Aerated concrete or foam concrete: a comparative review of the material, the pros and cons of products made from it

Aerated concrete and foam concrete are two of the most remarkable materials used in modern construction. When searching for economical and energy-efficient solutions, builders and homeowners frequently choose these lightweight materials. What distinguishes them, though? When preparing for your next building project, knowing the distinctions between foam and aerated concrete will help you make an informed choice.

Autoclaved aerated concrete (AAC), another name for aerated concrete, is renowned for its superior fire and heat resistance. It is made by incorporating a foaming agent into concrete to produce a structure that is porous and full of tiny air pockets. This improves the material’s insulating qualities and makes it lighter, which makes it a great option for environmentally friendly building.

On the other hand, foam concrete is made by combining cement, water, and a foaming agent. Certain characteristics, like being lightweight and having good insulation, are similar to those of aerated concrete. But there can be big differences between the final product’s characteristics and the production process. When creating non-structural elements or filling voids, for example, where load-bearing is not the main concern, foam concrete is usually utilized.

Choosing between aerated concrete and foam concrete depends on various factors, including the specific requirements of your project, budget constraints, and personal preferences. Each material has its own set of advantages and disadvantages, and weighing these can help guide your decision. Whether you"re building a new home, adding an extension, or simply exploring options for future projects, understanding these materials can lead to more successful construction outcomes.

Aspect	Aerated Concrete	Foam Concrete
Material Composition	Made from cement, lime, sand, and aluminum powder. It undergoes autoclaving for curing.	Made from cement, sand, water, and a foaming agent. Cures naturally in molds.
Density	Lightweight, usually ranging from 300 to 800 kg/m³.	Also lightweight, with densities typically between 400 and 1600 kg/m³.
Strength	Offers good compressive strength, making it suitable for load-bearing walls.	Lower compressive strength compared to aerated concrete, better for non-load-bearing walls.
Thermal Insulation	Excellent thermal insulation properties, reduces energy costs.	Good thermal insulation but slightly less effective than aerated concrete.
Sound Insulation	Provides good sound insulation due to its porous structure.	Offers moderate sound insulation, effective in residential settings.
Moisture Resistance	Low moisture resistance, requires additional waterproofing in wet areas.	Moderate moisture resistance, still benefits from waterproofing.
Ease of Handling	Lightweight and easy to cut, making it easy to work with.	Also lightweight, but may require more care during handling due to brittleness.
Environmental Impact	Energy-intensive production due to autoclaving process.	Lower environmental impact as it cures naturally without high energy usage.
Cost	Generally more expensive due to the autoclaving process.	Typically more affordable as it requires simpler production methods.
Durability	Durable with proper maintenance, suitable for long-term use.	Less durable than aerated concrete, may require more maintenance over time.

General concept of materials

Within the cellular concrete class, aerated and foam concrete are distinguished from other wall materials by virtue of their unique porous structure. It has gas or air bubbles in it. Certain production technologies that involve chemical reactions are used to achieve this outcome.

Their essence varies according to the material. The addition of a foaming agent, a unique additive, causes foaming in foam concrete.

Additionally, the reaction of quicklime with a blowing agent is typical for aerated concrete, leading to the expansion of the mortar mass. The classification of both materials is fairly broad, which surely affected their prevalence and application areas.

When comparing aerated concrete and foam concrete, it"s important to understand that both materials are popular choices for construction due to their lightweight nature and insulating properties, yet they differ in composition, manufacturing process, and performance characteristics. Aerated concrete, known for its superior strength and thermal insulation, is often favored for load-bearing walls, while foam concrete, with its simpler production and ease of use, is commonly used for non-structural applications such as insulation layers and void filling. Each material has its pros and cons: aerated concrete provides better durability and structural integrity, but at a higher cost and more complex installation; foam concrete is more affordable and easier to work with but lacks the strength needed for certain applications. Understanding these differences can help builders and homeowners make informed decisions about which material best suits their needs.

Comparison of the main characteristics of materials

Since the primary characteristics of the material determine the building’s future practicality, durability, and even energy efficiency, we will start the comparison with an examination of these characteristics.

Physical, mechanical and technical properties

For clarity of our analysis, let us first consider the table.

Table 1 lists the primary mechanical and technical characteristics of foam and aerated concrete.

