm. But the main thing is that they are almost uniform. This gives a homogeneous structure. Mixing time for all components is 5 minutes at high speed.

Aluminum powder is an explosive element, so strict compliance is required fire prevention measures in the room where AGB is produced.

Differences between autoclaved and non-autoclaved aerated concrete

The differences between the two building materials very large, from production to aging before delivery to the consumer. The composition of their recipes may be the same, but the technology in which autoclaved aerated concrete takes on the qualities artificial stone, differs significantly.

Specifications for comparison are presented below.

An important factor is saving time on assembling building structures. Due to the precise cutting of the AGB already at the factory to known dimensions, it takes less time to adjust at the construction site and, accordingly, the process is less labor-intensive.

The automated process makes such aerated concrete expensive, but the benefits and advantages indicate the right investment. Autoclaved aerated concrete higher quality, and proven with the best side what is it in technical properties, and by appearance. Manufacturing technology makes aerated concrete an excellent material both for the construction of buildings and for creating a business.

Aerated concrete is a popular building material, the main application of which is the construction of buildings 1-3 floors high. Low density and high thermal resistance make it possible to build walls from aerated blocks, the weight of which is 3-4 times lower than the weight of similar brick walls. Today, this is the only building material suitable for the construction of durable and warm walls minimum thickness.

This article discusses two types of aerated concrete - natural and autoclave curing. We will study their raw material composition and production technology, get acquainted with the differences, advantages and disadvantages, and also determine which cellular concrete is better.

Autoclaved aerated concrete is superior to natural hardening material in all performance characteristics. Let's look at its main advantages:

1. Stable quality. The production of autoclaved aerated concrete is possible only in large-scale production conditions, while a non-autoclaved analogue can be made even at home, which is why blocks of dubious quality often end up on the market.
2. Strength. Autoclaved aerated concrete is produced in densities D400-800, its compressive strength varies between B1.5-B5, while the maximum strength of non-autoclaved material does not exceed B3. On a wall made of thermally hardened blocks, you can mount not only cabinets and shelves, but also more heavy objects- speakers, air conditioners, the weight of which non-autoclaved cellular concrete cannot withstand.
3. No shrinkage during operation. Shrinkage associated with the evaporation of moisture contained in the material is the main reason for the appearance of cracks on walls made of aerated blocks. The lower the density of the material, the more it shrinks during the process of residual strength gain, which continues for 5-10 years after the production of the blocks. Atoclaved aerated concrete shrinks by an average of 0.5 m/mm, while non-autoclaved aerated concrete shrinks by 2-3 mm/m.
4. Geometry. Blocks cut from solid wood always have smaller deviations from the design dimensions than products formed by injection molding methods in separate molds. The discrepancy between the dimensions of naturally hardening cellular concrete leads to an increase in the thickness of the masonry joints (cold bridges are formed) and problems in finishing the building facade.

For comparison, here are the characteristics of both materials:

Based on the totality of operational characteristics, it is much better to use autoclaved aerated concrete for the construction of residential buildings, while its analogue can be used for the construction of technical buildings - garages, animal sheds, gazebos. The difference in the price of materials is about 15-20%.

About 90 large factories and countless small enterprises are engaged in the production of cellular concrete in Russia. Among the verified suppliers, we note the following companies:

• Aerok;
• Bonolite;
• AeroStone.

The largest manufacturer in Russia is Aerok, whose supply volume exceeds 400 thousand m 3 of aerated concrete throughout the year. It was Aerok who introduced into circulation blocks with strength B2.5 and density D400 in 2005, which subsequently became the standard in the field of low-rise construction.

The company's product range includes the following types of blocks:

• thermal insulation: EcoTerm (D400) and EcoTerm + (D300);
• structural: Classic (D500) and Hard (D600);
• lintels and U-shaped blocks.

The company supplies all common block sizes. The quality of its products is confirmed by full compliance production process requirements of GOST No. 31360.

As an analogue to Aeroc aerated concrete, it makes sense to consider the products of Bonolit, the second most popular manufacturer in Russia. First of all, the company is known for its line of autoclaved aerated concrete Bonolit40, which is designed specifically for the Russian climate and performs ideally at temperatures from -40 to +40. In addition to supplying products, the company offers turnkey construction services for cellular concrete houses.

With the increasing pace of construction activities, non-autoclaved aerated concrete has gained popularity among builders. The growing need for materials for construction requires an increase in production volumes and changes in technology.

In construction, professional terminology associated with types of raw materials is common. Autoclave and non-autoclave production methods are known. What are their features?

