Average density of expanded clay. Technical characteristics and specific density of expanded clay. How much does a cube of expanded clay weigh

Expanded clay is a unique material that finds its application in numerous areas of construction and some others. It is especially good for floor insulation.

What is expanded clay?

Expanded clay is a rather lightweight, as well as a porous material of a cellular structure, looks like gravel, sometimes crushed stone. It is obtained by firing clayey fusible rocks, which can be pushed in at fairly rapid heating for 30-45 minutes at a temperature of 1300 ° C.

The quality of expanded clay is determined by:

• the size of its grains;
• strength;
• volumetric weight.

Expanded clay, depending on the grain size, is divided into fractions: 20 - 40, 10 - 20, 5 - 10 mm. If the grain size is less than 5 mm, then such material is expanded clay sand.

The material of different fractions has different purposes

Depending on the bulk density, measured in kg / m3, expanded clay gravel is divided into grades 150 - 800. Expanded clay has a water absorption in the range from 8 to 20%.

What is it for?

Today, expanded clay is a fairly popular building material used for various purposes:

Material properties

Expanded clay is a unique material with the following properties:

• Good thermal insulation and sound insulation.
• High durability.
• Frost resistance, fire resistance and a certain moisture resistance.
• Durability.
• Inert to chemical attack, including acid resistance.
• Environmentally friendly.
• Excellent value for money.

How much does expanded clay weigh?

The weight of expanded clay directly depends on its dimensional characteristics and can vary in the range of 300-600 kg / m 3. When determining the average value, its weight will be equal to 400 kg per 1m 3.

Based on the ratio of its weight to volume, that is, the bulk bulk weight, it is determined from the expanded clay grade, which is in the range of 150-800. Grade 300 denotes expanded clay, which has a bulk density of 300 kg / m 3 and so on.

Expanded clay grades by bulk density

Thermal conductivity of expanded clay

This material is mainly used due to its thermal insulation characteristics. Therefore, when choosing expanded clay, one should take into account its thermal conductivity. The most the best expanded clay for insulation, there will be one whose thermal conductivity coefficient is lower. It can fluctuate in the range of 0.07-0.16 W / m.

The thermal conductivity of expanded clay will also depend on the fraction - if the size of the expanded clay grains decreases, then the voidness will also be smaller, the bulk density increases, and the thermal conductivity also increases.

Expanded clay production

1. Raw materials are mined in a quarry and transported to the clay storage.
2. The feedstock is processed to obtain the appropriate raw granules of specified sizes.
3. The granules are heat treated. It includes drying, roasting and cooling of the finished material.
4. Sorting takes place, if necessary, separation by density and partial crushing.
5. Warehousing and dispatch for sale.

Warming the floor with expanded clay - 5 ways in steps

Expanded clay is used in many areas, but its main application is associated with floor insulation.

Insulation of the floor of a private house is carried out in different ways, based on how the floor is laid. In private houses, the floor can be compacted soil, on logs, on top of a reinforced concrete slab or concrete screed... In urban apartments, the floor is most often done on top of a concrete slab. It is also possible to insulate the floor with expanded clay in saunas and garages.

1. On the ground on logs

• Preparation for insulation includes removing the floor covering.
• If the logs are removed, the soil surface is completely cleaned and compacted. After that, they lay on him waterproofing material 10 cm approaches based on bitumen (glassine, roofing felt, etc.).
• On top of the waterproofer, the gravel fraction of expanded clay is backfilled, followed by a layer of coarse sand (expanded clay or river).
• Reinforcing mesh is laid.
• The screed is poured.

If lags are left, then the order of work changes somewhat:

1. By removing flooring, bituminous waterproofing material is covered between the lags.
2. Expanded clay is poured onto it with a thickness of about 15 cm.
3. A vapor barrier is laid on top of the expanded clay.
4. Next are the insulation plates.

Then you can do it in different ways:

• a mesh for reinforcement is laid on the plates and a screed is poured;
• over the slabs, bars are laid on the logs, and a rough floor is created from boards or fiberboard plates.

2. Floor on logs, made on brick supports

Often this floor construction is used in private, especially log houses.

1. In this case, expanded clay is filled up with space to the logs laid on the posts.
2. Then cranial bars are nailed to the logs and boards or wood boards are laid.
3. A layer of vapor barrier and insulation is laid.
4. Next, a cement-sand reinforced screed or a wood sub-floor is laid, and then the finishing one.

