Aerated concrete blocks GOST: an overview of the material, its characteristics and qualities in accordance with technical documentation

Aerated concrete blocks are unique among building materials because of their many uses and special qualities. The remarkable performance and versatility of these blocks are making them more and more popular in the construction industry. This article will examine aerated concrete blocks in more detail, emphasizing their features and the requirements that GOST technical documentation states they must fulfill.

Autoclaved aerated concrete (AAC), another name for aerated concrete blocks, is a strong yet lightweight material. Cement, lime, water, and a foaming agent—which inflates the material—are combined to make them. This procedure yields an easy-to-handle block with superior thermal insulation. However, what precisely is GOST’s position on these blocks? Gaining an understanding of the GOST standards will help us assess their quality and appropriateness for various construction applications.

The Russian National Standard, or GOST for short, establishes standards for a wide range of building materials used in Russia and other nations that adhere to them. GOST specifies requirements for the density, thermal conductivity, and compressive strength of aerated concrete blocks. These specifications guarantee that the blocks fulfill strict quality standards and function effectively in a range of construction scenarios.

We can gain a deeper understanding of the benefits of aerated concrete blocks, including their energy efficiency and user-friendliness, by exploring the GOST specifications. With this information, homeowners and builders will be better equipped to choose which of these blocks to use for their projects. Join us as we examine the specifics of GOST standards and their implications for the dependability and efficiency of aerated concrete blocks.

The concept of aerated concrete

One type of cellular concrete is aerated concrete. Sand, lime, cement, water, and a blowing agent—typically aluminum powder—are combined to make it.

The process of the solution swelling happens as a result of the latter’s reaction with quicklime. Consequently, a material that is packed with cells is produced. Aerated concrete has unique properties and qualities because of this structure, which we will discuss below.

Let’s first identify the various varieties of aerated concrete, though.

Types of material and scope of application

According to GOST 25485-89, aerated concrete can be used for the following, depending on the purpose:

• Heat-insulating, density 300-400. It has a low thermal conductivity coefficient and is used exclusively as a material for insulation, since such products cannot withstand any loads other than their own weight due to their low density.
• Structural and heat-insulating. Its density varies from 500 to 900. It is more durable, used for the construction of building walls and partitions. This type of aerated concrete is the most common among private developers.
• Structural. The most durable type. Its density is 1000-1200. It is used for the construction of buildings up to 3 floors high.

But because of the considerable increase in the thermal conductivity coefficient, more insulation is needed for such materials.

Let’s use a table to examine how a product’s strength and thermal conductivity relate to each other.

Aerated concrete’s strength and thermal conductivity:

Type of aerated concrete	Strength grade	Coefficient thermal conductivity
Heat-insulating	D300	0.09-0.11
	D400	0.11-0.12
Structural and heat-insulating	D500	0.12-0.13
	D600	0.14-0.15
	D700	0.18-0.21
	D800	0.21-0.23
	D900	0.23-0.26
Structural	D1000	0.23-0.28
	D1100	0.28-0.34
	D1200	0.29-0.38

Since we’re discussing the material’s application, it’s important to note how construction projects’ drawings depict the use of both aerated concrete and concrete in general. On the drawings, the hatching of the aerated concrete is denoted by dotted lines, or angled lines. The picture below makes this quite evident.

Aerated concrete is further separated into autoclaved and non-autoclaved varieties based on the type of hardening. The final stage of production for autoclaved aerated concrete, also known as aerated concrete of synthetic hardening, involves processing the products in an autoclave under high pressure and temperature.

The material release process happens quite quickly. Aerated concrete that has not been autoclaved, also known as hydration-hardening aerated concrete, solidifies naturally. In certain cases, it is accelerated by briefly heating it to a low temperature in specialized machinery. In just 28 days, this type of aerated concrete gains its brand strength.

In comparison to its rival autoclave, it has a few less features. Strength, resistance to frost, thermal conductivity, and durability are the main issues here.

