Aerated concrete blocks disadvantages and declared characteristics. Gas silicate blocks Operating parameters of gas silicate blocks

Gas silicate blocks are in great demand in residential and industrial construction. This building material surpasses concrete, brick, natural wood, etc. in many respects. It is made from environmentally friendly raw materials, differs in lightness, fire resistance, ease of use and transportation. The use of this lightweight material allows you to reduce the cost of arranging a heavy reinforced foundation and thereby reduce the cost of building a building.

What are gas silicate blocks

The gas silicate block is a lightweight and durable wall material made of aerated concrete. Products have a porous internal structure, which has a positive effect on their heat and sound insulation properties. Such building material can be used in various areas of the construction industry - for the construction of country and country houses, car garages, utility structures, warehouse complexes, etc.

How are gas silicate blocks made?

There are two main technologies for the production of gas silicate building blocks.

Non-autoclave... With this method of production, solidification of the working mixture occurs in natural conditions. Non-autoclave gas silicate blocks stand out at a lower cost, but have some important differences from autoclave ones. First, they are less durable. Secondly, when they dry, shrinkage occurs almost 5 times more intense than in the case of autoclaved products.
Autoclave... For the autoclave production of gas silicate, more energy and material resources are required, which increases the final cost of products. Manufacturing is carried out at a certain pressure (0.8-1.2 MPa) and temperature (up to 200 degrees Celsius). Finished products are more durable and resistant to shrinkage.

Block types

Gas silicate blocks are divided into three main categories depending on density, composition and functional purpose.

Structural... They have high strength characteristics. The density of the products is at least 700 kg / m 3. They are used in the construction of high-rise buildings (up to three floors). They are able to withstand high mechanical loads. Thermal conductivity is 0.18-0.2 W / (m · ° C).
Structural and thermal insulation... Blocks with a density of 500-700 kg / m 3 are used when arranging load-bearing walls in low-rise buildings. They are distinguished by a balanced ratio of strength and thermal insulation characteristics [(0.12-0.18 W / (m · ° C)].
Heat insulating... They are characterized by increased heat-insulating properties [(0.08-0.1 W / (m · ° C)]. Due to their low density (less than 400 kg / m 3), they are not suitable for creating load-bearing walls, therefore they are used exclusively for insulation.

Sizes and weights

Gas silicate wall blocks have standard dimensions of 600 x 200 x 300 mm. The overall characteristics of the semi-blocks are 600 x 100 x 300 mm. Depending on the manufacturing company, the standard sizes of products may vary slightly: 500 x 200 x 300, 588 x 300 x 288 mm, etc.

The mass of one block depends on its density:

structural blocks weigh 20-40 kg, half-blocks - 10-16 kg;
structural and heat-insulating blocks and semi-blocks - 17-30 kg and 9-13 kg, respectively;
heat-insulating blocks weigh 14-21 kg, half-blocks - 5-10 kg.

Composition of gas silicate blocks

Gas silicate is an environmentally friendly building material made from non-toxic raw materials of natural origin. The blocks include cement, sand, lime and water. Aluminum chips are used as a foaming agent, which helps to increase the void ratio of the blocks. Also, in the production of the material, a surfactant is used - sulfonol C.

Material characteristics

Gas silicate building blocks have the following characteristics.

Heat capacity... Products made by autoclave technology have a thermal conductivity coefficient of 1 kJ / (kg · ° С).
Thermal conductivity... Structural and heat-insulating gas silicate has an average thermal conductivity of about 0.14 W / (m · ° С), while for reinforced concrete this parameter reaches 2.04.
Sound absorption... Gas silicate blocks significantly reduce the amplitude of external noise, the sound absorption index for this material is 0.2.
Frost resistance... Material with a density of 600 kg / m 3 can withstand up to 35 freeze and thaw cycles (which corresponds to the F35 index). Products with a higher density are assigned frost resistance class F50.

Advantages and disadvantages of gas silicate blocks

The main advantages of gas silicate are as follows.

Ease... Gas silicate blocks weigh almost 5 times less than concrete products of the same size. This facilitates construction work and reduces the cost of transporting construction materials.
Effective heat and sound insulation... Due to the presence of internal micropores, high heat and noise insulation characteristics of gas silicate are achieved. This allows you to create a comfortable indoor climate.
Environmental friendliness... The building material does not contain dangerous toxins and carcinogens that can harm the environment and human health.
Refractoriness... Gas silicate is produced from non-combustible raw materials, therefore it does not collapse under intense heating and does not contribute to the spread of flame in a fire.

