Heat capacity of a brick in comparison with other materials. Is modern fireclay brick harmful? Definition and formula of heat capacity

In construction, a very important characteristic is. The thermal insulation characteristics of the walls of the building depend on it, and, accordingly, the possibility of a comfortable stay inside the building. Before proceeding to get acquainted with the thermal insulation characteristics of individual building materials, it is necessary to understand what heat capacity is and how it is determined.

Heat capacity of building materials

Specific heat capacity of materials

Heat capacity is a physical quantity that describes the ability of a material to accumulate temperature from a heated environment. Quantitatively, the specific heat capacity is equal to the amount of energy, measured in J, required to heat a body of mass 1 kg by 1 degree.
Below is a table of the specific heat capacity of the most common building materials.

type and volume of heated material (V);
an indicator of the specific heat capacity of this material (Court);
specific gravity (msp);
initial and final temperatures of the material.

Heat capacity of building materials

The heat capacity of materials, the table of which is given above, depends on the density and thermal conductivity of the material.

And the coefficient of thermal conductivity, in turn, depends on the size and closure of the pores. A finely porous material with a closed system of pores has greater thermal insulation and, accordingly, lower thermal conductivity than a coarsely porous one.

This is very easy to follow on the example of the most common materials in construction. The figure below shows how the coefficient of thermal conductivity and the thickness of the material affect the heat-shielding qualities of external fences.

The figure shows that building materials with a lower density have a lower coefficient of thermal conductivity.
However, this is not always the case. For example, there are fibrous types of thermal insulation for which the opposite pattern applies: the lower the density of the material, the higher the thermal conductivity.

Therefore, one cannot rely solely on the indicator of the relative density of the material, but it is worth considering its other characteristics.

Comparative characteristics of the heat capacity of the main building materials

In order to compare the heat capacity of the most popular building materials, such as wood, brick and concrete, it is necessary to calculate the heat capacity for each of them.

First of all, you need to determine the specific gravity of wood, brick and concrete. It is known that 1 m3 of wood weighs 500 kg, brick - 1700 kg, and concrete - 2300 kg.
If we take a wall with a thickness of 35 cm, then by simple calculations we get that the specific gravity of 1 square meter of wood will be 175 kg, brick - 595 kg, and concrete - 805 kg.
Next, we select the temperature value at which the accumulation of thermal energy in the walls will occur. For example, this will happen on a hot summer day with an air temperature of 270C. For the selected conditions, we calculate the heat capacity of the selected materials:

Wood wall: C=SudhmudhΔT; Cder \u003d 2.3x175x27 \u003d 10867.5 (kJ);
Concrete wall: C=SudhmudhΔT; Cbet \u003d 0.84x805x27 \u003d 18257.4 (kJ);
Brick wall: C=SudhmudhΔT; Skirp \u003d 0.88x595x27 \u003d 14137.2 (kJ).

From the calculations made, it can be seen that with the same wall thickness, concrete has the highest heat capacity, and wood has the lowest. What does it say? This suggests that on a hot summer day, the maximum amount of heat will accumulate in a house made of concrete, and the least - from wood.

This explains the fact that in wooden house cool in hot weather and warm in cold weather. Brick and concrete easily accumulate a sufficiently large amount of heat from the environment, but just as easily part with it.

Heat capacity and thermal conductivity of materials

Thermal conductivity is a physical quantity of materials that describes the ability of temperature to penetrate from one wall surface to another.

To create comfortable conditions in the room, it is necessary that the walls have a high heat capacity and a low coefficient of thermal conductivity. In this case, the walls of the house will be able to accumulate the thermal energy of the environment, but at the same time prevent the penetration of thermal radiation into the room.

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TYPES OF BRICK

In order to answer the question: "how to build warm house brick? ”, You need to find out which one is best to use its type. Because modern market offers huge selection this building material. Consider the most common types.

SILICATE

Silicate bricks are the most popular and widespread in construction in Russia. This type is made by mixing lime and sand. This material has received high prevalence due to its wide scope in everyday life, and also due to the fact that the price for it is rather low.

However, if we turn to the physical quantities of this product, then everything is not so smooth.

Consider a double silicate brick M 150. The M 150 brand speaks of high strength, so that it even approaches natural stone. Dimensions are 250x120x138 mm.

The thermal conductivity of this type is on average 0.7 W / (m ° C). This is a fairly low figure compared to other materials. So warm walls from a brick of this type most likely will not work.

