What is aerated concrete: comparison with other materials

Every year aerated concrete is gaining more and more popularity on the construction market, significantly displacing such favorites as brick and wood. This happens in view of its unique characteristics and relatively low cost. But the material is relatively young and the people have a lot of questions, for example, is aerated concrete harmful and is it as good as it is told?

In this article we decided to present not only the well-known positive characteristics of the material that any sales manager will tell you, but also a number of alternative opinions connected with this topic.

What is the material

Aerated concrete is one of the brightest representatives of the cellular group of concrete. It was created about 100 years ago. But commercially produced about 30 - 40 years.

The material has a porous structure, obtained as a result of the interaction of an oxidizing agent, represented by lime and a foaming agent, in the role of which aluminum powder acts. In addition, it consists of Portland cement and sand. At the production stage, the solution is mixed in water.

The very principle of production resembles in part the preparation of yeast dough, only a mixture of cement, sand, lime and water is taken as the basis, and in this case yeast replaces aluminum powder. The properties of aerated concrete vary in the percentage ratio of the components and in the presence of fillers that reinforce certain characteristics.

The main advantages of the material

Since air acts as a large filler here, the material is light. Naturally, the higher the density, the heavier and stronger the block will be. Density varies according to GOST 25485-89 from 300 to 1200 kg / m ?.

Based on this standard, the blocks are divided into 3 types.

1. The material intended solely for thermal insulation of buildings, has a density of 300 - 500 kg / m?.
2. Thermal insulation structural units may have a density of 500 - 900 kg / m?. This is the most popular material for private construction.
3. The blocks having a density of 1000 - 1200kg / m? considered structural and intended for the construction of supporting structures.

Important: marks D500 or D600, according to laboratory data, with a wall thickness of 300 - 400 mm, provide thermal insulation comparable to brickwork having a thickness of 640 mm.

The dimensions of the blocks are 5 - 7 times larger than the size of bricks, therefore the speed of construction of buildings increases many times.

Also a small role is played by the low weight of the material, for raising the blocks the attraction of special equipment is not required.

• The laying of this material is carried out using special adhesives, which are applied with a thickness of 3-5 mm and do not affect the insulation.
• Along with rather high characteristics of durability, the gas concrete is very easily processed. It is easily cut into segments of the required configuration with a conventional hacksaw, and it is also easy to equip technological grooves or holes.

Tip: Of course you can cut the material with a hacksaw, but it will sit down quickly. To do this, there is a special hacksaw with pobeditsovymi soldering, designed for cutting 25m? gas blocks. For drilling holes using an unstressed drill.

• The material has a uniquely low thermal conductivity. For the most common brand D500, it is 0.12 W / m? S in laboratory conditions, and with an increase in humidity up to 12%, it only increases to 0.14 W / m? S. Due to this, in the conditions of Moscow, the maximum thickness of the masonry is 500 mm.
• Sustainability of aerated concrete among specialists is beyond doubt. It consists of natural materials and does not emit any harmful fumes. The radiation background, in this case, is within the permissible limits.
• The sound insulation characteristics of the material, due to the porous structure, are many times higher than the characteristics of the brickwork with similar parameters. Taking into account the cladding material, they can reach 50 dB.
• Aerated concrete consists of non-combustible materials, as a result it belongs to a completely fireproof, moreover, it can withstand a direct impact with open fire up to 7h.
• High vapor permeability is achieved due to the presence of open, communicating pores. The microclimate in such a room will be similar to wooden houses.
• Due to the presence of tongue-and-groove notches on the blocks and clear geometric forms, the installation manual is quite simple and accessible for development and installation by hand.

Production of aerated concrete

Aerated concrete can be produced on 2 technologies, using an autoclave and non-autoclave method. Each technology has its advantages, but autoclaved processing blocks are considered to be of higher quality.

Non-autoclaved production has a significantly lower cost price. For its organization requires much less investment. The strength of concrete products is achieved by introducing various kinds of hardeners and binders. Now the internal reinforcement of the composition as a result of the addition of synthetic or natural fibers is widely used.

But, despite the tangible achievements in this direction, the characteristics of the blocks are significantly inferior to the material processed by the autoclave method. So if autoclaved aerated concrete shrinks to 0.3 mm / m, then shrinkage without autoclaved material can reach up to 2 - 3 mm / m. Plus the cement is consumed more.

In autoclave production, the main components of the solution remain almost the same, but the blocks gain design strength not in the open air under natural conditions, but in autoclaves for 12-14 hours. The temperature inside the unit can reach up to 200? С, with a pressure of 10 - 12 bar. The price of such blocks is higher, but the quality characteristics are much better.