How critical are the flaws

Like any other building material, gas silicate has some disadvantages.

Low safety margin... A material with a low density (300-400 kg / m 3) has relatively low strength characteristics. Therefore, during construction, it is imperative to perform wall reinforcement work.
Smooth surfaces... The front parts of the gas silicate blocks have a smooth surface with a low roughness coefficient. Because of this, adhesion with finishing materials deteriorates, which complicates the process of decorating walls with plaster and other coatings.
Low moisture resistance... Due to the increased porosity, the material is sensitive to high humidity. Water and water vapor penetrate into internal micropores and, when frozen, increase in volume, destroying blocks from the inside. Therefore, gas silicate walls need additional waterproofing.

Where are gas silicate blocks used?

Gas silicate blocks are used in residential and industrial construction. This material is used not only for the construction of load-bearing elements of buildings, but also to increase thermal insulation, as well as to protect engineering networks (in particular, heating).

The scope of gas silicate is determined by its characteristics, primarily density.

Products with a density of 300-400 kg / m 3 have a low margin of safety, therefore they are used mainly for wall insulation.
Gas silicate with a density of 400 kg / m 3 is suitable for the construction of one-story houses, garages, office and utility outbuildings. Due to its higher strength, the material is able to withstand significant loads.
Blocks with a density of 500 kg / m 3 are optimal in terms of strength and thermal insulation properties. They are often used for the construction of cottages, country houses and other buildings up to 3 stories high.

The most durable are gas silicate blocks with a density of 700 kg / m 3. They are used for the construction of high-rise residential and industrial buildings. But due to the increased density, the porosity coefficient of the material decreases and, consequently, its thermal insulation properties. Therefore, walls built from such blocks require additional insulation.

Block construction and testing process.

Gas silicate blocks are a kind of lightweight cellular material that has a fairly wide scope of application in construction. The popularity of porous concrete products of this type has earned due to its high technical qualities and numerous positive characteristics. What are the advantages and disadvantages of gas silicate blocks, and what are the features of their use in the construction of houses?

Gas silicate is considered an improved analogue of aerated concrete. The production technology of its manufacture includes the following components:

high quality Portland cement, which contains more than 50 percent of an inorganic compound, calcium silicate;
water;
aluminum powder as a blowing agent;
slaked lime enriched by 70 percent with magnesium and calcium oxides;
quartz fine sand.

From a mixture of such components, a high-quality porous material with good technical characteristics is obtained:

Optimum thermal conductivity. This indicator depends on the quality of the material and its density. The brand of gas silicate blocks D700 corresponds to a thermal conductivity of 0.18 W / m ° C. This figure is slightly higher than many values for other building materials, including reinforced concrete.
Frost resistance. Gas silicate blocks with a density of 600 kg / m³ are able to withstand more than 50 freeze-thaw cycles. Some new brands have a declared frost resistance index of up to 100 cycles.
The density of the material. This value varies depending on the type of gas silicate - from D400 to D700.
The ability to absorb sounds. The noise insulation properties of cellular blocks are equal to a coefficient of 0.2 at an audio frequency of 1000 Hz.

Many technical parameters of gas silicate are several times higher than the characteristic indicators of a brick. To ensure optimal thermal conductivity, walls are laid out with a thickness of 50 centimeters. To create such conditions from bricks, a masonry size of 2 meters is required.

The quality and properties of gas silicate depend on the ratio of the components used for its preparation. It is possible to increase the strength of products by increasing the dose of the cement mixture, but at the same time the porosity of the material will decrease, which will affect its other technical characteristics.

Views

Gas silicate blocks are divided, depending on the degree of strength, into three main types:

Structural. Such material is used for the construction of buildings not exceeding three floors. The block density is D700.
Structural and thermal insulation. Gas silicate of this type is used for laying load-bearing walls in buildings no higher than two floors, as well as for the construction of interior partitions. Its density ranges from D500 to D700.
Heat insulating. The material has been successfully used to reduce the degree of heat transfer of walls. Its strength is low, and due to its high porosity, its density reaches only D400.

Gas silicate building blocks are produced in two ways:

Autoclave. The manufacturing technique consists in processing the material under a high steam pressure of 9 bar and a temperature of 175 degrees. Such steaming of blocks is carried out in special industrial autoclaves.
Non-autoclave. The prepared gas silicate mixture hardens naturally for more than two weeks. At the same time, the required air temperature is maintained.