The tested technological process involved obtaining products using an autoclave method. This narrowed the scope of application of the resulting concrete mass and made it possible to produce only standard elements - lintels, blocks. Manufacturing methods have improved. The result is the production of raw materials made without autoclaving. This expanded the scope of use and allowed it to be used in the construction of monolithic structures.

A wide range of building materials sold allows you to choose the concrete most suitable for specific conditions

Distinctive features

Let's figure out what is the main difference between autoclaved aerated concrete and non-autoclaved aerated concrete? These are the conditions for the hardening of concrete mortar. They are divided into the following types:

• artificial, in which the hardening of the concrete mixture is carried out under pressure exceeding atmospheric pressure, with an increased concentration of saturated vapors;
• natural, hardening naturally, using electrical heating or at atmospheric pressure, saturated with steam.

Non-autoclaved aerated concrete is different from autoclave features manufacturing technologies. It can be obtained quite simply without the use of autoclaves. This is a simple method carried out at a factory or landfill. To do this, a mixture consisting of lime, cement, gypsum, aluminum powder is poured into special forms. It hardens at normal conditions. This manufacturing method reduces costs electrical energy. No operation required special equipment. The resulting block is cut into finished fragments.

Autoclaved aerated concrete is produced by autoclaving. This is a complex operation that requires maintaining a steam pressure of 12 atmospheres and a temperature of up to 200⁰ C, at which the aerated concrete “hardens” and acquires performance characteristics. Due to its high strength and durability, autoclaved aerated concrete is widely used in the construction of various objects: country houses, garages, cottages. Offices, high-rise buildings, and industrial facilities are no exception.

Aerated concrete is concrete with air or gas pores evenly distributed in it.

How are properties improved?

The characteristics of the composition produced without steaming in containers are increased as follows:

• Modifying components are added - microsilica, semi-aqueous gypsum.
• Hardening is accelerated by introducing calcium chloride.
• Bringing strength closer to parameters artificial material. For this purpose, dispersed reinforcing fibers of natural origin are introduced - basalt fiber, asbestos, as well as artificial ones - fiberglass or polymer components.
• They are strengthened by introducing acidic ash with a total volume of 10% of the cement mass.

The naturally hardened solution has high thermal insulation properties. The blocks obtained from it are quality characteristics are not inferior to traditionally produced ones, hardening in autoclaves.

Technological features, properties

As a result chemical reaction Using aluminum powder with alkali, which promotes gas formation, a synthetic gas-filled composite is obtained. A uniformly distributed porous structure is formed by hydrogen bubbles. Strength characteristics can be improved by adding modifiers. There are reagents that accelerate the hardening process. Experts believe that using composites reduces construction costs by 10 to 20%. This depends on the proportion of the mixture among the total range of items used. The energy-saving indicators achieved during use are also important.

Non-autoclaved aerated concrete matures under natural conditions or under certain exposure to temperature and moisture, but at normal atmospheric pressure

If we compare it with the widely used brick, then natural concrete reduces the need for energy resources. When operating objects built from it, energy costs are reduced by 20-25%.

Difficulty of choice

Which composition is better? There are three fundamental points related to the characteristics of concrete solutions. Let's take a closer look:

• The first is the amount of shrinkage of concrete compositions. The natural mixture, which hardens naturally, has an increased shrinkage of 2-3 millimeters per meter of pouring depth. Autoclaved aerated concrete shrinks significantly less. The layer reduction is 0.3 mm/m. This does not affect the quality of construction of monolithic objects. During hardening and shrinkage, the solution spreads under the influence of its weight, which compensates for the change linear dimensions. This disadvantage manifests itself in the production of prefabricated structures.
• The next factor is the time required for curing. U ordinary material it takes more time to acquire the necessary strength properties.
• Strength factors are important. Autoclaving technology promotes the formation of a special mineral - tobermorite, which increases strength. This substance is not formed during the traditional method. This limits the scope of use of naturally curing composites. Scope of application: structures operating under light loads.

You can determine the difference between each type of concrete by considering autoclaving.

Non-autoclaved aerated concrete has a large number of pores with a diameter of up to 3 mm, evenly distributed throughout its volume

Production Features

Autoclaving is the operation of steaming a concrete composition in special metal containers called autoclaves. Concrete mortar at given parameters (temperature, pressure) acquires high strength properties that cannot be achieved in the usual way. This treatment not only reduces the hardening time of the mixture. The main feature is changes at the molecular level. The result is that the composition acquires unique strength characteristics. Aerated concrete produced in an autoclave is synthesized. This is an artificially obtained stone. It differs from cement-sand concrete, which hardens porous.

