Foam concrete in construction

The versatility of using foam concrete as a building material makes it increasingly widespread and popular. Cost-effectiveness, environmental friendliness, safety, the possibility of using it for thermal insulation, noise absorption and as the main material for the construction of building walls are strong arguments for the spread of foam concrete in different countries.

Foam concrete, having a porous structure, due to the inclusion of air bubbles in the composition, has important properties - low weight, low thermal conductivity and excellent sound-absorbing characteristics.

The main components included in foam concrete are: cement, sand, water, polypropylene fiber and a foaming agent, which provides the finished solution with the appropriate consistency.

Changing the ratio of the proportions of the components included in the composition allows you to change the physical properties of the finished solution, from more loose (airy), and, accordingly, light and warm, to a composition of a more dense consistency with an expected higher weight and higher thermal conductivity.

As mentioned above, foam concrete can be made in various designs according to its composition and grade, and depending on its intended purpose, it can belong to one of four groups - heat-insulating, structural-thermal-insulating, structural and structural-porous.

Thermal insulating foam concrete

The main advantages of foam concrete in this group include low density and low thermal conductivity.

This group includes foam concrete grades D150 (150 kg/m3) to D400 (400 kg/m3). Brands for insulation and sound absorption (up to D400) have their own purpose and are not standardized by strength class. Of the entire group, only D400 has a strength class ranging from B0.5 to B0.75, which is equal to 9 kg/cm3.

When high thermal insulation properties are required, grades no higher than D400, with a thickness of at least 300 mm, are considered. For cold regions, these parameters may be insufficient, which will require increasing the thickness of the walls, but this issue is entirely within the competence of the designer and HVAC (heating, ventilation and air conditioning) specialist.

*The frost resistance of the listed brands is not subject to standardization.

Porosity indicators

Structural thermal insulation foam concrete

The main advantages of foam concrete in this group include versatility, since the material, due to its low thermal conductivity and low weight, can simultaneously perform the function of load-bearing and thermal insulation. Foam concrete grades of this group can be used for the construction of low-rise buildings.

For clarity, we present a comparative table of the thermal conductivity of foam concrete and other building materials (below):

This group includes foam concrete grades D500 (500 kg/m3) to D900 (900 kg/m3). The strength of grade D500 is 13 kg/cm2. Its class is not standardized, nor is its frost resistance. Strength classes for other brands in the table below:

As can be seen in the table (above), the strength of foam concrete increases with increasing density/grade = specific gravity of foam concrete.

Thus, an increase in the specific gravity of foam concrete leads to an increase in its strength but a decrease in thermal insulation properties (increased thermal conductivity) and, if the strength is not excessive, then the situation with thermal conductivity is not entirely clear.

The higher the thermal conductivity coefficient, the faster the material transmits heat and this means that it resists the cold worse - the house cools down faster, and the heat is retained worse.

It can be stated that density is the main quantitative characteristic of the structure of cellular concrete. As a consequence, it determines the meaning of all its technical properties. The tables given below very eloquently demonstrate the existence of a connection between such characteristics as porosity, strength, thermal conductivity and density of foam concrete.

Porosity indicators

Structural foam concrete

The main advantages of foam concrete in this group include low weight with high strength values. Foam concrete grades of this group are used if more attention needs to be paid to strength during the construction of multi-story buildings.

The group includes foam concrete grades D1000 (1000 kg/m3) to D1200 (1200 kg/m3) and correspond to strength B5 - B12.5 (minimum strength indicator - 50 kg/cm3, maximum - 64 and 90 kg/cm3).

Porosity indicators

Structural porous foam concrete

Structurally porous. All brands up to D1600. The variety is produced in small batches, since it is used in practice quite rarely. Therefore, the characteristics of this variety are not described by current GOSTs.

The advantage of foam concrete

Foam concrete, in its thermal insulation, is many times superior to brick and, as a result, allows the construction of thinner walls without loss of heat. Also, an important criterion is that the relatively small weight of a cubic meter can significantly reduce the total weight of the structure of walls, partitions and ceilings and thereby reduce the load on the foundation, and this in turn will reduce the cost of its construction.

Usage areas of foam concrete

• production of building blocks for the construction of walls and partitions;
• monolithic housing construction
• insulation and thermal insulation of walls, slabs, floors, ceilings;
• filler of voids in hard-to-reach places, trench cavities;
• thermal insulation of pipelines;
• pouring floors and exposed roofs;

In terms of its manufacturability, foam concrete is superior to many structural materials due to ease of processing (milling, drilling, sawing) and in many respects it is close to wood, while being more durable and resistant to fire.

Classification of foam concrete by density

This characteristic is influenced by the volumetric concentration of the filler and the degree of porosity.

Porosity directly depends on the amount of foaming agent in the mixture. For example, to obtain concrete grade D400, you need to add 0.85 kg of foaming agent per 1 cubic meter of solution, while for D1200 only 0.45 kg is required.

Relationship between various characteristics

The size of the pores (cells) is determined by the specific gravity of the concrete. In turn, all the main parameters of cellular concrete depend on their volume, volume distribution and nature. Porosity is inversely proportional to the value of this quantity.

Thermal conductivity is one of the most important characteristics of foam concrete and reflects its ability to transmit thermal energy. Its value is determined directly by the density value. The combination of these parameters is the main factor on which the strength and warmth in the house depends.