The choice of aerated concrete or gas silicate still worries many novice builders. After all, these materials began to be widely used relatively recently. Nevertheless, both of them are representatives of aerated concrete, and their main advantages, as well as disadvantages, are quite predictable. It remains only to understand the nuances that distinguish gas silicate from aerated concrete.
To begin with, it would be good to understand how related these two species are. After all, gas silicate is often called autoclaved aerated concrete, and confusion arises. But the difference becomes obvious, once you determine the composition and technology of obtaining materials.
In its composition, foamed concrete, which is used in both cases, has few differences. The only question is knitting. Gas silicate blocks are made with the addition of lime (about 24%), while aerated concrete blocks contain only cement. The differences end there:
- in both cases, sand acts as a filler;
- large fractions such as crushed stone are not introduced - they are partially replaced by lighter blast furnace slag;
- foaming components based on aluminates are introduced, providing the gas blocks with a porous structure.
The next difference, which led to the separation of gas silicate and aerated concrete into two different groups, is the production technology, or rather, the solution hardening process:
1. Aerated concrete blocks are cut from non-autoclaved foamed concrete, that is, normal hardening. Although it is better and more expedient to use aerated concrete for the installation of monolithic structures. The solution is poured into the formwork or mold and there the hydration process takes place during the 28 days assigned to it.
2. Gas silicate blocks are also cut in parts, but from limited workpieces, standard size... The setting of the solution poured into the molds takes place in special ovens (autoclaves) under certain conditions of temperature and pressure. As a result, the workpieces have less shrinkage and an almost unchanged geometry.
The difference in the speed of solidification of autoclaved and non-autoclaved aerated concrete is simply enormous, because gas silicate, under the influence of hot steam, gains the necessary strength after 12 hours. And even if the hardening of non-autoclaved concrete is accelerated by means of thermal and moisture treatment, this will not shorten the hardening time to those shown by its "opponent".
The mixture is heated in autoclaves not only at an elevated temperature of about +180 .. + 190 ° C, but also under a pressure of 12-14 atm, which is provided by the supply of superheated steam. As a result of such treatment, hydrous calcium silicate (tobermorite) is formed in the massif - an artificially recreated analogue of a natural rare mineral. Thanks to it, gas silicate very well holds high loads, "unmanageable" for blocks made of ordinary aerated concrete, and acquires increased crack resistance. This significantly expands the possibilities for its application in construction.
Of course, autoclave technology has its drawbacks, and very significant ones:
- Energy intensity of production and, as a consequence, the rise in the cost of production. Moreover, it is quite inexpensive to make a mixture for home production of aerated concrete.
- The inability to produce products of any size, since their dimensions are limited by the dimensions of the oven. This difference from normal hardening technology is not too significant for the production of individual blocks. But it is precisely this that prevents the use of more durable foamed concrete in some construction work.
Like this: a slight change in the raw material composition, the creation of other hardening conditions - and at the output we get two completely dissimilar materials with a huge difference in characteristics. However, aerated concrete can also be loaded into furnaces, but gas silicate of proper quality cannot be obtained without the use of autoclaves.
Comparison of characteristics
Aerated concrete, in comparison with gas silicate, is less susceptible to moisture and, accordingly, frost. The reason for this is the closed pores of the surface. But this does not play a big role, since all aerated concretes need reliable protection from the water. And after cutting the foamed monolith into blocks, these advantages will be vanishingly small. This can be verified by comparing the water absorption rates for both materials - the difference is not significant.
It is much more important to take into account the differences in strength and thermal insulation characteristics in construction. Indeed, in order to choose the right material, you need to find the optimal combination of reliability and comfort.
The construction of a house from aerated concrete requires careful calculations regarding the bearing capacity of the foundation and walls, as well as their resistance to heat transfer. And in draft finishing works it is better to focus on the economic component and choose what is cheaper.