The gas silicate produced by autoclaving has the highest technical characteristics. Such blocks have good strength and shrinkage characteristics.

Size and weight

The size of the gas silicate block depends on the type of material and its manufacturer. The most common are the following dimensions, which are expressed in millimeters:

600x100x300;
600x200x300;
500x200x300;
250x400x600;
250x250x600.

Due to its cellular structure, gas silicate is a fairly light material. The weight of porous products differs according to the density of the material and its standard size:

D400 - from 10 to 21 kg;
D500-D600 - from 9 to 30 kg;
D700 - from 10 to 40 kg.

The small mass of blocks and the ability to select the required size greatly facilitates the construction process.

Scope of application of gas silicate blocks

In construction, gas silicate is successfully used for the following purposes:

construction of buildings;
thermal insulation of various buildings;
insulation of thermal engineering and building structures.

The number of cells per cubic meter in the produced gas silicate blocks is different. Therefore, the field of application of the material directly depends on the density of the material:

700 kg / m³. Such blocks are most effectively used in the construction of high-rise buildings. The construction of high-rise buildings from gas silicate is much cheaper than from reinforced concrete or brick.
500 kg / m³. The material is used for the construction of low-rise buildings - up to three floors.
400 kg / m³. This gas silicate is suitable for laying single-storey buildings. Most often it is used for inexpensive outbuildings. In addition, the material is successfully used for thermal insulation of walls.
300 kg / m³. Cellular blocks with a low density index are intended for thermal insulation of load-bearing structures. The material is not able to withstand high mechanical loads, therefore it is not suitable for the construction of walls.

The lower the density of cellular blocks, the higher their thermal insulation qualities. In this regard, structures made of gas silicate with a dense structure often require additional insulation. Expanded polystyrene plates are used as insulating material.

Advantages and disadvantages

The construction of houses from gas silicate blocks is quite justified by the low cost of the material and its many advantages:

Blocks for building houses are highly durable. For a material with an average density of 500 kg / m³, the mechanical compression rate is 40 kg / cm3.
The low weight of gas silicate products allows you to avoid additional costs for the delivery and installation of blocks. Cellular material is five times lighter than conventional concrete.
Due to good heat transfer, heat energy consumption is reduced. This property allows you to significantly save on heating the building.
High rate of sound insulation. Due to the presence of pores, the cellular material protects against noise penetration into the building ten times better than brick.
Good ecological properties. The blocks do not contain toxic substances and are completely safe to use. According to many environmental indicators, gas silicate is equated to wood.
High vapor permeability of products allows you to create good indoor microclimate conditions.
Non-combustible material prevents the spread of fire in the event of a fire.
The exact proportions of the block sizes make it possible to make even wall masonry.
Affordable material price. With good technical indicators, the price of gas silicate blocks is relatively low.

Along with a considerable number of advantages, a porous material has some disadvantages:

The mechanical strength of the blocks is slightly lower than that of reinforced concrete and bricks. Therefore, when driving nails into a wall or screwing in dowels, the surface crumbles easily. Blocks hold heavy parts poorly enough.
The ability to absorb moisture. Gas silicate absorbs water well and quickly, which penetrates the pores, reduces the strength of the material and leads to its destruction. In the construction of buildings from various types of porous concrete, surfaces are protected from moisture. It is recommended to apply the plaster on the walls in two layers.
Frost resistance of blocks depends on the density of the products. Gas silicate grades below D 400 are not able to withstand a cycle of 50 years.
The material is prone to shrinkage. Therefore, especially for blocks of grades below D700, the first cracks may appear a couple of years after the construction of the building.

When decorating walls made of gas silicate, gypsum plaster is mainly used. It perfectly hides all the seams between the blocks. Cement-sand mixtures do not adhere to the porous surface, and small cracks form when the air temperature drops.

The popularity of gas silicate is increasing every year. Cellular blocks have almost all the qualities necessary for the efficient construction of low-rise buildings. Some characteristics far exceed those of other materials. With the help of lightweight gas silicate blocks, you can build a reliable building at low cost in a relatively short time.

Gas silicate building blocks are a building material of universal value. It is an artificial porous stone. This structure is formed by a natural chemical reaction between aluminum and lime. During the reaction, these two components disintegrate and form hydrogen.

