How to build walls of aerated concrete?

Today, the construction of walls for various buildings is carried out from a large number of materials. One of them is aerated concrete, which favorably differs, first of all, by thermal conductivity. This becomes possible due to the use of aluminum powder in a conventional concrete mix. But the strength of such material will be somewhat lower. Today we will explain why aerated concrete blocks would be an excellent solution for building a house.

In order to understand whether it is worth building a wall of aerated concrete, it is necessary to analyze exactly what advantages and disadvantages this material has.

So, if we talk about the advantages of aerated concrete, it is necessary to highlight:

• good heat retention;
• the material is very easy to process, even with a hand tool;
• the required dimensions and rows of masonry can be easily observed due to the highest accuracy of the geometry;
• a significantly larger block size than a brick makes it possible to significantly reduce the time required for the construction of the object;
• the material has a small weight, which allows to significantly reduce the load on the foundation of the building, and thus extend its life;
• gas-concrete blocks are completely fireproof material, which favorably distinguishes it from its counterparts;
• even with proper implementation of waterproofing and reinforcement procedures, the cost of one square meter of aerated concrete wall will still be lower than that of similar materials.

But like any building material, aerated concrete, there are certain drawbacks that do not allow to call it the ideal solution.

These are the aspects:

• The porous structure of aerated concrete blocks causes water to be easily absorbed. That is, when using the material for the construction of walls it is necessary to carefully consider the moment of waterproofing.
• It is necessary to consider that the block substance is in the baked state.For this reason, in places where increased loads are observed, it may begin to crack. Because of this, before starting the construction of the object, it is necessary to correctly calculate the minimum size of the thickness of the walls of the future building. And in places most at risk, the masonry should be reinforced by reinforcement.

Due to not too much weight, if we compare the blocks with red or silicate bricks by weight, and fire resistance, frost resistance, good sound and heat insulation characteristics, aerated concrete is used to erect various elements of buildings of different types, starting from partitions and bearing parts of residential buildings and ending with elements country cottages and garages.

If we talk about the types of aerated concrete, then this material is of several categories:

• D300 - D500. Such blocks are considered light and have a low density coefficient, as well as good thermal conductivity. Usually they are used as insulation.
• D500 - D900. This category of blocks will be significantly stronger. But their mass will be significantly more, and they will spend the heat better. Most often they are used as the main material for the construction of walls.
• D1000 - D1200. Such aerocrete are heavy. Their density will be maximum among all existing categories. They are used for the construction of buildings that require the formation of a solid structure.

Types of aerated concrete blocks can also be divided into three groups by classes:

• B 2.0 - such aerated concrete is used to form bearing walls for buildings whose height is not more than two floors;
• B 2.5 - used as material for load-bearing walls, if the height of the structure is not higher than three floors;
• В 3,5 - it can be used for the formation of bearing type walls for buildings having a height of five floors.

The construction of buildings with the use of various concretes of the cellular group, which include aerated concrete, is regulated by the service station number 501-52-01-2007.

If we talk about the main points on the use of aerated concrete, it should be noted:

• Limit the maximum height of buildings.It is possible to create load-bearing walls for buildings of various categories of cellular concrete, the height of which is up to twenty meters (five floors). If we talk about the height of the walls of the self-supporting category, then it should not be more than nine floors or thirty meters. Foam blocks are used to create load-bearing walls, the height of which is not more than three floors or ten meters.
• To create self-supporting type walls, it is necessary to use blocks of category B 2.5. If we talk about buildings, where there are more than three floors, and B 2.0, if the buildings have a height of three floors.
• The regulatory document regulates the strength of concrete depending on the number of floors in the building. If it is required to erect external or internal walls of a 5-storey building, then it is necessary to use blocks with a strength of at least B 3.5, and the type of the solution itself should not be worse than M100. If we talk about three-story buildings, the class of concrete should be at least B 2.5, and mortar - M75. And for buildings in two floors - B2 and M50.
• This regulatory document also requires to calculate the most allowable height of the walls of the specified concrete only after the calculations.