It is worth taking a good look at the technical characteristics of both materials, as the difference between gas silicate and aerated concrete becomes obvious. The first one has a large take-off in density, which makes it possible to choose not only a structural, but also a "warm" version on the market. Large quantity pores in lightweight blocks make them an excellent insulating material.
Due to the increased density, aerated concrete does not retain heat so well, but at the same time, the difference in strength is clearly not in its favor. And the reason is the change in the mineralogical composition of the gas silicate, which has already been mentioned.
The degree of homogeneity of the resulting structure also plays an important role in such a large gap in characteristics. Aerated concrete, if you look at the cut, has pores different sizes, unevenly distributed in the body of the block. On the other hand, gas silicate, subject to the manufacturing technology, is structured better - it turns out to be more homogeneous with the same air cells with a diameter of 1-3 mm.
Despite such an abundance of differences, aerated concrete blocks have some properties similar to gas silicate ones. But only in terms of water absorption and air permeability.
Summary: what to consider and what to remember
Studying the difference between foamed concrete and gas silicate, most come to the conclusion that it is better to choose the second option for building a house. That is why in our country autoclaved concretes are more widespread, and the difference in price discourages few. But in some cases, one cannot do without aerated concrete, therefore, before finally choosing a building material, you need to weigh everything.
For each of them, it is better to determine the area of \u200b\u200bapplication where all its advantages will manifest.
Aerated concrete blocks and monolithic structures:
- Used where price, not quality, matters. For the construction of small objects that do not experience special loads, it makes no sense to buy expensive gas silicate. It is wiser and cheaper to choose aerated concrete.
- More ample opportunities opens and non-autoclave production method. Lightweight and warm floor screed, monolithic internal partitions do not put in the oven. Therefore, such structures are made only by the non-autoclave method.
- The monolithic method will come in handy when arranging small foundations, which are always better to do cheaper. Closed pores will be protected by a smooth concrete surface, while silicate is a mineral sponge on the outside.
Gas silicate blocks should be used where their strength is required: when erecting load-bearing walls and floor slabs, in structures that provide for additional reinforcement. It can only be supplied as individual prefabricated elements. But the dimensional accuracy and easily predictable volume allows them to be made more complex, for example, with tongue-and-groove locks.
Aerated concrete, although it costs much less, is used much less often in the form of blocks. But it is indispensable in the manufacture and monolithing of products non-standard form or sizes.
Modern building materials, essential differ from their predecessors and if not long ago houses were built of wood, brick or concrete structures, now multicomponent blocks are widely used. In particular, they include the recently appeared foam concrete and gas silicate.
Foam blocks or gas silicate blocks, which is better, can be confidently asserted only after all calculations and third-party studies have been made that reveal all individual characteristics each building in particular.
Manufacturing process
Both aerated concrete and foam blocks belong to cellular materials, therefore they are often confused, although by the type of production they are completely different. In particular, gas silicate blocks can be produced only in the factory, while foam concrete can be created independently.
In order to obtain a foam block, it is enough to pour a cement solution into the appropriate form, with special chemical and natural additives that will allow the concrete to foam and gradually harden, in this state.
In addition to foam concrete blocks, which are made as a material used for the construction of residential and utility buildings, the foam composition can be poured into permanent formwork , for obtaining monolithic structures.
The main production difference between foam block and gas silicate is that no chemical components can be used for foaming concrete, but only natural substances. To obtain a foam concrete solution, cement, lime, water and gypsum are kneaded. To improve gassing processes, a small amount of aluminum powder is added to the solution. Less commonly, aluminum is added as a chemical paste.
Unlike simple foam concrete gas silicate blocks need processing in special autoclaves... There, foaming processes also occur in the poured composition, but then the mass is exposed to certain temperatures and pressures.
Gas silicate is produced in large blocks of a given thickness, and from them, using string cutting equipment, small blocks of a given standard are cut. Thanks to this cutting technology, the cuts are perfectly flat, and equipped with figured locks that facilitate the process of laying out the walls.
