Production of aerated concrete (aerated concrete blocks): technology, equipment

Aerated concrete, sometimes referred to as autoclaved aerated concrete, or AAC, is a lightweight precast building material that has grown in favor due to its adaptability, simplicity of installation, and energy efficiency. Aerated concrete, in contrast to regular concrete, contains a foaming agent that produces a large number of tiny air bubbles, making the finished product lighter and more insulating. It is a great option for building walls, floors, and roofs in both residential and commercial buildings because of its distinctive composition.

Sand, cement, lime, gypsum, and water are the raw materials used in the production of aerated concrete. A small quantity of aluminum powder is added as a foaming agent. After combining these ingredients to create a slurry, a chemical reaction occurs, releasing hydrogen gas. This gas causes the mixture to expand and gain volume by creating bubbles within it. After the mixture has expanded, it is poured into molds and given time to solidify before being cut into the required size blocks or panels.

After the aerated concrete is shaped, it undergoes an autoclaving process to cure. The blocks or panels are strengthened and made more durable by autoclaving, which involves subjecting them to high pressure and temperature in an autoclave. This is an important step because it guarantees that the aerated concrete can withstand the stresses involved in construction and use, as well as helping to achieve the desired mechanical properties.

To guarantee consistency and quality in the production of aerated concrete, specialized equipment is needed. Mixers are used to combine the raw materials; molds are used to shape the concrete; and autoclaves are used to cure the concrete. Furthermore, the expanded mixture is trimmed into exact dimensions using cutting machines. To meet the demands of the construction industry, the entire production line is built to be effective and able to produce large quantities of aerated concrete.

Aerated concrete blocks have several advantages overall, such as lighter structural weight, better thermal insulation, and simpler handling and installation. These benefits, along with the effective manufacturing techniques and specialized tools, make aerated concrete a desirable choice for contemporary construction projects.

Aspect	Description
Raw Materials	Sand, cement, lime, and aluminum powder are the main ingredients used to make aerated concrete blocks.
Mixing	These materials are mixed with water to form a slurry, which is then poured into molds.
Reaction	The aluminum powder reacts with the lime and releases hydrogen gas, creating small bubbles that make the blocks lightweight and airy.
Cutting	After the initial setting, the blocks are cut into the desired shapes and sizes using wire cutting machines.
Curing	The blocks are then cured in an autoclave, where they harden and gain strength under high pressure and temperature.
Final Product	Once cured, the aerated concrete blocks are ready for use in construction, offering good insulation and fire resistance.
Equipment Needed	Key equipment includes mixers, molds, cutting machines, and autoclaves.

Technology

The manufacturing process for aerated concrete consists of multiple key steps. Since making blocks is a fairly simple process, no special knowledge or skills are needed. Aluminum powder is added to the concrete mixture to create aerated concrete. When lime and aluminum powder react, hydrogen and a lot of pores appear.

Once the finished mass is poured into unique metal containers, vibration is applied to speed up the reaction and facilitate setting and hardening. After the mass has slightly solidified, the monolith is divided into individual blocks using a wire string while closely monitoring the dimensions and eliminating any irregularities.

After that, the aerated concrete is either autoclaved or allowed to dry naturally before being adjusted for milling machines. Material properties are greatly enhanced by autoclave hardening. Concrete is treated with water vapor in less than 12 hours, which makes it more resilient, stable, and has better sound and heat insulation qualities. It also shrinks less.

Under normal circumstances, aerated concrete that is made without the use of an autoclave fully solidifies. Because you can make blocks by hand with this technology, which eliminates the need to buy and operate an autoclave, the cost of producing aerated concrete is greatly reduced. However, aerated concrete blocks have less durability and more size and pore homogeneity error.

The blocks’ geometry, which allows for multiple types, serves as the foundation for classification as well.

Aerated concrete is made by combining cement, lime, water, and a tiny quantity of aluminum powder. It is prized for being lightweight and insulating. This mixture produces a chemical reaction that gives concrete its distinct structure by forming small, uniformly distributed air bubbles. Certain tools are needed for the production process, such as mixers, molds, and autoclaves for curing. With the addition of improved thermal and acoustic insulation as well as ease of handling and transportation, aerated concrete blocks are becoming a common option in modern construction for both structural and non-structural uses.

