Thermal conductivity of foam concrete: what is this characteristic responsible for?

Because it’s lightweight and insulating, foam concrete is a versatile building material that’s becoming more and more popular. The thermal conductivity of foam concrete is a crucial factor in its effectiveness as a building material. However, what is thermal conductivity exactly, and why does foam concrete need to consider it?

The term "thermal conductivity" describes a material’s capacity to transfer heat. Put more simply, it’s a measurement of a material’s capacity to transfer heat. This property is important for building materials like foam concrete because it influences how well a structure can maintain heat or coolness, which has an effect on building comfort and energy efficiency.

Foam concrete transfers heat slowly due to its low thermal conductivity. Because of this, it functions as a great insulator, keeping houses cool in the summer and warm in the winter. Foam concrete construction can therefore result in more energy-efficient buildings, which can reduce heating and cooling expenses.

Homeowners, builders, and architects must all be aware of foam concrete’s thermal conductivity. It aids in the selection of appropriate building materials for various climates and requirements, guaranteeing that structures are not only sturdy but also energy-efficient and cozy throughout the year.

What is foam concrete

Since foam concrete’s coefficient of thermal conductivity is closely related to many other characteristics, let’s first take a quick look at the material and learn about its primary attributes.

One porous material that resembles cellular concrete is foam concrete. It is made up of a blend of cement, water, sand, and a foaming agent that makes the solution swell and leads to the creation of cells.

The primary set of properties, which we shall now examine, is primarily determined by the porous structure.

For foam concrete that hasn’t been autoclaved, the lowest value is B0.5, and the highest value is B12.5.

The material meant for external structure construction must have a minimum value of at least 25 cycles, as per the specifications outlined in the technical documentation.

However, the grade is not established at all for products such as partitions and thermal insulation.

It’s also important to note that foam concrete falls under a broad category. The type of siliceous component, the type of binder, the hardening process, and the density index are the factors that determine the type of material.

As will become clear, foam concrete is produced not just in liquid form but also in a variety of products with distinct properties and potential uses. These include lintels, slabs, panels, blocks, and much more.

What is thermal conductivity, and what are its values for foam concrete

Let’s get right to the core of our article now. What effects does the thermal conductivity of foam concrete blocks and foam concrete in general have?

The concept of thermal conductivity, its dependence on other characteristics

A material’s capacity to hold its temperature is known as its thermal conductivity. That is, a structure made of a particular structural material has the ability to heat up and cool down quickly or slowly. The heat retention indicator directly impacts this.

For products in a dry state, the characteristic values of foam concrete range from 0.08 to 0.37 W * mC, making it a highly competitive product. The value will marginally increase under operating conditions, but this is true for all materials, not just foam concrete.

As was previously mentioned, a material’s density affects its capacity to hold heat. Let’s investigate more closely.

• The thermal conductivity coefficient of foam concrete blocks intended for thermal insulation is about 0.08-0.10 W * mC. Such products are called thermal insulation. Their density grade is D300, D400.

• If we talk about structural and thermal insulation foam concrete, its thermal conductivity is slightly higher, and is about 0.11-0.18 W * mC, and the density grade varies from D500 to D900.

• If you use structural foam concrete blocks, the thermal conductivity of which will be up to 0.35 W * mC, know that in contrast to the weak ability to retain heat, such products are characterized by increased strength values. And their density reaches 1200 kg/m3.

Along with thermal conductivity, products’ resistance to frost and, generally speaking, their durability both rise with density.

Comparative analysis of thermal conductivity of foam concrete and other materials

It’s now time to contrast the thermal conductivity of foam concrete products with that of other widely used building materials.

Thermoconductive properties of foam concrete blocks: a comparison of their values with those of other materials

As you can see, any material is affected by the direct relationship between density and thermal conductivity, not just foam concrete. The product’s heat-retention capacity will be noticeably lower even if it passes the density indicator.

Polystyrene concrete is unquestionably the best in this regard, but its structural potential is severely constrained by its relatively low strength indicators.

One important factor that influences how well foam concrete insulates buildings by limiting heat flow is its thermal conductivity. This characteristic is crucial for preserving energy efficiency because it lessens the need for artificial heating and cooling by keeping interior spaces cool in the summer and warm in the winter. In order to design more affordable, comfortable, and sustainable buildings, architects and builders must have a thorough understanding of foam concrete’s thermal conductivity.

Methods for increasing heat retention capacity, calculating the minimum wall thickness

It is possible to affect the two indicators listed above. When it comes to products specifically, their density and thermal conductivity are determined during the production process, which we will go over in more detail below. First, though, let’s attempt to determine the minimum thickness required for a foam concrete wall to retain its high heat retention properties.

We calculate the thickness of a wall made of foam blocks taking into account the region

In order to determine the ideal wall thickness, it is necessary to ascertain the heat transfer resistance index. It is unique for every single region and is described in SNiP. We will rely on the average value of 3.4.

