Aerated concrete collapsed in the masonry. My explanation of what happened

In the vastness of youtube, a video came across where the author (supposedly a builder) shows an example of the destruction of the walls of an unfinished house and reports that the masonry of the walls made of aerated concrete collapsed:

Even from a distance it is clear that something is wrong with the upper rows of masonry. It is worth clarifying that the box of a house without a roof stood for several years. It is clear that the blocks were picking up moisture, it froze, and this affected the properties of the material. But not to the same extent!

The blocks have a very deplorable view close by. They cracked and pieces fell out. On the second slide, you can see pieces that have fallen off and a very strange trick of the builders: the blocks in the opening lie on boards 50 mm thick. Were the builders so lazy that they didn't want to make U-blocks or just reinforce whole blocks with reinforcement through grooves?

But this is not the case with all blocks. The lower rows of masonry look the same as at the very beginning of the construction. Their surface is not destroyed, not sprinkled. And initially, other products were clearly used: it was autoclaved aerated concrete. It's hard to say what was used in the upper rows of the masonry.

In the video below, the author gave the name of the manufacturer on the package. But this does not mean anything: it can be packaging both from the blocks of the upper masonry and from the lower one. In my opinion, the upper rows are not aerated concrete, but foam concrete.

The first rows of masonry, which were exposed to water from melting snow (with freezing at night), remained without a hint of destruction. This is exactly autoclaved aerated concrete.

This is how it behaves in harsh conditions when wet and freezing. It has a low class of frost resistance and compressive strength. Although, in appearance it is very similar to autoclaved aerated concrete. Highlighted in gray. These materials even have a different principle for obtaining internal pores, small voids. And in addition, autoclaved aerated concrete is called autoclaved because it gains its increased strength in an autoclave under pressure and at high temperatures.

The main characteristics of common wall materials. It is clear from the table that a combination of factors such as low frost resistance and high shrinkage (fracturing) destroy this material in the open air in a matter of years.

Another possible explanation is the upper rows of aerated concrete masonry, but not autoclaved. Produced on the same principle of pore formation as aerated concrete, but did not undergo a curing process in an autoclave. In fact, this is the same foam concrete.

The video itself, with an overview of this unfinished object:

Judging by the objects that I see, autoclaved aerated concrete without plaster can stand for decades without visible signs of surface destruction.

Conclusion: if you are building from materials that cannot be tolerated even for 2-3 years in the open air, build a house in one season at once (like a wooden house).

On this building, it is necessary to disassemble several upper rows of masonry, invite specialists for consultation, is it possible to leave these walls of the lower rows made of aerated concrete? Ideally, samples are cut out and sent to a laboratory for strength analysis.

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