© 2014-2015 site
When choosing this or that material for the construction of walls, it is in no way possible to say unequivocally that some of them are better and some are worse. Cellular concretes, 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 influence the choice between them.
So, in order to answer the question - “Which is better?”, you need to understand what each material consists of, and then carefully study all the main comparative characteristics both aerated concrete and gas silicate in general, which is what we will do now.
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 are made from them different sizes, from which walls are constructed for various purposes.
Structure and appearance of concrete - first comparisons
As already mentioned, aerated concrete and gas silicate belong to the class 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 they are considered to be the same thing, but this is far from the case; an aerated silicate block has slightly different technical characteristics from aerated concrete.
Despite such similarities, there are still external differences between aerated concrete and gas silicate, primarily 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 link is cement, which gives it a gray tint, and in aerated silicate it is lime.
Unlike aerated concrete, the production of aerated silicate without curing in autoclaves is not permissible. The 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 grade strength of concrete directly depends on the number and size of air pores. The fewer pores, the higher the strength, but the thermal insulation properties, in this case, are significantly reduced.
So we have looked at 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 take a closer look at all the parameters.
Since aerated concrete, as well as gas silicate, have many different grades in terms of strength and density, we will compare the average values of the characteristics of these materials not in numbers, but using the “better - worse” method:
| Characteristics | Aerated concrete | Gas silicate |
| Brand density (kg/m 3) | 350 - 700 | 350 - 700 |
| Strength (kg/cm2) | less | more |
| Specific gravity | more | less |
| Void distribution | more uniform | |
| Thermal insulation properties | worse | better |
| Frost resistance | better | worse |
| Water absorption | less | more |
| Soundproofing | worse | better |
| Geometric shape | worse | better |
| Color | grey | white |
| Fire resistance | better | worse |
| Durability | better | worse |
| Material price | less | more |
It is worth noting that all the main disadvantages of aerated 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 are better for aerated concrete. Let's look at them in a little more detail:
- Due to a more uniform distribution of pores (voids), aerated silicate has slightly greater strength compared to aerated concrete.
- An aerated concrete block weighs a little more than its counterpart, which will complicate the laying a little and put 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 lower water absorption, since water and frost are the worst friends for any building material.
- Thanks to the same, more uniform distribution of cells, thermal insulation properties gas silicate is better.
- The geometry of gas silicate blocks is more strictly maintained, which will slightly reduce the consumption of masonry adhesive and plaster material compared to its competitor.
- The color of gas silicate blocks is more pleasant, and a house built from them looks more aesthetically pleasing (of course, without external decoration).
- In terms of fire resistance, aerated concrete has slightly better performance.
- Durability is generally a separate topic, because both materials became widely used relatively recently, and there is no practical evidence of durability. I think that when correct use with technology, the indicators will be almost the same.
- And finally, the financial side of the issue. Blocks of the same volume made from aerated silicate are more expensive than those made from aerated concrete. This is due to more complex process manufacturing.
Laying walls from gas silicate blocks is similar to laying aerated concrete with glue; it is difficult to give anyone preference, but still, due to the more correct geometry, working with gas silicate is a little more pleasant. Although, as a rule, there is practically no difference in the cost of the masonry itself.
Which building material should you prefer?
Analyzing all of the above, we can conclude that gas silicate has little more benefits in front of aerated concrete, and this is not surprising. Gas silicate is produced 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 advantages, such as water absorption, fire resistance and price, which today plays a significant role in choosing between them.
I hope that this article will help you determine what is best for you – aerated concrete or gas silicate, depending on your needs and capabilities. And the choice in favor of one or another building material will be correct and logical.
Whether to use gas silicate blocks or aerated concrete in low-rise construction is up to everyone to decide for themselves. However, for this decision to be balanced, it is worth carefully studying both materials and analyzing both their advantages and disadvantages.
Choosing porous concrete for construction is not an easy task
Technology overview
Gas and foam concrete in construction
In recent decades, concrete-based porous materials have been widely used in the construction of private houses. They are produced using similar technologies, and only a few manufacturing nuances distinguish them from each other ().
That is why, before determining which is better - gas silicate or foam concrete - you need to understand the details.
- Foam and gas blocks are produced according to the same scheme. High-quality cement is used as raw material, into which special foaming reagents are introduced.
- During the “ripening” process, the reagents release a significant amount of gas bubbles, which are evenly distributed throughout the thickness of the building block.
