Density of expanded clay - what it is and what it depends on

Area of ​​use

When choosing the building material described, not only the weight of expanded clay is important, but also other characteristics. However, before purchasing, you must determine whether the insulation is suitable for a particular area. At first glance, it may seem that the scope of application is not so extensive, but the granules have excellent heat-saving characteristics, which makes it possible to use this insulation in the arrangement of floors, attics, and ceilings. It is worth noting that thermal insulation is not the least useful property.

Expanded clay, the density of which was mentioned above, is used as the underlying layer. More specifically, it can be used as a base when forming a concrete screed. Among other things, granules can be used when filling the foundation during construction work. Thanks to the use of expanded clay, it is possible to significantly reduce the depth of laying the foundation; sometimes the numbers can be halved. This way, you can save building materials and also prevent freezing of the ground near the base.

Expanded clay is quite often used in the construction of baths, when there is a need to properly insulate walls and floors. With the help of granules you can achieve a certain temperature, which will be maintained for quite a long time. If an accident occurs, the home owner will not be faced with the need to dig up all the soil.

Another advantage is that after repairs, expanded clay can be reused without losing its characteristics. The described building material is excellent for creating garden paths or a drainage system, which certainly leads to an increase in productivity. The main requirement for this is the use of small granules.

Peculiarities

Nowadays, most homes do not have perfectly smooth walls and floors.
This problem is not uncommon, and many users encounter it. Fortunately, this defect can be corrected. Suitable materials are sold in hardware stores specifically for smoothing various substrates. So, to level the floor before laying the decorative covering, you can use gypsum fiber board. These materials are found in many retail outlets and are in enviable demand.

Gypsum fiber boards are a special pressed material that contains reinforcement with loose waste paper. This coating is durable and reliable. Gypsum in its composition plays the role of a binding component.

The main distinguishing feature of gypsum fiber board sheets is their homogeneous structure, located under the cardboard layer - plasterboard. At the same time, the density of the latter is much lower, so we can safely say that gypsum fiber boards are reliable and strong coatings.

Currently, there are two types of gypsum fiber sheets. They are simple and moisture resistant.

Such materials should be laid exclusively on a dry and properly prepared floor. And it should also be taken into account that many problems can arise with a cement-sand or concrete screed at the stage of installing gypsum fiber sheets, since the base for such material must be completely dry. In cases where gypsum fiber boards are used as flooring on a subfloor, the result is a dry and neat base. It is permissible to immediately lay decorative finishing coatings on it.

Expanded clay density and material grade

Expanded clay is lightweight, and the density of the material determines its quality and area of ​​use. It is this value that affects its quantity per cubic meter and, consequently, the weight of the expanded clay bag. This indicator depends on the fraction: the larger the granules, the lower the density of the material.

Helpful advice! When purchasing expanded clay, you must take into account the bulk density, which indicates the grade of the material.

The quality of expanded clay is determined by its bulk density index and manufacturing method

Production technology affects the density of the material. There are four ways to obtain this material:

1. Dry. The simplest technology applied to homogeneous types of clay without impurities. Humidity does not exceed 9%.
2. Wet.
3. Plastic. The most common method. Granules are formed from wet clay and sent to the oven. The humidity of the raw materials reaches 30%.
4. Powder-plastic. It is similar to the previous method, but the basis is dry clay, which is crushed, and then moistened and subjected to temperature influences.

It is the bulk density that is the brand of expanded clay. It is designated by the letter M with the corresponding number. For example, M300 means that 1 cube of expanded clay weighs from 251 to 300 kg. The lower the grade, the higher the thermal insulation properties. This material is best suited for insulating ceilings and floors.

In construction, expanded clay is most often used to insulate floors, walls and ceilings.

Expanded clay of a lower grade (fractions 20-40) is used as a heat insulator in foundations and basements. It is widely used for landscape design. Material with a minimum density is used to insulate walls, communications and facades. The finest expanded clay (with a fraction of up to 10 mm) is used in the preparation of expanded clay concrete for pouring floors.