Gas silicate blocks are heat treated (up to + 190 ° C) at a pressure of 10-12 bar. Thanks to this material, additional strength is given, and the indicators of thermal conductivity and frost resistance are improved.

was developed in Sweden at the beginning of the last century, but gained popularity only recently. She practically did not undergo changes over time, which speaks of her convenience, simplicity and reliability.

Types of gas silicate blocks

All gas silicate blocks can be divided into three types:

Aerated concrete is an artificial stone. Its array contains closed air cells no more than 3 mm in diameter. The main components are: sand, cement, a set of gas-forming components. Air pores significantly increase its thermal conductivity.

Foam concrete Is a material similar to aerated concrete. The differences are in the production method. The cells are formed due to the introduction of foaming additives. The main components are quartz, lime and cement.

Gas silicate- building material formed by autoclave hardening. Its components are: crushed sand and lime, aluminum powder. Differs in lighter weight and better thermal conductivity.

Video on what you need to know about gas silicate blocks as a building material:

Classification by scope

Wall blocks designed for wall installation with minimal seams. In the process of making this material, new technologies are used, which include the use of cement, quartz sand, water and lime. Aluminum powder is used to form pores.

Depending on the density of the material, they can be used both for insulation (density 350 kg / m3) and for low-rise construction (400-500 kg / m3). Wall blocks have larger dimensions, which reduces material and labor costs.

Today it is a very common occurrence. Such a high popularity of gas silicate blocks is due to their low cost and thermal conductivity, which makes it possible to obtain energy efficient buildings.

Partition blocks can be used for the construction of partitions and walls. For the interior walls of the apartment, blocks of 10 centimeters thick are suitable. The height and width of 100mm blocks are irrelevant.

The average size of partition blocks for interior walls is 200 * 200 * 400mm, there are also very thin blocks with a thickness of 50 mm.

They are easy to install and have a number of advantages:

Good sound and heat insulation properties;
Profitability;
Low weight;
Low cost.

In addition to the advantages, these blocks also have disadvantages:

Complexity in processing;
Low strength;
High costs in further operation.

This is only a small part of such a building material as gas silicate. In this article, you can get acquainted with a more detailed list.

Types of blocks depending on sizes and strength categories

Dry laying with glue. Blocks with 1 category of accuracy allow deviations: in sizes up to 1.5 mm; straightness of edges and edges - up to 2 mm; chipping off corners - up to 2 mm; broken ribs - no more than 5 mm. (The standard size of the gas silicate block is 600x400x200)
Laying on glue. Blocks of the 2nd category of accuracy can differ in size up to 2 mm, have deviations from the straightness and rectangularity of the edges and edges up to 3 mm, the chipping of the corners - up to 2 mm, and the edges - up to 5 mm.
Laying on mortar. Category 3 accuracy can have deviations from block sizes up to 3 mm, rectangularity and straightness - up to 4 mm, chipped edges - up to 10 mm, and corners - up to 2 mm.

Tongue-ridged silicate blocks, in contrast to smooth surfaces, have hand grips. Scope of their application: monolithic frame construction, as well as the construction of multi-storey buildings.

When stacked, they have the function of a thermal lock and a guiding function. This erection system is able to save on glue solution.

The picture shows tongue-and-groove gas silicate blocks

Composition of gas silicates

The main component in the production of gas silicate blocks is lime. And therefore, increased requirements are imposed on it: activity and purity of the composition. The end result directly depends on the quality of this component.

In addition to lime, the gas silicate blocks include a mixture of quartz sand, water, cement and aluminum powder. The last component reacts with calcium oxide hydrate, carrying out the process of gas formation. Gas bubbles begin to form at the initial stages of production up to the placement of blocks in autoclaves.

In many ways, the composition and production technology determines the future and operational properties of gas silicate blocks.

Gas silicate grades

Structural grades reflect the purpose of gas silicate blocks:

D1000-D1200 - designed for the construction of residential, industrial and public buildings and structures;
D200- D500 - for thermal insulation of building structures;
D500- D900 - structural and thermal insulation products;
D700 - autoclave wall products.

Depending on the density of the material, gas silicate blocks can be used for the construction of low-rise buildings and high-rise buildings (up to the 9th floor) and differ in the following brands:

200-350 - thermal insulation materials;
400-600 - for load-bearing and non-load-bearing walls in low-rise construction;
500-700 - for buildings and structures no more than 3 floors high;
700 and above - for multi-storey construction with the use of reinforcement.