A comparison between synthetic and hydration-hardened aerated concrete:

Name of the indicator	Value for autoclaved aerated concrete	Value for non-autoclaved aerated concrete
Thermal conductivity of products in dry form	From 0.09 to 0.38	From 0.11 to 0.40
Frost resistance, cycles	Up to 150	Up to 50
Shrinkage, mm/m2	0.3	0.5
Strength grade	From B2.5	From B 1.5
Product color	white	Gray
Durability, years	Up to 200	Up to 50
Brand by density	300-1200	300-1200

The types of silica components that can be used to create aerated concrete blocks are as follows:

• Sand;
• Ash;
• Other secondary industrial waste.

Aerated concrete can be: based on the type of binder.

• On a cement binder;
• On slag;
• On limestone;
• On ash;
• On mixed.

15–50% of the primary component is present in the products.

Aerated concrete products are categorized into the following categories based on the accuracy category:

• Blocks of the first accuracy category;
• Blocks of the second accuracy category;
• Blocks of the third accuracy category.

Let’s use the table to examine the allowable deviations.

GOST 21520 89 Aerated Concrete Block: Variations according to Accuracy Levels:

Deviation name	First accuracy category (permissible maximum), mm	Second accuracy category (permissible maximum), mm	Third accuracy category (permissible maximum), mm
By thickness, length	2	4	6
By height	1	3	5
Deviation from squareness	2	4	6
Faces and edges	1	3	5
Damage to corners, including chips (no more than 2 on one product)	5	10	15

Similar allowable deviations are provided by GOST for aerated concrete blocks for both autoclaved and non-autoclaved products.

Kindly take note! When laying category 1 blocks on glue and category 2 and 3 blocks on mortar, the GOST for aerated concrete advises doing so. Different products only differ in geometric deviations, depending on the category. Other than that, the technical characteristics are the same.

Main technical, mechanical and other characteristics

Let’s now examine the characteristics and indicators that aerated concrete products possess. First, let’s talk about compressive strength. Let us examine the table.

GOST 21520-89, 31359 2007 for aerated concrete: density to compressive strength grade ratio

Density grade	Compressive strength, minimum permissible indicator for autoclaved aerated concrete	Compressive strength, minimum permissible indicator for non-autoclaved aerated concrete
D500	B2.5	B1.5
D600	B3.5	B2.0
D700	B3.5	B2.0
D800	B3.5	B2.5
D900	B3.5	B2.5
D1000	B7.5	B5
D1100	B10	B7.5
D1200	B12.5	B10

Technological documentation also governs the block sizes:

Sizes of aerated concrete blocks, GOST:

Types of products	Dimensions for laying blocks
	For mortar			For glue
	length	height	thickness	length	height	thickness
I	588	188	300	598	198	295
II			250			245
III		288	200		298	195
IV	388	188		398	198
V	288	288	250	298	298	245
VI	588	144	300
VII		119	250
VIII		88	300	598	98	295
IX			250			245
X	398		200	398		195

The following qualities should also be present in autoclaved aerated concrete, per GOST 31360 2007:

• Density material – from 300 to 1200
• Frost resistance of products intended for the construction of external walls should not be less than 35, for other products – not less than 15;
• The shrinkage during drying should not exceed 0.5 mm for structural and structural-heat-insulating aerated concrete, which were manufactured on sand, 0.7 mm – for structural and structural-heat-insulating aerated concrete, manufactured on other secondary industrial products.
• Vapor permeability directly depends on the density of aerated concrete products, and varies from 0.09 to 0.3
• Thermal conductivity, as already mentioned above, directly depends on the strength of the products, the numerical indicator is in the range from 0.09 to 0.38. These values ​​are typical for products in a dry state. When moistened, they increase.

Kindly take note! For products made on sand, the release humidity of blocks shouldn’t go above 25%, and for products made on ash, it shouldn’t go above 30%.

