A significant drawback of gas blocks, which is mentioned in building codes, but sellers are stubbornly silent

  • Mar 15, 2021

When erecting walls, regardless of the material, a certain technology must be observed. This is what the manufacturers advise to do. In addition, building codes must be adhered to. For example, if the SNiP says that there must be a gap in the wall, then it must be there.

A significant drawback of gas blocks, which is mentioned in building codes, but sellers are stubbornly silent
If the rules say that the thickness of the seam should be in the range from 1 to 3 millimeters, then it is not permissible to make it 5 or 10 mm. All this should be taken into account when laying the walls.

There are also properties of raw materials and the nuances of materials manufacturing technology that are worth paying attention to. For instance, ceramic block and brick contain clay, i.e. during the production process, materials are molded and fired. The composition of gas blocks includes lime, cement and sand. Bulk materials are mixed, then blocks are formed, and then they are dried.

To obtain a cellular material at the output, aluminum paste is added during its production. When interacting with lime, it begins to release hydrogen. As a result, pores from 0.5 to 2 millimeters are formed in the entire material.
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Actually, I propose to consider everything using the example of aerated concrete.

I get very angry when I bump into salespeople singing praises to their product. After listening to them, one gets the impression that aerated concrete has some advantages and absolutely no disadvantages. In fact, sellers just keep silent about the cons in order to sell the product.

I do not argue that the gas block has many positive aspects: it is light, fire-resistant, environmentally friendly, has low thermal conductivity, and is easy to process. But there is a fly in the ointment in this whole list of benefits. After erecting a house from gas blocks, they shrink strongly. This problem is relevant for any porous concrete.

If you turn to set of rules "Stone and reinforced stone structures", you will notice that when working with ceramics, the shrinkage values ​​are lowered, since they are very small. And in the case of aerated concrete, shrinkage ranges from 0.4 to 0.6 mm / m. It turns out that the 3-meter floor of the house will shrink in 1.5 - 2 mm.

Aerated concrete is strongly compressed, which is a natural process for such materials. Shrinkage will not stop until the concrete reaches its equilibrium state. Those. aerated concrete structure will go down for at least a year, and maybe longer.

I note that all concretes have shrinkage, both autoclaved and non-autoclaved!

Naturally, the stone also has shrinkage, but it is insignificant, and therefore the bearing capacity of the house does not suffer from it. Aerated concrete takes a leading position in this indicator. Therefore, cracks appear on the finishing plaster over the years.

To avoid problems, you need to wait at least a year after erecting the box of a house made of aerated concrete, and only then proceed to the finishing external work.

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