Thanks to the ideal cuts, the building erected from this material is practically has no joining seams, which are conductors of temperatures changing during the year. In particular, cold in winter and hot in summer. The cut and plasticized aerated concrete elements are hardened again at certain temperatures and humidity.
The main differences between gas silicate and foam concrete
Despite the fact that foam blocks and gas silicate materials are very similar in structure, they have a whole range of differences:
- Gas silicate blocks by an order of magnitude better resist open flames.
- It is much easier to process foam concrete, although gas silicate can also be sawed with an ordinary hacksaw on wood.
- Gas silicate blocks have several better thermal insulation.
- Considering that the foam concrete is poured immediately into separate formwork, and the gas silicate in one block, followed by cutting, the latter has the best geometric shapes.
- Foam concrete can be produced independently, but gas silicate is not.
- These materials do not differ in price, scope and ease of use. They are also very similar in terms of resistance to moisture absorption and the ability to use in different climatic conditions.
- The difference in appearance of these materials can also be seen with the naked eye. Gas silicate blocks are much smoother, both over the entire area and around the edges. Gas silicate has a homogeneous light tone, and foam concrete can be dirty gray with small stains.
In some cases, a perfectly flat surface of gas silicate can play a negative role, in particular, it is more difficult to apply certain types of finishing material to it. That is why the smoothness parameter does not always determine which foam concrete or gas silicate block is better.
- By structure... Gas silicate, like foam concrete, is cellular, but closed type, which can significantly reduce moisture absorption.
- By strength Gas silicate is several times superior to foam concrete, this is due to the technology of its manufacture, during which it is tempered in autoclaves. The strength of individual elements ensures the reliability of the entire structure as a whole.
The risk that the building will crack is reduced several times when using gas silicate. However, foam blocks and gas silicate blocks are recommended for use during construction in conjunction with a tiled foundation, which in itself is capable of compensating for distortions during shrinkage of the house and not allowing it to deform.
- Trying to determine how the foam block differs from the gas silicate block in terms of environmental friendliness, we can say with confidence that nothing. Both of these materials absolutely harmless and do not emit harmful impurities even under the influence of an open flame. The reason for this lies in their composition, which is 90% natural and therefore environmentally friendly materials. The percentage of chemical additives is so small that it is simply not taken into account.
- Necessity strengthening the structure... Again, this distinctive parameter is based on the different density and strength of foam concrete and gas silicate. Foam concrete is a less durable material and it is recommended to reinforce walls made of it every 3-4 levels of blocks. Gas silicate does not require reinforcement, the only exceptions are window and door openings, the reinforcement of which is due to installation window frames and door designs, as well as violation of the integrity of the masonry.
Scope of application
Foam concrete and gas silicate blocks widely used in various fields of construction... This material is used to build both internal and external walls of houses. Most modern high-rise buildings are built from this material. This is due to the low weight of the blocks, which allows significant reduce the load on the main frame and foundation of the house, while the blocks are strong enough so as not to worry about the integrity of the floors and walls.
Foamed concrete is also used in the construction of many auxiliary, industrial and agricultural buildings. The only thing the exception is buildings in which constant high humiditysuch as indoor pools, saunas and baths.
Though allowable norms humidity for the use of aerated concrete 75%, if a level of more than 60% is expected, then foam concrete and gas silicate blocks are not recommended to be used. In some cases it is allowed to use this material if after installation they will be hidden from steam moisture insulating materials that can protect the structure itself from negative impact high humidity.
Gas silicate blocks are more often used in the construction of houses, since, in addition to increased strength, they differ in perfectly flat surfaces, which allows you to create even masonry and subsequently spend less time and effort on cladding.
Gas silicate is not easy to connect cement mortar, but with a special glue, as a result of which the seams between the blocks remain thinner. This reduces cold bridges, improving the thermal performance of the entire structure.
