Foam: to be or not to be?
Regular readers FORUMHOUSE know well how difficult it is to choose a wall material for the construction of the house.
many nuances must be considered. Often the choice is complicated because of the mass of conflicting information. How not to get confused when choosing? It is necessary to consider all the positive and negative sides of a material, and then form his own opinion.
For information on how to do this, we will explain the example of foam.
Among the advantages of this material include:
- fast installation and ease of processing; foam well sawn, milled and drilled;
- environmental friendliness; cellular concrete blocks not allocate toxic substances;
- good thermal insulation properties due to the fact that the pores in the block are filled with air;
- insulation - why foam is often used when installing internal partitions in the house.
The main disadvantages of foam:
- fragility; during transportation often damaged part of blocks;
- gaining the necessary strength for a long time; in violation of production technology in the material structural changes occur over time, which could lead to shrinkage and cracks in the walls;
- insufficient bearing capacity; to hang heavy objects on foamed concrete walls, it is necessary to use special fasteners;
- hygroscopic; foam may accumulate water, which requires to protect it from atmospheric moisture and dirt;
- acquiring nedosushennyh blocks or blocks with low geometry; discrepancies may reach from 1 to 3 cm, which eliminates the foam laying on adhesive solution.
So whether or not to build a house out of foam, and what features have this material? Let us turn to the members of the forum experience.
Features foam
The properties and quality of foam is directly dependent on the characteristics of its production. Let us examine them in detail.
Cepera (Member FORUMHOUSE):
- Foam - an artificial stone material based on mineral binder and kremnezomistogo component with uniformly distributed throughout the volume of the pores.
Foam concrete block consists of a mixture of sand, cement, water and foamer.
The technology of manufacture of foam concrete is as follows: a cement-sand mixture is added a foaming agent and mixed under pressure in a pressure chamber.
After stirring the components from the mixture formed various building products: wall panels, partitions, webs and slabs.
Under the conditions of the handicraft, the so-called "garage" of production, the workers poured the mixture into the prepared mold.
In this large influence of "the human factor". If the mixture is evenly stir it gives shrinkage. Blocks made violation of the technology have uneven density, they have broken geometry and strength characteristics of the material significantly reduced.
In the natural drying method requires at least 28 days to collect the required strength of the foam block.
Often, many novice developers confused with each other two materials - foam concrete and aerated concrete.
Leo060147(Member FORUMHOUSE):
- There are concrete blocks, and there are gas-silicate blocks. The production technology for these blocks are different, which affects the properties of these materials.
In the production of aerated concrete or gazosilikata autoclave technology is used. This requires large investments of money that the small-scale production is economically inefficient.
Autoclave - a special furnace in which a long time maintained a high temperature and pressure.
When the autoclave method, thermal processing units are steam autoclaved at high temperature and pressure. Autoclave treatment accelerates the hardening mixture, due to which the strength of the block increases, and its shrinkage decreases.
In the manufacture of aerated concrete is used more often is simple - non-autoclaved technology. Therefore, the production of foam blocks is less costly than the production of gas silicate blocks and foam block has a lower price.
Thermal properties of foam concrete
The properties of the wall material directly affect the level of comfort of living in the house. Due to the constant rise in energy prices still more widespread construction of energy efficient homes. Can the foam serve as the basis for a homogeneous wall construction that meets all the requirements of the thermal properties?
Leo060147:
- Outside the building envelope, including walls, must have a thermal resistance equal to or greater than normable heat resistance for the area where the building is constructed.
For example, for Moscow and Moscow Region value Rreq = 3,15 square meters * C / W.
Rreq - normalized heat transfer coefficient of resistance for walling.
The value of the heat transfer wall of the foam block is dependent on the volumetric weight of the block.
Volumetric weight of the block may be from 300 to 1000 kg / cubic meter. Most often sold in unit volume weight of 400 or 600 kg / cbm.
Unit volume weight of 400 kg / cubic meter. and 300 mm has Rreq = 2,158 sq.m. * C / W, which is less than required by the standards.
If volumetric unit weight is in the range of 600 kg / m³, the thermal resistance of the wall thickness of 300 mm has Rreq = 1,312 sq.m. * C / W, which is also insufficient.
It should be borne in mind that the data is correct, if the unit is well dried. If the block is waterlogged, it has a negative impact on its thermal insulating properties.
According to calculations, to meet the thermal standards uniform wall thickness of the foam block should be at least 500-600 mm corrected for moisture percentage units.