An important advantage of such bricks in comparison with ceramic ones are soundproofing properties, which have a very favorable effect on the construction of walls enclosing an apartment or dividing rooms.

CERAMIC

The second place in popularity of building bricks is reasonably given to ceramic ones. For their production, various mixtures of clays are fired.

This view is divided into two types:

Building,
Facing.

Building bricks are used for the construction of foundations, walls of houses, stoves, etc., and facing bricks for finishing buildings and premises. Such material is more suitable for do-it-yourself construction, as it is much lighter than silicate.

The thermal conductivity of the ceramic block is determined by the coefficient of thermal conductivity and is numerically equal to:

Full-bodied - 0.6 W / m * ° C;
Hollow brick - 0.5 W / m * ° C;
Slotted - 0.38 W / m * ° C.

The average heat capacity of a brick is about 0.92 kJ.

WARM CERAMICS

Warm brick is a relatively new building material. In principle, it is an improvement on the conventional ceramic block.

This type of product is much larger than usual, its dimensions can be 14 times larger than standard ones. But this does not have a very strong effect on the total mass of the structure.

Thermal insulation properties are almost 2 times better compared to ceramic bricks. The thermal conductivity coefficient is approximately equal to 0.15 W / m * ° C.

The block of warm ceramics has many small voids in the form of vertical channels. And as mentioned above, the more air in the material, the higher the thermal insulation properties of this building material. Heat losses can occur mainly on internal partitions or in masonry joints.

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How is specific heat capacity determined?

The specific heat capacity is determined in the course of laboratory studies. This indicator completely depends on what temperature the material has. The heat capacity parameter is necessary so that in the end it can be understood how heat resistant the external walls of a heated building will be. After all, the walls of structures must be built from materials whose specific heat capacity tends to a maximum.

In addition, this indicator is necessary for accurate calculations in the process of heating various kinds of solutions, as well as in a situation where work is carried out at sub-zero temperatures.

It is impossible not to say about full-bodied bricks. It is this material that boasts a high thermal conductivity. Therefore, in order to save money, a hollow brick is most welcome.

Types and nuances of brick blocks

In order to eventually build a fairly warm brick building, you first need to understand what kind of this material is most suitable for this. Currently, a huge assortment of bricks is presented in the markets and in building stores. So which one should be preferred?

On the territory of our country, silicate brick is very popular with buyers. This material is obtained by mixing lime with sand.

The demand for silicate brick is due to the fact that it is often used in everyday life and has a fairly reasonable price. If we touch on the issue of physical quantities, then this material, of course, is in many respects inferior to its counterparts. Due to the low thermal conductivity, it is unlikely that it will be possible to build a truly warm house from silicate bricks.

But, of course, like any material, silicate brick has its advantages. For example, it has a high rate of sound insulation. It is for this reason that it is very often used for the construction of partitions and walls in city apartments.

The second place of honor in the ranking of demand is occupied by ceramic brick. It is obtained from mixing various kinds clay, which is then fired. This material is used for the direct construction of buildings and their cladding. The building type is used for the construction of buildings, and the facing type is used for their decoration. It is worth mentioning that ceramic-based brick is very small in weight, so it is an ideal material for self-implementation of construction work.

A novelty of the construction market is a warm brick. This is nothing but an advanced ceramic block. This type in size can exceed the standard by about fourteen times. But this in no way affects the total mass of the building.

If we compare this material with ceramic bricks, then the first option in terms of thermal insulation is twice as good. The warm block has a large number of small voids that look like channels located in a vertical plane.

And as you know, the more air space present in the material, the higher the thermal conductivity. Heat loss in this situation occurs in most cases on the partitions inside or in the seams of the masonry.

Thermal conductivity of bricks and foam blocks: features

This calculation is necessary in order to be able to reflect the properties of the material, which are expressed in relation to the density index of the material to its property to conduct heat.

Thermal uniformity is an indicator that is equal to the inverse ratio of the heat flux passing through the wall structure to the amount of heat passing through the conditional barrier and equal to total area walls.

In fact, both the one and the other version of the calculation is a rather complicated process. It is for this reason that if you do not have experience in this matter, it is best to seek help from a specialist who can accurately make all the calculations.

So, summing up, we can say that physical quantities are very important when choosing a building material. How could you see different types bricks, depending on their properties, have a number of advantages and disadvantages. For example, if you really want to build warm building, then you'd better choose warm look brick, in which the thermal insulation index is at the maximum level. If you are limited in money, then the best option for you will be the purchase of silicate brick, which, although minimally retains heat, but perfectly saves the room from extraneous sounds.