3. Floor laid on top of a concrete slab

Such insulation is used when there are high ceilings, and they allow you to raise the floor level. It can be used in private wooden house and in a city apartment. However, if the ceilings are not very high, and the floor is cold, then it is possible to insulate with expanded clay, even if there is a loss of height.

Cold concrete floor can be insulated with expanded clay backfill

First you need to remove the floor covering, make sure the floor is in good condition. In the case of rusty and cracks, they must be foamed with polyurethane foam... After that, you need to put waterproofing. Small expanded clay with a thickness of no more than 5 - 10 cm is laid on it, and then, on top of it, a mesh for reinforcement is laid and a rough screed is created.

You can also put a vapor barrier on top of the expanded clay pillow, a layer of slab insulation on top, after the bars and on them there is already a rough floor.

4. Creation of concrete-expanded clay floor in baths and garages

This option of insulation by design will be the simplest.

Garage flooring made of scrap materials
+ backfill with expanded clay

1. Waterproofing in the form of dense polyethylene or bituminous material is laid on the ground so that it goes onto the walls.
2. Further, beacons are mounted exactly on a horizontal surface using a level. They are strengthened with quick-drying gypsum or thick cement-sand mortar.
3. Then, using a concrete mixer, a solution is mixed (cement + sand in a ratio of 1: 2, 1 part of water and 3 parts of expanded clay). The most commonly used gravel fraction is to provide a reliable and denser slurry.
4. The expanded clay concrete mixture is then poured over the floor surface, observing the beacons. The mixture must be tamped to remove all air bubbles. As soon as the surface hardens, it must be leveled and cement laitance must be used to "iron" it.

5. Application of dry expanded clay screed

This insulation option can be used over concrete base or directly on the ground - the difference will be only in height: on the ground, the expanded clay layer can reach 20-25 cm, when laid on concrete - no higher than 10 cm.

1. To begin with, you should prepare the soil surface, that is, glue the damper tape slightly above the line to which expanded clay will be poured.
2. Then it is necessary to lay a dense plastic wrap on the ground.
3. Next, beacons are installed, and expanded clay is covered over them: if the layer is up to 10 cm, then it is recommended to use a fine fraction, if 20 cm - first gravel, then sand.
4. The layers are compacted with a small fiberboard plate, providing a flat surface along the beacons.
5. Next, two-layer GVL sheets are laid. They are strengthened with self-tapping screws.
6. On the sheets of gypsum fiber board, you can further lay any topcoat.

Expanded clay gravel is a building material obtained from clay by firing and representing fragments of a round shape with pores inside and a melted surface.

The document governing the requirements for expanded clay gravel: technical parameters, acceptance rules, test methods, transportation and storage is the Interstate Standard GOST 32496-2013 “Porous Aggregates for Lightweight Concrete. Technical conditions ”.

The production of expanded clay gravel is carried out in special drum furnaces, where the raw material, which is montmorillonite and hydromica clays, is brought to a certain structural state, after which it is cooled.

Production

The production process is divided into several stages:

1. Preparation of raw materials.
2. Burning.
3. Cooling.

Schematically, the production process looks like this:

Requirements for raw materials from which expanded clay gravel is made are determined by three parameters, these are:

1. The content of quartz should be no more than 30%, silicon oxide - no more than 70% and minerals - no less than 12%.
2. Low melting point - the firing temperature should not exceed 1250˚С;
3. Swelling interval - must meet the requirements.

The preparation of raw materials can be performed using several technologies. This is a dry preparation - when clay rock is crushed to the required grain size, followed by division into fractions. Plastic preparation - the formation of grains is carried out by kneading the feedstock in a special machine (clay mixer) and sculpting the granules, followed by drying. Powder - plastic preparation - the process is carried out similarly to the preparation by the plastic method, with the only difference that in this case, the initial raw material is converted into powder. Wet (slip) preparation - clay is mixed with water in special devices (mud slides), where a clay solution called slip is obtained, which is fed into the furnace. The furnaces, with this technology, are equipped with special curtains made of chains, which are heated during operation. The slip is fed to the chains, where it is broken into parts, which are further fired.

