Autoclaved aerated concrete production: step-by-step analysis of the manufacturing process and evaluation of the results

A lightweight precast concrete with exceptional strength and insulation qualities is called autoclaved aerated concrete, or AAC. AAC blocks are highly valued for their ease of installation and energy efficiency, making them widely utilized in construction. AAC is produced using an intricate set of procedures that guarantee the material’s performance and quality.

Raw materials like sand, lime, cement, gypsum, and aluminum powder are used to create AAC. After combining these components with water to create a slurry, the mixture is poured into molds. Tiny hydrogen gas bubbles are created during the chemical reaction between the aluminum powder and the other ingredients, which causes the mixture to expand and take the form of a porous structure.

The molds are taken out after the first setting phase is finished, and the aerated concrete is then cut into the appropriate-sized blocks or panels. This cutting process is important because it determines the final product’s size and form. After that, the green, or uncured, AAC blocks are put in an autoclave, a special pressure chamber that exposes them to high temperatures and steam pressures.

The materials go through a curing process in the autoclave, which greatly boosts the AAC’s strength and stability. The lime and silica react with the steam and heat to form calcium silicate hydrate, which gives the blocks their distinctive strength and durability. This stage of autoclaving, which usually takes a few hours, is essential to getting the required mechanical qualities.

The AAC blocks are prepared for packaging and quality inspection after curing. Every block is inspected to make sure it satisfies the required requirements for density, size, and strength. The blocks are only sent to construction sites where they will be utilized to create long-lasting, energy-efficient buildings after passing these quality inspections.

A precise and thorough manufacturing process is used in the production of autoclaved aerated concrete (AAC), which turns raw materials like sand, lime, cement, and aluminum powder into a lightweight, long-lasting building material. This article explains every stage, from combining the ingredients and adding them to the molds to the crucial autoclaving stage, which uses high-pressure steam curing to give the material its special qualities. We will comprehend why AAC is preferred for its insulation, fire resistance, and environmental benefits in contemporary construction by assessing the effectiveness and results of these procedures.

What is aerated concrete

The presence of pores that are produced by the chemical reaction of quicklime and a blowing agent—typically aluminum powder—defines aerated concrete as a kind of cellular concrete. We will start by talking about the unique characteristics and attributes that the products have, which are a result of the material’s composition and the manufacturing process.

Brief description of the material

The qualities of aerated concrete are indicated by the following:

1. Thermal conductivity is one of the main advantages of the products. The coefficient varies from 0.09 to 0.38. However, it is worth considering that such numerical indicators are typical for blocks in a dry state. With the operational humidity of the products, it can increase significantly.
2. Strength and density. The density grade, in accordance with GOST, can be from 300 to 1200.

Take note! The most commonly used blocks have a density of 500. This amount is more than enough to build a structure with multiple stories. Thermal conductivity will continue to be at the appropriate level at the same time.

1. Frost resistance. Aerated concrete is distinguished in this regard by an indicator enviable for many materials. Some manufacturers claim that their products can withstand up to 100, and sometimes up to 150 freezing and thawing cycles.
2. Shrinkage. It is typical for aerated concrete. The indicator is – 0.3 mm/m2. Often cracks appear on the walls as a result.
3. Water absorption – the main disadvantage of the material. Aerated concrete can absorb up to 25% moisture, so products need protection from its harmful effects.
4. Masonry layer thickness. Recommended – from 0.4 meters. However, in practice, if you go into the nuances, much more will come out. When calculating this thickness, manufacturers do not take into account cold bridges and other factors that contribute to heat loss.
5. Soundproofing. In general, aerated concrete is able to isolate a room from extraneous noise, it will be quite comfortable to be in it.
6. Vapor permeability. Coefficient – ​​0.2. Thanks to this ability, the most comfortable microclimate will be established in the room, since aerated concrete tends to absorb excess moisture and give it off when the air is excessively dry.

Now that the primary attributes have been discussed, it’s time to identify the various varieties of aerated concrete and their distinctions from one another.

Types of products

Aerated concrete classification according to GOST 21520-89:

Kindly take note! Third-category blocks are laid on mortar, which considerably increases the number of cold bridges. As a result, the products are most frequently utilized in the building of outbuildings, like garages and barns.

Overview of the manufacturing process

Only in a factory can autoclaved aerated concrete be produced. Let’s take it step by step and begin with the inventory of tools and supplies that we’ll need.

Necessary set of equipment and materials

A variety of equipment is available for autoclaved aerated concrete purchases:

• Stationary line – the most budget option. You can select the complete set yourself, but it is worth considering the fact that the volume of production, production speed and the final result will depend on this.

A block form, a cutting machine, a component dispenser, an aerated concrete mixer, a gasifier, and, of course, an autoclave are all part of the standard set.

• Conveyor line. The most expensive. The entire process takes place in the most automated mode, the participation of workers is minimal, only several operators are required to control the operation of the machines.

The equipment stands out for its high production speed and capacity to produce big batches of products every day. Additionally, the products have nearly flawless geometry and are of the greatest quality.

The autoclaved aerated concrete production line with a conveyor type comprises:

1. Mixer;
2. Component dispenser;
3. Railway for automatic movement;
4. Belt conveyor;
5. Mixer;
6. Mold block;
7. Heat treatment chambers;
8. Block cutting units;
9. Autoclave.

It is now worthwhile to arrange the required supplies.

The following raw materials are needed for the production of autoclaved aerated concrete:

1. Quartz sand;
2. Clean water;
3. Cement grade not lower than M 400;
4. Quicklime;
5. Aluminum powder or paste;
6. Additives to accelerate hardening and improve qualities and properties.

Autoclaved aerated concrete (AAC) is made using a complex process that requires multiple important steps to guarantee that the finished product fulfills strict performance and quality requirements. The preparation of the raw materials through mixing, molding, cutting, and curing are all crucial steps in determining the properties of the AAC blocks.

Precision and consistency are prioritized throughout the process, which starts with the selection and preparation of raw materials. To create a slurry, raw ingredients such as sand, lime, cement, and aluminum powder are precisely measured and combined. After that, this mixture is poured into molds, where it starts to solidify and expand, giving AAC its distinctive porous structure and its insulating and lightweight qualities.

The partially hardened blocks are then precisely shaped and sized using specialized cutting tools after they have set. This is a critical step in cutting waste and guaranteeing consistency. After that, the cut blocks are placed in autoclaves and given a high-pressure steam curing process. The blocks’ strength and durability are increased through the autoclaving process, which qualifies them for a variety of construction uses.

The analysis of the findings demonstrates that AAC blocks have many advantages, such as superior fire resistance, sound absorption, and thermal insulation. In comparison to conventional concrete blocks, they require less energy to produce and result in lower greenhouse gas emissions, making them more environmentally friendly. Their low weight also lessens the overall load on structures, which makes them perfect for contemporary construction projects that prioritize efficiency and sustainability.

All things considered, the process of producing autoclaved aerated concrete is well-organized and results in a high-quality building material. Manufacturers can guarantee the quality and dependability of AAC blocks and satisfy the increasing demand for environmentally friendly building materials by closely monitoring every stage of the process.

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