Regardless of the brand of blocks, before taking on the construction of walls made of gas silicate, you need to find out the features and.

Gas silicate or foam block

Both of these building materials have the same origin: concrete mortar and porous structure. Differences are in the technology of the appearance of bubbles. In the process of foam concrete production, bubbles are formed by the interaction of aluminum dust and lime, which release hydrogen.

And the porous structure of gas silicates is achieved by adding a special foaming agent. Both materials harden faster than air leaves their structure. If in the first variant the bubbles try to leave the mixture and rise up, in the other case they are held by the foaming agent.

When its action ceases, the bubbles burst and compact the structure. Therefore, both materials differ in hygroscopicity. It is easier to get moisture into foam concrete than into gas silicate.

The foam block, in contrast to gas silicate, has a perfectly smooth surface. It is more difficult for moisture to penetrate into it. If we compare blocks with the same strength, then gas silicate blocks will have less weight. This is due to its higher porosity.

Table 1

Gas block and gas silicate

The gas block is an artificial stone with cells with a diameter of 1 to 3 mm. They are evenly distributed throughout the structure of the material. It is the degree of uniformity of these bubbles that affects the quality of the final material. In the production of an aerated block, cement with autoclave or natural hardening is the basis.

Gas silicate is a lime-based material. In addition to it, the composition includes: sand, water and gas-forming additives. The blocks are autoclaved. The mixture for gas silicate is poured into a mold and undergoes an oven heat treatment, after which the finished block is cut with a string into smaller blocks of the required size.

Gas blocks have a lower sound insulation coefficient. If the gas silicate absorbs moisture and its structure suffers from this, then the gas block passes it through itself, creating a comfortable microclimate in the room.

Gas silicate blocks are more durable due to their uniform porosity. And they have a higher cost than less durable gas blocks.

table 2

Gas silicate blocks or expanded clay blocks

Important advantages of gas silicate blocks are safety: environmental and technical. The low coefficient of thermal conductivity allows it to withstand contacts with natural phenomena and fire, and at the same time retain heat even in severe frosts.

The absence of radioactive substances, heavy metals and other components hazardous to life and health in the gas silicate blocks allows you to erect any buildings without fear for your health. The strength of the blocks makes it possible to erect 2-3-storey buildings.

But, despite its advantages, gas silicate has a competitor - expanded clay concrete. Its tongue-and-groove structure makes it possible to lay out walls without seams. Such construction eliminates the formation of cold bridges and saves glue solution.

The porous structure of expanded clay blocks retains heat better in the room than gas silicate blocks. And in terms of frost resistance, 15 cycles more than that of a competitive material. The cost of these materials is almost equal.

Gas silicate and expanded clay blocks have practically equal physical and chemical properties. They are out of competition with wood and brick - this is also shown by statistics on developers. Gas silicate blocks are more in demand in the building materials market due to their availability and low cost.

Practicality

Strength

Environmental friendliness

Price

final grade

Operational parameters of gas silicate blocks

Life time- the nominal value is up to 100 years in a normal climate and up to 50 - in a humid one. With proper care, the presence of plaster and gutters, the standard terms are quite consistent with the real ones.

Material consumption- depends on climatic conditions. Recommended wall thicknesses range from 400 mm in temperate climates to 800 mm in northern regions.

Strength class for compression- characterizes the guaranteed pressure that will not lead to destruction. Blocks with a density of 600 kg / m3 have a strength class from B1.5 to B3.5 (2-3 times less than that of bricks). For thermal insulation structures with a material density of 300 kg / m3, the strength class is much lower - B0.75-B1.5.

Note that a decrease in the strength class of gas silicate blocks does not mean a real decrease in the strength of the structure. For a porous material, the mass of the entire masonry (as a result, the pressure exerted) is 2.5-3 times lower than that of a brick structure.

Frost resistance- numerically shows the number of thawing cycles that a particular type of material can withstand without losing more than 15% of its strength. In this case, the designation that looks like F50 means that the guaranteed number of cycles is 50.

Technical tests are carried out under harsh conditions, far exceeding environmental changes. The block is immersed in water until it is completely saturated and then placed in a freezer. In reality, such harsh conditions do not exist, therefore the main function of the parameter is to orient the buyer in a more acceptable version for a specific climatic zone.