Firing takes place in special furnaces of various designs:

• Rotary, one- and two-drum kilns - with this design, the prepared raw material is fed into the upper part of the drum, which is placed at a certain angle to the surface of the earth. In the lower part of the drum there is a nozzle that provides heating of the internal space of the device. Clay granules roll down the walls of the drum and undergo heat treatment, during which the clay boils and swells, its top layer is melted.
• Ring - the production of expanded clay is carried out by the method of thermal shock. Finished granules are 25-40% lighter than when firing in drums.
• Vertical, aerial - expanded clay is produced in an upward flow of incandescent gases. With this design, thermal shock also occurs, which causes active swelling in the clay.

Cooling occurs in several stages with a gradual decrease in temperature: 1st stage - at the end of clay swelling - to a temperature of + 800-900 ° С, 2nd stage - within 20 minutes, until a temperature of +600 - 700 ° С and 3 -th stage - final cooling.

In accordance with GOST 32496-2013, gravel is produced in three fractions, these are:

1. Fine fraction - the size of fragments (grains) ranges from 5.0 to 10.0 mm;
2. Middle fraction - grain size is from 10.0 to 20.0 mm;
3. Coarse fraction - grain size is from 20.0 to 40.0 mm.

The main technical parameters expanded clay gravel are:

• Bulk density (bulk bulk density).

It is measured in kg per m3, 11 brands are produced - from the M150 to M800 brands, the most in demand are M450, M500, M600.

True density (bulk density) is 1.5-2 times more than bulk density.

• Strength.

The strength of the material is measured in MPa (N / mm2), 13 strength grades are produced - from P15 to P400.

There is a connection between the grades of expanded clay in terms of density and strength - an increase in density leads to an increase in strength.

• Compaction factor - the value (K \u003d 1.15) is used to take into account the compaction of the mass of the material during transportation or storage.
• Soundproofing. Expanded clay has increased sound insulation.
• Frost resistance.

Expanded clay has fairly high frost-resistant properties. It is characterized by the loss of mass of the material, measured in%.

• Thermal conductivity is the most important indicator.

Measured in W / m * K. Characterizes the ability of a material to retain heat. As the density increases, the thermal conductivity coefficient increases.

• Water absorption.

Measured in mm. Determines the amount of moisture that expanded clay can absorb. Expanded clay refers to relatively resistant materials to moisture.

• The amount of radionuclides.

The specific effective activity of radionuclides should not exceed 370 Bq / kg.

In accordance with GOST 32496-2013, the grade of expanded clay gravel should be:

• Strength, depending on the brand:

Gravel grade	Strength, MPa
	Up to 0.5	0,5 – 0,7	0,7 – 1,0	1,0 – 1,5	1,5 – 2,0	2,0 – 2,5	2,5 – 3,3	3,3 – 4,5	4,5 – 5,5
By strength	P15	P25	P35	P50	P75	P100	P125	P150	P200

• The bulk density should correspond to the strength grade, namely:

Gravel grade
By bulk density	M150	M200	M250	M300	M350	M400	M450	M500	M600	M700	M800
By strength	P15	P25	P25	P35	P50	P50	P75	P100	P125	P150	P200

The frost resistance of the material is also normalized by GOST - the weight loss of expanded clay gravel should not exceed 8%.

Thermal conductivity depends on the preparation technology and composition of raw materials, the design of the firing furnace and the cooling conditions. Depending on the density of the material obtained and the manufacturing technology, the specific thermal conductivity ranges from 0.07 to 0.18 W / m * K.

The ability of expanded clay to absorb moisture (moisture absorption) is also an important parameter characterizing this building material. The moisture absorption coefficient for different brands ranges from 8.0 to 20.0%. The ability to absorb moisture, in relation to the mass of the material, within 1 hour, should be no more, for brands:

• Up to М400 - 30%;
• M450 - M600 - 25%;
• M700 - M800 - 20%.

The total moisture content of the shipped batch of material should not exceed 5.0% of the total mass of gravel.

After the expanded clay is made, the finished material is sent for sale, in the form of a scatter or in a certain package, while the amount of damaged (split) grains should not exceed 15% of the total mass of the manufactured material.

In addition, in the production of expanded clay gravel, the shape of the grains is controlled, which is determined by the shape factor. The shape factor should be no more than 1.5, and the number of grains exceeding this indicator should also be no more than 15% of the total amount in the batch of material.