Specific density and specific gravity of expanded clay

The density of expanded clay is measured using the bulk method, as well as by calculating its volumetric weight. This characteristic indicates the true weight of sand, crushed stone or gravel - without taking into account the space in the middle of the expanded clay granules. This feature underlies the difference between bulk and true density, which almost always differ from each other. True density is a constant indicator; it can only be measured in special laboratories. The specific gravity varies depending on the grain fraction.

The table clearly shows how much a cube of expanded clay weighs:

The weight of sand can reach 600 kg per cubic meter, fine gravel - 450 kg, coarse gravel - 400 kg. A cube of crushed stone will weigh at least 350 kg. The higher the density of expanded clay, the greater the weight of the material. These indicators are regulated by the existing GOST.

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The exact specific gravity of expanded clay is difficult to determine; you can only establish the average value, which is 400 kg/m³ (0.4 g/cm³). This indicator is influenced primarily by the size of the fraction. For example, a bag of expanded clay with a volume of one cube and a fraction of 10-20 weighs approximately 16.7 kg.

• https://www.ivd.ru/stroitelstvo-i-remont/stroitelnye-materialy/iz-chego-delayut-keramzit-i-dlya-chego-ego-mozhno-ispolzovat-34831
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• https://teplogalaxy.ru/keramzit-oblast-primeneniya/
• https://ky-ky.org/keramzit-svoystva-vidy-primenenie/

Briefly about the main thing

Expanded clay is a processed clay, a pure natural material, perfect for various types of construction work, has heat-insulating properties and other specific characteristics. Different fractions of expanded clay have different specific gravity, different grades, and the porosity of the pellets affects the density.

The determination of the density of this material is not entirely standard and familiar from physics. Having a classification of fractions and bulk weights of expanded clay grades, the required indicators for application are determined. The use of experience and scientific advice is required in any business.

Density of expanded clay concrete products: kilogram per cubic meter

The density of the material directly depends on the expanded clay itself, namely its mass and density, which can vary depending on the porosity. Another important factor is the proportion of cement and expanded clay in the composition. Expanded clay exhibits the lowest density of all components and the more of it in the composition, the lower the weight and density of expanded clay concrete will be.

When planning to use expanded clay concrete in construction, the density of the material must be taken into account. After all, properties such as strength and reliability, resistance to mechanical loads, heat/sound insulation, weight, etc. largely depend on density.

The higher the requirements for strength and loads, the higher the density indicator should be. But the heat/sound insulation values ​​decrease proportionally. Therefore, certain grades of material are used for different tasks and purposes.

The main types of expanded clay concrete by density and weight:

1. Structural – used for the construction of load-bearing walls and various structures that must withstand high loads. Density is in the range of 1200-1800 kg/m3, compressive strength is 100-500 kg/cm2. Positive characteristics such as high frost resistance (up to 500 cycles can reach) and lower weight compared to classic concrete make the material popular in low-rise private and industrial construction.
2. Thermal insulation - the density is lower, but the thermal insulation characteristics are significantly higher than those of the structural material. The density indicator can be in the range from 350 to 600 kg/m3, the compressive strength is approximately 5-25 kg/cm2. The material is used for insulation and sound insulation.
3. Structural and thermal insulation - the material is used to create wall panels and large blocks. The density of the blocks varies in the range of 700-1200 kg/m3, expanded clay concrete grades demonstrate compressive strength in the range from 35 to 100 kg/cm2. But frost resistance is in the range of 15-100 (freezing/thawing cycles).

Types of expanded clay concrete and its purpose

Before considering how much a cube of expanded clay concrete weighs and what its specific gravity is, it is necessary to understand for what purposes it can be used.

The material differs in purpose:

1. Structural - used for the production of high-strength wall and road slabs.
2. Thermal insulation - applied to load-bearing walls from the inside or outside to improve thermal insulation characteristics and the production of blocks used in low-rise construction.
3. Structural thermal insulation - differs from standard thermal insulation in that it is laid during the construction of load-bearing structures.

