Gas silicate blocks - disadvantages and dubious qualities. Features of building from gas silicate blocks: pros and cons Pros of aerated concrete houses

Continuing the topic of building materials based on concrete and various additives, we will analyze such a popular material as gas silicate blocks. Many advantages, as well as versatility of use, have brought this material high popularity in many regions of the world, including in our country.

The blocks are based on high-quality cement, gypsum, lime and water. All these materials are mixed together, after which aluminum powder is added to the solution. The latter reacts with lime, due to which gas evolution begins and the composition is filled with small pores. Modern technologies allow you to adjust the size of the pores.

After mixing the material, pouring it into molds and cutting the latter, the blocks are sent to autoclaves, where they undergo the final set of strength and impart those performance characteristics for which gas silicate is valued. However, there is also a non-autoclave production method, however, in this case, gas silicate blocks are less durable and less environmentally friendly.

Advantages of gas silicate blocks

• The gas silicate block has high compressive strength. This is a reliable building material that will allow you to get strong load-bearing or internal walls. Naturally, we are talking about load-bearing structures in low-rise construction;
• Ease. Aerated concrete is five times lighter than ordinary concrete with high strength. Light weight not only facilitates construction, but also makes it possible to save time and money on the construction of a massive foundation;
• The material is 8 times superior to ordinary concrete in terms of thermal insulation properties. In winter, you will spend less resources on heating even if you save on thermal insulation of walls during construction;
• The porous structure makes the gas silicate block an order of magnitude more effective sound insulator than brick;
• Such blocks are mainly made by high-class professionals. So the quality of the goods is usually very high. Deviations are minimal, so that, with proper masonry, the walls will be as even as possible;
• For rodents, gas silicate blocks are of no interest;
• Large dimensions allow you to build walls much faster than bricks. At the same time, you can work independently. Observing a number of simple rules, you can build a structure from these blocks without great knowledge in construction;
• The material is completely environmentally friendly, and is also not subject to fire;
• High vapor permeability allows for full gas exchange, creating a pleasant microclimate in the premises.

Material disadvantages

• Hygroscopicity, as in the case of other types of cellular concrete, is very high for gas silicate blocks. Having absorbed a lot of water, such a block becomes prone to destruction, loses its performance, and also provides the fungus with an excellent breeding ground. As a result, additional waterproofing measures are required;
• Low strength. When attaching heavy structures to walls, it is necessary to use special dowels;
• Moderate frost resistance, which also increases the cost of protective measures;
• The shrinkage of these materials can be quite significant. For this reason, every three to four rows it is better to use reinforcing mesh or reinforcement. Otherwise, the walls may crack over time;
• As is the case with all porous concretes, thermal insulation properties decrease with increasing strength characteristics.

Glue or cement?

The laying of gas silicate blocks is carried out either on a standard cement-sand mortar or on a specialized glue. What to choose? First of all, it is worth noting that both binders have a higher thermal conductivity than the gas silicate blocks themselves.

On the cement side, the cost is several times lower. The disadvantage is the large thickness of the layer, which increases the width of the cold bridges. The glue allows the blocks to be almost back to back, which is very good. However, for laying the first layer of blocks directly on the concrete base, cement mortar is still needed, as it will allow you to perform the alignment necessary in this case.

Technology of laying gas silicate blocks

The construction of the foundation, which can be tape, will be described in more detail in another article, since this topic is very large. As for the laying of blocks directly, the first row is placed on the concrete mixture from the highest corner of the foundation. If necessary, we make additional adjustments with a solution. Use levels.

• Important! The high ability of the gas silicate block to absorb water should be taken into account when installing the first row of blocks on the mortar. To prevent moisture from the latter from being absorbed into the block, the bottom of the block is wetted with water before being installed on a concrete support.

All other rows can be laid on special glue. In this case, every three or four rows, reinforcement of the walls should be carried out in order to reduce shrinkage.