Products obtained in different ways have their own performance characteristics, composition, and physical and technical parameters. The main indicators of the concrete produced are quite high. Manufacturing features and parameters are regulated by various regulatory documents. Innovative technological methods used by Europeans are gradually replacing ineffective, outdated production methods.

Important Details

Let's look at how each material differs. The scope of application is determined by:

• Quality. The synthesized product is produced at large enterprises. It is transported to construction site ready-made blocks. It is impossible to make this gas concrete by hand. Many parameters are controlled during its manufacture. Enterprises equipped with autoclaves have a high automation rate of 95%. Human factor has virtually no effect on production. Quality is confirmed by certificates of conformity. Natural compositions do not require major investments and are inexpensive.

• Strength factors. Cellular composites differ in density and strength class. With equal density, conventional products are inferior in terms of physical characteristics and strength.
• Fastening properties. The synthesized composite makes it possible to secure heavy equipment: ventilation systems, air conditioners, heaters. For this purpose, an expansion type anchor is used.
• Stable density. Gas formation using the autoclave method occurs throughout the entire environment. At the same time, the mixture hardens, the pores are uniformly distributed throughout the volume. The formation of blocks from the resulting mixtures is carried out by cutting the hardened mass. This is a guarantee of the quality of the blocks. When producing naturally hardening concrete, foam with gas-forming agents is introduced into the solution. During mixing, light components float and heavy fillers settle. Uneven distribution of cavities occurs. The density of different blocks is different. Stability of indicators is associated with homogeneity, which affects strength.
• Environmental friendliness. Synthetic is completely safe for others gas composition. This affects the microclimate of the building, which is favorable for living. The mineral components used do not rot. This ensures that mold and fungi cannot form. The decrease in the environmental friendliness of foam concrete is due to the use of waste from the production of crushed stone, local sand, and chemical fillers. This negatively affects the microclimate of the room.
• Compliance with dimensions. Standards regulate deviations in the length, width, and thickness of blocks obtained in autoclaves. The tolerance value does not exceed 3 millimeters. Naturally hardening concrete products are characterized by large dimensional deviations - up to 5 mm. Tolerances in the geometry of the blocks worsen the masonry: more mortar is required, labor intensity increases, and costs increase.

The construction industry has been developing since the advent of man. IN modern world The development of this industry plays a vital role in the life of today's society.
Concrete- a material that has proven its reliability and strength over its hundred-year history. It is these characteristics that allowed the above material to take its rightful place in construction. One type of concrete is the so-called aerated concrete.

Types of concrete

According to the method of pore formation, cellular concrete is divided into the following types:

• aerated concrete;
• foam concrete.

As for hardening conditions, there is also its own classification. Concrete divisions according to hardening conditions:

1. Autoclaved. Solidification occurs in a saturated steam environment and under pressure that is much higher than atmospheric pressure.
2. Non-autoclaved. The hardening process occurs under natural conditions, with electrical heating or at atmospheric pressure in a saturated steam environment.

Aerated concrete

The main difference from the material that everyone is used to is that it is cellular concrete. This material has found its application in the construction of walls of any type (load-bearing or non-load-bearing), reinforced slabs, and it is also used to provide thermal insulation.

Advantages of aerated concrete

The distinctive characteristics of this building material are:

• high level of thermal insulation;
• Fire safety;
• long service life;
• relatively low cost.

It should be noted that the level of quality of aerated concrete blocks, as well as buildings made from it, depends on the raw materials used, production technology and enterprise equipment.

Characteristics of aerated concrete

Aerated concrete– a cellular material (concrete), in which there is a huge number of air-filled pores, which significantly reduce the density of the material. In most cases, the percentage of air in aerated concrete can reach 90% of the total volume.

What types of aerated concrete are there?

Depending on what production technology was used during the manufacture of blocks, aerated concrete is divided into two types. Such as:

• autoclave;
• non-autoclave.

Nowadays, quite often the question arises related to which of the above types is better. In order to understand this, it is necessary to take a closer look at each of these types.

Which is better, autoclaved or non-autoclaved concrete?