When selling in bulk and using containers, the selling organization must have certificates of conformity, test results and consignment notes for the material. When sold in containers (packaged), products are marked on the packaging. The marking indicates: the name of the filler, manufacturer's data, date of manufacture, thermal conductivity value, amount of filler, test results and designation of the standard.

For packing, paper, polypropylene and fabric bags are used, which must meet the requirements of GOST for this type of container. Marking is applied to each bag, in accordance with the requirements for marking goods indicated above.

Control over the quality of the material is carried out by the manufacturer, at the same time, control is carried out from the moment of receipt of raw materials until the end of the production process (input, operational and acceptance control), data about which are recorded in special journals and drawn up in protocols.

When conducting acceptance tests, the following are determined:

• grain composition in each batch;
• bulk density;
• strength;
• grain shape factor;
• the content of broken grains in the gravel;
• humidity.

With long-term storage of the finished material, periodic tests are carried out, which are carried out:

• once every two weeks - the weight loss on ignition and the content of lightly fired grains are checked;
• once a quarter - the weight loss during boiling is checked;
• once every six months - frost resistance and softening coefficient are checked;
• once a year - the specific effective activity of natural radionuclides and thermal conductivity are checked.

At the start of production and each time the raw material changes, tests are performed to check for radinuclides and thermal conductivity of expanded clay.

Expanded clay prepared for sale is shipped, while the amount of material is measured by volume or its mass, taking into account the compaction coefficient (K \u003d 1.15).

Advantages and disadvantages

Advantages of using:

1. Sufficient material strength.
2. Low thermal conductivity, and as a result - good thermal insulation properties.
3. It is a good sound insulator.
4. High refractoriness, defines this material as non-combustible, fireproof. When exposed to an external fire source, combustion does not support, harmful substances into the surrounding space - does not emit.
5. Frost resistance.
6. Small specific gravity - allows you to use, if necessary, reduce the mass of building structures being built
7. Not affected by atmospheric agents (humidity, temperature changes).
8. Inert towards chemical attack.
9. Does not rot or decay.
10. Long service life.
11. It is an environmentally friendly material.
12. Ease of installation work.
13. Low cost in comparison with other heat-insulating materials.

The disadvantages are:

1. When laying horizontally, the sub-base must be laid.
2. In case of poor manufacturing or manufacturing without the formation of a surface crust, it absorbs moisture, after which it cannot be used as a heat insulator.
3. When used as insulation, it occupies a large volume, thereby reducing the space in the insulated room.

Thanks to its positive properties, expanded clay gravel is widely used in various types of construction work, such as:

• monolithic construction - used as a filler;
• thermal insulation is the roofs, floors and floors of buildings, structures and structures;
• thermal insulation different systems - "warm floor", water pipes, external heating pipes and other pipe systems.
• protection against noise of the interior space;
• production of concrete and building blocks;
• thermal insulation of the foundation - allows you to reduce the depth of the foundation;
• road construction - used for thermal insulation and drainage during the construction of embankments for roads and during construction in wetlands.

Expanded clay is also used to create landscape design site (creation of alpine slides and terraces), if necessary, thermal insulation of the soil (when growing plants) and in crop production - to create drainage of the root system of plants.

When choosing ceramic gravel, you must follow the selection criteria, which are:

• The quality of the material.
• Availability of a certificate of conformity.
• Storage conditions for the finished material.
• The integrity of the fragments (grains) of the material.
• Color and presence of crust on expanded clay grains.

Expanded clay gravel, due to its positive properties, is widely used in various industries industry and economy, both in our country and abroad.

Density of expanded clay
Natural lightweight material expanded clay has many characteristics. At the same time, one of the most important is its density, which directly depends on the chosen mode of clay processing - that is, the manufacturing method.

Due to the fact that initially expanded clay has a low density, its derivatives - expanded clay concrete and expanded clay concrete blocks - also have a low density, unlike other materials. However, this parameter has no effect on the mechanical strength of the material. Due to the special internal structure, expanded clay granules have high resistance to loads, due to which panels, blocks and monolithic structures made of it are reliably protected from destruction.

Divide expanded clay into fractions allows the size of their granules. So, they distinguish expanded clay sand (the smallest particles of 0-5 mm), expanded clay gravel (material with sizes of 5-10, 10-20, 20-40 mm) and expanded clay crushed stone (large particles of 0-10, 10-40 mm ).