• Concrete concrete slabs cannot be laid directly on this type of concrete blocks due to the lack of strength of the latter. In this case, it is necessary to build a reinforced concrete belt along the perimeter of the wall, made using the technology of monolithic construction. In the construction of two-story and higher houses, reinforced concrete load-bearing structures are required. In addition, reinforced concrete belts need thermal insulation;
• The strength of the block is one of the determining factors. In the case of the construction of a one-story structure, you will need a block with a density of at least half a ton per cubic meter. If we are talking about the construction of two-story houses, then you need to choose options of 600 kilograms per cubic meter. We have already said that with an increase in strength, insulating qualities are lost, therefore, walls from such a block must have a minimum of 40 centimeters in thickness. Otherwise, additional insulation will be required. A plinth cannot be built from such blocks;
• The appearance of chips and other damage on the blocks is not allowed. Since the material is fragile, it must be transported, stored and handled with care. Try to buy more blocks than necessary, as some of them may be damaged. It is necessary to cut blocks with a special tool and as accurately as possible.

Construction Materials

Pros and cons of gas silicate blocks - myths and reality

From the author: good afternoon, dear readers! As soon as we start dreaming about our own house and planning its construction, the first thing we face is the question of the material from which it will be built. The modern market offers a lot of options, each of which has certain characteristics necessary for our purpose.

Some of the materials have long been known to us - for example, bricks. Others are just starting to gain popularity. Today we will talk about just one of the last categories, namely, about, the use of which is becoming more and more relevant.

In the article, we will analyze in detail the pros and cons that distinguish gas silicate blocks. I note right away that not all of them are real, because quite often building materials are overgrown with some kind of myths. Therefore, we will also turn to the opinion of experienced experts in order to get an objective picture and decide whether this option is suitable for our purposes.

What is a gas silicate block

The progenitor of this material was invented at the beginning of the last century. At birth, he was called "miracle concrete", although, let's be honest, his characteristics were not so close to miraculous.

But a lot of time has passed since then. Production developed and improved, science also did not stand still. As a result, at the moment, we have a certain category of materials called aerated concrete, which is divided into two varieties.

One of them is made using an autoclave in which the solidification process takes place. It is this method that gives the material high strength and other good indicators. Blocks made by autoclave are called gas silicate blocks.

For the production of another type of aerated concrete, the autoclave is not used, so the output result is rather poor quality: heterogeneous and overly porous. It is not very suitable for construction, because after some time after completion of work it shrinks strongly. We will not analyze this variety in detail, but will return to our gas silicate blocks.

The main components that make up this material are lime, gypsum stone, cement, sand and water. First, all this is mixed, and then another necessary ingredient is added to the resulting mass - aluminum powder.

It is this additive that causes internal gas formation in the mixture. The air bubbles formed as a result of it give the blocks a porosity that positively affects some of its characteristics, which we will talk about a little later.

After preparing the mixture and solidifying it, the material is cut into even, neat blocks, the dimensions of which can vary:

• thickness from 20 to 25 centimeters;
• height from 10 to 50 centimeters;
• length up to 0.6 meters.

The density of the finished gas silicate also varies. Depending on this indicator, each group is assigned a specific brand, which indicates the possible intended use:

• D400 - low density, the material is not able to withstand loads, is used only as a supplement to increase the heat capacity of an already erected wall;
• from D500 to D700 - these blocks are suitable as both thermal insulation and structural material. Loads can withstand, but low. Therefore, it is used for the construction of walls, the height of which is no more than two floors. Also, interior partitions are made from the material of this brand;
• D700 and higher rates - but this group is already used directly for structural work. From such blocks it is possible to build load-bearing walls, which will subsequently be subject to heavy loads.

Now that you can roughly imagine what kind of material it is, let's look at its advantages and disadvantages.

Advantages

So, what exactly are the advantages that attract builders to the use of gas silicate blocks? It's no wonder it's been gaining more and more popularity lately. Let's remember what characteristics are necessary for the material from which the walls of a residential building are built:

• strength;
• low thermal conductivity;
• vapor permeability.

We have already talked about strength - if you choose the right brand, then the blocks are perfect for building any type of wall. Now let's take a closer look at the rest of the characteristics.

Thermal conductivity

As mentioned above, during the production of gas silicate blocks, aluminum powder is added, due to which the material is saturated with many air bubbles. And this, in turn, gives the blocks a very low thermal conductivity.

Of course, it cannot be said that one thin wall is enough to keep the heat in the house. Some say that the 35 cm thick construction will perfectly protect the home from the cold even during the harsh Russian winters. Let's debunk this myth.

If your region is characterized by frosts, then the walls of the house made of gas silicate blocks should have a thickness of 50 centimeters or more. If you failed to catch up with this indicator, then you will also have to mount an outer insulating layer over the entire surface.