Use of expanded clay in construction

1. Thermal insulation of floors, ceilings, attics, basements;
2. Thermal insulation of strip foundations and blind areas of houses;
3. Thermal insulation of flat roofs, creating a slope on the roof;
4. Production of lightweight concrete;
5. Thermal insulation of soil - lawns and drainage on the site;
6. , in case of repair, expanded clay is reused;
7. Hydroponics, expanded clay creates an optimal microclimate for plant roots.

As you can see, the scope of application of this insulation in construction and in the home is diverse, which can be explained by the excellent thermal conductivity, environmental safety and strength of the insulation. In addition, the material is free-flowing and takes any shape; it can be used to fill any media. When used correctly, it can reduce heat loss in the room by 50-75%.

Expanded clay is a building material obtained by accelerated heating of clay raw materials, which can carry out the process of pore formation at a temperature in the oven of 1050 - 1300 C, within 25 - 45 minutes from the moment the heating begins.

1. Gravel – oval shaped.
2. Crushed stone - has a multifaceted shape with corners and edges.
3. Sand.

GOST 9759-76, fundamental document on expanded clay. It regulates the expanded clay fractions: 5-10, 10-20 and 20-40 mm; it also specifies restrictions on the presence of other fractions in the expanded clay in the base fraction.

The table shows data on the tensile strength and brand of expanded clay filler. GOST divides the produced expanded clay filler into 10 grades, according to density, from 250 to 800. Thus, grade 250 is designated expanded clay filler with a density of up to 250 kg/m3.

To determine the density of expanded clay, measuring containers are used. The average water absorption value of expanded clay gravel ranges from 8 to 20%. Existing technologies for producing expanded clay have been developed in full accordance with this GOST.

Its frost resistance indicator is at least 25 cycles of temperature difference from minimum to maximum. In other words, the service life of the filler is at least 25 years.

The thermal conductivity characteristics of expanded clay may not always meet the requirements for resistance to low temperatures, so they require careful examination before use.

The thermal conductivity of expanded clay is determined by the number and size of air pores and their humidity. A decrease in this property of expanded clay can be influenced by the formation of the so-called glassy phase that appears in the pellets.

Expanded clay weight.

"Gleb Novikov"

Indeed, in practice, when purchasing expanded clay, it is often important for us to know its weight, while manufacturers usually indicate only the volume. In this article I will dwell on this topic in detail and show techniques with which you can quickly find out your weight

In this article, I will dwell on this topic in detail and show techniques with which you can quickly find out your weight.

Weight often means different things.

In relation to expanded clay, it is customary to distinguish two key concepts: the specific gravity of expanded clay and simply weight, usually in terms of 1 cubic meter. volume.

Let's take a closer look at these concepts.

Specific gravity of expanded clay.

The specific gravity of expanded clay refers to the mass of one cubic meter of expanded clay.

Moreover, a cubic meter of expanded clay refers to the volume of pure substance.

From here it becomes clear that the specific volume of expanded clay is in no way equal to its bulk density, since bulk density is understood as the ratio of the mass of a given substance to the sum of the volumes of air and the expanded clay granules themselves.

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If, however, there is a need for an approximate calculation of the density of expanded clay, then we can recommend a simple but quite effective method of measurement and calculation.

Let's take some container, the volume of which is known to us (for example, a glass jar).

Fill it completely with expanded clay granules.

Weigh it and write down the mass value.

Now let’s close the jar with a lid with a hole pre-made in it for the straw.

Next, insert the tube into the lid and through this tube carefully fill the jar with expanded clay with water to the very top.

Now all that remains is to drain the water back from the jar into a measuring container (for example, a measuring cylinder or glass) and measure the volume of water.

The last step is calculation.

Let mt be the mass of the container, vt the volume of the container, Mk the mass of a jar filled with dry expanded clay without water, and Vw the measured volume of water.

Then we get the calculation of the approximate specific gravity of expanded clay:

1. the net weight of expanded clay will be Mk-mt,

2. the volume of expanded clay in the measured container is equal to vt-Vw,

3. the density of expanded clay will be (Mk-mt)/(vt-Vw),

4. We do the calculation for 1 cubic meter. meter and we get the approximate specific gravity of expanded clay.

It turns out that the specific gravity of expanded clay is always greater than its bulk density.