The frost resistance indicator for non-autoclaved blocks is a little lower, at least 25 for external walls and 15 for the remaining blocks. The initial modulus of elasticity of autoclaved aerated concrete is also significant.

Using the table, let’s examine how the aforementioned values alter as density and strength rise.

Initial concrete elasticity modulus after aeration:

Density grade	Compressive strength and the corresponding initial elasticity model (compression/tension)
D400	B1	B1.5	B2	B2.5	B3	B3.5	B5	B7.5	B10	B12.5	B15
D500	0.75/7.65	1/10.2	1.25/12.7	1.7/17.3
D600	1.4/14.3	1.7/17.3	1.8/18.4
D700	1.8/18.4	2.1/21, 4
D800	2.5/25.5	2.9/29.6
D900	3.4/34.7	4/4.8
D100	3.8/38.8	4.5/45.9	5.5/56.1
D1100	6/61.2	7/71.4
D1200	7.9/80.6	8.3/84.68.6/87.7
9.3/94.6

Basic requirements for materials used for the production of aerated concrete

GOST specifies specifications for the materials used in the creation of aerated concrete in addition to technical and other features.

The following is a list of some requirements:

• The cement grade in the composition must not be lower than M400;
• The main binding components used are: cement (GOST 31108, 10178), highly basic ash, quicklime (GOST 9179), the content of various chemical substances in them is strictly regulated;
• The following can be used as a siliceous component: natural material in the form of quartz sand and secondary industrial products – fly ash, ore enrichment products, and products of our own production;
• It is recommended to use aluminum powder or paste based on it as a blowing agent;
• To improve the qualities and properties of aerated concrete, it is recommended to use various additives: granulated slag, gypsum stone and other additives provided by GOST 24211;
• Water must be clean and meet the requirements of GOST 23732.

Advantages and disadvantages of aerated concrete and products made from it

Aerated concrete will have both advantages and disadvantages, depending on whether the manufacturer complies with all of the aforementioned specifications and whether the products meet all of the indicators.

Let’s examine them, beginning with the advantages:

1. Due to its porous structure, aerated concrete is lightweight, which can significantly reduce the load on the foundation;
2. Products made from it are quite large in size, which can significantly speed up the construction process;
3. Since the composition includes components that are safe for humans and the environment, aerated concrete is environmentally friendly;
4. In accordance with GOST, the material does not burn and does not interact with fire;
5. Aerated concrete is easy to handle, it is quite easy to saw and polish;
6. As we have already found out, it has a low thermal conductivity coefficient, which, in turn, will help save the budget on insulation of the structure, and, in the future, on heating the building;
7. High frost resistance is an undoubted plus, the number of freeze and thaw cycles that aerated concrete can boast of is truly surprising;
8. Good soundproofing, vapor permeability.
9. A large selection of sizes and manufacturers;
10. The strength indicator allows you to erect buildings several stories high;
11. You can also highlight as a plus the possibility of a variety of external and internal decoration. The main thing is to strictly adhere to the technology so as not to worsen, but to emphasize the advantages of the material.
12. The possibility of making the material yourself. This applies only to non-autoclaved aerated concrete. The production process is simple and does not require significant costs, and the savings are obvious.

You will require a minimal amount of raw materials and equipment, along with instructions, in order to produce products.

1. The price of the products is relatively low. If you compare aerated concrete with brick, the latter is about 15-20% more expensive.

The drawbacks include:

1. Hygroscopicity. Aerated concrete tends to absorb moisture, which has a detrimental effect on the structure of the block, especially when freezing. This problem is solved with the help of properly executed finishing.
2. Poor adhesion with finishing materials. This fact can be leveled by preparing the wall, by treating it with primers and concrete contact. When plastering, mandatory reinforcement is carried out using a mesh.
3. Fixing the elements is another problem that developers may face. When planning the fastening of heavy objects, it is necessary to plan the fixation units. It is also necessary to use specialized hardware designed for cellular concrete.
4. Fragility of the material. Aerated concrete should be handled with extreme caution.
5. Shrinkage of products is a significant drawback. Cases of cracks appearing on the blocks themselves are not uncommon, and during finishing – on it too.