But in fact, even the required 50 centimeters is an excellent characteristic. Let's compare with other material for clarity. For example, to achieve the same thermal conductivity, it must be at least one and a half meters thick! And here you need only 50 cm. Agree, the difference is impressive.

If you live somewhere in the south, where the climate does not bring unpleasant surprises, then a thickness of 35-40 centimeters is quite enough for walls.

Vapor permeability

Vapor permeability is the same necessary indicator as thermal conductivity. For the microclimate in the house, the possibility of natural circulation of steam is very important. Thanks to the same air bubbles, gas silicate walls perfectly take away excess moisture from the living space and bring them out into the street.

And in winter, for example, on the contrary - the air in the room becomes very dry due to the inclusion of heating, so the wall blocks kindly take some moisture from the street and transfer them to the house. Of course, all this is possible only if the walls are not covered with a non-breathing insulating layer. But, as we found out in the previous paragraph, it is not at all mandatory.

As you can see, the main required characteristics are successfully present. But the advantages of gas silicate blocks are not limited to strength, thermal conductivity and vapor permeability. You can also note:

• ease. Compared to concrete blocks, gas silicate is five times lighter. This, firstly, is very pleasing in the process of work, and secondly, it clearly reduces the load on the foundation of the building. And the transportation of such material is less expensive due to the low weight;
• . Gas silicate, due to its porous structure, perfectly dampens sound vibrations;
• environmental friendliness. Natural components are used for production, so the resulting product can be used for any construction purposes. Roughly speaking, even as a child's cradle, they will not harm;
• fire resistance. Gas silicate blocks can be directly exposed to flame for three hours. Often just this time is enough to cope with the fire in case of fire.

disadvantages

Of course, like any other material, gas silicate blocks do not consist of only advantages. Expert reviews indicate that there are points that must be taken into account during construction:

• very little mechanical strength. Despite the ability of the gas silicate block to withstand heavy loads, it is very sensitive to penetration into its inner world. Simply put, if you screw a dowel in there, it will quickly fall out, and sometimes along with a piece of the wall. You can hang on a gas silicate structure, perhaps, a light shelf for placing photo frames, but a book shelf is already fraught with the destruction of the block;
• frost resistance of the material is also quite low. That is, it can withstand about five cycles of freezing and thawing without problems, but then it slowly begins to become unusable;
• the very ability to absorb moisture, which we praised in the paragraph about vapor barrier, is actually a double-edged sword. Moisture absorbed into the porous block gradually destroys its structure. Therefore, with all the advantages of providing a microclimate in the house, such walls gradually lose their strength;
• for the same reason, they are prone to mold formation. This point must be taken into account. Firstly, it is worth regularly treating the walls with special agents against the occurrence of fungus. Secondly, in no case do not insulate the outer walls from the inside. In general, this procedure is contraindicated for all materials, but in this case the consequences can be especially detrimental. Condensation will begin to form between the insulation and the wall, and constant humidity will very quickly lead to the formation of mold and the destruction of the wall;
• limited number of finishing options. It will not work on gas silicate walls, consisting of sand and cement, since it will immediately fall off. Gypsum is also poorly suited, because it will not be able to hide the seams with high quality. Basically, there is only one solution. You can apply gypsum plaster in a double layer, thereby increasing its masking properties and strength. But with sudden temperature changes, it will still gradually crack, the house will lose its beauty and aesthetics.

As you can see, gas silicate blocks are fraught with many advantages and disadvantages. But, if you pay attention to the growing popularity of its use, we can conclude that the advantages still outweigh.

By the way, you can add one more item to them - the price. Building from gas silicate is quite cheap. At the same time, you get both the ease of the process and a high-quality building with the necessary characteristics.

And we temporarily say goodbye to you and wish you an exceptionally successful construction!

Aerated concrete is one of the types of cellular concrete, an artificial stone, consisting of 85% air. Due to its good ability to retain heat, low weight, ease of cutting and processing, relatively affordable price, it is often used in individual and professional construction of houses and other buildings. Large blocks are made from it, with which it is convenient to lay out walls due to the small mass.

The density index is determined by marking:

• D350 - 350 kg / m3, used only as a heater;
• D400 - 400 kg / m3, for laying openings;
• D500 - 500 kg / m3, for one-story houses;
• D600 - 600 kg/m3, for laying two or three storey buildings, as an additional material for multi-storey construction.