Raw materials for aerated concrete

A traditional concrete mixture is combined with a few special ingredients to create a cellular block.

She is to blame for the pores’ appearance (they should have a composition of 0.04-0.09%).

Aerated concrete blocks can be made using a variety of recipes; in many cases, the choice of composition relies on the tools and technique employed.

Currently, pre-made dry mixes are available for purchase that simply require mixing and the addition of water in the amount specified on the container to create a solution for aerated concrete. These mixes are especially useful for novices as they can be used for both factory and home production.

Overview of the necessary equipment

A wide range of equipment is currently available on the market for the production of both non-autoclaved and autoclaved aerated concrete. There are many options available in Moscow with respect to quality, cost, performance, etc.

Conveyor

The following distinctions are implied by this kind of equipment: high cost, high volumes, minimal time and effort required to create blocks, maximum automation of production, and the presence of all starting materials. A significant degree of profitability is ensured by conveyor equipment for individuals who wish to engage in the manufacturing of aerated concrete.

Bins and containers for raw materials; belt conveyors for feeding components; a special unit for mixing the mixture; an autoclave; molds; machinery for slicing the mass into individual blocks; a moving conveyor; trolleys; a crushing plant; a control panel; and a forklift are all part of the standard delivery set.

The cost of this equipment is approximately 40–55 million rubles, but the line can produce 300,000 cubic meters of blocks annually at minimum. You must manage a 4,000 m2 site in order to accommodate all the equipment. You could search for a used line to lower your expenditures.

Up to 75–150 m3 of blocks can be produced daily by such a line, which needs multiple workers to maintain (the process is large-scale and requires supervision even with automation).

Stationary

Although the cost of such aerated concrete production equipment is significantly lower, the daily productivity is only 50 m3 less. Belt conveyors, raw material dispensers, a mixing unit, and all other required components are included in the installation kit.

However, such equipment cannot be referred to as fully automated because human intervention will still be required to operate it. Installing all the components can be done in a 500 m2 room.

The forms drive up to a stationary mixer, fill it with mortar, and then proceed through the remaining steps on the line. This is the main feature. Technology is straightforward and simple to maintain.

Mobile

Gas blocks are produced privately using this kind of installation. The installations are reasonably priced, but they quickly pay for themselves—they save 30% on average when building a home, especially during construction. A compressor is included in the kit for mobile installations, which can also run off a household electrical network.

Beginners can easily use this kind of equipment, and you can even install it yourself. 2 to 10 m3 of material are produced on average each day.

Independent production

The same general procedures apply when creating aerated concrete by hand, but it takes a lot more work and time. If the plant has a lot of automated processes, then everything will need to be done independently of installations in order to have independent production. For intermediate tasks, you can either make certain units or buy a mini-line.

• Concrete mixer for preparing mass.
• Forms for filling blocks.
• Trough or other container.
• Steel string for cutting the monolith into blocks (if you are using forms that have already been divided into blocks, then this is not necessary).
• Scales for measurements.

Here, anything can be bought or made by hand, depending on what the master wants.

Therefore, you can use a bucket mixer to manually mix the solution in place of a concrete mixer, though this will probably compromise the structure and quality. Molds can be made from metal or plywood sheets, or they can be bought.

• Mixing the solution – the recipe largely depends on the desired result, the raw materials used, but on average it looks like this: 50-70% cement, 20-40% purified quartz sand, 1.5% lime, sodium sulfate or caustic soda, less than 1% aluminum powder. Changing the proportions changes the thermal conductivity and density of the material. All components must be thoroughly mixed for 10 minutes.
• Pouring the mixture into molds lubricated with diluted machine oil up to half (the mixture will increase in volume), waiting for the gas formation process to begin (this stage takes 4 hours on average). Removing excess solution.
• Covering the poured mixture with heat-insulating material.
• Dismantling the formwork on the 2nd day after pouring, after which the blocks can be laid out on pallets and dried.
• Sending products to the warehouse – after 2-3 days of drying.
• Waiting for full strength gain in blocks for 28 days and sale or use in construction.

