What's wrong with aerated concrete: an overview of the main disadvantages

Aerated concrete is a relatively new, but extremely popular material in private housing construction. It is rapidly conquering the construction market, taking away a niche from traditional brick. But despite its manufacturability and revolutionary nature, aerated concrete has weaknesses, which we will consider in the article.

Low fracture strength

Aerated concrete is a type of aerated concrete - a lightweight artificial stone with evenly distributed pores. It includes: quartz sand, cement, lime and aluminum powder (foaming agent). All cellular concrete pays for its lightness with strength. This is logical.

One of the disadvantages of aerated concrete is the lack of elasticity and, therefore, low fracture strength. If the low compressive strength can be compensated for with a reinforced concrete belt or support cushions, then the fragility of aerated concrete is a problem.

What threatens the fragility of aerated concrete

Slight deformation of the foundation, and this is any, exceeding the permissible: 2 mm per 1 meter; will lead to cracks in the walls. One conclusion suggests itself: aerated concrete requires a stable and reliable foundation.

This contradicts the stories of the sellers of aerated concrete, who say that, for example, the gas block is light and therefore it is possible to save a lot on the foundation. In fact, this is not the case, you need to build an aerated concrete house on a high-quality monolithic strip foundation or on a slab. It is not recommended to do this on shallow foundations that may be subject to the forces of frost heaving. Simply put - you need to ensure the complete immobility of the aerated concrete wall.

There is one more feature: aerated concrete block is a large-format material. And if large-format material also has low bending strength, it will surely break when deformed.

High moisture absorption

Aerated concretes are absorbent materials, that is, they absorb moisture well, and they do it even from the air. Water, in turn, reduces all the declared characteristics of aerated concrete: strength; durability; frost resistance; thermal insulation qualities. This material requires protection from getting wet, which sometimes costs a lot of money.

In case of rain, the moisture content of aerated concrete reaches 30%, and in such conditions, all of its thermal technical characteristics simply disappear. In winter, moisture trapped in the wall can freeze in the porous structure, leading to the destruction of the outer layer. Hence the conclusion suggests itself: the aerated concrete block is not recommended to be used in its pure form for an open facade.

The aerated concrete wall must at least be hydrophobized, and as a maximum, be protected from atmospheric influences with a facade. Hydrophobization will not allow precipitation and atmospheric moisture to quickly penetrate into aerated concrete; but at the same time the coating is vapor permeable and allows steam to escape from the wall. It is necessary to carry out hydrophobization every three years.

On the inside of the room, you need to make a vapor barrier so that moisture does not penetrate the walls. To do this, it is enough to cover the walls with a deep penetration primer - this will limit the vapor permeability of the material.

Questionable thermal insulation

Thermal insulation - this quality of aerated concrete is also controversial. Manufacturers declare the thermal insulation characteristics of the material, which is, so to speak, in greenhouse conditions. In real operating conditions, the thermal resistance of aerated concrete may differ from the declared one for the worse.

We consider aerated concrete as a separate block - it has air pores and, logically, it should be warm. But in fact, the block is part of the wall, in which there are numerous cold bridges. One of these bridges is a cement-sand masonry joint, which reduces the thermal resistance of the aerated concrete wall by 25%. Thin-layer glue on which the masonry is made increases heat loss by 10%. Armopoyasa, lintels, pillows - all this, in general, reduces the thermal insulation characteristics of aerated concrete by 10-30%.

The thermal insulation qualities of aerated concrete should not be exaggerated. If the manufacturer talks about a sufficient wall thickness for central Russia of 380 mm, it should be understood that this is not enough under operating conditions. According to the calculations of some builders, an aerated concrete wall that meets all standards should be at least 600 mm.

And also considering aerated concrete as a good heat insulator, you should pay attention to large developers who use this material only as partitions. Professionals are not very impressed with gas silicates.

Mediocre noise isolation

Sound insulation of aerated concrete is mediocre, one might even say - bad: partitions from it perfectly conduct sounds, especially high-frequency ones. Most often, residents of new buildings suffer from this, who involuntarily hear everything that is happening with their neighbors.

Low burglar resistance

You can hack any obstacle, but representatives of cellular concrete lend themselves best to this. Some will argue - will the robbers break the wall? They may not be able to punch a hole in the wall, but they will gladly pick open door hinges or grilles. Aerated concrete is a light material not only for processing, but also for burglars. For this reason, one should not hope for the complete safety of the property if the walls of a remote garage or country cottage are made of aerated concrete.

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