Technical characteristics of aerated concrete. advantages

Recently, aerated concrete has become widespread in housing construction, as it has a number of unique properties. Moreover, this material can be used for the construction of all types of walls, both internal and bearing. Next, we take a closer look at this material, consider the characteristics of aerated concrete and its features.

General information

Gas concrete относится к категории легких ячеистых бетонов. Причем, ячеистая структура занимает 85 процентов от всего объема материала, чем и обусловлены его характеристики.

The composition of aerated concrete uses the following components:

• Quartz sand;
• Lime;
• Cement;
• Gas generator (aluminum paste or powder).

All of these components are closed with water, like ordinary concrete, and stirred for five minutes. As a result of the chemical reaction between lime and aluminum powder, bubbles of 0.6–3 mm in size are formed, which are evenly distributed throughout the material.

As a rule, aerated concrete is used in construction in the form of blocks, so all reactions take place in a solution poured into metal forms. At the same time, the mixture is subjected to vibration and some other processes, depending on the type of technology. After setting the material, the irregularities are cut off by metal strings, which ensures the accuracy of the geometric forms of aerated concrete blocks.

Types of aerated concrete

Characteristics of the material largely depend on the type of production.

Gas concrete бывает:

• Non-autoclaved - the process of formation and hardening of the composition is carried out in natural conditions. Due to this, such aerated concrete can be made by hand, as its manufacture does not require special equipment. However, the material as a result turns out to be less durable. The manufacture of the mixture in this case regulates the GOST for aerated concrete Nos. 25485-89 and 21520-89.
• Autoclave - в этом случае, после схватывания, пласт газобетона разрезают на блоки металлическими струнами и отправляют в специальные печи. Здесь происходит затвердевание материала в условиях высокого давления пара и температуры около 200 градусов по Цельсию. Данный этап позволяет улучшить технические характеристики газоблоков, так как нагрев делает структуру материала более однородной. Strength автоклавного газобетона возрастает не менее чем на 28 кгс/м?, а удельная теплопроводность находится в пределах 0,09-0,18 Вт (м•К). Эти свойства позволяют возводить стены в один ряд блока (400 мм) в любых климатических условиях, за исключением северных районов.

Tip! The thickness of the walls depends on the thermal conductivity of the material. Before construction, it is possible to calculate what thickness aerated concrete should be according to SNiP 23-02-2003.

Thus, autoclaved aerated concrete is used as a carrier material, especially in the construction of houses. Non-autoclave material is more used for the construction of partitions or as thermal insulation. However, it can be used for the construction of small, light buildings.

Properties of aerated concrete

Virtues

Among the main advantages of aerated concrete are the following points:

• Ease - a D500 brand block with a size of 30x25x60 cm weighs no more than 30 kg. This simplifies the work with the material, and also increases the speed of wall construction. For example, to perform the laying of the same volume, you need 22 bricks, which weigh much more.
• Thermal conductivity - thanks to the cellular structure, filled with gas, the material has a good insulating effect. At low temperatures, it retains heat, and in summer it is able to provide a pleasant coolness. It should be noted that the wall thickness of 375 mm is equivalent to thermal insulation properties with a brickwork thickness of half a meter.
• Fire safety - components that are used in the manufacture of aerated concrete, have a mineral origin. As a result, the material does not burn and is even able to withstand the effects of an open flame for three hours.
• Frost resistance - if in the manufacture of aerated concrete did not violate the technology, it can withstand at least 25 cycles of freezing and thawing.
• Strength - as mentioned above, after passing the material through autoclaves, this indicator increases and, as a result, the carrying capacity of aerated concrete improves.

• Ease of processing - Aerated concrete can be given any shape with the help of hand tools. For example, it is not difficult to cut it with a regular hacksaw, and to make a hole, you need a regular drill without a punch. Accordingly, it will not be difficult to make a hole under the socket or a gate for laying the wires. Also, thanks to these properties, you can embody original and interesting projects of aerated concrete, regardless of their complexity.
• Efficiency - due to low density, the cost of this material is not high. In addition, due to the ease of installation, you can do this work yourself, without the help of specialists. A small proportion of aerated concrete also reduces the cost of building the foundation.
• Environmental friendliness - The composition of the material does not contain harmful substances that produce toxins. It should also be noted that aerated concrete has a high vapor permeability, which contributes to the formation of a human-friendly microclimate inside the room.
• Slight shrinkage - this parameter is 0.2-0.5 percent. For comparison, the shrinkage of a wooden house reaches 15 percent.

