During its existence, aerated concrete became an equal building material for a private houses along with brick and wood. How did he succeed and what determines the choice of this particular material for the construction of a country house?
Significant advantages of air filling
Aerated concrete got its name due to the foamed internal structure. A kind of concrete “pillow” with countless air-filled pores. And the main technical characteristics of these materials are due to the presence of this air filling.
The most important property of porous concrete is a high degree of thermal insulation. Thanks to the porosity of the material, the walls retain heat no worse than wooden ones. To ensure the necessary thermal insulation of a country house, a wall of porous concrete with a thickness of about 0.5 meters is enough. Such a house warms up quickly. Porous concrete itself can be used for thermal insulation. On average, the use of porous concrete as a building material reduces heating costs by 20-40%. At the same time as thermal insulation, sound insulation characteristics also improve. Maybe it is not as essential for suburban construction as it is for urban construction, but such a feature will not be superfluous.
The low density of the material gives rise to another important quality of porous concrete – lightness. These materials are most often produced in large blocks. They are easier (and cheaper) to transport. In addition, the large size of the blocks reduces the number of construction operations.
And one more important point due to the low density of porous concrete: they, unlike bricks, can be sawn with a hacksaw, drilled, destroyed and even hammered into them with nails.
It is especially worth mentioning the microclimate of a house built from porous concrete. Due to the increased porosity, this material “breathes”. Some siding contractors claim that in this sense porous concrete approaches the characteristics of wood. It may not be worth idealizing this material, but its air permeability has a positive effect on the climate inside the cottage. At the same time, concrete is environmentally friendly, durable and, unlike organic building materials, does not rot or burn.
Aerated concrete blocks have exact geometric dimensions. This not only simplifies the construction process, but also allows you to use a special construction glue from a dry mixture instead of cement mortar, which is used economically, as it is applied in a thin layer. The seams are thin, and the wall is practically monolithic. Solid manufacturers of aerated concrete have a maximum error of 1 mm. Such accuracy allows you to avoid cold bridges that occur if you use a thick layer of mortar, which usually compensates for the unevenness of the blocks. Yes, even when finishing a flat wall, a much thinner layer of plaster is required, and if you use facing tiles, then such a surface can do without preliminary plastering.
Aerated concrete allows you to produce masonry continuously, without waiting for the solidification of the previous row, as the blocks do not squeeze the adhesive solution from the seams due to their low weight.
And finally, aerated concrete has the best diffuse properties, that is, the ability to “breathe”. According to the coefficient of vapor permeability (0.16-0.23), only wooden walls surpass aerated concrete – neither brick nor foam concrete is competitor for this indicator of aerated concrete.
The standard thickness of aerated concrete blocks for external walls is 375-400 mm, for internal load-bearing walls – at least 250 mm, for decorative partitions – at least 100 mm.
the basis of foam concrete is also a “dough” made of cement, sand and water. Manufacturers can add dyes, plasticizers and means for reinforcing foam concrete. The foam produced in an organic foam generator is used to achieve a foamy texture. It is either added to the solution and mixed in a concrete mixer, or mixed with dry components (in this case, the so-called low-density foam is used), as a result of which small particles settle on the surface of the bubbles and the foam concrete mixture turns out to be particularly stable. In the third common method of foam concrete production, a pressure mixer is used, into which synthetic foaming agent, water and all components of the concrete solution are loaded, and then air is injected under pressure. The foam mixture under pressure is fed into the forms. After that, the foam concrete hardens and gains strength without external influence.
Foam concrete is usually cheaper than aerated concrete. The method of its production cannot ensure the geometric accuracy of the dimensions. As a result, when building from foam concrete, the risk of cold bridges increases, which means that thermal insulation properties decrease.
But foam concrete also has advantages. For example, its water absorption is slightly lower than that of aerated concrete. Sometimes this is explained by the difference in the shape of the bubbles in these two materials, referring to “closed” and “open” cells. However, the cells are closed in all porous concretes (only in foam concrete these bubbles are of less regular shape). Water penetrates the material through microscopic pores-capillaries, which are formed during the hydration of cement grains and permeate aerated concrete of any type.
If desired, the production of foam concrete can be set up directly at the construction site, so it is often used for pouring monolithic structures and in such nodes of the building structure, where it is impossible to use blocks.
Without foam and gas
There are several concretes that conventionally belong to the striate family or, as they are also called, light. However, instead of air in these materials, the cells are filled with other substances. We are talking about expanded clay concrete, polystyrene concrete, pumice concrete, and fire concrete.
So, for example, polystyrene balls play the role of “magic bubbles” in polystyrene concrete. Manufacturers claim that in this way polystyrene is reliably protected from external influences and is completely harmless. This material is very light, it is well processed by hand and has good thermal insulation properties. In addition to building blocks, polystyrene concrete is actively used in the production of decorative panels.
In expanded clay concrete, the cells are, accordingly, filled with expanded clay granules, and in pumice concrete the filler is natural pumice.
No matter what type of porous or light concrete you choose, you will have to decide on the finish when choosing a material for the walls of your house. Not too aesthetic appearance and high water absorption strongly dictate this decision. However, decorating a house made of lightweight concrete is a pleasure, as the choice is practically limitless. Plaster systems, siding, facing tiles or decorative bricks – any of the finishing materials can be easily combined with aerated concrete and can be easily fixed on such walls. The only thing that should be taken into account is their high vapor permeability. Therefore, when applying plaster, it is better to stop at scratched plaster mixtures.