In practice, however, it is easier to use ready-made tables that indicate specific gravity data depending on its brand or fraction.

Weight of a cube of expanded clay.

Sellers of expanded clay usually indicate the volume on bags or other containers.

Another common case is the sale of expanded clay in bulk.

In both cases, it is sometimes necessary to know the weight of expanded clay.

This is easy to do if its bulk density is known.

Then, multiplying the value of bulk density by volume, we can easily obtain the mass of expanded clay in a given volume, and recalculating it by 1 cubic meter - the weight of one cube of expanded clay.

If the bulk density is unknown, then simple measurements can be made.

To do this, we should take a container whose volume is known to us in advance.

It is important to emphasize here that the larger the container volume, the more accurate results we will get. If there is no large container, then you can use another well-known method - take several (about 10) measurements and then calculate the average values

If there is no large container, then you can use another well-known method - take several (about 10) measurements and then calculate the average values.

We weigh the container and write down its mass.

Then we fill our container with expanded clay pellets and weigh again.

The difference in mass of the weighed container with pellets and the container itself is the mass of pure expanded clay of a given fraction.

Dividing this by the mass by the volume of the container, we get the bulk density.

Now let's convert it to 1 cubic meter. meter of volume, the resulting bulk density and we get the weight of one cube of expanded clay.

Thus, we obtain both the mass and at the same time the bulk density of expanded clay.

Obviously, the weight of one cube of expanded clay will increase when weighing its different fractions as the size of the pellet decreases.

Some interesting information

It has long been known about defects in pottery products - swelling and bubbles in fired clay. But only a hundred years ago this phenomenon was thoroughly studied and began to be used to extract new material - the production of “haidite” aggregate was patented and established in the USA. An experimental plant for firing expanded clay was built in the USSR in 1938, and production from low-melting clays was established in 1947 with new firing technologies using a stepwise principle, with rotating kilns, pressing and perforated rollers.

When making expanded clay, clay is pre-granulated and then fired in a kiln at a temperature of 1100-1350 ° C and high pressure. Clay particles boil, become bubbles, baked like bread with a crust - the outer shell, but porous inside, and are of unequal diameter. Fraction sizes range from 0-40 mm.

Porous structure of pellets Source sdelaipotolok.com

The granules are then sorted and distributed according to size. The types, grades, density, water absorption, strength, frost resistance, volumetric weight of expanded clay and areas of application depend on the grain size and shape.

Insulation of walls using expanded clay

The optimal option for wall insulation using this material is considered to be a three-layer type construction.

The supporting structure, made of expanded clay concrete, serves as the first layer with a thickness of about 40 cm. The blocks are durable, safe, and have high thermal insulation characteristics.

When performing the second layer, use a mixture of expanded clay and cement laitance in a ratio of 1:10 - capsimet. Gluing of cement granules to each other occurs after filling the mixture under the influence of natural humidity. A layer thickness of 10 cm is sufficient to provide a high level of thermal insulation. The mass of a fairly rigid structure is distributed over the surface of the house building foundation.

The third layer, made of wood or brick, protects the insulating material from the influence of external environmental conditions.

Another simple way to insulate walls is to pour expanded clay into the space between the wall and the sheathing, for example, clapboard. The dry material is poured with a specially prepared cement solution of liquid consistency.

Quite often the material is used in the construction of additional walls. The essence of the method is that fine gravel is poured into the space between the wall and a metal frame fenced with plasterboard.

How to calculate?

To calculate the reliability of blocks, use the formula for true density: Pu = m / Ve * 1000, where Pu is the average density, m is the mass of dry matter (expanded clay) and Ve is the volume of the material in its natural state. The resulting number is an average, which has an inverse relationship to factors such as porosity and humidity.

If the first value is zero, then the average strength of the building material is true. With increased humidity in expanded clay concrete, the indicator increases, so calculations should be carried out when the material is in its natural state. To prepare expanded clay concrete blocks with a good density of kg m3, special equipment is required.