Coefficient of thermal conductivity- depends on the density and moisture content of the material. So, the lightest gas silicate block (300 kg / m3) has a thermal conductivity of about 0.08 W / (m ?? C), and the heaviest (600 kg / m3) - almost 2 times more. An increase in material moisture by 1% increases thermal conductivity by 4-5%.

The table shows the differences between different brands of blocks in terms of thermal conductivity, shrinkage, frost resistance and vapor permeability:

Gas silicate blocks are a good choice for small homes, especially in colder climates. For summer cottages or walls in an apartment, porous material will also become a convenient and inexpensive way out. When buying, you should carefully check the contents of the pallets - unscrupulous sellers can sell blocks with a high percentage of rejects.

Gas silicate blocks are a building material of universal value. It is an artificial porous stone. This structure is formed by a natural chemical reaction between aluminum and lime. During the reaction, these two components disintegrate and form hydrogen.

In the context of a constant rise in the price of energy resources, the need for building materials with high thermal performance is increasing. To reduce heat loss in modern projects, aerated concrete and gas silicate blocks are increasingly used - materials of the class of heat-insulating cellular concrete. They are often confused due to their common properties and the same area of application. Even specialists cannot always immediately tell a potential customer which material is in front of him - gas silicate or aerated concrete, which is better, what is the difference between them and whether there is any at all. In part, the manufacturers themselves introduce confusion when they define aerated concrete as a type of gas silicate or vice versa.

What is the difference between aerated concrete and gas silicate? In particular, in the manufacture of aerated concrete, natural hardening of the block in the open air is allowed, for gas silicate - autoclave furnaces are a prerequisite. In addition, for aerated concrete blocks, the main binder is cement, for silicate analogs, lime. The use of different components affects the color of the finished blocks.

If we talk about specific characteristics, you can notice the following differences:

Gas silicate blocks have a uniform distribution of hollow cells, which ensures high strength.
The weight of aerated concrete blocks is much greater, which requires a reinforced foundation during construction.
In terms of thermal insulation, gas silicate blocks outperform aerated concrete ones.
Aerated concrete absorbs moisture better, which provides a greater number of freezing cycles.
Gas silicate blocks have a more consistent geometry, as a result, the finishing of wall structures can be simplified.

Externally, finished products are distinguished by color: gas silicate or autoclaved aerated concrete is practically white, gray color is typical for non-autoclaved aerated concrete.

Average values for each parameter are shown in the following table:

In terms of durability, the materials are identical and can last over 50 years.

If you answer the question: "What is the best, aerated concrete or gas silicate?", Gas silicate blocks have much more technical advantages. However, the manufacturing technology forces to increase the cost of finished products, so aerated concrete blocks are cheaper. Therefore, those who want to build a house from high-quality and modern materials choose gas silicate; those who want to save money on construction prefer aerated concrete.

In this case, the region of application must be taken into account: in areas with high air humidity, the operating life of gas silicate blocks is noticeably reduced.

Composition and technology of production of gas silicate blocks

The mixture for the production of gas silicate blocks has the following composition:

astringent (Portland cement according to GOST 10178-76, calcium boiling lime (according to GOST 9179-77);
silicate or silica filler (quartz sand with 85% quartz content, fly ash, etc.);
lime, with a content of magnesium and calcium oxides of more than 70%, and a slaking rate of up to 15 minutes;
technical water;
gas-forming additive (aluminum powder and others).

Gas silicate belongs to the class of lightweight aerated concrete. This material is a mixture of 3 main components: cement, water and fillers. Lime and quartz sand in a ratio of 0.62: 0.24 can act as fillers. Separately, it is worth talking about additives that give gas silicate its individual characteristics. Fine aluminum powder acts as an additive. All these components are thoroughly mixed, and under certain conditions observed, foaming of all these materials occurs. When aluminum powder reacts with lime, hydrogen is released. A huge number of released hydrogen bubbles make up the porous structure, which is the main distinguishing feature of gas silicate. Its structure resembles a concrete "sponge", since the entire volume of the block consists of cells (bubbles with a diameter of 1-3 mm).

Gas silicate blocks

The cellular structure makes up almost 85% of the volume of the entire block, so this material is very light in weight. First, a mixture of components is prepared in a special mixer for 5 minutes, which includes Portland cement, fine sand (quartz), water, lime and a gas generator (most often, this is a suspension of aluminum). Hydrogen, formed by the reaction between aluminum paste (powder) and lime, forms pores. Bubbles ranging in size from 0.6 to 3 mm are evenly dispersed throughout the material.