• Let"s assume that we will use a block with a density of D500 with a thermal conductivity coefficient of 0.17 W * mC for masonry.
• 3.4 * 0.17 = 0.578 m. This is how many meters the wall thickness should be.
• Since insulation is usually done, it is necessary to subtract the value of its thermal conductivity of the material used for it, and multiply the values ​​again.
• Let"s assume that the thermal conductivity of the insulation is 0.02 W * mC.
• 0.17 – 0.02 = 0.15. 0.15 * 0.34 = 0.51 m. This means that when planning insulation, the thickness of the walls may not exceed 50 cm. If the insulation is made more intensive, then the value can be reduced to laying one block, 400 mm wide.

Methods for changing the thermal conductivity coefficient of the future material at the stage of the production cycle

At the production stage, all future material indicators are determined.

• The first stage will be the preparation of the recipe, or, more precisely, the selection of the composition. At the beginning of production, the nominal composition is determined, which is preceded by the preparation of a special task, which contains all the requirements for future indicators.
• After development, the mixture is mixed and a kind of test is carried out, upon completion of which, in case of a positive result, the composition is transferred to production. If the results do not correspond to the planned ones, then an adjustment is made.
• All these actions are carried out, of course, during the manufacture of the material in factory conditions.
• When producing products with your own hands, all proportions of raw materials are measured manually, guided only by recommendations, since there is no exact recipe for making foam concrete mixture.
• That is why with independent production it is not always possible to obtain the necessary indicators of thermal conductivity and density.

Kindly take note! The cost of building can be greatly decreased by creating foam concrete at home, and block prices will undoubtedly go down. The only drawbacks are high labor and time expenses and a high likelihood of products not meeting GOST regulations.

What precisely affects the way the indicators change?

1. Type of silica component;
2. Ratio of cement in the composition: the more of it, the higher the density and thermal conductivity coefficient;
3. Specialized additives;
4. Method of material hardening. With the autoclave method, as a rule, blocks are obtained with a much better combination of the indicators we are discussing, but it is not available for home production.

This article’s video will walk readers through the primary techniques for making foam concrete.

Options for insulating structures erected from foam concrete

However, it is possible to insulate a wall to improve its capacity to retain heat. There are many options available, and we will quickly go over the most widely used insulating materials by developers.

The most popular materials used to insulate foam concrete walls are:

• Environmental friendliness of products;
• Low weight;
• Easy to use, no need to involve specialists;
• Vapor permeability;
• Durability;
• Acceptable cost of products;
• Resistance to biological impact.

• Hygroscopicity;
• Fire hazard;
• Tendency to deformation.

Has a lot of benefits and drawbacks as well.

Important benefits include low cost, quick installation, light weight, and moisture resistance.

High performance qualities, resistance to moisture, and non-flammability are the benefits.

Briefly about well masonry

I want to talk about the well masonry method of insulation for buildings separately. It is only utilized when facing a brick building.

• In this case, brickwork is carried out in parallel with the main one, and the gap is filled with loose insulation.
• Expanded clay is most often used, but other materials can also be used, such as: polystyrene granules, penoizol, vermiculite, sawdust, crushed stone, slag and others.
• Those materials that are not subject to biological influence are used as dry backfill. But, for example, sawdust or other organic materials are used together with binders in the form of lightweight concrete with filler.

As a result, the wall’s capacity for thermal insulation rises noticeably. The fact that the work process is labor-intensive and skill-specific is one of its drawbacks.

Thermal Conductivity	Explanation
Definition	Thermal conductivity measures how well a material conducts heat.
Importance	Low thermal conductivity in foam concrete means better insulation and energy efficiency.
Factors	The density and composition of foam concrete affect its thermal conductivity.
Applications	Used in buildings to reduce heating and cooling costs.

Both homeowners and builders must be aware of foam concrete’s thermal conductivity. This quality has a big impact on how well the material insulates buildings, which lowers energy expenses and helps to maintain interior temperatures. Because foam concrete has a low thermal conductivity, it effectively slows down heat transfer, which makes it a great material for energy-efficient building.

The enhanced comfort that foam concrete offers is an additional advantage of its thermal properties. It keeps the heat inside during the winter, making the interior feel warmer. On the other hand, it keeps the heat out in the summer and keeps the interior cooler. This year-round natural temperature regulation makes living or working spaces more comfortable.

Using foam concrete can also result in substantial long-term savings. Reduced need for a lot of heating and cooling means cheaper utility bills for homeowners. Because of this, choosing foam concrete is not only wise for the environment but also economical. Its insulating qualities aid in safeguarding the building’s structure, possibly increasing its lifespan and lowering maintenance expenses.

In conclusion, one of the main qualities that makes foam concrete more appealing in contemporary construction is its heat conductivity. Its cost-effectiveness, enhanced indoor comfort, and effective insulation make it an important component of sustainable and economical building techniques. The thermal advantages of foam concrete make it an exceptional option for upcoming building projects, especially as the need for energy-efficient solutions increases.

Video on the topic

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