Expanded perlite

Expanded perlite is produced by firing perlites - silicate rocks containing water. Perlites are a natural material, a rock that is volcanic glass, which contains 70-75% SiO2; 12-14% AI2O3; 3-5% Na2O, about the same amount of K2O, up to 1% Fe2O3, CaO, MgO. A distinctive feature of perlite rock is that it contains from 2 to 5% bound water. Due to its nature and chemical composition, perlite, like any glass, is inert, chemically and biologically resistant.

In the 30s of the 20th century, one of its unique properties was discovered. With sudden thermal shock heating to temperatures of 1100-1150°C, particles of this rock become porous. The volume of internal pores increases sharply. Light porous sand in the poured layer can reach a density of 50÷600 kg/m3 (according to GOST 10832-74).

The global consumption of expanded perlite is at least 20 million m3 per year. The largest producers of expanded perlite in the world are the USA (about 7 million m3), Germany (about 4 million m3), France, Italy, Greece, Spain, Israel, China (up to 1 million m3 each).

In Russia, until 1991, about 2.5 million m3 of this product were produced. It is currently quite difficult to estimate the production volume of expanded perlite, but according to Perlite LLC (website https://www.ooo-perlit.ru) the volume of perlite production after the decline (1994 - 80 thousand m3 per year) in 2000 reached 150 thousand m3 per year and continues to grow, although it is constrained by the low demand for the material in construction due to its consumer properties. Thus, having a good ability to be wetted by water, expanded perlite sand can absorb up to 400% of water (by weight) and retain it well. Therefore, the material is widely used in agriculture to improve soil properties.

However, this same property - high moisture capacity - hinders the use of the material in construction. According to this property, the material is close to another mineral heat insulator - expanded vermiculite.

Application

In many regions of our country, expanded clay concrete has become the basis for mass construction. Its most effective use is for the manufacture of blocks of grades 300, 400, 500. The tensile strength of these blocks lies in the range of 5 to 7.5 MPa.

The properties of expanded clay concrete ensure the simultaneous performance of load-bearing and thermal insulation functions. In multilayer structures, it is possible to use both structural expanded clay concrete and manufactured thermal insulating concrete with a density of 600 kg/m3.

Studies have shown that the use of combined (structural and heat-insulating concrete) reduces material consumption and ensures the quality and reliability of such panels.

Expanded clay filler with grades 700, 800 is used for the production of lightweight structural concrete, in particular, for the needs of bridge construction, where one of the main tasks is to reduce the weight of structures.

The ease of extraction of raw materials, the relative ease of production, the low cost of expanded clay - all this has made it a popular building material.

Obtaining expanded clay

Expanded clay is produced through the process of firing specialized clay. Initially, this raw material undergoes all the necessary processing, and then it is subjected to a sharp thermal effect. In about 20-40 minutes, the temperature rises from 1050 degrees to 1300 degrees.

Thanks to this, the raw material swells and acquires a new structure - cellular or, in other words, porous. In this case, the surface of the granules themselves melts, resulting in an almost ideal hermetic shell. This is why the granules have such high strength and become much less susceptible to mechanical stress.

Production

For the insulation to be effective, the density of expanded clay should be small. This can be achieved by foaming clay. This happens along the technological chain at the plant:

1. In special installations, low-melting clay is subjected to powerful thermal shock. This ensures high porosity of the raw material.

2. Next, the raw porous granules are melted from the outside - this achieves high strength and tightness, necessary for the balls to resist moisture and aggressive environmental influences.

The technical characteristics of expanded clay directly depend on the accuracy of production processes: deviation from manufacturing standards can lead to insufficient porosity and tightness, and brittleness of the insulation.

Main characteristics

Comparison table for the thermal conductivity of building materials.
The excellent heat and sound insulation properties of the material (shown in the table above) are due to its porous structure and density. This makes the blocks quite light. In the production of expanded clay concrete, a special annealing technology is used, similar to that used in the production of bricks.

The base of the blocks is a solution of cement, water, sand filler and expanded clay granules. In this case, the main role is played by the concentration and size of the latter in the composition.

