Autoclaved aerated concrete blocks: distinctive characteristics and production features

AAC (autoclaved aerated concrete) blocks are becoming a popular option in construction because of their special qualities and advantages. These blocks are an environmentally friendly choice because they are made of natural materials and are well-known for being lightweight and energy-efficient. They are a favorite of both architects and builders due to their adaptability and simplicity of use.

The exceptional thermal insulation qualities of AAC blocks are one of their best features. They lessen the need for disproportionate heating or cooling by assisting in maintaining a comfortable indoor temperature. This reduces utility costs and conserves energy, making them a cost-effective option for homeowners.

Sand, cement, lime, and water are among the raw materials that are combined and poured into molds during the manufacturing of AAC blocks. The strength and durability of the blocks are obtained by curing them in an autoclave, a high-pressure steam chamber. This manufacturing process guarantees that the blocks are consistent in size and quality, making them a dependable building material.

Apart from their strength and energy efficiency, AAC blocks also provide an extra degree of safety and comfort by being soundproof and fire resistant. Because of their light weight, they are simple to handle and transport, which cuts down on labor expenses and construction time. These features make AAC blocks a sensible and environmentally friendly option for contemporary building projects.

Brief description of the material

Because of the unique way the material is hardened—under pressure and at a relatively high temperature—the block is referred to as autoclaved. The block’s properties are greatly enhanced as a result of this procedure. But this fact has an impact on the high quality indicators as well; we will discuss this in more detail later.

Strengths and weaknesses of autoclaved aerated concrete

Perhaps we should begin by outlining the advantages and disadvantages of an autoclaved aerated concrete block.

Among the benefits are:

1. Material safety. The environmental friendliness of the blocks leaves no doubt.
2. Fire resistance. This material does not burn and does not interact with fire.
3. The products are quite large in size and at the same time lightweight. They are easy to process and can be sanded and cut. This allows you to significantly increase the construction process.
4. Block strength and density – also a definite advantage. It allows the construction of buildings up to 3 floors high with high performance characteristics. In addition, the structure will have the most comfortable microclimate, thanks to its ability to vapor permeate.
5. Thermal conductivity of products will provide the maximum level of heat retention and cost savings during the heating period. If desired, you can also reduce the budget for insulation.
6. Autoclaved aerated concrete blocks are presented in the building materials market in a wide range. A large number of sizes will allow any future homeowner to choose the optimal product suitable for the desired wall thickness.
7. Frost resistance index – quite enviable for most similar materials. It fluctuates between 35 and 150 cycles. This means that walls built from these blocks can withstand at least 35 freezing and thawing processes.
8. Biological resistance – is also characteristic of products. A wall made of this material is not prone to mold and rot.
9. In conclusion of the consideration of the advantages, it is worth paying attention to the almost ideal geometry. Autoclaved aerated concrete blocks, due to the production features, are distinguished by high accuracy and minimal deviations.

Although there aren’t many drawbacks, it’s still important to consider these details.

The primary flaws are:

• High level of moisture absorption capacity. This is perhaps the most important negative point. The fact is that the autoclaved aerated concrete block has a porous structure. Drops of water penetrating into the cells tend to crystallize in the winter when temperatures are below zero.

As a result, frozen moisture damages the block’s structural integrity. Consequently, the products’ qualities degrade. The most affected performance characteristics are going to be heat exchange, durability, and structure strength.

• Another disadvantage is fragility. Blocks are not able to withstand mechanical impact, they are easy to split, break. This is especially common during transportation.
• The last disadvantage is poor fixation of fasteners. However, this problem is quite solvable by purchasing specialized hardware for aerated concrete blocks.

Only when fixing heavy objects could things get complicated; you’ll need to plan ahead for how to fasten them and reinforce the nodes with additional materials, like brick.

Comparative characteristics of products

The fact that autoclaved aerated concrete blocks are among the most widely used building materials is not by accident. Several quality indicators fall short of the competition, even with the newest products. Let’s use the table to examine this in more detail.

Table 1 shows how autoclaved aerated concrete compares to alternative wall materials.