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Definition and formula of heat capacity

Each substance, to one degree or another, is capable of absorbing, storing and retaining thermal energy. To describe this process, the concept of heat capacity is introduced, which is the property of a material to absorb thermal energy when the surrounding air is heated.

To heat any material with mass m from temperature t initial to temperature t final, it will be necessary to spend a certain amount of thermal energy Q, which will be proportional to the mass and temperature difference ΔT (t final -t initial). Therefore, the heat capacity formula will look like this: Q \u003d c * m * ΔT, where c is the heat capacity coefficient (specific value). It can be calculated by the formula: c \u003d Q / (m * ΔT) (kcal / (kg * ° C)).

Conditionally assuming that the mass of the substance is 1 kg, and ΔТ = 1°C, we can obtain that c = Q (kcal). This means that the specific heat capacity is equal to the amount of thermal energy that is spent on heating a 1 kg material by 1°C.

The use of heat capacity in practice

Building materials with high heat capacity are used for the construction of heat-resistant structures. This is very important for private houses in which people live permanently. The fact is that such structures allow you to store (accumulate) heat, so that a comfortable temperature is maintained in the house for quite a long time. First, the heater heats the air and the walls, after which the walls themselves heat the air. This saves cash on heating and make your stay more comfortable. For a house in which people live periodically (for example, on weekends), the large heat capacity of building materials will have the opposite effect: such a building will be quite difficult to heat quickly.

The values of the heat capacity of building materials are given in SNiP II-3-79. Below is a table of the main building materials and the values \u200b\u200bof their specific heat capacity.

Table 1

Speaking of heat capacity, it should be noted that heating furnaces it is recommended to build from brick, since the value of its heat capacity is quite high. This allows you to use the oven as a kind of heat accumulator. Heat accumulators in heating systems (especially in water heating systems) are used more and more every year. Such devices are convenient in that it is enough to heat them well once with an intensive firebox. solid fuel boiler, after which they will heat your home for a whole day and even more. This will significantly save your budget.

Heat capacity of building materials

What should be the walls of a private house in order to comply with building codes? The answer to this question has several nuances. To deal with them, an example will be given of the heat capacity of the 2 most popular building materials: concrete and wood. The heat capacity of concrete is 0.84 kJ/(kg*°C) and that of wood is 2.3 kJ/(kg*°C).

At first glance, one might think that wood is a more heat-intensive material than concrete. This is true, because wood contains almost 3 times more thermal energy than concrete. To heat 1 kg of wood, you need to spend 2.3 kJ of thermal energy, but when it cools, it will also release 2.3 kJ into space. At the same time, 1 kg of a concrete structure is able to accumulate and, accordingly, release only 0.84 kJ.

But do not rush to conclusions. For example, you need to find out what heat capacity 1 m 2 of a concrete and wooden wall 30 cm thick will have. To do this, you first need to calculate the weight of such structures. 1 m 2 of this concrete wall will weigh: 2300 kg / m 3 * 0.3 m 3 \u003d 690 kg. 1 m 2 of a wooden wall will weigh: 500 kg / m 3 * 0.3 m 3 \u003d 150 kg.

for a concrete wall: 0.84*690*22 = 12751 kJ;
for wooden structure: 2.3 * 150 * 22 \u003d 7590 kJ.

From the result obtained, we can conclude that 1 m 3 of wood will accumulate heat almost 2 times less than concrete. An intermediate material in terms of heat capacity between concrete and wood is brickwork, in the unit volume of which under the same conditions will contain 9199 kJ of thermal energy. At the same time, aerated concrete, as a building material, will contain only 3326 kJ, which will be much less than wood. However, in practice, the thickness of a wooden structure can be 15-20 cm, when aerated concrete can be laid in several rows, significantly increasing the specific heat of the wall.

The use of various materials in construction

Tree

For a comfortable stay in the house, it is very important that the material has a high heat capacity and low thermal conductivity.

In this regard, wood is the best option for houses, not only for permanent, but also for temporary residence. Wooden building, not heated long time, will well perceive changes in air temperature. Therefore, the heating of such a building will occur quickly and efficiently.