It should be noted that this standard regulates only the issues of concrete strength, but absolutely does not give any explanation on the issue of thermal insulation of the room.Comply with the requirements of regulatory documents should legal entities in the first place. Individuals can use them only as recommendations or a landmark in the construction of a garage, country house, or any other building.

The thickness of the external concrete walls can, if desired, be calculated by yourself. It is necessary to take the standard indicator of resistance to heat transfer for a specific area and the block thermal conductivity index.

This figure can be calculated by multiplying these figures on each other. To ensure comfort, the resistance to heat transfer must either be equal to or be greater than the digit of the index nominated, which is calculated by adding the degree-day coefficient of the heating period and the usual time coefficient.

In addition, when determining the thickness of the aerated concrete wall of the carrier group, the thermal conductivity index of the material is computed, which directly depends on the density. Than it will be more, the more will be its thermal conductivity.

If we talk about cottage construction, then the most commonly used aerated concrete M500. Such solutions are thermal insulation and structural. M600 models with high thermal conductivity also have high strength, which indicates that they will release a lot of heat from the building.

For thermal insulation is great to use the option M400. Here the ratio of pores in the total weight will be higher than 75 percent. This indicates that the material will keep warm well. But its strength will be significantly lower. The best for the creation of aerated concrete walls on the properties of thermal insulation are brands of aerated concrete D300 and D400. Their thickness is in the range from 20 to 45 centimeters. Despite such indicators, these materials contain a large number of air pores and little solution, which bears the burden.

The highest strength, but a large wall thickness (from 1 meter or more) needed to retain heat indoors, will differ in aerated concrete grades D800 and D1000. As a rule, these brands are used in the construction of trade pavilions and public buildings, as well as buildings, where there is additional insulation and a large load. But the golden mean, from which interior and interior walls can be made, will be D500-D600 blocks, which are usually used in the construction of cottages, residential buildings, as well as other buildings. They have the best ratio in terms of strength and thermal conductivity.

Aerated concrete masonry is made on the adhesive compound, which is created from a dry mortar with special characteristics, and consists of sand, cement and various kinds of additives of water-retaining, plasticizing and hydrophobic type. The minimum suture thickness should be 2-5 millimeters, but laying on such a mass is possible with a suture thickness of 8-10 millimeters. Aerated concrete can be put on the sand-cement mortar with an average suture thickness of 12 millimeters horizontally and 10 millimeters vertical.

Creating an adhesive solution for the construction of aerated concrete wall partitions should be started right before work.

Moreover, the preparation work must be done clearly according to the instructions:

• First, pour a certain amount of water indicated on the pack with the mixture into a bucket made of plastic.
• Now gently pour the dry solution into the required proportion, stirring constantly. It must be left for 10-15 minutes, and mix again.
• In the process of laying, it is necessary to stir the mixture several times so that its consistency remains at the right level.
• In order to carry out the laying in the cold period of time, it is better to use an adhesive solution, which contains antifreeze additives in its composition.

Laying rows of aerated concrete is better for glue. First you need to pour the prepared solution into a container, and using a trowel or a scoop,gently smudge it along the entire length of the first row of the wall and level it with a special notched trowel. After that, aerated concrete blocks should be put on top of the glue. Their horizontal movement should be no more than 5 millimeters. The seams must be carefully filled with glue to keep the blocks better. You should also follow the dressing rules. Vertically, the seams should be displaced by no more than 0.4 block heights, or approximately 9-11 centimeters. The glue that will be squeezed out during this must be removed immediately in order to prevent it from grappling. Now it only remains to check how smooth the brickwork was and to level it using a rubber hammer.

To help make the construction of walls easier can various kinds of fixtures. This is a rake order, which makes it possible to designate masonry angles. To use them, you must install them in a vertical position, apply labels that will correspond to the height of the masonry rows. After that, it is necessary to tighten the mooring rope between the orderings in order to lay the next row of gas blocks more conveniently.Now, focusing on the rope-mooring, you can simply align the aerated concrete. To do this, you just need to knock a little bit with a mallet until the glue completely grabs.