The higher the grade, the better the strength, but the lower the thermal insulation properties. By size, wall elements, partition elements, for lintels are distinguished. For load-bearing structures, options not lower than D400 are used.

They are made in two ways: autoclave and natural drying in the open air. If there is a choice, then preference should be given to the first option - the autoclaved one is stronger (about such blocks of the INSI brand).

Advantages of aerated concrete houses

Advantages of gas blocks:

1. relatively low price;

2. savings in heating costs, gas-block houses require less energy for heating in winter;

3. low load on the foundation, but it requires high strength, eliminating shrinkage;

4. optimal for the individual construction of houses, outbuildings, baths, the ratio of "strength-lightness";

5. one person can lay out the walls of aerated concrete;

6. convenient transportation due to the small weight of the blocks;

7. minimal radiation background;

8. the ability to perform various bends, arched openings, stairs and other structures of any, including complex configuration;

9. good level of sound insulation;

10. ease of processing without the use of special equipment, aerated concrete blocks are easily cut, sawn, polished with hand tools;

11. biological stability, fungi, mold, etc. do not appear on the surface;

12. vapor permeability, walls "breathe";

13. fire resistance, aerated concrete does not support combustion, tolerates exposure to temperatures up to + 1200C, almost does not collapse during a fire for 3 hours;

14. Houses are easy to repair and rebuild.

Disadvantages of buildings from gas blocks

1. unsuitability for multi-storey construction as the main material of load-bearing walls due to low compressive strength;

2. a house made of aerated concrete warms up quickly (from 0 to 20C in 2 hours), but it also quickly gives off heat in the absence of heating (by 1C per hour);

3. even with minor violations of the technology when pouring the foundation, causing shrinkage, up to 20% of the blocks are covered with cracks, this does not lead to the destruction of the house, but it has a bad effect on the appearance;

4. the foundation must be resistant to any ground movements, otherwise the problem of cracks will arise again;

5. aerated concrete masonry for glue must be made very high quality, otherwise the house will be “blown through”;

6. the material is hygroscopic, it quickly absorbs moisture from the air, including during fog, which makes it necessary to finish the walls immediately after the completion of the masonry, be sure to waterproof and insulate;

7. the gas block has low frost resistance - up to 35 defrosting-freezing cycles in total;

8. restrictions on finishing materials for facades;

9. before plastering, careful preparation of the walls is required, since their surface is too smooth, due to which there is a very low level of adhesion with any coatings, it is necessary to use a special primer;

10. lime contained in aerated concrete and adhesive mixtures for it quickly renders any metal objects unusable, including communication pipes in contact with the blocks;

11. gas blocks do not hold any type of fasteners well (under shelves, wall cabinets, etc.), special fasteners are required (for example, plastic butterfly dowels, anchors);

12. low burglary resistance, thieves can simply cut a passage with a chainsaw, and the bars on the windows hold up worse than houses made of other materials.

Comparing the advantages and disadvantages of aerated concrete houses, you need to pay attention to the fact that most of the disadvantages are eliminated during the installation process. To do this, you only need to carefully observe the technology, take into account all the nuances.

Owner reviews

“A year ago I finished building my house from aerated concrete blocks. The walls "breathe", perfectly keep the heat in the room. Laying is quick and easy. Several people can build a one-story house in half a month. The elements are impressive in size, but they weigh little. To carry them according to one's strength and one. During the use of the house, I did not find any serious problems. In frosty weather it is warm and cozy. It took a little finance, dignity - to build cheaply and quickly. The disadvantage is fragility, it is necessary to pay utmost attention to the foundation, to exclude the possibility of any soil movements, to reduce the effects of shrinkage. Otherwise, cracks cannot be avoided.

Alexey, Irkutsk.

“Due to the low price between gas block and brick, the first option was chosen for building a house. In the process, it turned out that high costs for a good vapor barrier and finishing are inevitable. As a result, the house came out relatively expensive, but still much cheaper than brick. No significant shortcomings have been noticed yet, but we have been using the cottage for only three years.”

Peter, Moscow.

“I built a house of aerated concrete myself. It is fragile, so I had to spend more time and money on the foundation than I expected. Posted quickly and without any problems. Only at the stage of final finishing I had difficulties. Special fasteners were expensive, plus insulation costs. Advantages: the walls are dry, the blocks are lightweight. Cons: the material is fragile, a lot of work on steam and heat insulation and related financial costs.