Given the difference in density and strength of materials, foam concrete is recommended for use only in small buildings, for example, in private houses up to two floors. It is not recommended to use it as load-bearing structures, and it is also better to combine foam concrete with brick or monolithic concrete columns.
The construction of high-rise buildings from gas silicate blocks is allowed, as well as load-bearing supports in small buildings, without additional reinforcement with concrete belts.
There is a wide variety of aerated concrete on the building materials market today. Not every professional builder can say which is better - gas silicate or aerated concrete, foam concrete or expanded clay concrete, as well as in what conditions to use this or that type of this building material. Let's figure out how the blocks differ from each other, what are their advantages and disadvantages.
What it is?
According to GOST, both of these concretes belong to cellular, or as they are also called, porous concrete. During the manufacturing process, evenly spaced rounded pores-cells with a diameter of 1 to 3 mm are formed inside each of them.
The main difference between them is in the method of solidification. So, gas silicate blocks harden only as a result of autoclaving (under the influence of steam and pressure), and aerated concrete can be produced both by autoclave and non-autoclave hardening.
Comparative review
These two types of cellular concrete are made by mixing various components. The basis of gas silicate is a mixture of quartz sand with lime, giving it a grayish tint, and aerated concrete - Portland cement, due to which the material has a white color.
According to the method of hardening, both types can be autoclaved, but only aerated concrete can be non-autoclaved.
The table below clearly illustrates the difference between aerated concrete and gas silicate:
Parameter | Aerated concrete | Gas silicate |
| Strength (kg / cm 2) | ||
| Density grades | 350, 400, 500, 600, 700 | 400 - 700 and above |
| Thermal conductivity coefficient (W / mGrad) | ||
| Bulk weight (kg / m 3) | ||
| Frost resistance (number of cycles) | ||
| Water absorption (in%) | ||
| Cost (rub / 1m 3) | 3000 - 4000 |
|
| Soundproofing | average and below | |
| Durability | Over 70 years | 50 and above |
| Vapor permeability coefficient, (μ) mg / m · h · Pa |
After analyzing the table, one can understand that aerated concrete is superior to gas silicate in frost resistance.
Which building material is better?
Those who are going to build own house, the question will arise: so which of these concrete to choose? Let us dwell in more detail on the advantages and disadvantages of each of them, in comparison with each other.
In autoclave gas silicate blocks, practically perfect shape, which greatly facilitates their transportation, storage and laying out. They are also used for the construction of external and internal walls, as well as various partitions... In addition, gas silicate is also better because its pores are open and allow the surface built from it to "breathe". The disadvantage of this material is its hygroscopicity, that is, the ability to accumulate and absorb moisture from the surrounding air.
That is, if blocks made from it are not protected in a special way, when they are in conditions of high humidity, they will accumulate moisture in themselves. If this happens with a sharp drop in temperature, then the wall, built of gas silicate, will freeze very quickly, and in the future it will crack and collapse. Thus, aerated concrete is good when the humidity level is high, since its water absorption capacity is 5-10% lower than that of gas silicate.
The advantage of aerated concrete blocks is that they fit on a special adhesive composition, thanks to which it is possible to do without "cold bridges", since the seams are only 1-4 mm.
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Choosing one or another material for the construction of walls, in no way can it be unequivocally said that some of them are better, and some are worse. Aerated concrete, such as aerated concrete and gas silicate, are no exception. Each of these materials has its own advantages and disadvantages, which to one degree or another can significantly affect the choice between them.
So, in order to answer the question - "Which is better?", You need to understand what each of the materials consists of, and then carefully study all the main comparative characteristics both aerated concrete and gas silicate in general, which we will now do.
To begin with, it is necessary to clarify that none of these materials are practically used in construction as monolithic concrete... As a rule, ready-made blocks of different sizes are made from them, from which walls for various purposes are constructed.