In reality, the wall of the foam is not monolithic, and inhomogeneous structure. Masonry joints armpoyasa, reinforced concrete frames - all cold bridges, increasing the rate of the thermal conductivity. Therefore, in order to achieve acceptable performance wall thickness must be increased even more.
Irkutsky(Member FORUMHOUSE):
- The higher the density of the blocks, so it is stronger in compression (i.e., it can be used for masonry bearing walls). Typically such blocks have a density of 600-900 kg / m3. And the higher the figure, the stronger the unit, but higher and its thermal conductivity.
Blocks of this density is typically used for the construction of one- and two-storey house.
With Yuri(Member FORUMHOUSE):
– To meet all of thermo-technical standards, the thickness of the supporting walls of the house of foam stamps D800 for Moscow should be 1150 mm, which is very expensive.
Conclusion: not economically feasible to increase the thickness of the foam wall, and further insulate it. For example, to use block D600- D800, 400 mm thick mineral wool layer (the outside) of 100 mm.
If you take a brand of the D300, then the rules of the thickness of the wall will be 400 mm, but this unit has a low bearing capacity and is suitable only as a material for the building envelope, not bearing designs!
Features of the construction of houses made of aerated concrete
Depending on the design and the project at home, you need to select the appropriate brand foam.
There are three types of foam:
1. Thermal insulation - D200-D500. Used for heat insulation of load-bearing walls.
In this case, blocks are used as filler reinforced concrete frame, for example, in the construction industry.
2. Heat-insulating-structural - D600-D800. Used for masonry bearing walls with sufficient insulating performance.
3. Structural - D800-D1200. Used for masonry bearing walls, often require additional insulation.
Y quality foam pores on the fracture have a uniform structure, their diameter should not exceed 3 mm. High-quality foam water resistance.
The structural strength of foam blocks, usually increases the addition of sand. In addition to strength characteristics, must pay attention to frost indicator of foam concrete blocks.
Irkutsky:
- The average value of frost in blocks of 25 cycles.
This figure suggests that the blocks withstand 25 cycles of freezing and thawing in the natural moisture without loss of original characteristics. Then the blocks, though not begin to fail, but will lose their properties.
25 cycles are obtained if the mother tests under laboratory conditions. Those. unit to limit filled with water, then frozen at a certain temperature, then thawed and look when it begins the process of destruction.
usa (Member FORUMHOUSE):
- To avoid the appearance of cracks in the foam concrete:
1. You can not use "fresh" units. The unit must stand at a temperature of + 10C or higher for two or three weeks. The unit must be packaged in film.
2. When masonry blocks have to use masonry grid three, but better - in two series.
3. Plaster the walls of foam can be 3-4 months after completion of masonry, as the unit gives a certain shrinkage.
Best of all aerated concrete for the construction of one- and two-storey houses with wooden beams.
Also, special attention in the construction of houses made of aerated concrete should be paid to the construction Laying nets.
Laying nets - a monolithic reinforced concrete frame, distributing load along the perimeter of the building, for example, between the first and second floor.
Laying nets needed, because blocks do not like to point load, and can crack and crumble in the absence of the foam block.
Maxsmax (Member FORUMHOUSE):
- In order to foam block is not destroyed by the RC slab pressure, including through Laying nets under Laying nets, I suggest putting a few rows of bricks.
Laying nets exerts uneven pressure on the relatively large foam concrete blocks, whereby cracks may occur. Brick also distribute the load more evenly.
It is believed that the foam block is difficult to mount heavy items or equipment. For this purpose, we use special anchors, anchor bolts and fasteners. For example, for attaching the metal doors or grilles on the windows, on the perimeter of the opening can be installed metal corners.
To summarize. The quality of foam, and hence the walls depends on compliance with the technical regulations in its manufacturing. Therefore, the foam should only buy from trusted manufacturers. In addition, the house of foam is necessary to build strictly on the project, with careful calculation of loads and the choice of the appropriate strength of the unit.
Learn more about the construction of stone houses users forumhouse.ru can in this section our forum. A detailed account of our new posts on the construction of the house of foam read here. Discussion of the material from which to build the wall, is carried out here.
Detailed description of all stages of the construction of the house of monolithic foam available this link.
A familiarized with this video reelYou will learn how to approach the construction of aerated concrete building.
Discuss the article and read other materials devoted to country life you can on the websiteFORUMHOUSE.
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