Ilya, St. Petersburg.

“I have a cottage made of gas blocks. For the construction of the first floor I used D500, the second was laid out from D400. To increase the strength under the ceiling, I mounted an armored belt. Outside applied vapor-permeable plaster. The result is a warm, comfortable home, but there is a downside. The heat is only while it is being heated, after turning off the heaters, it quickly cools down.

Vasily, Krasnoyarsk.

“I chose gas blocks as a material for a country house, primarily because of the low price. In one summer he himself built a two-story house. Be sure to additionally insulate. The disadvantage of aerated concrete is that due to its porosity, it strongly absorbs moisture. With the onset of winter, the water freezes and it begins to crack. I solved this problem by insulating the walls with styrofoam. The cost of heating a house is much less than that of the neighbors for a brick house, while ours is much warmer. Pros: Quick and easy to build. I recommend purchasing in reliable stores from trusted manufacturers. I bought two cubes very cheaply, but they began to crumble, I had to buy more.

Dmitry, Moscow region.

Among the large number of wall building materials offered by domestic manufacturers and representatives of foreign companies, there are many discussions on the properties, characteristics and conditions for the use of lightweight concrete blocks. In particular, gas silicate blocks, the disadvantages and advantages of these products are considered in detail from all sides. Moreover, to what extent some actively position these blocks as an ideal tool for obtaining strong, warm and durable walls, so others diligently prove inapplicability of European developments for the Russian climate.

Given the prevalence and availability of gas silicate blocks, it is advisable to calmly and in detail consider all the pros and cons of this material.

What blocks can be called gas silicate

First of all, it makes sense to decide what building blocks are gas silicate, since in discussions this category includes almost all types of products made of lightweight concrete, with the exception of expanded clay and cinder blocks. In accordance with an international patent received in 1924 for this material, blocks can be called gas silicate:

1. which, in addition to the filler (quartz sand with a limited content of impurities, water with regulated hardness), as a binder includes lime-cement mortar with a weight content ground quicklime about 75%, but as blowing agent - aluminum pastes or powders containing at least 90% metal fraction from 20 to 45 microns;
2. in which pore formation occurs due to the occurrence in the process of mixing a liquid mixture of hydrogen, which saturates the finished mass with bubbles; as a result, the hardened material has many small, evenly distributed pores of the same size and regular shape;
3. hardening of which is carried out in autoclaves at a pressure of 8 to 12 atmospheres and at a temperature of about 200ºС, which allows you to fully bind the active aluminum, eliminating the possibility of its impact on the environment, as well as to achieve the stability of the thermal characteristics of the material due to the hydrophobization of the cement stone.

In order to determine the reasonableness of the cost of, the disadvantages and advantages of these products should be compared with materials of the same purpose and with similar properties.

Disadvantages are known in comparison

The most correct comparison for gas silicate blocks are building blocks made of foam concrete. In this case, blocks should be analogous autoclaved, since foam concrete blocks of natural hardening, manufactured in the conditions of a construction site or an adapted room:

• due to the need to fill in metal molds, they have a limited size range;
• need a certain time to gain the necessary strength;
• have non-uniform physical characteristics by volume due to unstable mixing of the mixture;
• may have significant deviations from the geometric dimensions, which leads to an increase in the thickness of the seams and, accordingly, to the appearance of "cold bridges".

Deviations are due to production in separate forms, while autoclaved blocks are made by sawing a single volume of concrete into blocks of the required dimensions.

That's why it is advisable to compare the main indicators of gas silicate and foam concrete blocks manufactured in accordance with GOST 31360-2007 (“Wall products, unreinforced, from autoclaved cellular concrete”)from autoclaved cellular concrete in accordance with GOST 31359-2007(“Autoclaved cellular concrete”).

Based on the analysis of the given technical characteristics, it is possible to makefollowing conclusions:

• with equal strength, the density of gas silicate blocks is lower than that of foam concrete, which indicates their lower thermal conductivity and, accordingly, the smaller wall thickness required in specific climatic conditions;
• at the same density and thermal conductivity, the strength of gas silicate blocks will be higher.

The indicators of each of the materials vary depending on the manufacturer, the parameters of the materials used, and the differences in technology, so the table shows average values.

Gas silicate blocks: disadvantages and advantages - what more?