Concrete structure and appearance - first comparisons
As already mentioned, aerated concrete and gas silicate belong to the class of cellular concrete. This means that their structure is very similar, both external and internal. In most cases, because of this, they are often confused, and sometimes it is believed that this is the same thing, but this is far from the case, the gas silicate block has slightly different technical characteristics from the aerated concrete one.
Despite this similarity, external differences between aerated concrete and gas silicate, there is, first of all, color. The first is characterized by a whiter color, and aerated concrete has a dark gray tint.
Another important difference is their production. In aerated concrete, as in most block materials, the main connecting link is cement, which gives it a gray tint, and in gas silicate it is lime.
Unlike aerated concrete, the production of gas silicate without hardening in autoclaves is not permissible. Production of aerated concrete, in turn, allows the natural hardening of the material in the fresh air.
The structure of aerated concrete and gas silicate, as already mentioned, is very similar and consists of many cells with air, thanks to which the walls retain heat very well.
Attention! The brand strength of concrete directly depends on the number and size of air pores. The smaller the pores, the higher the strength, but the heat-insulating properties, in this case, are significantly reduced.
So we examined the external similarities and differences of concrete, now let's start comparing the characteristics of both materials.
Comparative table of aerated concrete and gas silicate
First, let's look at the table of characteristics of both concretes, and then we will analyze all the parameters in more detail.
Since aerated concrete, as well as gas silicate, have many different grades in terms of strength and density, we will compare the average values \u200b\u200bof the characteristics of these materials not in numbers, but using the "better - worse" method:
| Characteristics | Aerated concrete | Gas silicate |
| Grade density (kg / m 3) | 350 - 700 | 350 - 700 |
| Strength (kg / cm 2) | less | more |
| Specific gravity | more | less |
| Distribution of voids | more uniform | |
| Thermal insulation properties | worse | it's better |
| Frost resistance | it's better | worse |
| Water absorption | less | more |
| Soundproofing | worse | it's better |
| Geometric shape | worse | it's better |
| Color | grey | white |
| Refractoriness | it's better | worse |
| Durability | it's better | worse |
| Material price | less | more |
It is worth noting that all the main disadvantages of gas silicate blocks are very similar to the disadvantages of aerated concrete, so we will not consider them separately.
As can be seen from the table, some characteristics are better for gas silicate, and some for aerated concrete. Let's take a closer look at them:
- Due to a more even distribution of pores (voids), gas silicate has a slightly higher strength compared to aerated concrete.
- The aerated concrete block weighs a little more than its counterpart, which will slightly complicate the laying and give an additional load on the foundation for the house.
- The thermal insulation properties of gas silicate are also slightly better than those of aerated concrete.
- In frost resistance, aerated concrete is significantly superior to its competitor, mainly due to its lower water absorption, since water and frost are the worst friends for any building material.
- Thanks to all the same, more even distribution of cells, thermal insulation properties gas silicate is better.
- The geometry of the gas silicate blocks is more strictly maintained, which will slightly reduce the consumption of masonry glue and plastering material, compared to its competitor.
- The color of gas silicate blocks is more pleasant, and the house built from them looks more aesthetically pleasing (naturally, without external finishing).
- Fire resistance - aerated concrete has slightly better performance.
- Durability is generally a separate topic, because both materials have become widely used relatively recently, and there is no practical evidence of durability. I think that when correct use with the observance of technology, the indicators will be almost the same.
- And finally, financial side question. Blocks of the same volume from gas silicate are more expensive than from aerated concrete. This is due to a more complex manufacturing process.
The laying of walls made of gas silicate blocks is similar to laying aerated concrete on glue, here it is difficult to give preference to anyone, but still because of more correct geometry, working with gas silicate is a little more pleasant. Although in the cost of the masonry itself, as a rule, there is practically no difference.
What building material should you give preference to?
