Characteristics of aerated concrete blocks: pros and cons,

Operational properties of aerated concrete blocks allow you to actively apply them to solve a wide range of engineering problems. This material is used both for thermal insulation of structures, and for the erection of supporting structures, which initially have high thermal performance.

In our article, we will describe in detail the manufacturing technology of such products, and give a list of their main characteristics, advantages and disadvantages.

Description of aerated concrete

Raw materials for production

In the manufacture of aerated concrete used such materials:

• Binder - Portland cement M400 or M500. This component must be very high quality, because it is responsible for the mechanical properties of the mixture.
• Filler - sifted sand. Usually used material with a minimum content of organics and clay fractions, since they can reduce the strength of the product.
• Water is a key ingredient for solution preparation. To ensure sufficient quality of the finished blocks, take purified water with low salt content (sulphates, carbonates, chlorides) and organics (oils, petroleum products).

• The gasifier is aluminum powder or paste based on it. The reaction of aluminum hydroxide with water produces hydrogen, which is then distributed in the bulk of the solution in the form of microscopic bubbles.

As you can see, all the components included in the material are quite simple. However, its properties are largely determined by the peculiarity of the structure, which is obtained as a result of production by special methods.

Manufacturing technology

The main point of the technological process is the involvement of gas in the structure of the material and giving the structure the necessary strength.

The instruction assumes such an operation algorithm:

• First, a binder with sand comes into the mixer, which are combined and mixed until a homogeneous mass is obtained.
• Next is mixing the solution with water and bringing it to the desired consistency.
• At the next stage, a gas-forming powder is introduced into the container with the material, which reacts with water.

• Gas-saturated material is poured into molds, the dimensions of which correspond to the dimensions of building modules. It is also practiced pouring large blocks, which are then sawn on a special machine.

Note! Not only dimensions affect the mass of the finished product - the weight of aerated concrete blocks is also determined by the ratio of the solid fraction and the number of pores. This aspect will be covered in more detail in the next section.

• In the forms of the primary curing of concrete products. Then the monoliths are removed and fed to the sawing, where the parts are finally cut to the desired size.
• If cassette forms were used, the modules of them are immediately transferred to the drying section.

Next, you must wait until the binder is completely cured.

This process can occur in two ways:

• Natural drying. It takes a lot of time, does not guarantee a uniform set of strength. The main advantage is the lack of costs.
• High temperature treatment. With a uniform heating of the concrete blocks, the cement reacts more actively with water, as a result of which the mechanical properties of the material increase. The disadvantage of this technique is the somewhat higher price of finished products due to the cost of autoclaving.

Material characteristics

Main settings

Rather simple manufacturing technology allows this material to be produced at a relatively low cost. That is why the range of gas-block in recent years significantly expanded.

First, these modules are presented in various configurations and sizes. The most popular dimensions of aerated concrete blocks range from 200x200x600 mm to 500x200x600 mm, but there are products with other parameters.

The dimensions of the foam concrete blocks (products manufactured using similar technology) are practically the same as those mentioned above, and even interchangeable formwork can often be used. For this reason, a combination of both types of material in one design is allowed.

Note! There are also products with curved mounting slots on the market that facilitate the process of laying and joining.

Secondly, the amount of air involved plays an important role in determining the basic characteristics. It determines the porosity, density, and thermal conductivity of the resulting gas block. So that you can quickly find an aerated concrete block that meets your goals - the characteristics of the most frequently used varieties are given in the table:

Virtues

This material has a whole list of advantages that make the choice in favor of aerated concrete as the main material for construction is fully justified.

Among the main advantages are:

• The exact dimensions of aerated concrete blocks, especially those that were made using the sawing method. This advantage allows you to make the seams between the rows of masonry thickness of not more than 3 mm, which has a positive effect on the insulating qualities of the structure.
• Relatively small proportionreducing the load on the capital base.

Note! The rigidity of the blocks remains sufficient for use in low-rise construction.

• Easy to do it yourself: the blocks are effortlessly sawn and drilled using conventional tools, which makes it easy to fit parts to size.

• Good thermal insulation performance.
• Resistance to external factors: aerated concrete does not burn, it is able to withstand severe temperature changes, it does not affect fungi and microorganisms.

As you can see, the list of advantages is impressive, which fully explains the growing popularity of the material on the market.

disadvantages

Having learned how much an aerated concrete block weighs, and having been inspired by its thermal insulation properties, many do not pay attention to the minuses of this material. And they are, though not critical.

Among the negative properties of the building gas block can be identified:

• Fragility - the reverse side of simplicity in processing. The foundation for the construction of aerated concrete blocks may not be too powerful, but it just has to be extremely rigid, otherwise cracks will inevitably appear.

• Another aspect of this problem is the difficulty of fixing in a gas-concrete wall. Conventional anchors during installation can destroy the drilled nest from the inside, because you should use special fasteners. It is, of course, more expensive than common plastic and metal dowels.
• Another disadvantage is high water capacity. Material without finishing actively absorbs water, which in some cases can lead to freezing of the masonry.
• We should also talk about finishing. Because of its high hygroscopicity, aerated concrete literally “pulls” moisture from any plaster, so that gypsum compounds quickly become covered with cracks. However, this problem has another side: externally, the plaster layer does not look very attractive and requires disguise, but holding on - you will not tear it off!

Tip! The problem is solved by arranging a multi-layer finish: cheap gypsum plaster - fiberglass - high-quality putty. Yes, labor costs are substantial, but reliability in this case will increase many times.

Conclusion

The various sizes of blocks of aerated concrete, their good performance and ease of use significantly expand the scope of application of this material. It can be used for the construction of load-bearing elements, and for external insulation of houses, and for building complex architectural forms.

The main thing is to soberly evaluate the pros and cons of the gas block and take into account its features when designing and installing. This information is described in more detail in the video in this article, therefore we recommend that you familiarize yourself with anyone who plans to use cellular concrete in their work.