Coniferous species are mainly used in construction: pine, spruce, cedar, fir. In terms of price-quality ratio, pine is the best option. Whatever you choose to build wooden house, you need to consider the following rule: the thicker the walls, the better. However, here you also need to take into account your financial capabilities, since with an increase in the thickness of the timber, its cost will increase significantly.

Brick

This building material has always been a symbol of stability and strength. The brick has good strength and resistance to negative influences. external environment. However, if we take into account the fact that brick walls are mainly constructed with a thickness of 51 and 64 cm, then in order to create good thermal insulation, they must additionally be covered with a layer thermal insulation material. brick houses great for permanent residence. Having heated up, such structures are able to give off the heat accumulated in them for a long time.

When choosing a material for building a house, one should take into account not only its thermal conductivity and heat capacity, but also how often people will live in such a house. Right choice will help maintain coziness and comfort in your home throughout the year.

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What it is?

The physical characteristic of heat capacity is inherent in any substance. It denotes the amount of heat that a physical body absorbs when heated by 1 degree Celsius or Kelvin. It is a mistake to identify the general concept with the specific one, since the latter implies the temperature required to heat one kilogram of a substance. It is possible to accurately determine its number only in laboratory conditions. The indicator is necessary to determine the heat resistance of the walls of the building and in the case when construction work is carried out at sub-zero temperatures. For the construction of private and multi-storey residential buildings and premises, materials with high thermal conductivity are used, since they accumulate heat and maintain the temperature in the room.

The advantage of brick buildings is that they save on heating bills.

The creation of an optimal microclimate and the consumption of thermal energy for heating a private house in the cold season largely depends on the thermal insulation properties of the building materials from which this building was built. One of these characteristics is heat capacity. This value must be taken into account when choosing building materials for constructing a private house. Therefore, the heat capacity of some building materials will be considered further.

Definition and formula of heat capacity

To heat any material with mass m from temperature t initial to temperature t final, it will be necessary to spend a certain amount of thermal energy Q, which will be proportional to the mass and temperature difference ΔT (t final -t initial). Therefore, the heat capacity formula will look like this: Q \u003d c * m * ΔТ, where c is the heat capacity coefficient (specific value). It can be calculated by the formula: c \u003d Q / (m * ΔT) (kcal / (kg * ° C)).

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The use of heat capacity in practice

Building materials with high heat capacity are used for the construction of heat-resistant structures. This is very important for private houses in which people live permanently. The fact is that such structures allow you to store (accumulate) heat, so that a comfortable temperature is maintained in the house for quite a long time. First, the heater heats the air and the walls, after which the walls themselves heat the air. This allows you to save money on heating and make your stay more comfortable. For a house in which people live periodically (for example, on weekends), the large heat capacity of building materials will have the opposite effect: such a building will be quite difficult to heat quickly.

The values of the heat capacity of building materials are given in SNiP II-3-79. Below is a table of the main building materials and the values \u200b\u200bof their specific heat capacity.

Table 1

Brick has a high heat capacity, so it is ideal for building houses and building stoves.

Speaking about the heat capacity, it should be noted that heating furnaces are recommended to be built of brick, since the value of its heat capacity is quite high. This allows you to use the oven as a kind of heat accumulator. Heat accumulators in heating systems (especially in water heating systems) are used more and more every year. Such devices are convenient in that it is enough to heat them well once with an intensive firebox of a solid fuel boiler, after which they will heat your house for a whole day and even more. This will significantly save your budget.

Back to index

Heat capacity of building materials

What should be the walls of a private house in order to comply with building codes? The answer to this question has several nuances. To deal with them, an example will be given of the heat capacity of the 2 most popular building materials: concrete and wood. has a value of 0.84 kJ / (kg * ° C), and a tree - 2.3 kJ / (kg * ° C).

At first glance, one might think that wood is a more heat-intensive material than concrete. This is true, because wood contains almost 3 times more thermal energy than concrete. To heat 1 kg of wood, you need to spend 2.3 kJ of thermal energy, but when it cools down, it will also release 2.3 kJ into space. At the same time, 1 kg of a concrete structure is able to accumulate and, accordingly, release only 0.84 kJ.

for a concrete wall: 0.84*690*22 = 12751 kJ;
for a wooden structure: 2.3 * 150 * 22 = 7590 kJ.