Pay attention! Expanded clay concrete stands apart, into which ready-made porous granules from baked clay are introduced - expanded clay.
- Then the nuances that we talked about above begin. The foam block hardens at a temperature of about 15-25 0 C and atmospheric pressure, therefore it is very sensitive to both the composition of the filler and the drying regime.
- There's often a catch here: low price material may indicate problems with hardening, and as a result, low strength of foam concrete. That’s why you shouldn’t save money by purchasing blocks made using “handicraft” technologies.
- Unlike the previous variety, aerated concrete is cured in special autoclaves or drying chambers with significant heating. That is why the material is more expensive, but its strength is much higher.
And although the advantages of aerated block in this case are obvious, both materials are actively used in construction. They have good thermal insulation qualities, relatively low weight and low density. The last factor greatly facilitates installation: if cutting reinforced concrete with diamond wheels is very labor-intensive, then porous modules can be sawed with a special hacksaw with your own hands.
Production and characteristics of silicate blocks
The difference between gas silicate and foam concrete is easy to see if you analyze the manufacturing technology:
- The raw material used is a mixture of cement, sifted sand and lime.
- During the mixing process, pore formers are added to the composition, which are responsible for the formation of microscopic cavities in the thickness of the block.
Pay attention! In some brands of material, the instructions also recommend adding aluminum shavings, which act as an activator of gas-forming additives.
- Curing is almost the same as for sand-lime brick: the workpieces are fed into an autoclave, where under pressure (8 - 12 atmospheres) they are treated with high-temperature water steam.
As a result, the answer to the question of which is better - gas silicate or expanded clay concrete (foam concrete, aerated concrete) becomes almost obvious. Due to this treatment, building silicate blocks acquire absolutely identical properties throughout their entire volume, which has a positive effect on their performance characteristics.
The technology of installation and finishing is practically no different from the method of using other porous concrete. The products are quite easy to cut, have good contact with both the mortar and special glue, and have acceptable adhesion to plasters and other finishing materials.
Pros and cons
To decide which material should be preferred in construction, you first need to analyze the dry numbers, as we did in the table below ().
Aerated concrete or gas silicate - table of comparative characteristics:
If we consider both materials in more detail, we can draw the following conclusions:
- Gas silicate blocks and foam concrete blocks preferably used where load-bearing structures do not experience extreme loads, namely in low-rise construction.
- The thermal insulation properties of both materials are quite good, and some lag of foam and gas blocks in this parameter can be compensated for by additional insulation.
- Big mechanical strength gas silicate walls good where it is necessary to ensure maximum bearing capacity with a minimum thickness of the structure.
- The same applies to the mass of the material: a building made of aerated concrete modules will require a more powerful foundation, which means its price will be higher.
- These materials are also equivalent in terms of frost resistance.. However, in a variable climate with frequent thaws (and this is almost all middle lane Russia) the gas block looks somewhat more advantageous due to lower water absorption.
Pay attention! The relatively high moisture capacity of gas silicate masonry puts forward increased demands on the quality of waterproofing.
- Analyzing the properties of materials, it is also worth noting that both varieties belong to the category of non-combustible. However aerated concrete blocks withstand more high temperature, while the use of products produced using silicate technology is allowed when heated to no higher than 400 0 C.
If we talk about cost, then foam concrete will occupy the most budget niche. At the same time, gas blocks and gas silicate are quite expensive, but provide savings on additional thermal insulation erected structures.
The expanded range of construction raw materials offered by enterprises makes it difficult for customers to make a decision on the choice required material for the construction of a building. Wanting to ensure a long service life, high strength, and environmental friendliness of the building being constructed, developers are actively using aerated concrete, gas silicate, as well as expanded clay concrete and foam composites.
Various building products made from cellular concrete used in the construction of residential and industrial facilities differ in their production method, performance characteristics, appearance and, of course, price.
Not knowing the specifics of construction terminology and characteristics, amateurs mistakenly consider aerated concrete and gas silicate to be synonymous words. When discussing the features of using materials, they are often simply called blocks.
Currently, in the construction of low-rise buildings, blocks made of light cellular types of concrete - aerated concrete and gas silicate are used
Choosing the wrong material to solve the given construction tasks causes a violation construction technology, reduces the quality of work associated with rework, unforeseen financial expenses. Knowing the difference between aerated concrete and gas silicate, you can avoid serious mistakes. Let us consider in detail how aerated concrete differs from gas silicate.