The process of steaming in metal capsules, so-called autoclaves, during operation high pressure and temperature is called autoclaving.
It should be noted that pressure, sometimes reaching 12 atmospheres, and a temperature of 190 degrees Celsius make it possible to create a unique material that cannot be obtained under normal conditions.
The main task of autoclaving is not only to accelerate the hardening process of the solution, but also under extreme conditions, changes occur at the molecular level, which leads to the formation of a mineral such as tobermorite. That is why aerated concrete made using autoclaving is an artificially produced stone, and non-autoclaved concrete, in turn, is a solution of cement and sand hardened in a porous state.
Do not forget that aerated concrete of the above types (autoclaved and non-autoclaved) have a number of differences. From composition to performance characteristics, autoclaved aerated concrete surpasses its rival in all respects. Let's look at this issue in more detail.

Firstly, one of the most significant differences is the consistency of quality.
An autoclaved aerated concrete block can only be produced in a large production facility. Since for its production it is necessary to control several dozen different processes, as well as parameters. Factories involved in the production of gas blocks have sufficient high degree automation (about 95%) and practically do not allow human influence on the manufacturing process.
If we take into account GOST, then each batch of autoclaved aerated concrete has its own quality certificate. So the client can be completely confident in its reliability.
But many will think that the production of non-autoclaved aerated blocks does not require a huge enterprise and this factor will affect the cost of this building material. However, can this be considered a virtue? Because at its core, this can be called “handicraft” production, which has rather unstable quality indicators.

Secondly, strength is also important characteristic for absolutely any building material.
Characteristics that influence the strength of a material are density and compressive strength. The most common are D500 and D600, in which case aerated concrete produced by autoclaving has a compressive strength of about B2.5 and B3.5, respectively. In this version non-autoclaved concrete also loses significantly, since with a density of D600 its compressive strength is best case scenario will reach B2.

Third, possibility of fastening. The autoclaving process allows you to achieve impressive strength characteristics of the material. Thanks to this, one anchor at the base of autoclaved aerated concrete can withstand an impressive load of up to 700 kilograms.

Fourth, environmental friendliness also plays an important role when choosing a material. It’s worth saying right away that autoclaved aerated concrete is a completely environmentally friendly material. This characteristic allows you to create a cozy living climate in the house, which is quite similar to the microclimate of a house built of wood.

Fifthly, homogeneity of the material.
During its production, a block of aerated concrete is filled with gas evenly throughout its entire volume. Also, parallel to this process, hardening of the material occurs. Thanks to this production strategy, the pores are most evenly distributed throughout aerated concrete block, which guarantees the buyer the maximum level of quality and reliability.

A non-autoclave block, on the contrary, is obtained by introducing foam and a blowing agent into the solution, and then mixing them. In the end, it turns out that air bubbles “float” to the surface, and all the remaining components settle to the bottom. This leads to the fact that the pores are randomly distributed throughout the volume of the material, which does not allow achieving the required quality on all blocks.

At sixth, thermal insulation properties. Every person will say that thermal insulation characteristics is influenced primarily by the density of the material. That is, the higher the density of the material, the lower the level of thermal insulation. This proves that foam concrete, non-autoclaved and autoclaved aerated concrete have better thermal insulation properties due to their low density.

Conclusion. Based on the foregoing, it can be noted that the construction of non-autoclaved aerated concrete much cheaper. But this should not be considered a virtue. Since the characteristics of this material are quite inferior to its competitor - an autoclaved aerated concrete block.

Comments:

Autoclaved aerated concrete is a prominent representative of porous concrete and has proven itself quite well in many countries around the world. Such materials have now been found wide application in the construction of residential and industrial facilities.

The main components of autoclaved aerated concrete: cement, quartz sand and special gas generators.

Currently, many companies are engaged in the production and sale of the material. Autoclaved aerated concrete is available in a wide range of products on the building materials market: different shapes, sizes and color. One thing remains the same - high performance characteristics, which distinguish it from other products.

Material structure

Aerated concrete is a type of cellular concrete in which air pores measuring 1-3 mm are located throughout the entire volume. Its basis is concrete mixture from a binder, filler and water.

In general, the class of aerated concrete includes (divided by type of binder composition) cement-based aerated concrete, gas silicate concrete with lime as a binder, slag-based aerated concrete and gas gypsum. Like autoclaved aerated concrete, the most widely used material is cement-based with the addition of lime.

Air pores in the structure are created due to a chemical reaction with the release of gas. To initiate this reaction, aluminum powder or paste is added to the mixture. Thus, the composition of aerated concrete, in general, is a mixture of cement, lime, sand, water and aluminum powder residues. If necessary, additives can be added to impart specific properties. Accordingly, the structure autoclaved concrete- a hardened concrete mass with numerous small pores evenly distributed throughout the volume.

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Manufacturing Features

Autoclaved aerated concrete gets its name from the method of hardening the concrete mass after a chemical reaction with the release of gas. A diagram of the complete material production cycle is shown in Fig. 1.