However, gas silicate blocks are not only characterized by advantages, they also have disadvantages. The negative properties of this material include:

1. high water absorption, which limits the use of gas silicate concrete blocks in rooms with humidity above 60%. Therefore, for the installation of gas silicate blocks of external walls in areas with a humid climate, partitions in sanitary facilities, a special finish is required;
2. relatively low heat resistance of gas silicate blocks, which cannot be used at temperatures above 400ºС;
3. the impossibility of obtaining gas silicate concrete in construction conditions for its use for thermal insulation of building structures.

And if the second and third shortcomings do not matter to the vast majority of potential buyers, then high water absorption can seriously limit the scope of application of gas silicate blocks.

This limitation can be removed by special plaster mixtures, with high vapor permeability, water-repellent properties, good adhesion to the base, strength and frost resistance. This plaster is applied with a layer of 7 - 9 mm thick on the outer surface of primed gas silicate blocks with a grid of alkali-resistant glass fiber fixed on it. The plaster is being painted vapor-permeable paints and covered with a layer of water repellent. This technology makes it possible to ensure the durability of external walls made of gas silicate blocks, regardless of climatic conditions.

Conclusion: each block is good in its own system

Summarizing all the above, we can say that gas silicate and foam concrete autoclave blocks are almost equivalent. However, on the domestic market, mainly blocks of naturally hardened foam concrete are presented, the properties and characteristics of which are much lower. As for gas silicate blocks, disadvantages they are connected with the fact that in Western European countries, from where this material came to us, blocks as an independent structural material are rarely used. Basically, in the construction, primarily of individual residential buildings, complex systems of compatible wall and finishing materials that allow leveling negative properties, like high water absorption, highlighting the positive– low thermal conductivity, smooth surfaces, excellent geometry.

Hence the conclusion: having certain knowledge of the rules for using autoclaved gas silicate blocks and following them, you can build a light, strong and durable house with beautiful facades.

Gas silicate was invented as an alternative to concrete and brick. The main goal of the developers of the new building material was to reduce the cost of erecting buildings without losing the strength characteristics of load-bearing and non-bearing structures. Manufacturers of gas silicate blocks position them as one of the best building materials for low-rise buildings. However, the practice of its application shows that the gas silicate block has its pros and cons.

What is a gas silicate block

The gas silicate block is a building stone intended for laying walls, supports and partitions. It is made of cellular gas silicate concrete, a feature of which is the absence of cement in the composition. The binder function is performed by a mixture of lime and quartz sand in a ratio of 0.62:0.24.

The production technology is simple:

1. Measure the required amount of lime and sand.
2. Sifted on a vibrating sieve.
3. Joint fine grinding of the listed ingredients is carried out in a ball mill.
4. Add water.
5. Aluminum powder is introduced, which acts as a blowing agent.
6. The resulting mixture is poured into molds, filling each of them by ½ volume.
7. Within two hours kept at a temperature of +40°C, waiting for the completion of the chemical reaction, during which hydrogen is formed.
8. The blocks are placed in an autoclave, where they are kept for 12 hours at a pressure of 0.8–1.3 MPa and a temperature of up to +200°C.
9. The blocks are removed by a divider crane and they are laid for further hardening and gaining brand strength.

The resulting material is a porous stone with the following technical characteristics:

• dimensions of voids (cells) - 1–3 mm;
• density - 200–1200 kg / m 3 (corresponds to the brand: D200-D1200);
• thermal conductivity - 0.11–0.16 W / ° С * m 2.

Frost resistance deserves special attention. For blocks of grades D200-D400, this indicator is not standardized. Building stones with a density of 500–600 kg/m 3 can withstand up to 35 freeze-thaw cycles without loss of strength and other characteristics. Frost resistance of blocks of higher grades (D700-D1200) corresponds to F50-F75.

Outstanding technical performance due to the porous structure of the material

Application area

Residential and non-residential buildings are erected from gas silicate blocks. Construction technology involves the use of stones of different densities for certain purposes:

• D200-D350 - construction insulation.
• D400-D600 - masonry material for the construction of load-bearing and non-bearing walls in low-rise construction.
• D700-D1200 - masonry material for the construction of high-rise buildings, subject to reinforcement in every fourth row.

Gas silicate allows you to significantly save on space heating

Difference from aerated concrete

Gas silicate and aerated concrete blocks are materials of the class of cellular concrete. They have much in common in properties and technical characteristics, they are used for the same purposes. All this confuses the classification of these materials, and due to the external similarity, even experts cannot accurately determine which block is in front of them: gas silicate or aerated concrete.