Visual differences
At first glance at products made from cellular composites, it is easy to determine whether it is aerated concrete or gas silicate. Knowing that the aerated silicate block does not contain cement, and aerated concrete is formed with cement, which is the binder base, it becomes clear why there are differences color range:
- the white color of gas silicate blocks is associated with a high content of silicate (lime) and the absence of cement in the composite mass, which hardens using the autoclave method;
- The gray tint of aerated concrete is determined by cement, which is the basis of the massif, which acquires hardness naturally.
Depending on the concentration of cement, which is the basis of the aerated concrete block, and lime, which is part of the gas silicate, the products may have slight differences in color. There is a light gray palette of aerated concrete blocks, as well as gray and white shades of gas silicate products.
The difference between them lies in the quantitative content of raw materials and at what stage it enters the manufacturing process
Array structure
Gas silicate and aerated concrete have another distinctive feature- This is hygroscopicity. The increased hygroscopicity of gas silicate contributes to the saturation of the concrete mass with moisture, which promotes the gradual destruction of concrete under the influence of temperature changes. Aerated concrete has increased resistance to moisture absorption and has a more durable structure of the concrete mass. It is easy to conduct an experiment by immersing each of these materials in water.
Despite the varying degrees of hygroscopicity, the blocks require protection of the cellular surface with plaster. Premises built from cellular concrete provide comfortable temperature regime, microclimate favorable for living.
Features of cellular concrete
The optimal solution in the field low-rise construction is the use of economical gas silicate or aerated concrete blocks. Everyone should make a choice in favor of one or the other based on a thorough study of the material, analysis of the advantages and disadvantages.
Structure and appearance of concrete
Aerated concrete and aerated silicate are classified as cellular concrete, so 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 fewer, the stronger the block. However, higher grades lose strength in thermal insulation.
Gas silicate white, which is given to it by the lime used as a filler. Aerated concrete has a dark gray tint due to the use of cement as a binding component.
Production Features
Aerated concrete blocks are made from a mixture of water with cement (50-60%), sand, lime and aluminum powder, which acts as a blowing agent. Blocks harden naturally or forcibly. 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 aerated silicate is more uniform than in aerated concrete, therefore its strength and thermal insulation properties are somewhat higher. The mass of an 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 due to the reduction in the consumption of masonry adhesive and finishing materials. Gas silicate masonry The walls turn out smoother and are easier and faster to build.
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 contrary, 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 it is inferior in noise insulation to gas silicate. The durability of both materials is difficult to assess, since they began to be used relatively recently. When purchased, one volume of aerated silicate blocks will cost more than aerated concrete, which is due to more sophisticated technology manufacturing. Although the cost of the masonry itself from both materials is almost the same.
Comparison of materials
To compare both in detail building materials, 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 uniform distribution of the formed air bubbles depends on the interaction of the components of the raw material. In this respect, aerated concrete products are inferior to gas silicate blocks. Due to this uniformity, the strength of the autoclave block increases, so walls made from 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 and the construction of high-rise buildings. In this case, 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.
The more uniform structure of the gas silicate product increases its noise insulation properties, therefore, when constructing buildings with good noise protection, this material should be chosen. Thanks to autoclave processing, gas silicate blocks have a more even and smooth surface with a pleasant white color. Wall material You don’t have to decorate it, which will save on finishing costs. In terms of heat and sound insulation characteristics, gas silicate is slightly superior to the second product. This also allows you to save on consumables.
Cellular concrete is an artificial porous material from which building blocks. Thanks to the pores distributed throughout the entire volume of the material, the blocks have low weight with relatively large overall dimensions.
The speed of production of work from cellular concrete blocks, combined with low labor and material costs, ensures the popularity of blocks in the domestic building materials market. According to the production method and design features there are two main types lightweight concrete– foam concrete and aerated concrete.
Foam concrete or aerated concrete
The difference between two cellular concretes that are similar in structure is due to different technologies for their production. The binding composition of cement, sand and water, which is the same for foam concrete and aerated concrete, is saturated with gas in different ways.
