We analyze the main misconceptions about aerated concrete

In the comments to the article After the start of construction from aerated concrete, I understood why many people build from wooda lot of criticism and, in my opinion, misconceptions have been written about the properties of aerated concrete. I propose to analyze the main ones that are most often referred to.

1. Aerated concrete - fragilematerial

In most cases, "sofa experts" confuse strength with fragility. The strength criterion includes the properties of a material to withstand compressive and tensile deformations. All concrete-based materials have high compressive strength values. But in tension - they are fragile.

No one would argue that granite is not a durable material. But it is brittle, like most rocks - it can be split with wedges.

Yes, aerated concrete is not granite and not even concrete, and chips are easily formed on it upon impact. But will you hit the walls with a hammer in the house? The walls will be plastered. Even if there is deformation, the plaster will take over this effect. And it covers both brick houses and houses from other blocks. Outside - the facade, everything is also closed.

Aerated concrete is of different density and, accordingly, strength. There are D200 (almost insulated) and D600. The figure means the mass in kg in 1 m3. For example, the strength of the D500 is B2.5. The values ​​can be viewed here:

We see that the brand of concrete B2.5 can withstand a pressure of 32.7 kgf / cm2. Block with an area of ​​626x400 mm will withstand weight pressure 8.175 tons. Will the lower rows of masonry of an average house withstand such pressure? We count. Approximately 1,700 blocks in two floors of a 9x9 m building. Wall weight: ~ 68 tons. Plus floors, roofing, furniture, etc. Let it be 100 tons. The strength of the block with a large margin, provided that there are no deformations in the walls from improper masonry (steps in vertical seams).

2. Aerated concrete is hygroscopic and easily absorbs moisture

When moisture is collected, heat-saving properties are lost, frost resistance decreases. Yes, that's all true. But aerated concrete just as easily picks up moisture - so it gives it away easily. In order for the block to get wet through, it is necessary for it to rain slantingly for days. Completed construction, the house should have a facade. Here everyone chooses their material.

Frost resistance class of aerated concrete is on average F100. This says that it will withstand freeze-thaw a hundred times. And those who say that a house in spring only undergoes dozens of such changes in a month, probably, believe that a house made of aerated concrete will stand without heating for decades.

But other materials, like bricks, also gain moisture a lot and low-grade materials saturated with water from this category can generally collapse in one winter.

3. Cracks form in aerated concrete

If the formation of a crack is not associated with deformation of the foundation, then two reasons remain: masonry (finely seamed, but on an unprepared surface with "steps"), or with material shrinkage walls. For aerated concrete, shrinkage is 1 mm / m. Whereas for foam concrete - up to 4 mm / m. And since very many do not distinguish aerated concrete from foam concrete (in the comments they constantly write "foam blocks"), then the formation of cracks in foam concrete is projected onto aerated concrete.

Cracked foam concrete masonry.

4. Aerated concrete is a cold material and must be insulated

It all depends on the density you use and the climate where you are.

For central Russia, with a density of aerated concrete D500 and a wall thickness of 400 mm, insulation is not required. And if you do it, then the savings on heating will be no more than 10%. And the payback period for insulation costs will be more than 20 years.

Thin-seam masonry (or masonry in general on glue-foam) excludes cold bridges (as in other masonry). The jumpers are made insulated inside (described the technology). You can generally purchase ready-made factory reinforced aerated concrete lintels. Whereas when building from other blocks, the lintels over the windows are a cold bridge to the facade insulation.

The answers to criticism and my choice do not end with this argumentation. I cited other advantages of the material in the articles. The only drawback in aerated concrete for me is its fragility. It must be handled with care during construction. And when using various, as they say, life hacks, techniques that facilitate the process of masonry, construction becomes easier for the self-builder.

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