The subtleties of construction or what manufacturers are silent

Manufacturers claim that the strength of the brands D500 and D600 is enough for the construction of buildings. But not everyone will tell you that while the building can not be higher than 12 - 14m, that is, no more than 3 floors.

But at the same time there is another nuance. Interfloor slabs are made of heavy concrete and are heavy. As a result, they can not be laid directly on the wall of aerated concrete, requires the arrangement of a reinforcing belt of solid concrete or brick. And these are additional cold bridges.

Theoretically, a house with a higher number of floors can be built, but for this you will need structural blocks with increased strength and higher thermal conductivity. Their price is higher, so this construction is not profitable.

In addition, aerated concrete material is brittle and does not withstand bending stress. As a result, even a slight shrinkage of the foundation can lead to cracks in the structure as a whole. Houses made of aerated concrete need a solid strip foundation, otherwise they do not make sense to build.

To fix the insulation or other necessary additions, you will need special dowels designed for cellular materials. Compared to similar products for masonry, the price of such fittings will be several times higher, which can level the low cost of the blocks.

Calculations of the thermal conductivity of a material are usually presented for ideal laboratory conditions. For real calculations by region, there is a SNiP 23-01-99 according to which, for the same Moscow region, the masonry thickness should be already 535 - 650 mm, in some regions it can reach up to 1m.

Important: the declared high frost resistance, no less than heat conductivity and vapor permeability, will be valid only on condition of arrangement of high-quality facing, both from within, and outside. Moreover, the finish should be vapor-permeable, foam will not work here.

As for durability, as mentioned earlier, this material appeared in mass construction no more than 40 years ago, while brick houses have been standing for centuries. Therefore, this statement is based on purely theoretical calculations.

Aerated compared to other materials

Foam concrete is considered to be the closest relative of the gas block, so people most often wonder what foam or gas concrete is better. Answer definitely can not be here. The gas-block is produced mainly by the industrial, autoclave method, therefore it has fixed dimensions and characteristics.

While the foam is more done in semi-handicraft mini-shops. As a result, both characteristics and geometrical dimensions may be inaccurate. In addition, the strength of aerated concrete is at least 3 times higher.

The video in this article gives a comparative description of porous materials.

But the price of foam blocks is more affordable. For their laying is most often used cement-sand mortar, which also reduces the cost of the estimate. Plus foam blocks have a closed pore structure, so they are not afraid of high humidity.

Summarizing all the above, we can say that it is more preferable to use aerated concrete to build a cottage, and for the construction of outbuildings you can safely take cheaper and affordable foam block.

With the question, what is better aerated concrete or wood, the answer is also ambiguous. First of all, you should understand what kind of tree in question. If it is a glued laminated timber or rounded log, treated with a protective compound, it is better to give preference to wood.

But in the usual profiled bar, most of the characteristics are much lower than in the gas blocks and in the aggregate data, in this case it is better to give preference to a house from gas blocks.

Comparing aerated concrete with competitors can not forget about the shell rock. Answering the question whether aerated concrete or rakushnyak is better, we would say that the main component here is the price. The fact is that the structure and characteristics of both materials are similar.

The shell rock has been built for several thousand years, and gas blocks have appeared recently, plus the shell rock is 100% eco-friendly material, it enriches the air with iodine and heals the atmosphere. If you live near the sea, the shell rock will be optimal. But for most of our country, transportation costs may be astronomical.

The video in this article shows some moments of working with the coquina.

Myths about the harmfulness of gazoblokov

Hearing type approval, do not build from aerated concrete, it is worth asking such “experts” what harmful aerated concrete is. Surely you will hear a convincing story about the presence of lime in it, and it has a negative effect on health.

But then, why is the same lime so widely used in gardening? Plus, in many areas of our country for hundreds of years, people have whitened houses with lime.

May also indicate the presence in the composition of the aluminum powder. But aluminum food utensils have been used for decades and no one doubts its environmental cleanliness. Moreover, in this case we are dealing with aluminum oxide, which is considered absolutely safe.

It is good that no one doubts the purity of cement and sand. The result is that the harm of aerated concrete, to put it mildly, is exaggerated.

On the video in this article you can see the techniques of working with gas blocks.

Conclusion

Aerated concrete is a quality building material, it is certainly not perfect, but there are no ideal materials in nature. If we analyze all the above, we can see that with strict adherence to the technology of this material, you can build a good house.