Basic chemical reactions take place in metal containers or molds. The mixture is subjected to vibration, which promotes swelling and seizure. After hardening, all irregularities from the surface are removed with a steel string. The seam is divided into blocks, and then they are sent to an autoclave unit. The final calibration of the finished blocks is done with a milling machine.

Gas silicate blocks are made only by autoclaving. Aerated concrete blocks can be produced both by autoclave and non-autoclave methods (natural hardening of the mixture):

Autoclave treatment. This stage significantly improves the technical characteristics of the gas silicate. Here, for 12 hours at high pressure, steam treatment is carried out, the temperature of which is almost 200 ° C. This heating process makes the texture more uniform, thereby improving the strength properties (not less than 28 kgf / m²). Its specific thermal conductivity is 0.09-0.18 W (m ∙ K), which makes it possible to erect walls in one row (400 cm) in almost any climatic conditions, but excluding the northern regions.
Non-autoclave technology. It consists in the natural hardening of the mixture: moistening and drying in natural conditions. In this case, it is quite possible to make it with your own hands, since special equipment is not required here. The strength of the blocks in this production does not exceed 12 kgf / m².

The first variety is more expensive. This is due to significant manufacturing costs, as well as the best technical characteristics of gas silicate blocks produced by this method. They are much stronger, their coefficient of thermal conductivity is lower. The pores inside such gas silicate are distributed extremely evenly, which affects the strict compliance of the material with the specified parameters.

Gas silicate blocks: characteristics

Density of gas silicate blocks

The brand and density of gas silicate blocks is indicated in the marking and determines the purpose of the block:

constructional gas silicate blocks - D1000-1200, have a density from 1000 to 1200 kg / cubic meter;
structural and heat-insulating blocks - D500-900, have a density of 500-900 kg / cubic meter;
heat-insulating D300-D500, the density of their materials is 300-500 kg / m3.

Blocks of different density are easy to distinguish from each other visually.

There are several classifications of gas silicate blocks with specific technical characteristics. Today, during construction work, the following grades of this material are used. The best option for low-rise construction is the d500 gas silicate block and d600 gas silicate block.

The numerical designation of the grades listed earlier shows the density of the material. In particular, the d500 gas silicate block has a density of 500 kg / m³.

Gas silicate block d600

Gas silicate block d600 is used in the construction of load-bearing walls of a house. It is also recommended to use it when installing ventilated facades, which are well attached to blocks of this density. Gas silicate block d600 has a strength of 2.5-4.5 MPa and has a thermal conductivity of 0.14-0.15 W / (m ° C)

Gas silicate block d500

Gas silicate block d500 is most popular for low-rise (up to 3-storey) construction. This variety is also used in monolithic construction. Its parameters are 2-3 MPa (strength) and 0.12-0.13 W / (m ° C) (thermal conductivity).

When building a house above three floors, preference should be given to gas silicate marked above D600 and additionally insulate the walls. Based on the value of the thermal conductivity coefficient, it can be concluded that the d500 gas silicate block is 15-17% warmer than the d600 gas silicate block.

Gas silicate block d400

This type is used for arranging insulation, for working with openings in the construction of multi-storey buildings using a monolithic method. The D400 brand is also popular in private construction. With high strength, it has great thermal insulation properties. These indicators are in the range of 1 MPa to 1.5 MPa (strength), 0.10-0.11 W / (m ° C) (thermal conductivity).

Gas silicate block d300

D350 brand can only be used as insulation. In the domestic market, this is a rather rare brand due to its fragility. Strength is in the range of 0.7-1.0 MPa. But it differs in thermal conductivity, which is 0.08-0.09 W / (m ° C).

Thermal conductivity of gas silicate blocks

Depending on the proportions of the starting ingredients, a product with different performance characteristics can be obtained. The thermal conductivity coefficient of a gas silicate block depends on its density and is determined by the marking: D300, D400, D500, D600, D700.

The thermal conductivity of gas silicate depends on a number of factors:

Building block dimensions. The thicker the wall block is, the higher its thermal insulation properties.
Humidity of the environment. A material that has absorbed moisture reduces the ability to store heat.
Structure and number of pores. Blocks with a large number of large air cells in their structure have increased thermal insulation performance.
Density of concrete partitions. Building materials of increased density retain heat worse.