From the result obtained, we can conclude that 1 m 3 of wood will accumulate heat almost 2 times less than concrete. An intermediate material in terms of heat capacity between concrete and wood is brickwork, in the unit volume of which, under the same conditions, 9199 kJ of thermal energy will be contained. At the same time, aerated concrete, as a building material, will contain only 3326 kJ, which will be much less than wood. However, in practice, the thickness of a wooden structure can be 15-20 cm, when aerated concrete can be laid in several rows, significantly increasing the specific heat of the wall.

The thermal conductivity and heat capacity of bricks are important parameters that allow you to decide on the choice of material for the construction of residential buildings, while maintaining the necessary level of heat in them. Specific indicators are calculated and given in special tables.

What is it and what affects them?

Thermal conductivity is a process that occurs inside a material when thermal energy is transferred between particles or molecules. In this case, the colder part receives heat from the warmer one. Energy losses and heat releases occur in materials not only as a result of the heat transfer process, but also during radiation. It depends on the structure of the given substance.

Each building component has a certain heat conductivity value, obtained empirically in the laboratory. The process of heat distribution is uneven, therefore it looks like a curve on the graph. Thermal conductivity is a physical quantity, which is traditionally characterized by a coefficient. If you look at the table, you can easily see the dependence of the indicator on the operating conditions of this material. Extended directories contain up to several hundred types of coefficients that determine the properties of building materials of various structures.

For a guide when choosing, the table indicates three conditions: normal - for a temperate climate and average humidity in the room, the "dry" state of the material, and "wet" - that is, operation in conditions of an increased amount of moisture in the atmosphere. It is easy to see that for most materials the coefficient increases with increasing ambient humidity. The "dry" state is determined at temperatures from 20 to 50 degrees above zero and normal atmospheric pressure.

If the substance is used as a heat insulator, the indicators are chosen especially carefully. Porous structures retain heat better, and denser materials give it away more strongly. environment. Therefore, traditional heaters have the lowest thermal conductivity coefficients.

As a rule, glass wool, foam and aerated concrete with a particularly porous structure are optimally suited for construction. The denser the material, the greater the thermal conductivity it has, therefore, it transfers energy to the environment.

Types of materials and their characteristics

Brick, produced today in many types, is used in construction everywhere. Not a single object - a large industrial building, residential multi-apartment or small private house, not built without a brick base. The construction of cottages, popular and relatively inexpensive, is based solely on brickwork. Brick has long been the main building material.

This happened due to its universal properties:

reliability and durability;
strength;
environmental friendliness;
excellent sound and noise insulation characteristics.

There are the following types of bricks.

Red. It is made from baked clay and additives. Differs in reliability, durability and frost resistance. Suitable for building walls and building foundations. Usually placed in one or two rows. Thermal conductivity depends on the presence of gaps in the product.

Clinker. The most durable and dense facing brick. A solid, solid and reliable furnace material, due to its high density, also has the most significant thermal conductivity coefficient. And therefore, it makes no sense to use it for walls - it will be cold in the house, significant wall insulation will be required. But clinker brick is indispensable in road construction and when laying floors in industrial buildings.

Silicate. Inexpensive material from a mixture of lime and sand, often products are combined into blocks to improve operational properties. When building buildings, not only full-bodied, but also silicate with voids is used. The durability indicators of the sand block are average, and the thermal conductivity depends on the size of the joint, but still remains high enough, so the house will require additional insulation.

The indicator for a slotted briquette is lower compared to an analogue without internal gaps. It should also be noted that the product absorbs excess moisture.

Ceramic. Modern and beautiful material produced in a wide range. If we talk about thermal conductivity, then it is significantly lower than that of ordinary red brick.

There is a full-bodied ceramic briquette, refractory and slotted, with voids. The coefficient of heat conductivity depends on the weight of the brick, the type and number of slots in it. Warm ceramics are beautiful on the outside, but they also have many thin gaps inside, which makes them very warm and therefore ideal for construction. If the ceramic product also has pores that reduce weight, the brick is called porous.

The disadvantages of such bricks include the fact that individual units are small and fragile. Therefore, warm ceramics are not suitable for all designs. In addition, it is an expensive material.

As for refractory ceramics, this is the so-called fireclay brick - a burnt block of clay with a high thermal conductivity, almost the same as that of an ordinary solid material. At the same time, fire resistance is a valuable property that is always taken into account during construction.

Fireplaces are built from such a "stove" brick, it has an aesthetic appearance, keeps heat in the house due to high thermal conductivity, frost-resistant, resistant to acids and alkalis.

The specific heat capacity is the energy that is spent to heat one kilogram of material by one degree. This indicator is needed to determine the resistance to heat of the walls of the building, especially at low temperatures.