For internal partitions, a structural and heat-insulating type of material is suitable

But there are significant differences between them. First of all, it is the composition and method of production. There are other differences, which can be found in the table.

Differences between gas silicate and aerated concrete

The dimensions of gas silicate blocks are standardized by GOST 31360–2007. All enterprises specializing in the production of cellular concrete adhere to the accepted recommendations. But this does not exclude the possibility of manufacturing building stones according to the individual dimensions of the customer.

Generic Block Parameters

The choice of objects for construction is carried out based on the pros and cons of gas silicate blocks.

pros

The indisputable advantage of gas silicate is its low thermal conductivity. This property is due to the porosity of the material. It consists of a large number of hollow cells filled with air and having an irregular spherical shape. They are the best heat accumulator. The principle of insulation of buildings and communications with fibrous materials (mineral wool in rolls and slabs) is based on this property of air.

Gas silicate has other advantages:

• High accuracy of geometric parameters of products. According to GOST 21520 89, there are three categories of accuracy, each of which allows small deviations: in height - 1–5 mm, in thickness and length - 2–6 mm. The use of even stones of the same size in masonry allows you to save on a binder: cement-sand mortar or glue.
• High rates of vapor and air permeability, corresponding to similar parameters of most types of wood. In this regard, gas silicate can be called a "breathing" material.
• Environmental safety due to the absence of components harmful to human and animal health.
• Fire resistance, allowing the use of gas silicate blocks for the construction of fire barriers. In a building made of this material, the fire spread limit is 0.
• A light weight. The mass of the block depends on its density and geometric dimensions. The weight of a standard stone 625x300x250 with a density of 400 kg / m 3 - 17 kg; with a density of 1200 kg / m 3 - 28 kg. A low-rise building made of gas silicate blocks does not require a powerful foundation. In most cases, private developers choose between shallow tape (MZLF) or slab. But with the foundation device, not everything is so simple, which will be discussed below.
• Flexibility in processing. Blocks of cellular concrete can be sawn with a conventional hacksaw for wood. Nails are easily hammered into them and self-tapping screws are screwed in. All this greatly facilitates the implementation of construction and finishing work.
• Do not attract rodents and insects, are not damaged by them.

The heat-insulating type of gas silicate blocks has the least weight

Minuses

Private developers often express a negative opinion about gas silicate and aerated concrete, report on their experience in building and operating houses from these materials. Based on the reviews, we can draw conclusions about the inherent shortcomings of these blocks.

Hygroscopicity

Gas silicate has one significant disadvantage that can minimize and cross out all the advantages of this material: a high degree of hygroscopicity. It defines many problems that arise in the construction and operation of houses.

Moisture permeability of porous stones is due to the presence of air in them. It is able to penetrate into the smallest cracks and fill them. The moisture contained in it is absorbed by a mixture of sand and lime (components of the gas silicate composition). Aerated concrete is also exposed to the same danger, since the presence of cement in it is not an obstacle to the penetration of water into the structure of the block.

We draw conclusions: a wet block is a cold block. Therefore, the thermal characteristics of the material declared by the manufacturer correspond to the conditions of its operation: at low or normal air humidity.

In reality, this cannot be achieved, since a natural phenomenon - precipitation in the form of rain and snow, will always increase the humidity level of the atmosphere surrounding the house. In addition, this indicator is inevitably affected by the proximity of water bodies: rivers, ponds, pools.

In confirmation of the information presented, one of the recommendations regarding cellular concrete can be cited.

According to paragraph 1.7 of the "Handbook to SN and P for engineering and technical workers of research and design organizations", cellular concretes, including gas silicate blocks, are categorized as non-moisture resistant and non-bioresistant materials not recommended for building walls of rooms with wet and wet conditions.

Beams can be used to protect external walls

fragility

With all its advantages, gas silicate has a low bending strength. This causes the fragility of the blocks and the appearance of cracks in the walls and partitions. The lack of elasticity makes gas silicate structures responsive to the slightest deformations.

Practice shows that houses above three floors are not built from this material. For the construction of high-rise buildings, high-density blocks are required: from D700, which have lower thermal insulation characteristics. The cost of construction increases significantly, as the cost of purchasing more expensive blocks, heat and waterproofing materials increases.