Thermal conductivity table of gas silicate blocks

Types of gas silicate blocks

In appearance, there are several configurations of the gas silicate block. The classification is based on the purpose of the block.

Smooth (straight) gas silicate block with hand grip

Absolutely smooth rectangular gas silicate block with recesses for gripping by hand. The gripper is easy to use as it allows you to easily move the blocks. The presence of gripper handles increases the consumption of glue, since the technology of laying gas silicate blocks provides for filling all the voids in the process.

Wall gas silicate blocks with flat edges

The usual rectangular shape reduces the consumption of glue, but makes it difficult to move the block. In practice, when constructing load-bearing walls where larger blocks are used, the grab block is preferred.

Gas silicate blocks for partitions

They are blocks with flat edges. Baffle blocks are thinner and lighter. It is convenient to work with them.

On straight blocks, using a screwdriver, you can cut out any patterns. But such a decor is more likely to be applied in finishing the site with the remains of blocks from construction than in the construction itself, since it is desirable to protect gas silicate with an external finishing material.

Wall gas silicate groove-comb blocks

The formation of the groove-ridge connection system in terms of the complexity of production refers to the high-tech processing of the block. Therefore, they are distinguished by a higher cost. However, it is justified because: it increases the speed of work, reduces the consumption of glue (vertical joints do not need to be glued), it becomes possible to eliminate cold bridges in the places of vertical joints.

If the house will not be exposed to exterior decoration. It is better to apply a thin layer of glue to the junction from the front side of the masonry. This will provide additional insulation for the seam.

Gas silicate blocks, U-shape

The purpose of U-shaped blocks is to install hidden construction elements (for lintels and monolithic belts). According to the technology, laying walls from gas silicate blocks provides for mandatory reinforcement of the first and every fourth of the following rows. It is in order to conveniently hide the reinforcement that the voids in the U-shaped blocks are intended. After laying the reinforcing metal, the space must be filled with concrete mortar or glue. In this case, a cheaper filling material should be used.

What are the sizes of gas silicate blocks

Of course, manufacturers produce gas silicate blocks of various sizes. However, most of the enterprises try to follow the established norms of GOST No. 31360 of 2007. The following sizes of finished products are spelled out here:

250*250*600.
250*400*600.
500*200*300.
600*100*300.
600*200*300.

It is important to understand that according to GOST, deviations in the length and diagonal values are allowed, which classify finished products as the 1st or 2nd category.

The deviations in the dimensions of the gas silicate blocks reduce the installation time due to the absence of the need for grinding and fitting.

Thickness of gas silicate blocks: 200, 250, 300, 350, 375, 400, 500 mm;
The thickness of the partition blocks is 100-150 mm;
Length of gas silicate blocks: 600, 625 mm;
Height of gas silicate blocks: 200, 250, 300 mm;
Gas silicate blocks weight: 14-34 kg;
In 1 cbm. from 13 to 33 pcs. (depends on the thickness);
Consumption for 1 sq.m. the wall is 6.7-7 pcs.

The exact parameters are shown in the tables below:

Dimensions of the U-shaped gas block The size of the gas silicate block for walls (LxWxH) from different manufacturers and the number of pieces on the pallet.

Number of blocks in a pallet

Gas silicate block weight

The structural mass of the block changes depending on the density of the finished product. Judging by the marking, the following weight can be distinguished:

D400. Weight 5-21 kg.
D500 / D600. Weight - 9-30 kg.
D700. Weight - 10-40 kg.

In addition to density, the overall size of the finished block is considered the fundamental factor in the change in weight.

Pros and cons of gas silicate blocks

Like any building material, gas silicate blocks have strengths and weaknesses. Positive characteristics include the following points:

Gas silicate concrete belongs to the category of non-combustible materials and is able to withstand exposure to an open flame for up to 5 hours, without changing its shape and properties.
Large overall dimensions ensure fast erection of wall structures.
The blocks have a relatively low weight, which greatly simplifies the workflow.
In production, only natural materials are used, therefore, gas silicate blocks are environmentally friendly.
The porous structure provides high thermal insulation values for the premises.
The material is easy to process, which helps to build walls with complex geometry.

The disadvantages include the following:

They absorb moisture well, which reduces the service life.
Application for adhesion of special adhesives.
Obligatory exterior decoration.

It should be noted that a solid foundation is required for gas silicate blocks. In most cases, a reinforcing belt is required.