Autoclave processing

The autoclave method of producing aerated concrete blocks can only be carried out in a factory setting with the necessary tools.

• Feeding raw materials into the component dispenser, mixing the solution with a mixer.
• Pouring the mixture into the mold as a single monolith, waiting for the gasification process to pass with an increase in the size of the blocks.
• Tilting the block array and cutting into individual blocks.
• Processing the blocks in an autoclave, where they acquire the required strength and other characteristics under the influence of temperature and steam, pressure (within 12 hours).
• Use of aerated concrete in construction work immediately after drying in an autoclave.

Comparative analysis of autoclave and non-autoclave production

The autoclave method is preferred by the majority of aerated concrete manufacturers for producing blocks due to its superior material characteristics and faster production time. Therefore, autoclaved concrete can be sold or used in construction right away after drying, which happens in 12 hours, if non-autoclaved concrete hardens in 28 days.

Instructions for the production of block material

The process of producing aerated concrete on its own is labor-intensive despite being relatively simple. If purchasing forms is not in your plans, you will need to begin the process of making them. To do this, build a box out of metal or board, and mount lintels inside to divide the frame into individual cells. If plywood is utilized, it needs to be resistant to moisture. In order to achieve superior fixation, the boards are sliced.

The blocks’ dimensions and the cells’ size must coincide exactly. You can create multiple forms (there are several standard ones) for gas blocks of the same or different sizes to expedite the process.

To enable the blocks to be removed later, the inside of the form and the lintels need to be treated with machine oil that has been diluted in water or special compounds.

It is best to buy a compressor, mixer, hoses, and wire to remove any excess mixture before mixing the solution. If you don’t have any of these, you can mix the mass yourself in a bucket or concrete mixer. After combining all the ingredients in a container and mixing them well until the mixture is smooth, it is poured into half of the forms and left to rise.

When the reaction has begun and passed, gas formation should increase the blocks almost twice, excess mixture is removed after 5-6 hours after pouring. The formwork can be dismantled after 14 hours, carefully tapping on the walls. The material is stored in an open area or indoors, and allowed to fully gain strength (28 days).

The production of aerated concrete, commonly known as aerated concrete blocks, is a fascinating process that combines modern technology with time-tested methods. By incorporating air into the concrete mixture, manufacturers create a lightweight yet strong material that offers excellent insulation and durability. This makes aerated concrete blocks a popular choice for building projects around the world.

Aerating agents are mixed with cement, lime, sand, and water in the technology of aerated concrete. After that, this mixture is poured into molds, where it starts to solidify and expand. The blocks receive their ultimate strength and stability during the curing process in an autoclave, a high-pressure steam chamber. The entire procedure is made to be energy- and waste-efficient while also being environmentally benign.

Three essential pieces of machinery are used to produce aerated concrete: autoclaves, molds, and mixers. While molds form the concrete into uniform blocks, mixers make sure the ingredients are well combined. In order to cure the blocks and give them the appropriate strength and durability, autoclaves are essential. Precision machinery and cutting-edge technology are necessary to keep aerated concrete blocks consistent in quality.

There are many advantages to using aerated concrete blocks in building. Because they are lightweight, handling and transporting them is simple. Their long-lasting performance is guaranteed by their durability, and their superior insulation qualities contribute to lower energy expenses. Their appeal in today’s environmentally conscious market is further enhanced by the relatively eco-friendly production process.

Overall, the production of aerated concrete blocks represents a blend of innovation and practicality. By understanding the technology and equipment involved, builders and architects can make informed choices that contribute to more efficient and sustainable construction practices. Whether for residential, commercial, or industrial projects, aerated concrete blocks provide a versatile and reliable building material.

Video on the topic

Aerated concrete | How it"s made | Autoclaved aerated concrete

Aerated concrete blocks. Production // FORUMHOUSE

Aerated concrete production: top 5 tips for starting a business from scratch

Equipment for the production of aerated concrete.

Production of aerated concrete blocks