Methods of control, testing and acceptance of products

GOST offers procedures for inspecting and testing goods to make sure they live up to their advertised features.

Control of physical and technical indicators

Let’s use the table to think about them.

Aerated concrete control techniques in compliance with GOST 25485-89:

Method name	Brief description
Tensile and compressive strength	The method consists of measuring the forces that destroy a pre-prepared sample. The load is constantly increased and the stress is measured, assuming elastic work of the material.
Sorption moisture	The essence of the method is as follows: samples are brought to an equilibrium state, having been pre-dried in steam-air environments that have a relative humidity of 40 to 97%. Then the change in the weight of the samples is measured.
Shrinkage during drying	The method consists of measuring the change in the length of the controlled sample when its humidity is from 5 to 35%.
Dispensing moisture	The test samples are removed from finished products or selected from among those that have already passed the strength test.

You can learn more about testing aerated concrete blocks from the video in this article.

Acceptance

Products are accepted based on their compliance with the following requirements:

• The number of products whose deviations exceed those specified in Table 3 should not be more than 5% for each parameter of the total number in the batch;
• Acceptance is carried out in accordance with the test data for all indicators;
• The buyer has the right to conduct a control test;
• To conduct control tests, 30 samples are selected randomly from the batch, both from the inner and outer rows of the packaging;
• If the test result is negative for one or more parameters, the test is repeated for these indicators;
• If the result is again unsatisfactory, the test is carried out individually;
• The possibility of using products that do not meet the required parameters is determined by a special design organization;
• The blocks in the packaging must not be stuck together, they must be easily disassembled manually;
• Each batch of products must be accompanied by a document indicating the following data: address and name of the manufacturer, standard designation, batch number, volume or quantity of shipped products, date of issue of the document, designation of the blocks themselves.

Aerated concrete blocks are an efficient and user-friendly material option for construction because of their insulating qualities and lightweight nature. This article examines the definition and regulation of these blocks in accordance with GOST standards, emphasizing their material composition, salient features, and functional attributes. Builders and homeowners can ensure longevity, energy efficiency, and overall construction quality in their projects by using aerated concrete blocks by knowing these specifications and making informed decisions.

Requirements for transportation and storage

The following are the requirements for storage and transportation:

1. Transportation of products is carried out in containers or on wooden pallets. Blocks should be rigidly fixed so that the immobility of the product and its safety is ensured;
2. Transportation can be carried out by any type of transport, which does not contradict the requirements of GOST 9238 and the requirements of fastening and loading of cargo;
3. It is strictly forbidden to transport blocks in bulk and unload them by dumping from the vehicle;
4. The blocks should be stored on pallets or in containers, they must be protected from moisture.
5. Products must be distributed in accordance with the size, category, strength. Stack height should not exceed 2.5 meters.

In conclusion, aerated concrete blocks are a common option in contemporary construction because they provide an exceptional blend of strength, insulation, and usability. Builders and homeowners can feel secure knowing that these blocks fulfill strict quality and safety requirements because of their adherence to GOST standards.

The advantages of the material, such as its lightweight nature, which facilitates handling and lowers construction costs, are highlighted in the technical documentation. Furthermore, the thermal insulation qualities of the blocks support energy efficiency, gradually increasing the comfort and economy of buildings.

All things considered, aerated concrete blocks are an effective and adaptable building material. For a variety of construction requirements, you can rely on their dependability and performance if you adhere to the GOST specifications. These blocks are practical and long-lasting, so your project will last for years—whether you’re building a new home or remodeling an old one.

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