The production of such aerated concrete is carried out in an autoclave in the following order. The concrete mixture is mixed to the consistency of sour cream and poured into molds to half the volume, while a shock load is applied to the mixture, during which the process of slaking lime occurs with the release of heat. Since all this happens in an autoclave, the temperature rises to 80 degrees.

Figure 1. Scheme of the full production cycle of autoclaved aerated concrete.

An active reaction of aluminum and lime begins with the release of hydrogen. The concrete mass increases in volume and fills the entire form. Pressure rises in the autoclave. Under the influence of temperature and pressure, cement hardens, clogging the pores inside its volume. During the reaction, air displaces hydrogen from the pores, filling them. In this way, a concrete structure is formed in which air pores occupy up to 80% of the total volume. By changing the mode and amount of introduced aluminum powder, the pore concentration can be changed over a wide range.

Autoclave hardening of the mass is carried out within 1-2 hours. Then the lid of the autoclave is removed and the aerated concrete is cut into blocks the right size, while complete hardening of the concrete has not yet been achieved. When cutting, the end elements of block engagement are formed (if necessary). After cutting, the blocks are again placed in an autoclave, where they are moistened at a temperature of about 190 degrees and a pressure of up to 1.2 MPa. Under this influence, the mass finally crystallizes to form a durable mineral. Final hardening and crystallization occur within 12 hours. Typically, the concrete mixture is prepared in the following proportion: cement (usually Portland cement) - 20%, quartz sand - 60%, lime - up to 20%. Aluminum residues - no more than 1%.

The main advantage of the autoclave hardening method is that when exposed to high temperature and pressure cellular aerated concrete forms a special mineral formation - tobermorite, which has an increased mechanical strength and is not subject to shrinkage. In addition, such artificial conditions significantly accelerate the hardening process of the mass, which is very important in industrial production.

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Basic properties of the material

Due to its porous structure, aerated concrete has a low specific gravity (from 300 to 700 kg/m³) and high thermal insulation properties. The autoclave production method also provides high compressive strength, up to 50 kg/cm².

By varying the pore volume, the density of aerated concrete changes; At the same time, strength and thermal conductivity change. At the same time, changes in the main parameters occur in different directions. A decrease in density (increase in porosity) leads to an increase in thermal insulation properties and a decrease in strength, and an increase in density leads to the opposite effect.

Based on this dependence, autoclaved aerated concrete is divided into 3 categories: thermal insulation, structural and structural-thermal insulation. Autoclaved concrete with a density of up to 400 kg/m³ is a thermal insulation type and is intended for private low-rise houses in areas with a fairly cold climate. Aerated concrete with a density of 700 kg/m³ is structural and is used in load-bearing structures and houses with several floors, but it will have to be additionally covered with thermal insulation. Structural and thermal insulating concrete with a density of 500 kg/m³ has optimal properties, which, with sufficiently high strength, provide good thermal insulation.

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What are the block sizes?

The low weight of porous concrete makes it possible to use building elements with increased dimensions. Building blocks made of aerated concrete are 625 mm long, 200 and 250 mm high, 100-400 mm wide. Such dimensions make it possible to significantly speed up and simplify the laying of walls, while the weight of the block remains within reasonable limits for its manual movement and laying.

An important advantage of autoclaved concrete is the accuracy and stability of the geometry of building elements (blocks). Autoclave curing of the concrete mass in the mold allows for clearly defined edges and corners, even smooth surfaces of the edges, very high dimensional stability, which remain almost unchanged over a long production time. If you take blocks from different production batches, then deviation is only possible within 1.5 mm in all directions (first category of accuracy) or up to 3 mm for the third category. Very strict standards have also been established for the stability of ribs and corners.

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Other properties of aerated concrete

Autoclaved aerated concrete has high vapor permeability. In terms of its breathability, it belongs to “breathable” building materials, i.e. capable of removing steam from the room to the outside. This property prevents the formation of mold or fungi in areas of steam condensation.

The porous structure provides increased sound insulation properties.

The material will gain wide popularity in Europe due to its environmental friendliness. The composition of aerated concrete does not contain any harmful impurities (even aluminum is found in small quantities and in a bound state), which eliminates harmful emissions both during construction and during operation. The environmental friendliness of the composition is not disturbed even by exposure high temperatures and other climatic factors. In its own way fire safety and fire resistance, aerated concrete can be considered unique. Even long-term exposure open flame and thermal load does not ignite or destroy the material.