Differences in production technologies for foam and aerated concrete
The foam concrete manufacturing method is based on mixing cement mortar with foaming natural or synthetic material:
- sand is loaded into the concrete mixer;
- Portland cement M400 or M500 and water are gradually added;
- the foaming agent and water are mixed in a foam generator until a stable foam is formed;
- after preparing the cement mortar, foam is fed into the concrete mixer and mixing is continued for 3–5 minutes;
- foam concrete is poured into block molds or slab formwork.
After hardening, the foam blocks are removed from the molds, and the slabs are sawn into pieces of specified sizes.
Foam concrete acquires its final strength 4 weeks after production. The blocks are stored in film under a canopy and thus brought to marketable condition.
If the production technology is followed, the density of foam concrete should be the same over the entire surface, the distribution of air cells should be uniform, and the cells themselves should be round and closed in shape.
The quality of foam concrete blocks can be checked visually:
To increase the strength of foam blocks in concrete mixture Fiber fibers are added, which reinforce foam concrete and allow heavy structures to be attached to it. You can check the presence of thin nylon threads in the structure of the material at the fracture of the foam block.
Aerated concrete is produced as a result of a chemical reaction of lime, which is part of the cement mortar, and finely dispersed metallic aluminum.
The production process is fully automated:
- sludge is prepared from sand and water in a ball mill;
- the sludge enters the concrete mixer via a conveyor;
- Cement, gypsum and lime are gradually added to the concrete mixer;
- an aluminum suspension is introduced into the solution and mixed thoroughly;
- from the concrete mixer the solution is poured into a mold where chemical reaction at a temperature of 40 0 with the release of hydrogen;
- after the mixture has hardened (after 3–4 hours), the aerated concrete is cut into blocks using stretched strings;
- autoclave processing of aerated concrete blocks lasts 12 hours at a temperature of 180 0 under pressure up to 14 atm.
As a result, aerated concrete acquires a porous structure with a uniform distribution of open cells of various diameters.
High-quality gas silicate blocks made using the autoclave method always:
- white due to the presence of lime in the original composition;
- have accurate overall dimensions thanks to cutting with thin strings;
- They have hand grips and tongue-and-groove end grooves for precise joining with each other.
Comparative characteristics of foam concrete and gas silicate blocks
| Performance characteristics | Building blocks | |
| foam concrete | aerated concrete | |
| Working density, kg/m 3 | 400–1000 | 350–600 |
| Ultimate compressive strength, mPa | 2,0–7,5 | 2,5–15 |
| Durability, years | 30 | 70 |
| Water absorption,% by weight | 10–16 | 20–25 |
| Thermal conductivity (structural blocks), W/m 0 C | 0,12–0,32 | 0,09–0,14 |
| Vapor permeability resistance coefficient, m 2 *h*Pa/mg | 15 | 10 |
| Sound absorption, dB | 50 | 66,7 |
| Frost resistance, cycle | 25 | 50 |
| Environmental friendliness, coefficient | 2 | 4 |
| Error in overall dimensions, mm | 20 | 2 |
| Masonry, material (thickness, mm) | solution (10–15 mm) | glue (1–2 mm) |
| Shrinkage, mm/m per year | 3 | 0,1 |
| Weight of 1 m 2 walls, kg | 70–90 | 200–300 |
| Scope of application | insulation, partitions, enclosing walls in 1- and 2-story buildings | load-bearing and enclosing walls |
Advantages and disadvantages of materials
Cellular concrete blocks, due to their porous structure, have high heat and sound insulation properties, low weight and density with fairly large sizes. Differences between blocks made of foam or aerated concrete, which are due to different composition and production technology determine the pros and cons of these building materials.
Foam concrete blocks have:
- Low thermal conductivity, which allows:
- use foam blocks as an insulating material;
- arrange the wall masonry in one row.
- Moisture resistance, allowing the use of foam concrete without waterproofing.
- Soundproofing properties, allowing the construction of residential buildings near busy highways.
- Light weight with large dimensions, which makes it possible:
- increase the speed of construction;
- reduce labor costs;
- facilitate transportation and storage.
- Fire resistance, not requiring additional processing walls of the building.
- Environmentally friendly, due to the natural composition of the blocks.
- Low cost, reducing material costs when purchasing building materials.
The disadvantages of foam blocks include:
- Fragility of foam concrete, which:
- causes fighting during transportation and laying;
- complicates the fastening of hanging furniture and equipment during operation.
- Inaccurate overall dimensions, forcing the use of cement mortar when laying blocks, which creates “cold bridges” in the walls.