For products made of clay and ceramics, this indicator ranges from 0.7 to 0.9 kJ / kg. Silicate brick gives indicators of 0.75-0.8 kJ / kg. Fireclay is capable of giving an increase in heat capacity from 0.85 to 1.25 when heated.

Comparison with other materials

Among the materials that can compete with bricks, there are both natural and traditional - wood and concrete, and modern synthetic - foam and aerated concrete.

Wooden buildings have long been erected in the northern and other areas characterized by low winter temperatures, and this is no accident. The specific heat capacity of wood is much lower than that of brick. Houses in this area are built from solid oak, coniferous trees, and chipboard is also used.

If the wood is cut across the fibers, the thermal conductivity of the material does not exceed 0.25 W/M*K. Chipboard also has a low indicator - 0.15. And the most optimal coefficient for construction is wood cut along the fibers - no more than 0.11. Obviously, in houses made of such wood, excellent heat preservation is achieved.

The table clearly demonstrates the spread in the value of the thermal conductivity of a brick (expressed in W / M * K):

clinker - up to 0.9;
silicate - up to 0.8 (with voids and cracks - 0.5-0.65);
ceramic - from 0.45 to 0.75;
slotted ceramics - 0.3-0.4;
porous - 0.22;
warm ceramics and blocks - 0.12-0.2.

At the same time, only warm ceramics and porous bricks, which are also expensive and fragile, can compete with wood in terms of the level of heat preservation in the house. However, brickwork is used more often in wall construction, and not only because of the high cost of solid wood. wooden walls afraid of precipitation, burn out in the sun. He does not like wood and chemical influences, besides, wood is able to rot and dry out, mold forms on it. Therefore, this material requires special processing prior to construction.

In addition, fire can destroy a wooden structure very quickly, since wood burns perfectly. In contrast, most types of bricks are quite resistant to fire, especially fireclay bricks.

As for others modern materials, for comparison with brick, foam block and aerated concrete are usually chosen. Foam blocks are concrete with pores, which include water and cement, foaming composition and hardeners, as well as plasticizers and other components. The composite does not absorb moisture, is highly frost-resistant, retains heat. It is used in the construction of low (two or three floors) private buildings. Thermal conductivity is 0.2-0.3 W / M * K.

Aerated concrete is a very strong compound of a similar structure. They contain up to 80% of pores, providing excellent heat and sound insulation. The material is environmentally friendly and convenient to use, as well as inexpensive. The thermal insulation properties of aerated concrete are 5 times higher than those of red brick, and 8 times higher than those of silicate (the thermal conductivity coefficient does not exceed 0.15).

However, gas-block structures are afraid of water. In addition, in terms of density and durability, they are inferior to red brick. One of the building materials in demand on the market is called extruded polystyrene foam, or penoplex. These are plates designed for thermal insulation. The material is fireproof, does not absorb moisture and does not rot.

According to experts, this composite can withstand comparison with a brick only in terms of thermal conductivity. The insulation has an indicator equal to 0.037-0.038. Penoplex is not dense enough, it does not have the necessary bearing capacity. Therefore, it is best to combine it with brick during the construction of walls, while the laying of one and a half hollow bricks, supplemented with foam plastic, will achieve compliance with building codes for the thermal insulation of a residential building. Penoplex is also used for the foundations of houses and blind areas.

Choosing the right material for a particular type of construction work, special attention should be paid to its specifications. This also applies to the specific heat capacity of bricks, on which the need for a house for subsequent thermal insulation and additional wall decoration largely depends.

Characteristics of a brick that affect its use:

Specific heat. A quantity that determines the amount of thermal energy required to heat 1 kg by 1 degree.
Thermal conductivity. A very important characteristic for brick products, which allows you to determine the amount of heat transferred from the room to the street.
To the level of heat transfer brick wall the characteristics of the material used for its construction directly affect. In cases where we are talking about multilayer masonry, it will be necessary to take into account the coefficient of thermal conductivity of each layer separately.

Ceramic

Helpful information:

Based on the production technology, the brick is classified into ceramic and silicate groups. Moreover, both types have significant material, specific heat capacity and thermal conductivity. The raw material for the manufacture of ceramic bricks, also called red, is clay, to which a number of components are added. Formed raw blanks are fired in special furnaces. The specific heat index can vary within 0.7-0.9 kJ/(kg·K). As for the average density, it is usually at the level of 1400 kg/m3.