Name of the indicator	Aerated concrete	Foam concrete
Thermal conductivity	0.1-0.14	0.14-0.22
Frost resistance, cycles	35-150	35-75
Shrinkage	0.3 mm/m2	0.5 mm/m2
Brand by density	350-700	600-900
Strength, class	At D500-B2.5	At D 750-800 – B2.5
Environmental friendliness, moisture absorption coefficient	2	2

Let’s examine this data now:

• Thermal conductivity of aerated concrete and foam concrete is quite good for both materials, but aerated concrete is still slightly ahead of its competitor. Despite the low indicator, the building will still need insulation, but with some savings.
• In terms of frost resistance, aerated concrete also remains ahead. This is especially true for autoclaved products. Some manufacturers claim its ability to withstand up to 150 freeze-thaw cycles, while foam concrete cannot boast such a high indicator.
• Pay attention to the strength class of the products: the same numerical value is typical for blocks of different densities, that is, for aerated concrete, the strength class will be 2.5 with a density of D500. But for foam concrete it should reach 750-800.
• As you can see, the environmental friendliness of both materials is at its best. They do not emit toxic substances and do not harm the environment and people. For comparison, this coefficient is 1 for wood, and 10 for brick
• Aerated concrete and foam concrete are prone to shrinkage. However, the latter is still slightly inferior.
• Due to the closed pore structure of foam concrete, it absorbs moisture in slightly smaller quantities than aerated concrete. This fact is the most significant drawback of the latter.

Practical and operational advantages

The features of foam concrete and aerated concrete are demonstrated not only in terms of their physical, technical, and mechanical properties, but also in terms of how practical they are in terms of cost, construction time, and other variables. Use the table, please.

Table 2: Practical characteristics of foam concrete and aerated concrete compared.

Utilizing the products is simple. They are simple to cut, grind, and saw. All you’ll need to accomplish this is the right tool, like a hacksaw, for example.

In addition to this, the size of the materials will cause the construction process to proceed much more quickly. In terms of size, one block can be as big as fifteen bricks.

Walls can be built by almost any developer using only his hands.

For instance, a sealed finish from the inside will make the facade’s cladding simpler because the built-up steam within the space won’t be able to escape by soaking through the layer that sits between the blocks and the cladding.

Analysis of the main disadvantages of aerated and foam concrete

Although the materials are fairly similar to one another, variations in raw material composition and production technology are noticeable. These elements aid in the formation of the primary indicators and, consequently, a variety of product strengths and weaknesses.

Let’s first examine the benefits and drawbacks of foam concrete and aerated concrete, which are features shared by both materials:

1. The answer to the question: foam concrete or aerated concrete, which is warmer – has already been given. We found out: both products retain temperature perfectly, and this, of course, is a plus.
2. It should also be noted that the materials have good vapor permeability, due to which the most favorable microclimate will be established in the finished building. The whole point is that they are able to absorb excess moisture from the air and give it off when it is excessively dry.
3. Fire resistance is characteristic of both foam and aerated concrete, they do not burn and do not interact with fire.
4. Both are light in weight and easy to use.
5. The frost resistance, density and strength indicators are quite sufficient for the construction of a building with high performance characteristics.
6. The production process is simple, but requires investment

These are the primary benefits that apply to all materials.

It is important to note foam concrete separately. Its closed pore structure gives it a clear advantage over aerated concrete in that it absorbs significantly less moisture and is therefore less vulnerable to environmental factors.

However, this feature is a weak point for gas block when compared to the material previously mentioned. particularly when the temperature is below zero. Products that have crystallized moisture in them suffer structural damage.

This also applies to foam blocks in general. Why then is this a benefit for one kind of material and a drawback for another? It’s easy! Since we are comparing materials, this is the area where a division like this is most pertinent.

Fragility is another flaw in both products. They are easily broken and do not withstand mechanical impact. They can also be cut rather easily. In this sense, shipping needs to be done with extra caution and adherence to all regulations pertaining to fastening goods.

Kindly take note! Make sure you formally establish your relationship as a customer and contractor before using a carrier’s services. Otherwise, nothing can be salvaged in the event that the material is damaged.

Another point that requires attention is the fastener. Its fixation causes some difficulties. Only specialized hardware intended for these materials is allowed.

Let’s go back to the topic of thermal conductivity. The distribution of pores in foam concrete is unique in that they vary in size, ranging from 1 to 3 mm, and they are not entirely uniform across the surface. Blocks within the same pallet may therefore have marginally different thermal conductivities. The indicators won’t differ significantly, but they can’t be referred to as being the same.

Experts’ opinions on density almost universally indicate that foam block is significantly less effective than its competitor. It is challenging to link this to the drawbacks because the indication is more than adequate for building a house several stories high, but the fact remains that aerated concrete is superior.