As for the thermal conductivity itself, its coefficient is the amount of heat passing through a certain building element (body) per hour. In this case, the data is indicated for a body with a base area of ​​1 m2 and a thickness of 1 m.

Strength of materials

During the production of the blocks themselves, the number of granules in the composition can be varied, while creating elements with the desired characteristics. Taking them into account, expanded clay concrete blocks are divided into:

• Structural. Used to construct load-bearing elements of a building.
• Thermal insulating. They have low strength indicators, but provide high insulation.
• Structural and heat insulating. They have average strength and heat saving characteristics. Mainly used for the manufacture of prefabricated panels.

As the size of expanded clay granules in concrete increases, the ability of the material to transmit heat decreases, which makes it possible to construct structures with narrow walls in places where their level of strength will be sufficient to withstand the imposed loads.

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Such material characteristics are a godsend for construction. With a small width of the walls and, accordingly, weight, there is no need to create a high-strength foundation, which reduces construction costs.

Advantages of slabs

The monolithic expanded clay concrete floor structure is durable, rigid and easy to assemble. The material is innovative. Manufacturers highlight the following advantages of its use:

Any mounting options can be attached to the surface. Builders often use screws, dowels and self-tapping screws. The structure of the slab remains the same for a long time. No cracks or chips appear on it. Other materials cannot boast of such an advantage. For example, aerated concrete cannot withstand heavy loads. Expanded clay concrete does not interfere with the internal repairs of the entire structure.

Low material cost. A minimum amount of technology is required to produce a slab

During the selection process, it is recommended to pay attention to the brand and quality of the product. The difference is small

The client is guaranteed to purchase high quality building materials. The material is easy to use. It is often used to build structures with your own hands. You can also make the stove yourself. It will be light in weight and size. It is easily lifted by a man of average build. Expanded clay concrete slabs are used in the construction of single- and multi-story buildings. However, pay attention to the porosity and density of the overall structure. There are heavy product options. They are not subject to deformation, because cracks do not form on their surface. Indoor partitions are made from blocks with a lower density. Thanks to this, it is possible to significantly save on construction work. Hollow slabs are ideal for one-story houses. Thanks to the structure, it is possible to retain heat inside the room. The material's characteristics are close to natural wood. There is no need to use additional material for insulation. An optimal humidity environment is created in the room. The slabs are lightweight, so the construction process is carried out quickly and efficiently.

Some builders are interested in the question: is it possible to lay floor slabs on expanded clay concrete blocks? The two materials combine well with each other and form a frame with the necessary strength. Expanded clay concrete is a material that forms the required level of vapor barrier. Thanks to this, it is possible to save money for interior and exterior decoration. The slabs are even suitable for constructing the facade of any building.

Description of thermal conductivity

The low level of thermal conductivity of expanded clay is explained by its porous structure

The ability of insulation to transfer energy from heated layers to parts with a lower temperature is called thermal conductivity. The process is ensured by the chaotic movement of molecular particles, its intensity depends on humidity, compaction, and pore size.

The physical process of heat conduction accelerates when there is a large temperature difference between the outside and inside of the building. Spontaneous energy transfer always occurs from a hotter environment towards a colder environment and occurs before thermodynamic equilibrium occurs.

Coefficient of thermal conductivity

To numerically express a material's ability to transfer energy, there is a thermal conductivity coefficient. The indicator indicates the amount of heat flowing through a sample of material under given conditions. The test standard always has the same dimensions in length, width and area and is tested at a standard temperature difference (1 K). Heat transfer coefficient is measured in W/mK, which corresponds to the International System of Units.

The name thermal resistance coefficient is used in the construction field. The thermal conductivity of expanded clay is 0.1 – 0.18 W/m·K. High-quality material is characterized by a numerical value of 0.12 – 0.17 W/m K; insulation with such properties retains up to 80% of internal heat.

True and specific density of expanded clay

The production of expanded clay is based on the firing of low-melting clay rocks under certain temperature conditions, as a result of which the clay swells and expanded clay granules are obtained. Depending on the clay processing mode, the density of expanded clay will differ. The following processing modes are distinguished:

Since the density of expanded clay is not high, the strength of expanded clay concrete blocks and other building materials made from it is also lower in comparison with analogues. True, mechanical strength does not depend on low strength, so expanded clay of any brand is characterized by high mechanical strength.