Note! Since the dew point in aerated concrete is located in the thickness of the material, it is necessary to use vapor-permeable materials for wall finishing, which will allow moisture to be expelled to the outside.

disadvantages

Of course, like any other building material, aerated concrete has its own drawbacks.

The most significant among them are the following points:

• The sufficiently high water absorption of aerated concrete, as a result of which the walls must be protected from environmental exposure. Otherwise, the material absorbs moisture and cracks, losing its strength and heat-shielding properties.
• Low strength, as a result, gas blocks can not be used for the construction of the foundation. In addition, slight movements of the soil lead to cracks on the walls.
• All porous types of concrete do not hold the load. Therefore, if it is necessary to carry out mounted installation of furniture or, for example, household appliances, it is necessary to use special fasteners.

Specifications

Now let's take a closer look at the characteristics of aerated concrete and compare them with the characteristics of some other building materials:

Note! Depending on the brand of aerated concrete, its compressive strength can be from 1.0 to 7.5 MPa.

The sizes of gas blocks

Gas concrete по ГОСТу31360-2007 Может быть следующих размеров:

I must say that at the request of the customer, the dimensions of aerated concrete can be non-standard, if the party was made to order.

Features masonry aerated concrete

Despite the fact that the process of laying aerated concrete blocks is extremely simple, it contains a number of nuances. If you do not comply with them, then get a strong and durable structure simply will not work.

First of all, it should be said that when laying the blocks it is possible to use both standard cement-sand mortar and special glue. Of course, the price of glue is higher, but it allows to reduce the layer thickness between the blocks up to 3 mm. In the case of using cement-sand mortar, the layer thickness is 7-10 mm.

It must be said that the reduction of the layer allows not only to reduce the consumption of material, but also to reduce cold bridges. Using the cement-sand mortar eliminates the advantage of aerated concrete as low thermal conductivity.

So, the instructions for laying gas blocks looks like this:

• The laying of blocks is carried out on a concrete foundation. Before embarking on the construction of walls, you must perform its horizontal waterproofing. To this end, several layers of roofing material or another waterproofing material are laid on the foundation.
• Then along the future walls, string beacons are stretched in a horizontal plane.
• Next, you need to dissolve the glue - pour water into the container and gradually fill the required amount of dry mix. The proportions are shown on the packaging to the material.
• Work starts from the corner. The finished glue is applied with a notched trowel onto the base, and the blocks are laid on top of it. Their position must be verified by the building level, and, if necessary, adjusted. In parallel with the outer walls, internal partitions are also being erected.
• After laying the first row, you should move the beacons and lay the second row with an offset of 8-12 cm. As mentioned above, to obtain additional elements, blocks should be cut with a hacksaw.

• Every three to four rows, reinforcement must be performed. For this, two grooves are made in the blocks along the walls, into which the bars of the reinforcement with a diameter of 12 millimeters are laid. At the corners, the recesses must be rounded so that the reinforcement does not bend at a right angle.
• In those places where a reinforced belt is needed, U-shaped blocks are placed. Rebar is put into their cavity and cement-sand mortar is poured. Instead of U-shaped blocks, you can make formwork from thin aerated concrete panels, then put reinforcement in it and pour concrete.
• As lintels for window and door openings, polystyrene concrete beams are commonly used.

Note! Adjustment of the position of the block can be performed within 10-15 minutes after laying.

Otherwise, construction is carried out in the same way as when using bricks or other materials.

Finishing features

As mentioned above, finishing is a mandatory procedure for aerated concrete walls. At the same time, this operation requires a special approach.

Therefore, below we consider the most appropriate options:

• Brick cladding is the most common way of finishing, which will give the building a respectable appearance. Cladding can be carried out both in parallel with the construction of walls, and after the construction of the house. The most important thing is that the laying is carried out on the foundation or foundation beam.
• Painting and plaster - in this case, a thin layer of plaster is applied to the walls, reinforced with reinforcement mesh. The finish layer is paint. When choosing this finish option, it is important that all materials are vapor-permeable.
• Ventilated facade - this finish option is relatively new. It allows you to reliably protect the walls from the negative effects of the environment and at the same time give the room an attractive appearance.

As for the interior, there are no special requirements for it. The most common options are plaster and plasterboard plasterboard.

Conclusion

Gas concrete, как мы выяснили, имеет множество положительных характеристик, которые превосходят параметры других строительных материалов. Однако, чтобы получить положительный результат от его использования, необходимо учитывать ряд нюансов, которые касаются в первую очередь возведения стен и их отделки.

From the video in this article, you can get more information on this topic.