Another serious drawback is shrinkage. That is more common with foam blocks. Consequently, the surface of the wall may start to crack.

Classification of materials and their scope of application

Cellular concrete comes in two varieties: foam concrete and aerated concrete, as was previously mentioned. For this reason, they are classified in the same way as per GOST. There is no denying the similarities in this uncommon parameter. Let’s examine them.

Aerated and foam concrete can be the following depending on the curing technique:

• Autoclaved (synthetic) curing. This indicates that products made from these materials have been processed in a special machine – an autoclave under the influence of high temperature and pressure.
• Non-autoclaved (hydration) curing. With this method, products reach technical maturity through natural curing or light heating.

It is noteworthy that the indicators for autoclave material are significantly higher. It is smoother, more aesthetically pleasing, and more resilient.

Based on the numerical values ​​of the brand by density, cellular concrete is divided into:

• Heat-insulating.
• Structural and heat-insulating.
• Structural.

Insulation is the only application for the first choice. The heat-insulating block has an extremely high heat-retention capacity despite having a very low density of up to 400.

The most common and widely used option is the second one, which is structural and heat-insulating. These blocks are used by almost all private developers to construct homes. A multi-story house can be constructed with a density of 500–700.

The most robust products are structural ones. The building can reach a height of 12–15 meters when they are in use. Nonetheless, the thermal conductivity coefficient is fairly high and directly relates to the density indicator. As a result, insulation will become much more expensive during construction.

It’s also important to draw attention to the classification that is based on how accurate the block geometry is:

• Blocks of the 1st accuracy category may have deviations in size not exceeding 1.5 mm. Such products are usually laid on glue with a minimum seam thickness.
• Blocks of the second category are characterized by the possibility of more significant deviations from geometry: up to 2 mm – in size, up to 3 mm – diagonally, chipped corners and edges – up to 2 and 5 mm, respectively.
• Blocks of the 3rd category are more suitable for outbuildings. Their permissible deviations are quite large, which will lead to an increase in the thickness of the seam, and this, in turn, to cold bridges. The numerical values ​​are as follows: in size – up to 3 mm, diagonally – up to 4 mm, chipped edges – up to 10 mm, and corners – up to 2 mm.

Blocks are classified according to the kind of silica component:

• Made on quartz sand;
• Produced using secondary industry products;
• On ash.

Materials are classified based on the type of binder:

At least half of the mass of the primary raw material is present in each type.

It is important to note separately that foam concrete has its own unique qualities in addition to these classifications. It has a direct bearing on the kind of manufactured goods and the technology used in production.

Foam blocks are thus identified as follows:

1. Cut.
2. Molded, made by casting.
3. Reinforced.

The latter are the most cost-effective yet also the most resilient. In addition to wall and partition blocks, specialized units are also produced using aerated concrete and foam concrete. We can use a U-shaped block as an example.

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Description of technological processes

As was already mentioned, there are some technological similarities between the production of foam and aerated concrete. The generation process itself is the primary distinction. To better understand what aerated concrete and foam concrete are, let’s take a step-by-step look at the process of creating products from both materials.

Production of aerated concrete

You will require a stationary or conveyor line for production. Although the second option is more costly, productivity rises dramatically in this instance. There is little to no worker participation in the process, which happens automatically. In essence, only operators are needed.

The following steps are part of the production process:

• The necessary raw materials pass through the component dispenser and move to the aerated concrete mixer. The composition of the aerated concrete block is presented as follows: lime, cement, water, sand, aluminum powder and chemical additives.
• Everything is thoroughly mixed, the finished solution is poured into the mold.
• Then the process of pore formation occurs. The mixture is swelling.
• Then the single layer is turned over and cut into standard sizes.
• The final stage is autoclaving the blocks.

In the instance of non-autoclaved aerated concrete, the task can be completed on its own. But the material quality will be very different, and not in a good way.

The steps are the same: pore formation, stripping, mixing the ingredients and pouring into molds. The hardening process makes a difference. The technical maturity of non-autoclaved aerated concrete develops organically.

The following are some drawbacks of home production:

1. Frequent errors in the proportions of components due to the human factor;
2. Poor geometry;
3. A considerable number of defective products;
4. High labor costs;
5. The process takes a lot of time;
6. It takes a premises for production and storage during a set of strength of products, which lasts about 28 days.

Manufacturing foam concrete

A specific set of tools is also needed to produce foam concrete; these tools can be a mini-kit, a stationary line, or a conveyor, and they are ideal for private developers and entrepreneurs who wish to make their own products.