Among the strengths of ceramic bricks are:

1. Smooth surface. This enhances its external aesthetics and ease of installation.
2. Resistance to frost and moisture. Under normal conditions, the walls do not need additional moisture and thermal insulation.
3. Ability to endure high temperatures. This allows you to use ceramic bricks for the construction of stoves, barbecues, heat-resistant partitions.
4. Density 700-2100 kg/m3. This characteristic is directly affected by the presence of internal pores. As the porosity of the material increases, its density decreases and the thermal insulation characteristics increase.

Silicate

As for silicate brick, it can be full-bodied, hollow and porous. Based on the size, single, one-and-a-half and double bricks are distinguished. On average, silicate brick has a density of 1600 kg / m3. The noise-absorbing characteristics of silicate masonry are especially appreciated: even if we are talking about a wall of small thickness, the level of its sound insulation will be an order of magnitude higher than in the case of using other types of masonry material.

Facing

Separately, it is worth mentioning the facing brick, which with equal success resists both water and temperature rise. The specific heat index of this material is at the level of 0.88 kJ/(kg·K), at a density of up to 2700 kg/m3. On sale facing bricks presented in a wide variety of shades. They are suitable for both cladding and laying.

Refractory

Represented by dinas, carborundum, magnesite and fireclay bricks. The mass of one brick is quite large, due to the significant density (2700 kg / m3). The lowest rate of heat capacity when heated is for carborundum brick 0.779 kJ / (kg K) for a temperature of +1000 degrees. The heating rate of the furnace, laid from this brick, significantly exceeds the heating of fireclay masonry, however, cooling occurs faster.

From refractory brick furnaces are being equipped, providing for heating up to +1500 degrees. The specific heat capacity of this material is greatly influenced by the heating temperature. For example, the same fireclay brick at +100 degrees has a heat capacity of 0.83 kJ / (kg K). However, if it is heated to +1500 degrees, this will provoke an increase in heat capacity up to 1.25 kJ / (kg K).

Dependence on the temperature of use

The technical performance of bricks is greatly influenced by temperature regime:

trepelny. At temperatures from -20 to + 20, the density varies within 700-1300 kg/m3. The heat capacity index is at a stable level of 0.712 kJ/(kg·K).
Silicate. A similar temperature regime of -20 - +20 degrees and a density of 1000 to 2200 kg / m3 provides for the possibility of different specific heat capacities of 0.754-0.837 kJ / (kg K).
adobe. With the same temperature as the previous type, it demonstrates a stable heat capacity of 0.753 kJ / (kg K).
Red. It can be applied at a temperature of 0-100 degrees. Its density can vary from 1600-2070 kg/m3, and its heat capacity from 0.849 to 0.872 kJ/(kg K).
Yellow. Temperature fluctuations from -20 to +20 degrees and a stable density of 1817 kg / m3 gives the same stable heat capacity of 0.728 kJ / (kg K).
Building. At a temperature of +20 degrees and a density of 800-1500 kg / m3, the heat capacity is at the level of 0.8 kJ / (kg K).
Facing. The same temperature regime of +20, with a material density of 1800 kg/m3, determines the heat capacity of 0.88 kJ/(kg K).
Dinas. Operation in mode elevated temperature from +20 to +1500 and a density of 1500-1900 kg/m3 implies a consistent increase in heat capacity from 0.842 to 1.243 kJ/(kg K).
carborundum. As it is heated from +20 to +100 degrees, a material with a density of 1000-1300 kg / m3 gradually increases its heat capacity from 0.7 to 0.841 kJ / (kg K). However, if the heating of carborundum brick is continued further, then its heat capacity begins to decrease. At a temperature of +1000 degrees, it will be equal to 0.779 kJ / (kg K).
Magnesite. A material with a density of 2700 kg/m3 with an increase in temperature from +100 to +1500 degrees gradually increases its heat capacity of 0.93-1.239 kJ/(kg·K).
Chromite. Heating a product with a density of 3050 kg/m3 from +100 to +1000 degrees provokes a gradual increase in its heat capacity from 0.712 to 0.912 kJ/(kg K).
fireclay. It has a density of 1850 kg/m3. When heated from +100 to +1500 degrees, the heat capacity of the material increases from 0.833 to 1.251 kJ / (kg K).

Choose the right bricks, depending on the tasks at the construction site.