The method of laying wall partitions, as well as the suture size should be selected depending on the category of walls. For example, single-layer walls can be 30-42 centimeters thick. For their construction is usually used options D300-D500. If the blocks have exact dimensions, then thin glue seams should be done better. In other cases, you should use a heat-insulating type solution with a suture thickness of 1-1.5 cm.

The thickness of the two-layer blocks can be from 17.5 to 30 centimeters. For them, usually used lime-cement or insulation solution. Aerated concrete groups 600 and 700 can be combined with a glue joint. It is better to heat the partition made according to this technique with a thin layer of insulating material. The thickness of the insulation in this case should be 9-14 centimeters.But the three-layer walls that are made of this type of concrete will have the same thickness as the two-layer. And the method of construction they will be identical. That's just the thickness of the insulation may be even less. It is about 8-13 centimeters.

Cellular concrete requires great care when laying the first layer, because the strength of the walls and the final appearance of the structure will depend on the success of this. That is why it is necessary to carefully align the walls, and the mixture for the seams should be applied only with the help of a special cage or trowel with teeth. If the blocks have profiled grooves on the sides, then during their laying on the vertical seams there is no need to apply a solution or glue. It should be applied exclusively on a smooth surface, and the slots filled with special elastic material with sound-absorbing characteristics.

For example, foam based on polyurethane or mineral wool. Only after the solution dries, which was used to lay the blocks, you can begin to make the grooves for communication.After that, you can start applying putty on the partitions to align them, as well as improve sound insulation and vapor barrier properties. Although to improve the properties of the vapor barrier should not be used putty, and special types of plaster. Usually we are talking about cement plaster.

Its main components are sand, water and cement. Such a solution is usually made either from a dry special mixture, or simply by mixing the above components. Make it simple, but the quality will be extremely low. With an independent production of a cement-type plaster mortar, the special mixture is prepared according to the volume of one part of cement of type M400 or higher and three to five parts of quartz sand.

But a good cement-based plaster mortar can only be made from dry mixes that are produced at the factory.

In such mixtures, there are also additives that can:

• adjust the setting time of the solution;
• to keep moisture in the fresh layer of plaster, not allowing it to go into the material of the wall partition;
• improve ductility and ease of laying;
• do not allow efflorescence to appear on the surface;
• strengthen the adhesion of plaster and base;
• improve the strength and durability of the layer of plaster to cracks.

Aerated concrete is an effective building material due to its high thermal insulation properties. They are due to its cellular structure.

In order to fully appreciate the advantages of the material in question, you should know some aspects:

• During the construction of walls, a special adhesive solution is applied, which is laid on the surface of the aerated concrete block with a thin layer several millimeters thick. But the seams should be exactly like that. If they are larger, the seam will turn into a “cold bridge”, and the properties of aerated concrete in terms of thermal insulation will decrease significantly.
• When erected in a cold and temperate climate, it is necessary to warm the aerated concrete walls not only inside but also outside.
• Be sure to apply cement plaster on aerated concrete and use materials with the highest vapor barrier properties. This is necessary to protect the material from constant exposure to moisture and keep it from cracking. If, however, horizontal cracks appear, they need to be painted over with plaster and everything should be done to reduce the effects of steam and moisture.

• Slabs of such material should be carefully coated with an adhesive solution in order to avoid the appearance of cold bridges and a decrease in the thermal insulation properties of the entire building.
• To obtain a warm home, it is necessary not only to increase the wall thickness to the maximum possible value. You must also use the correct type of aerated concrete. For most climatic zones, it is better to use aerated type D600 or categories B2.5, B3.5 with a thickness of 300 millimeters. But this choice is best to do, relying on the thermal and strength characteristics.

To learn how to make a partition of aerated concrete blocks, see the following video.