Included in the standard kit are:

• Foam generator;
• Mixer;
• Molds;
• Compressor;
• Pump for foam concrete.

There are three different technologies: barotechnology, dry mineralization, and classical.

The steps involved in applying the classical method are as follows:

1. Water is mixed with a foaming agent and sent to the foam generator;
2. After this, the foam solution is mixed with cement-sand;
3. The finished mixture is poured into molds;
4. The array is cut, and the blocks are left to reach technical maturity in an autoclave or by hydration hardening.

The components are combined with foam in a dry form, which sets the dry mineralization method apart. The process of mixing the foam mixture under high pressure is what defines barotechnology.

You can only use your hands to create a non-autoclaved block, just like with aerated concrete. The idea remains the same. All of the inquiries that come up throughout the creation of cellular concrete have thorough answers in the video included in this article.

Alternative technology and modified materials

The existence of cellular concrete types like fiber-reinforced foam concrete will be pertinent to discuss in this chapter. It includes a foaming agent, cement-sand mortar, and a tiny amount of synthetic fiber, or fiber.

When deciding between fiber-reinforced foam concrete and aerated concrete, it’s important to keep in mind that the latter does not include lime, doesn’t require the use of blowing agents, and isn’t autoclave treated. Their intolerance for moisture unites them.

It’s also important to keep an eye on a relatively recent innovation that combines the processes used to make foam and aerated concrete. These changes led to the creation of a substance known as aerated foam concrete, which combines the best qualities of the two substances.

There are numerous patents for this technology in use right now. But because it’s new, the technique hasn’t been adopted widely. The prospects are favorable if aerated foam concrete is created with the intention of using it as a heat-insulating material in the future.

In this instance, the products will have the following specifications: The thermal conductivity coefficient will only be 0.066 W (M k) at a density of 260 kg/m3. Yes, the outcome is fantastic. There will be a tensile density of 0.35 MPa and a compressive strength of 0.8 MPa.

To get this effect, two stages of porization are used. Here, the mixture that had previously undergone foam porization experiences gas evolution without any breakthroughs. There is swelling, up to the estimated height.

Features of masonry work

A common technology is used to lay all wall materials associated with the various types of cellular concrete.

Let’s take a quick look at the work order:

1. The first row of blocks is laid on the solution in order to improve the adhesion of the base and the strength of the structure.
2. Laying begins – from the corners, which will serve as beacons. The highest of them is chosen first.
3. A construction thread is pulled between the products laid in the corners. If the length of the wall is more than 4-5 meters, it is allowed and even recommended to install additional landmark blocks.
4. After completing the above steps, the first row is laid out completely.
5. If there is a gap that does not fit the block size, then the products are usually cut with a hacksaw.
6. Between the first and second rows, as well as every time after laying every 4th, reinforcement must be made.
7. The second and subsequent rows are laid mainly on glue, maintaining a small layer thickness to minimize cold bridges.

Counseling! Make sure the seam is offset by roughly 20–25% when you begin laying the second row.

1. Correction of evenness of laying blocks is carried out using a building level and a rubber hammer.
2. The adhesive is usually applied using a trowel.

Take note: You will have no more than 10 to 15 minutes to make any necessary adjustments because the adhesive solution sets fairly quickly. The wall will eventually become unrepairable and impossible to disassemble.

There is no distinction in the materials used for masonry work.

Calculation of mortar composition for masonry work

It is crucial to take into account the distinct qualities of both aerated concrete and foam concrete when making your construction project decision. Both have advantages like lightweight constructions and strong insulation qualities, which make them perfect for a variety of building applications. Nonetheless, being aware of each option’s unique advantages and disadvantages will aid in your decision-making.

Because of its exceptional strength and longevity, aerated concrete is a good choice for load-bearing walls and other structures that need strong support. Because of its high thermal efficiency, it can also contribute to the maintenance of a cozy interior temperature, gradually lowering energy expenses. However, the cost of aerated concrete may increase, and its installation may call for specialized equipment and methods.

On the other hand, because foam concrete is lightweight, it is frequently more affordable and simpler to work with. It is especially helpful for non-load-bearing applications like insulation layers and partition walls. Foam concrete can be less durable and strong than aerated concrete, which could make it less useful for some structural applications.

The decision between foam and aerated concrete should ultimately be based on the structural requirements, budget, and needs of your particular project. Both materials have shown their worth in contemporary building, but the best option will rely on the particular requirements of your project as well as your long-term objectives for efficiency and durability.

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