The choice of brick as a building material for the construction of walls of any premises, stoves or fireplaces is carried out on the basis of its properties associated with the ability to conduct, retain heat or cold, and withstand high or low temperatures. The most important thermal characteristics: thermal conductivity coefficient, heat capacity and frost resistance.

Previously, this name meant only elements standard size(250x120x65) from baked clay. Now produced and sold building products, made from any suitable components, having the shape of a regular parallelepiped and dimensions similar to the dimensions of the classic ceramic version.

Main varieties:

ceramic ordinary (construction) - classic stone red color from baked clay;
ceramic facial - has better external qualities, increased resistance to weathering, usually has cavities inside;
silicate full-bodied - light gray from a pressed sand-limestone mixture, inferior to ceramic in all respects (including thermal engineering), except for strength;
silicate hollow - characterized by the presence of cavities that increase the ability of walls to retain heat;
hyperpressed - from cement with pigments that give shades natural material, aggregates of the mixture are crumbs of limestone, marble, granules of blast-furnace slag;
fireclay - designed for laying stoves, fireplaces, chimneys;
clinker - differs from the usual one in that special grades of clay and higher firing temperatures are used in its production;
warm ceramics (porous stone) - its characteristics far exceed the thermal conductivity of red brick, this is achieved due to the presence of air-filled pores in the clay mass and the special design of the element, which has a large number of voids inside.

Coefficient of thermal conductivity

The thermal conductivity of a substance is a quantitative characteristic of its ability to conduct energy (heat). To compare it with different building materials, the coefficient of thermal conductivity is used - the amount of heat passing through a sample of unit length and area per unit time with a unit temperature difference. It is measured in Watt/meter*Kelvin (W/m*K).

When choosing a brick for building walls, they pay attention to the thermal conductivity index, since the minimum allowable thickness of the structure depends on it. How less value, topics better wall retains heat and the thinner it can be, more economical consumption. The same parameter is taken into account when choosing the type of insulation, the size of its layer and technology.

Thermal conductivity depends on such factors:

material: the best performance - for warm porous ceramics, the worst - for hyper-pressed or silicate bricks;
density - the higher it is, the worse heat is retained;
the presence of voids in the products - the cavity inside the slotted wall stone fills the air after installation, due to this, heat or coolness in the room is better preserved.

According to the coefficient of thermal conductivity in a dry state, the following types of masonry are distinguished:

highly efficient - up to 0.20;
increased efficiency - from 0.21 to 0.24;
effective - from 0.25 to 0.36;
conditionally effective - from 0.37 to 0.46;
ordinary - more than 0.46.

When performing calculations, choosing front and building bricks and insulation, it is taken into account that the ability of a wall to conduct heat depends not only on the properties of the material, but is also characterized by the thermal conductivity of the solution and the thickness of the joints.

Heat capacity

This is the amount of heat (energy) that must be supplied to the body in order to raise its temperature by 1 Kelvin. The unit of measure for this indicator is Joule per Kelvin (J/K). Specific heat capacity - its ratio to the mass of a substance, the unit of measurement is Joule / kg * Kelvin (J / kg * K). For a brick, its value is from 700 to 1250 J / kg * K. More accurate figures depend on the material from which a particular type is made.

The parameter affects the consumption of energy required for heating the house: the lower the value, the faster the room warms up and the less money will be spent on payment. It is especially important if the residence in the house is not permanent, that is, it is periodically necessary to warm up the walls. The best way- silicate, but it is recommended to entrust the exact calculations to a specialist. It is necessary to take into account not only the heat capacity of the wall, but also its thickness, the heat capacity of the masonry mortar, the width of the joints, the location of the room and the heat transfer coefficient.

Frost resistance

It is expressed in the number of freeze-thaw cycles that the element can withstand without significant deterioration in properties. What matters is not the lower temperature level, but the frequency of freezing moisture in the pores. Water, turning into ice, expands, which contributes to the destruction of the stone.

Usually, frost resistance is indicated by an index that contains a large Latin letter F and numbers. For example: marking F50 indicates that this material begins to lose strength no earlier than after 50 freeze-thaw cycles. Possible brick grades for frost resistance (GOST 530-2012): F25; F35; F50; F100; F200; F300. Focusing on the designated figure, you need to understand that the number of cycles does not match the number of seasons.

In some regions, during one winter, a sharp change in temperature can occur many times. For bearing walls it is recommended to use at least F35, for facing - from F75. Options with lower rates are only suitable for regions with a mild climate.