The construction of aerated concrete: the choice of wall

The subject of this article is suburban construction of aerated concrete blocks. We have to explore the key features of the material, recommendations on the choice of brand of aerated concrete, wall thickness, type of foundation and mortars. In addition, we will be affected construction technology. So go.

Material Features

Let's start with the key properties of aerated concrete.

• Thermal insulation quality is beyond praise. Thermal conductivity, depending on the density of the material is 0.09 - 0.14 W / m * s, which roughly corresponds to the thermal conductivity of wood.

However: wetting the walls leads to a sharp drop in their insulating qualities.

• Speaking of moisture: the material is hygroscopic.. Its structure includes a large number of open pores that absorb water literally like a sponge.
• Mechanical strength is low; with bending loads, aerated concrete blocks easily crack. If so - the foundation should eliminate even a hint at the deformation of the walls. In addition, in earthquake-prone areas, houses are being built with arm-belts or arm-carcasses.

Aerated concrete is classified primarily by density grade, which corresponds to the mass of a cubic meter of material in kilograms. It is easy to guess that the density strongly affects other characteristics.

We present data from the site of the Chelyabinsk Insi-Block company.

Please note: with the same density, two positions in the table are distinguished by mechanical strength. The difference is due to different ratios of aggregate and binder.

Foundation

Building blocks of aerated concrete can be used for the construction of walls on the foundations of several types:

• Belt shallow-bar (rectangular section).
• Tape shallow-deepened for heaving soils (expanding downwards).
• Tape recessed.
• Pile, on bored piles with reinforced concrete grillage.
• Slab.

What is the foundation to stay on?

The answer depends primarily on the type of soil.

• On dry, stable soils, you can safely dwell on the variant, the price of which is minimal - a fine-lined strip foundation.
• A pile foundation with a monolithic grillage will provide the optimal balance between the required strength and costs on heaving soils.

• Finally, the most expensive slab concrete foundation is a solution for swampy soils with a consistently high groundwater level.

Selection of wall blocks

What are the parameters to choose material for exterior walls?

Strength

Novosibirsk producer of cellular concrete blocks Betolex proposes to follow the following rules for the construction of load-bearing walls:

As already mentioned, in earthquake-prone areas, construction is often carried out with the construction of Armakarkas, which absorbs the load from the walls and floors; in this case, the strength marks are not limited.

Thermal conductivity

Requirements for the material of the walls in terms of energy efficiency are set out in SNiP II-3-79: the heat transfer resistance of the wall together with the layers of internal and external plaster should be at least 3.2 m2 * C / W (data relevant for the center of Russia).

According to the calculations of the same company Betolex, the wall corresponding to these standards should have a thickness of:

• With a mark on the density of D500 - 50 centimeters.
• With a mark on the density of D600 - 60 centimeters.

Interior walls

For the bearing internal walls the instruction looks like this:

• При опирании на стену одной плиты и/или для одноэтажного дома рекомендуется возводить стену толщиной 200 мм из блоков плотностью D600 класса прочности B3.5 и 240 мм - из блоков D600 B2,5.
• При двух-трех этажах и опирании на стену двух плит минимальные рекомендованные значения толщины составляют 300 мм для блоков D600 B3.5 и 400 мм для D600 B2,5.

For interroom partitions, it is recommended to use D600 V 2.5 - 3.5 blocks with a thickness of 240 - 300 millimeters; interior partitions are built from partition walls with a thickness of 100 - 150 mm.

Building mixtures

What glue and plaster mixtures used in the construction and decoration of the walls with your own hands?

The answer is quite predictable: special mixtures are used, which are positioned by the manufacturer as a material for the laying of cellular concrete. Cement - sand masonry mortars are not used.

The reasons?

• The solution does not allow to make the glue line thin. The thick seam is a cold bridge in a heat-insulated structure.

In addition: a thick layer of masonry mortar can disrupt the geometry of the walls. One of the main advantages of our material is that it allows you to bring out perfectly even rows.

• For porous aerated concrete, the vapor permeability of the finishing material is extremely important: at least the exterior finish should not be inferior to the aerated concrete in this parameter. Otherwise, the walls begin to collect moisture.

Jumpers

The thickness of the lintel must match the wall thickness in the opening area; parallel laying of two lintels of smaller thickness is also not forbidden (for example, 200 and 300 mm lintels are used for 500 mm thick walls).

The length of the web should be at least 100 mm wide in each direction.

Overlaps

And in the construction of monolithic ceilings, and the laying of plates should be guided by several simple rules.

• The maximum span length is 6 meters.
• The slab must enter the bearing walls by at least 100 millimeters.
• The longitudinal (guide) wall overlaps by at least 50 mm.

Masonry walls

What is the construction technology of aerated concrete walls?

1. The surface of the foundation is waterproofed. For this purpose, as a rule, laying a pair of layers of roofing material is used.
2. The level determines the highest corner of the foundation.
3. The first row is laid out on the cement-sand mortar. The thickness of the cushion at the highest angle should be approximately 20 mm. The first is the corner block on this corner; then, other corner blocks are strictly aligned.

1. Between the corners the moorings are tightened - cords along which rows will be placed.
2. The first row is laid out along the entire length and reinforced with a pair of reinforcing bars, which fit into the grooves cut through the surface of the blocks. The grooves are cut at a distance of 60 mm from the edges of the masonry and after laying the reinforcement are filled with glue. In the future, every third - fourth row is reinforced.

Each row ends with a finishing block, which is cut at the place with a manual hacksaw or a circular saw. The second and subsequent rows are laid on the glue, which is applied to the surface of the blocks with a trowel and is distributed over it with a notched trowel. To fit adjacent blocks in a horizontal row, a rubber mallet is used.

Pay attention: binding of vertical seams between rows is obligatory. Ideally, the seam should fall in the middle of the lower block; allowable minimum displacement - 8 cm.

Inset Partitions

How to embed the partition into the longitudinal wall?

1. Across the entire height, a groove is selected for the thickness of the partition.
2. Holes are drilled into the groove, into which rebar sections are tightly inserted. In the future, these segments are attracted by the knitting wire to the longitudinal reinforcement of the partition.
3. When laying each row, the groove in the longitudinal wall is coated with adhesive, the excess of which is squeezed out when the block is fitted.

Armokarkas

How to build aerated concrete houses with reinforced concrete frame?

1. On the foundation is marked the location of the vertical reinforced concrete pillars (they are located at the corners and in the middle of the long walls).
2. The walls themselves are laid out of the blocks. The gaps under the frame remain blank.
3. When constructing formwork, part of its functions are assumed by masonry; at the same time, the adhesion of concrete to aerated concrete blocks increases the final strength of the structure. The cross section of the longitudinal reinforcement in the general case is 5% of the cross section of the frame element.

Conclusion

We hope that the reader will benefit from our recommendations for planning the construction and technology of work. To see more clearly what aerated concrete looks like and the construction of it will allow the attached video in this article. Successes!