Property name	Autoclaved aerated concrete	Foam concrete	Expanded clay concrete	Polystyrene concrete	Brick
Frost resistance, cycles	35-150	From 25 to 50	50-150	35-50	50
Thermal conductivity	0.1-0.14	0.09-0.38	0.15-0.45	0.1-0.3	0.3-0.8
Shrinkage	0.3 mm/m2	2-3 mm/m2	0.4 mm/m2	0.4 mm/m2	Up to 13%
Water absorption, by weight	10-20%	10-16%	10-15%	10-15%	10-16%
Wall thickness, meters	From 0.4	From 0.6	From 0.5	From 0.6	From 1.2
Vapor permeability	0.2	0.2	0.25	0.22	0.3-0.4
Compressive strength class	B 2.5 at D500	B 2.5 at D750	B 3.5 at D600	B 2.5 at D500	V 3.5-V-7.0
Density grade	M350-M700	M400-M1200	M600-M800	M250-M600	M1000-M1200
Average price, rubles	3200	2600	3000	3000	From 7.5 rub/piece

As you can see, expanded clay concrete far outperforms autoclaved aerated concrete block D500 in terms of compressive strength. Products benefit from reduced shrinkage, resistance to frost, and some degree of thermal conductivity.

Although the block has a relatively high water absorption rate, this is one of the material’s few notable drawbacks, as was already mentioned.

Classification and scope of application

There are multiple classifications for autoclaved aerated concrete. Each is predicated on a distinct metric, application range, or compositional and production characteristics. The first one establishes the hardening technique as well as a minor variation in the raw material composition.

This is the process of isolating aerated concrete:

• Autoclaved, or synthetic hardening, which is processed in an autoclave.
• Non-autoclaved, or hydration hardening, achieving technical strength independently in a natural way.

Based on the binder component, which separates the blocks, the division is as follows:

• Cement.
• Lime.
• Mixed.
• Slag.
• Ash.

At least half of the total quantity of raw materials is the primary component of each kind of block.

The following list is based on the kind of siliceous component:

1. Blocks made using sand, most often quartz
2. Products with the addition of secondary industrial products.

The strength of the block and, consequently, the application’s range dictate another classification:

• Heat-insulating aerated concrete blocks
• Structural
• Heat-insulating and structural

The purpose of the products can be easily understood just by looking at the name.

Heat-insulating materials are utilized as thermal insulation since they have the lowest density. The second kind, which is more resilient, can be utilized to build walls and other partitions.

Structures up to ten or twelve stories high are typically constructed with structural aerated concrete; however, because thermal conductivity rises with density, additional insulation is needed.

Production technology

The production of autoclaved aerated concrete is limited to factories due to the large space requirements and high costs of the required equipment. As a result, creating the content yourself is not feasible.

The positive side is the high quality of the product and certified production in accordance with GOST.

Equipment and raw materials

Various production line types are available for use in the manufacturing process:

1. the most automated and expensive,
2. more budgetary, but requiring the involvement of a certain number of employees.

The first option entails purchasing a conveyor that is equipped with all of the required machinery to enable continuous production during every cycle. In this line, the highest daily volume of products will be produced.

The stationary production line is the second choice for a set of machinery. Simultaneously, you have the option to select an entire set on your own; ultimately, this will depend on the price, performance, and outcome.

Among the standard set are:

1. Component dispenser
2. Concrete mixer
3. Forms
4. Storage for components
5. Liquid dispenser (for water)
6. Cutting complex

The autoclave is purchased separately in this instance.

Autoclave-aerated concrete composition:

1. Brand cement of at least 400
2. Quartz sand
3. Lime, sometimes – gypsum
4. Water
5. A gas former in the form of aluminum powder or a similar component with a similar property
6. Specialized supplements in the form of industry waste

Description of the manufacturing process

The specifications for autoclaved aerated concrete blocks are outlined in the documentation.

• "Unreinforced wall products made of autoclaved aerated concrete" GOST 31360-2007
• "Instructions for the manufacture of aerated concrete products" SN 277-80
• "Cellular concrete" GOST 25485-89
• "Autoclaved aerated concrete. Technical conditions" GOST 31359-2007
• "Small wall blocks made of aerated concrete" GOST 21520-89

A succinct set of guidelines that includes a sequence of material manufacturing stages:

1. Water enters the mixer first.
2. The component dispenser automatically supplies bulk raw materials in a proportion preset by the operator.
3. All components are mixed and are sent to a form in which the gas formation process takes place.
4. After a few hours, excess mixture is removed, and the block array is cut into products of the required size.
5. This is followed by the final stage, during which the blocks are transferred to the autoclave.
6. After autoclaving, the finished products are sent to the warehouse.