- Shrinkage of material under load, which:
- does not allow the construction of multi-story buildings;
- causes the formation of cracks in masonry;
- requires a strip foundation.
- Unaesthetic appearance, requiring cladding with decorative materials.
Along with the general properties of cellular concrete, gas silicate blocks differ:
- strength, allowing the construction of buildings with increased number of storeys without fear of material shrinkage;
- lower thermal conductivity, which allows you to accumulate heat in the walls and save on heating;
- high vapor permeability, creating a favorable microclimate in the house thanks to the “breathable” structure of the material;
- exact dimensions and shape, which makes it possible to lay blocks on thin layer glue and reduces construction time.
The main disadvantage of aerated concrete blocks is hygroscopicity due to the open cells of the internal structure of the material. The ability of aerated concrete to absorb moisture can create conditions for the formation of mold and fungal microorganisms in the walls of the house. Therefore, enclosing structures must be covered with waterproofing, both outside and inside the building.
What are the benefits of houses made of foam concrete or gas silicate blocks?
Depending on the density of the source material, cellular concrete blocks are produced in various grades from D300 to D1800.
Markings help select blocks for identification
special types of construction work:
- thermal insulation materials grades D300–D500 used as insulation for brick and concrete houses;
- structural and thermal insulation materials D600–D1400 used in the construction internal partitions and external walls of one-story houses;
- construction materials D1400–D1800 used in the construction of load-bearing structures of multi-story buildings.
For the construction of houses in temperate climatic zone The minimum wall thickness should be 350–450 mm. In the northern regions this figure reaches 600-650mm. At the same time, it is recommended to insulate the walls both inside and outside.
Advantages of houses made of cellular concrete:
Facts and Misconceptions
Advertising articles on manufacturers' websites various types cellular concrete confuses potential consumers. In the hope of persuading them to purchase their products, manufacturers of foam and gas silicate blocks are trying to embellish their product and reduce the advantages of their competitor. This is how myths and misconceptions are born.
Misconception #1. It is impossible to build load-bearing structures from foam blocks and gas silicate blocks without strengthening the walls with monolithic columns.
Fact. STO 501-52-01-2007 “Design and construction of enclosing structures made of cellular concrete”:
clause 6.2.7. Load-bearing walls It is recommended to build from autoclaved cellular concrete blocks (aerated concrete blocks) up to 5 floors high inclusive, but not more than 20 m, self-supporting walls of buildings - up to 9 floors high, inclusive, but not more than 30 m.
clause 6.2.8. Blocks made of non-autoclaved cellular concrete (foam blocks) are recommended for use in load-bearing and self-supporting walls buildings with a height of up to 3 floors inclusive, but not higher than 10 m.
Misconception No. 2. Walls made of aerated concrete cannot be plastered so as not to disrupt the vapor permeability of the material.
Fact. When choosing finishing materials, you should take into account their vapor permeability. Each subsequent layer must have a higher vapor permeability coefficient than the previous one, then the wall will remain “breathable”.
Misconception #3. The lime used in the production of aerated concrete is harmful to the health of people living in the house of their aerated silicate blocks.
Fact. Lime reacts with aluminum powder and cement. As a result, hydrosilicates are formed, which, after autoclave treatment, turn into a chemically resistant mineral.
Misconception #4. The use of cement mortar when laying foam blocks leads to the formation of cold bridges.
Fact. Yes, if you use ordinary mortar and foam blocks of dubious production with poor geometry. Industrially produced foam blocks are held together with special glue. Foam blocks that are not even enough can be laid on a heat-saving solution with joints up to 1 cm thick.
Facts and experience of professional builders confirm the true properties of cellular concrete, which occupy an increasingly large segment in the building materials market.
The purchase of building blocks should be carried out in accordance with GOST 21520-89 “Small cellular concrete wall blocks”.
The standard specifies technical requirements, types and sizes of blocks, control methods, storage and transportation conditions.
The choice of foam concrete and gas silicate blocks from major manufacturers ensures material characteristics that comply with GOST standards and the reliability of the building structure.
Use of certified equipment and strict adherence technological process, responsible manufacturers, guarantees the quality and declared performance characteristics of blocks made of cellular concrete.
Regular quality control in large productions confirms the brand of the material and gives the right to complete each batch of goods with certificates of conformity. At such enterprises there is convenient system discounts and free shipping blocks to the construction site.