The most important characteristic when choosing expanded clay as a lightweight porous material is bulk density.

How is the bulk density of expanded clay determined and what does it affect?

The density of expanded clay gravel is determined by weighing this material in a container, after which the result obtained is divided by the volume of the container used. This is how the bulk density of expanded clay is obtained, and the lower it is, the higher its quality indicators. Depending on the density of expanded clay, in accordance with GOST 9757-90, it is divided into several grades:

Its density indicates that in one cubic meter of volume the weight of expanded clay is, for example, for the M250 brand – 250 kg. Grades with a higher bulk density are produced to order. This gradation is valid for expanded clay gravel, while for expanded clay sand the density is indicated, starting from the minimum grade M500 and ending with the maximum grade M1000. With the same fraction size and the same volume, the quality will be higher for the expanded clay that has less weight. The quality indicators of expanded clay will be influenced by the types of clay used in the production process and the accuracy of compliance with the technological process for manufacturing this material. Consequently, when choosing expanded clay, the density and weight of a cubic meter will be of decisive importance, even if expanded clay is purchased in bags.

It is necessary to distinguish between the true density of expanded clay and its specific density. The true density of expanded clay shows the mass per unit volume in a dense state; it is used to determine the specific density of a given bulk building material. True density is a constant value, while the specific density of expanded clay is variable. For expanded clay gravel it ranges from 450 to 700 kg/m3, for expanded clay gravel it varies between 600 and 1000 kg/m3, and for dry expanded clay concrete mixture it is 800 kg/m3.

Types of expanded clay screeds

Screeds using expanded clay are divided into two types:

1. Dry screed
2. Screed using sand and cement

In these cases, it is very important to be able to calculate the rate of expanded clay. Since a screed with expanded clay is the easiest way to make the floor more even

Why is this material so good?

Helps create greater insulation from noise and temperature changes Very lightweight Environmentally friendly, which is very important for health Quite practical and durable It does not absorb moisture It is not afraid of high temperatures It resists drops in temperature Well It does not shrink much

Dry method

The most common method of screeding with expanded clay is dry. The fact is that this method can save time and effort, because it is much simpler than the method using concrete. On the base of the floor, if it is made of concrete, a film is applied, if it is made of wood, impregnated paper or roofing felt. Dry expanded clay is poured onto the bedding and secured on top with sheets of chipboard or gypsum fiber board.

The advantages of this method are:

• Easy to mount
• There is almost no debris and dust during work
• Sound and heat are well isolated
• Decorative coating can be laid immediately after screeding

There are, of course, disadvantages, but compared to the advantages they are insignificant. The most important of them is the cost, which is quite high. But this concerns the material, but the work itself will cost pennies. There is another minus: the screed is very thick and may not be suitable for rooms with low ceilings.

How to calculate expanded clay and its consumption

In order to make a screed, you must first calculate all the materials and proportions.

• Amount of expanded clay
• How much oilcloth, roofing felt or paper is needed?
• Also, do not forget about screws and bolts
• The area of ​​chipboard or other materials that will complete the screed

All this can be calculated using the following indicators:

Coating thickness Square footage of the room in which the screed will be made It is also important how the material will be placed

Expanded clay consumption is determined by the thickness of the screed that is planned. In this case, the base value becomes the average value. It is worth finding the average thickness of expanded clay by calculating it from the highest and lowest measurement points over the entire area. To get the correct expanded clay indicators, you need to take the room size data and multiply it by the thickness you want to fill. It is very difficult to obtain accurate data, so it is worth buying material with a small margin.

