Lightweight concrete: structure, specifications,

What is lightweight concrete? In this case, the name perfectly copes with the description of the material, the main differences of which are lightened weight, increased porosity and low thermal conductivity. But let's talk about everything in more detail.

General provisions

Concrete is reliability, durability, resistance to atmospheric phenomena, but not heat. Cement mortar has a high level of thermal conductivity and can not provide an acceptable indicator of thermal insulation in the room.

For this reason, concrete houses are either subjected to additional insulation, or require a greater consumption of coolants in the winter. In any case, additional financial costs are required.

Ways to reduce thermal conductivity directly of the solution itself were patented in the middle of the last century. They consisted in increasing the porosity of the material due to special additives or the use of appropriate fillers. But at the same time, the strength of the finished structures also decreased, which was unacceptable according to the State Standards of that time.

The current price of energy, which has increased significantly in recent years, and the introduction of new production technologies, which make it possible to achieve higher strength properties even with the condition of low density, have given lightweight concrete a new life, having risen to pedestal popularity.

All structural features of the material under consideration are determined according to GOST 25820 2000 and provide them with a mass of advantages:

Virtues

1. Low thermal conductivity. This contributes to a significant increase in porosity, which usually reaches forty percent of the total volume of the structure. In the table below you can get acquainted with the heat conductivity coefficients for some types of light concrete, using different fillers, in comparison with the classic brick:

1. Little weight.

The lightness of this building material provides several additional advantages at once, making it possible to save on its use:

• Ease of transportation.
• No need to strengthen the foundation.
• The possibility of high-altitude work without special lifting equipment.

1. High noise isolation. The used porous fillers perfectly impede the advancement of any sounds along the structure of the erected structure.
2. Versatility. A possibility of use, both as a heater, and as bearing walls.

1. Simple instruction manual.

There are several points to note here:

• Ready blocks have large convenient sizes.
• In some cases, due to the exact geometry, the use of special glue is allowed for fixing the masonry elements instead of cement mortar, which allows to hide joining seams as much as possible.

• Ease of processing. Due to the low density, cellular concrete products are easily sawn with a regular hacksaw, if necessary, to shorten their dimensions, and there are no problems with supplying all the necessary communications.

1. The possibility of making their own hands. Using the necessary fillers, and in some cases, frothers, you can mix the solution you need at home.

Tip: in the case of home production organization, it is recommended to use a concrete mixer. With its help, you can achieve the necessary uniformity and greatly accelerate the process.

1. High frost resistance. This indicator determines the number of cycles of freezing and subsequent thawing without adverse consequences. In this case, depending on the binder used and coarse aggregate, it can vary from F25 to F

Tip: to increase the coefficient of frost resistance you can always use the appropriate modifying additives. Their use may allow to increase the number of transferred cycles up to 300, which will favorably affect the durability of the whole structure.

1. Long service life. With proper care it reaches several decades.

disadvantages

Increased porosity, which provides most of the advantages listed above, adversely affects several other parameters:

1. Strength reduction Due to the use of less resistant to mechanical stress fillers than in the case of heavy concrete.
2. Moisture absorption. Pores are channels for the penetration of a liquid; the larger, the higher the danger.

Tip: It is recommended that after plastering the construction of the material in question, external plastering work be performed. So you exclude the possibility of contact with water.

But today there are representatives of lightweight concrete, with high enough strength to play the role of load-bearing elements in a high-rise building, and non-dangerous level of hydrophobicity.

Features of the structure and types

From the general provisions now let's move on to the specifics, since the types of properties the use of lightweight concrete depend on the characteristics of its structure and the filler used.

Structure

The classification of light concretes according to their structure is as follows:

1. Ordinary. Here there is a classic concrete composition: a binder, fine aggregate, coarse aggregate and water. Air involvement in this case does not exceed six percent.
2. Large pores. In such solutions in the process of mixing there is no sand, so that the voids between the large components remain intact, and they themselves are covered with a thin layer of cement. This ensures 25% of the air in the finished product.

1. Porous. The addition of a blowing agent to the cement stimulates the formation of stuffy cells in it, due to which there is an increase in the insulating properties and a decrease in the strength properties.

Purpose

Depending on whether you are going to use light concrete blocks only as a heater or intend to erect bearing walls from them, a different approach to their production is used. To increase the strength characteristics, special autoclave treatment is carried out. This allows the following classification of ready-for-use items:

Possible fillers

The composition of lightweight concrete differs depending on the coarse aggregate used for its creation, which can be used as:

1. Natural. Produced by crushing and fractionation of porous rocks.

These include:

• pumice;
• volcanic lava;
• shell limestone.

Tip: The best choice from this group will be pumice because of the closed pore system, which significantly reduces the moisture-absorbing properties of the material.

1. Industrial waste without prior processing:

• metallurgical slags;
• fuel slags;
• chemical slags.

1. Industrial waste and stone materials that have undergone appropriate treatment:

• Expanded clay. The granules of the clay mass are expanded using special additives, and then placed in a furnace, where they are treated with a temperature of 1200 degrees Celsius. By the end of the forming process, an increase of 17 times occurs, which guarantees a very high porosity.

• Agloporit. It is made by sintering clay with processed coal residues.

• Perlite. In order to get it, the eruptive polymineral rocks are heated to 1300 degrees Celsius, as a result of which they swell and form a material that looks like porous crushed stone.

Increased lightness

You can also select light and especially lightweight concrete. The most light can be attributed to those types of solutions in which no large filler is added, and the porosity is realized by artificial foaming in the binder itself.

Such ultra-light foam concrete has unique qualities:

1. Durability. Such destructive processes as decay, corrosion and attack of pests are not peculiar to it.
2. Very low thermal conductivity, only 1 W / (m?⁰WITH).
3. Environmental friendliness. The most environmentally friendly building material is wood, but foam concrete is in second place, and expanded clay concrete, for example, is in the twentieth.
4. Simplicity and ease of installation. Absolutely correct forms and low weight contribute to fast and high-quality construction work.

1. High fire resistance. With direct and prolonged exposure to flame, foam concrete does not split and does not explode, as can happen with heavy concrete.
2. Beautiful appearance. Taking into account the use of glue as a fixing substance, it can completely do without finishing work.

1. Low moisture absorption. The pores of this material are closed, which allows it to float on the surface of the water for a week. This allows him to endure any precipitation and severe frosts.

If you are wondering how to make the lightest of lightweight concrete, then you will need information about the composition of the most universal class D600:

1. Cement - 330 kg, brand not lower than M400.
2. Sand - 210 kg, preferably dry and cleaned.
3. Frother - 1,1 kg.
4. Water - 180 l.

Conclusion

Lightweight concrete perfectly combines low thermal conductivity and relatively high strength. Add to this efficiency, low weight, ease of operation, ease of processing and durability. As a result, we obtain an almost perfect building material, which will allow you to build a reliable and comfortable house in the shortest possible time.

The video in this article will give you the opportunity to read more information that is directly related to the above materials. Use the most efficient building materials when building your own home.