Analyzing all of the above, we can conclude that gas silicate has slightly more advantages over aerated concrete, and this is not surprising. Gas silicate is manufactured using more high-tech equipment and is a more modern building material. But this in no way means that aerated concrete is not suitable for building houses.
Aerated concrete also has its own advantages, such as water absorption, fire resistance and price, which, today, plays an important role in the choice between them.
I hope this article will help you determine which is best for you - aerated concrete or gas silicate, depending on your needs and capabilities. And the choice in favor of this or that building material will be correct and logical.
The optimal solution in the field of low-rise construction is the use of economical gas silicate or aerated concrete blocks. Everyone should make the choice in favor of one or the other on the basis of a thorough study of the material, an analysis of the advantages and disadvantages.
The structure and appearance of concrete
Aerated concrete and gas silicate are aerated concrete, therefore both products are similar in appearance and structure. Both materials consist of a large number of pores filled with air, due to which the walls have high thermal insulation properties. The number of cells determines the grade of the blocks in both cases - the smaller, the stronger the block. However, higher grades in terms of strength lose in thermal insulation.
Gas silicate white, which gives it used lime as a filler. Aerated concrete has a dark gray tint due to the use of cement as a binder.
Features of production
Aerated concrete blocks are made from a mixture of water with cement (50-60%), sand, lime and aluminum powder, which works as a blowing agent. The blocks are hardened in a natural or forced way. The second method increases the strength, reliability, and thermal insulation of the finished product.
Gas silicate blocks are prepared from 62% sand, 24% lime with an admixture of aluminum powder during autoclave hardening.
General characteristics
The distribution of pores in gas silicate is more uniform than in aerated concrete, therefore its strength and thermal insulation properties are somewhat higher. The mass of the aerated concrete block is greater, so its laying is more difficult and requires a more powerful foundation. Autoclaved concrete has precise geometry, therefore it is considered more economical by reducing the consumption of adhesive for masonry and finishing materials... Gas silicate masonry makes the walls smoother, easier and faster to erect.
The thermal insulation of gas silicate is superior. In frost resistance, it is inferior to aerated concrete, since the latter has a lower degree of water absorption. Due to the fact that it allows water to pass through without absorbing it, a favorable microclimate is created in the house. Gas silicate, on the other hand, is able to absorb moisture, from which it gradually begins to deteriorate.
The white color of gas silicate blocks looks aesthetically pleasing, so the walls do not need additional decorative finishing... The fire resistance of aerated concrete is higher, although in terms of sound insulation it is inferior to gas silicate. The durability of both materials is difficult to assess, since they have been used relatively recently. One volume of gas silicate blocks when buying will cost more than aerated concrete, due to a more complex manufacturing technology. Although the cost of the masonry itself from both materials is almost the same.
Comparison of materials
To compare in detail both building material, you should familiarize yourself with the main advantages and disadvantages of one over the other.
Advantages of gas silicate over aerated concrete
An important advantage of gas silicate is the absence of "shrinkage". The raw material composition of the blocks determines their properties, which are the main parameters for comparison. The uniformity of the distribution of the formed air bubbles depends on the interaction of the components of the raw material. In this, aerated concrete products are inferior to gas silicate blocks. Due to this uniformity, the strength of the autoclave block increases, so the walls made of it practically do not shrink and do not crack. This quality determines the possibility of using gas silicates in the creation of load-bearing partitions, the construction of high-rise buildings. Moreover, the density of the material is 600 kg / m3 and higher. A two- or three-story house can be built from aerated concrete only if its density is 800-900 kg / m3.
A more homogeneous structure of a gas silicate product increases its noise insulation properties, therefore, when building buildings with good noise protection, this material should be chosen. Thanks to autoclaving, the gas silicate blocks have a smoother and smoother surface with a pleasant white color. It is possible not to decorate the wall material, which will save on finishing. Gas silicate slightly surpasses the second product in terms of heat and sound insulation characteristics. It also saves on consumables.