But even for a three-story building, a high-quality foundation made of heavy concrete is required. Moreover, it is important that the base of the house has a high bearing capacity and has a perfectly flat, horizontal surface. In this case, the risk of shrinkage deformation of the walls and the formation of cracks in them is minimal.

The experience of builders suggests that without a reliable foundation, it makes no sense to deal with cellular concrete. When choosing an MZL or a shallow slab as the base, experts recommend building a brick basement. And only after that proceed to the laying of gas blocks.

Poorly laid out foundation leads to cracking of gas silicate

Low mechanical strength

To fix massive structures, heat and waterproofing materials on walls made of gas silicate, special fasteners will be needed. Ordinary, in the form of dish-shaped dowels, will not work. Aerated concrete blocks have a rather loose structure, so they require special screw-in dowels or chemical anchors. The price for these fasteners is 5-6 times higher than for dish-shaped ones.

On average, the cost of insulation, waterproofing or finishing 1 m 2 only due to the use of specialized fasteners increases by 250–300 rubles. The total area of ​​the facade of a private house is at least 300 m 2, so this feature of gas silicate blocks leads to a significant increase in the cost of construction estimates.

The structural type of gas silicate has low thermal insulation

The use of material for the construction of a bath

The bath from the gas-block differs in an optimum ratio of the price and quality. Adherents of log cabins will find many negative aspects in the construction of cellular concrete, but not every owner has the means to purchase expensive wood. In this situation, affordable materials help out: gas silicate and aerated concrete. They have a number of characteristics that can be regarded as positive for the construction of a bath:

• Fast erection. Due to the light weight and the correct geometric shape of the blocks, masonry can be done independently without involving specialists. The large sizes of building stones provide a high speed of wall construction.
• Low thermal conductivity. With the same wall thickness, a gas-block bath will be warmer than a brick one.
• Small load on the foundation. A small-sized one-story building can be erected on a strip or column base. Recently, the foundation of Semykin, patented by the author, has been gaining popularity. Such a base is built from sand-filled car tires. It is great for building a bath from gas blocks.
• Walls made of cellular concrete hold well and give off heat for a long time.

The negative aspects of building a bath from gas silicate blocks:

• high-quality hydro- and thermal insulation of walls is required;
• installation of a warm floor is desirable, which will ensure quick drying of the building;
• it is important to comply with the increased requirements for storage, transportation and laying of the gas block, preventing the appearance of chips and cracks.

A bath made of this material is an advantageous structure in all respects. It is only required to properly protect it from moisture and veneer.

Gas silicate can be easily cut into pieces of the desired size

The construction of the walls of the house from blocks

For the construction of a private house, a gas block is not the best material. If there is no other way out, it can be used, but you need to be prepared for additional costs for insulation and waterproofing of walls and ceilings. Special attention will be required to the quality of foundation construction: it must be reliable and even.

An important point in building a house from gas silicate blocks is the thickness of the walls. Manufacturers claim that 380 mm is enough for Moscow and the Moscow region, but this does not meet accepted standards.

When calculating in accordance with SNiP 23–01–99 “Construction climatology” and SNiP II-3–79 “Construction heat engineering”, it turns out that the minimum wall thickness for Moscow and the Moscow Region (when using gas silicate and excluding seams) is 535 mm, the maximum - 662 mm. Taking into account the seams - 588–827 mm, respectively. It is irrational to build such walls, so you will have to make high-quality expensive insulation.

Facing gas silicate blocks will protect them from destruction and extend the life of the material

Video: gas silicate house

How to choose

When choosing gas blocks, they are primarily determined by their type: wall or partition. The first are necessary for the construction of load-bearing structures, the second - for non-bearing. The market offers a wide range of blocks of different brands. For building a house, the best choice would be the following:

• D400 B2.5 - suitable for the construction of buildings up to three floors;
• D500 B3.5 - used for the same purposes, more dense and durable, but the thermal conductivity is higher than that of D400 B2.5;
• D600 B3.5–5 - high-strength stones recommended for the construction of basement floors, houses with a ventilated facade and suspended structures.

A visual inspection of the blocks is also important, which will give an idea of ​​the state of the building material of the entire purchase batch. High-quality stones are even, with clear edges and without cavities. The autoclaved gas block is much lighter than the one that gained brand strength through natural drying.

The high density of the material reduces its thermal insulation qualities