AAC (autoclaved aerated concrete) blocks are a well-liked building material because of their adaptability, energy efficiency, and light weight. These blocks are made of a mixture of cement, lime, sand, water, and an expanding agent. They are given their special qualities by a high-pressure steam curing process. AAC blocks are a sustainable option for building because they offer superior fire resistance, soundproofing, and thermal insulation. Their accurate dimensions and ease of handling make construction work simpler, requiring less time and labor. Making educated decisions regarding the use of AAC blocks in different projects can be facilitated by having a thorough understanding of their unique properties and production features.

Features of masonry of autoclaved aerated concrete

Building walls with aerated concrete is a simple process. Additionally, virtually anyone can complete the task if they follow all the guidelines.

When constructing walls, you ought to adhere to the proper sequence and the following guidelines:

1. The first row of the block is laid on cement-sand mortar
2. Laying should be started from the most protruding corner. In this place the layer thickness will be the smallest.
3. Next, the blocks are placed at the remaining three corners, which will serve as a guide for laying. A cord is stretched between them.
4. If the length of the wall exceeds 9-10 meters, it is allowed and even recommended to install additional beacon blocks, in addition to the corner ones.
5. The first row is laid out completely and, after 2-3 hours, it is reinforced without fail.

Take note: The block needs to be cut to the appropriate size if a gap is left after installation. Any suitable tool will work, such as an electric saw or hacksaw.

1. The second and subsequent rows are placed mainly on glue with a seam offset of approximately 20%.

Counseling! Should you choose to construct a wall with self-made cement mortar, bear in mind that the thickness of the joint will ultimately determine the presence of cold bridges, which will impact the room’s ability to retain heat.

1. The adhesive composition is applied in a thin layer using a trowel, leveled using a comb
2. The evenness of the masonry is controlled using a level and a rubber hammer

Counseling! Because the adhesive mixture sets quickly and makes it impossible to take the wall apart or make changes, it is important to level the laid blocks as soon as possible.

1. After laying every 3-4th row, mandatory reinforcement is carried out in order to strengthen the structure.

It’s evident that the list of works is not very long. But if you adhere to these guidelines, the outcome will be better than you could have imagined.

This article’s video provides extensive information about the masonry profession.

Overview of popular manufacturers of autoclaved blocks

1. Aerated concrete blocks sibit. The manufacturer focuses on the excellent quality of the products, as well as on a special manufacturing technology and composition of components. The products are distinguished by an increased ability to withstand climatic conditions and geometric evenness.
2. Aerated concrete blocks teplon. Are one of the most popular. Their price is quite high, but at the same time, these products are characterized on the positive side among developers.
3. Aerated concrete blocks AeroStone. As the manufacturer assures, when constructing masonry using these blocks, a sufficient wall thickness will be 37 cm. Thus, the manufacturer emphasizes the combination of high density and, at the same time, thermal insulation.
4. Aeroc gas silicate blocks. You can lay 1 m3 of products in just 20 minutes. Maximum block deviations are only 0.5 cm. It is resistant to moisture, mold and fungal infections.

Characteristic	Description
Lightweight	These blocks are much lighter than traditional concrete, making them easier to handle and reducing the load on structures.
Insulation	Autoclaved aerated concrete blocks provide excellent thermal and sound insulation, helping to keep buildings warm and quiet.
Fire Resistance	They are highly fire-resistant, offering better safety in case of a fire.
Eco-friendly	Made from natural raw materials, they are environmentally friendly and have a smaller carbon footprint.
Precision	The production process allows for precise dimensions, reducing the need for extra plastering.
Production	These blocks are made by mixing raw materials, pouring the mixture into molds, and curing them in an autoclave at high pressure and temperature.

Blocks of autoclaved aerated concrete (AAC) have a special combination of advantages that make them a desirable option for building. They offer a number of advantages over conventional building materials, including being lightweight and having excellent insulation qualities. AAC blocks lower energy costs and have a positive environmental impact by improving comfort and energy efficiency in both residential and commercial buildings.

AAC blocks are made using a precise mixture of ingredients under carefully monitored conditions. An expanding agent, sand, water, cement, and lime are combined to give AAC blocks their unique cellular structure. These blocks are made stronger and more resilient through the autoclaving process, which also makes them easier to work with. This means that they can handle the demands of a variety of construction projects.

All things considered, the performance, sustainability, and adaptability of AAC blocks make them exceptional. They provide homeowners and builders with an alternative that emphasizes efficiency and eco-friendliness and is in line with contemporary construction requirements. With the growing demand for eco-friendly building materials, AAC blocks are expected to become more and more significant in the building sector.

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