Wet method

To properly make a wet screed, you should use the following calculations:

• Cement, one part
• Sand three parts
• Expanded clay four parts

According to these calculations, you will get twenty-five kilograms of expanded clay per thirty kilograms of solution. Before preparing this mass, it is worth soaking the expanded clay for a short time in water. You can calculate the solution for the screed

• It is necessary to determine the thickness of the layer
• Then the dimensions of the room
• We take the weight of a bag of expanded clay per 0.05 m3
• One cubic meter of expanded clay will be four hundred kilograms

When calculating the material, it must be assumed that a layer of one centimeter of expanded clay is 0.01 m3 per 1 m2 of area located in the room. There are construction sites where the quantity is calculated in liters, then we consider that ten liters per 1 m2 will be needed per centimeter. It turns out that for dry and wet screed, the material is calculated depending on the thickness. It is also worth remembering that on the lower floors the floor is made at least ten centimeters. For warmer upper floors, four centimeters is enough. To accurately calculate the consumption of materials for a room, you need to do the following: multiply the area by the volume, which are consumed per 1 m2. An example of calculating an expanded clay screed: The area is 20 m2, the thickness of the expanded clay is four cm.

• In cubic meters: 0.04 m3 multiplied by 20 m2 equals 0.8 m3
• In liters: 40 liters times 20 m2 equals 800 liters. or 16 bags of 50 l.

We must remember that the material must always be taken with a reserve, since, despite clear calculations, there is often not enough material. When using the wet method, do not forget about sand and cement, which also need to be calculated.

Methods for producing expanded clay granules

There are several ways to make expanded clay from raw materials. Each of them is used due to certain circumstances.

Dry method

Dry method
The use of rocky clay or shale as raw materials leads to the use of this method. The method is to do the following:

• crushing of raw materials on a powerful crushing apparatus, which helps to obtain granules with sizes ranging from 1 to 20 mm;
• firing of processed raw materials in a drum kiln;
• cooling of the composition and subsequent sorting by grain size.

In most cases, production ends here. All that remains is to load the substance into bags and send it for sale. There are no grains formed here, giving them a neat appearance. Therefore, fractions obtained by the dry method can be determined by the uneven edges of each grain.

Wet method

Wet method

The wet method is implemented as follows:

• the raw materials are poured into large containers;
• water is poured into these containers, increasing the humidity of the mixture to 50%;
• using pumps, the mixture is pumped into large pools, from which it passes into the oven;
• In drum ovens, separation into granules by size is carried out, as well as drying of the resulting grains.

The method is very suitable for raw materials that initially have high humidity. By adding water and subsequent drying, it is possible to get rid of excess inclusions and obtain a uniform surface of each granule. It is worth noting that this method requires more energy consumption, but helps to obtain a higher quality product.

Plastic method

Plastic method

This expanded clay manufacturing technology is used if the raw material has a moisture content of less than 30%. The clay is passed through hard rollers, which grind the granules to obtain fractions with grain sizes from 5 to 10 mm. Then everything is placed in drying drums and rolling machines, which give each grain the correct oval shape.

After this, the entire mixture is fired in ovens at a temperature of about 1000 degrees. Firing is carried out in drum kilns, the drums of which rotate all the time. The finished granules are transferred to cooling units and dried. And only after that all expanded clay is sorted by granule size.

Powder-plastic method

Powder-plastic method

This method involves pre-grinding the clay to a powdery state. The powder is mixed with water, thus obtaining a homogeneous mass. Then granules of the correct shape are formed from this mass and the same thing is done as in the previous methods. The fraction is fired and dried. This method helps produce the most accurate mixtures that can be used. However, you have to pay more for high-quality granules, since the method contains additional steps.

The powder-plastic method requires the use of well-processed raw materials, since otherwise the quality of the granules will be significantly reduced.

Main characteristics of the material

It is known that houses built from baked bricks will be much more comfortable than concrete buildings. Processed clay is a poor conductor of cold and heat. Construction expanded clay has similar characteristics due to its porous structure. However, what is the thermal conductivity of this material? This question is especially relevant for those who are going to use bulk insulation for thermal insulation.

The thermal conductivity of this material averages 0.12 W/mK. True, the size of the fractions must also be taken into account. In addition, granules have a number of other properties, which makes them so popular among developers. First of all, this is the strength of the material. During compression tests, expanded clay was destroyed by no more than 13% of its volume, which created additional compaction of the layer of this material.