Before choosing a material fraction, it is necessary to determine the density of expanded clay. Its quality will be influenced by the bulk density, grain volume and porosity. Density of bulk material varies from 250 to 800 kg per cubic meter.

Calculation of the true density of expanded clay
This indicator allows you to determine the specific weight of expanded clay. To carry out the calculation, it is necessary to know its dry weight, which must be divided by the volume of the substance in the dense state.

Determination of the specific density of expanded clay
This value is variable, measured in kilograms per 1 cubic meter and depends on the fraction of the material: for gravel - 450-700, for crushed stone - 600-1000, for sand - 800.

Density of expanded clay concrete
Expanded clay concrete can be of various types, which determines its bulk density (unit of measurement - in kilograms per 1 cubic meter):

• constructive - 1200-1800;
• thermal insulation - from 350-900;
• heat-insulating and constructive - 700-1400.

Comparative characteristics of bricks and lightweight aggregate blocks

• the density of the brick is greater than the density of expanded clay blocks, which is why brickwork 2.5 times heavier than block;
• 7 bricks are comparable in volume to 1 block of expanded clay - this allows you to triple the speed of masonry;
• walls made of expanded clay blocks are thinner than brick walls, but they are distinguished by high thermal insulation.

Due to low density expanded clay blocks help to construct buildings with light walls, reduce the load on the foundation and significantly reduce heat loss - up to 75%, which allows you to save money. Expanded clay wall panels have different densities due to the type of construction - they can be one-, two- or three-layer.

It is safe to say that such material as expanded clay refers to those types of insulation that are still difficult to find a replacement for. This is primarily due to its harmlessness to the people present in the building.

The physical parameters of expanded clay - specific gravity and density - are characterized by relatively small values. The internal structure is shaped like the smallest cells. When it comes to the main purpose of expanded clay, they talk about bulk density as the main characteristic of the material.

Possession of this information allows a specialist to select a faction in relation to a specific situation. But, for more objective calculations, it is required to know the numerical values \u200b\u200bof all three parameters: specific gravity, volume and size of the fraction.

Expanded clay production technology

As a raw material for the manufacture of expanded clay, specialized clay is used. In general, the process is reduced to the burning of raw materials. Before being turned into a final product, the clay must go through all the technological stages of processing. At the last stage, within a short period of time, which usually takes from 20 to 40 minutes, the temperature rises from the initial value of 1050 to 250 degrees Celsius.

An interesting effect is observed - the swelling of the heated mass, pores (or voids) are formed inside, i.e. cells filled with air. Strong granules are obtained, the surface of which melts under the influence high temperature, forming a sealed shell. The granules are able to withstand moderate mechanical stress.

What fractions of expanded clay exist?

It is interesting that with a relatively low density, expanded clay has good strength. High performance of the last parameter to granules is provided by their specific structure. The material retains its integrity, being under enormous weight, but also thanks to this, various objects in contact with the granules remain protected. Due to the existing difference in the sizes of granules, there are reasons to conditionally divide expanded clay into three types or fractions: crushed stone, gravel and sand.

Of the listed types the smallest fraction is considered sand - the size of grains of sand ranges from zero to five millimeters. Depending on which the average size granules (in millimeters), gravel is conventionally divided into three subspecies:

• from 5 to 10;
• from 10 to 20;
• from 20 to 40.

Expanded clay crushed stone is formed from crushed gravel. The most popular is the fraction called crushed expanded clay. Its particles are no more than ten millimeters in size. The required gravel density is achieved by applying plastic, wet, dry and powder-plastic modes in the manufacturing process.

About bulk density and grades of expanded clay

The density or bulk density of expanded clay, like all other materials, is measured in the same units - kilograms in cubic meter (kg / cubic meter). When it comes to expanded clay, we mean its thermal insulation properties. The main parameters - cellularity, the total volume of cells inside the granules, bulk (bulk) weight - affect the quality of expanded clay. It is impossible to say unequivocally that the bulk density has such and such a numerical value - it fluctuates between 250 and 800 kg / cu. m.

This is due to the fact that each brand has its own meaning. To distinguish them, a standard was introduced - the letter "M" and, accordingly, the number are written in front. For example, if the density is slightly less than 250 kg / cu. m, then the marking is "М250". For a density ranging from 250 to 300 kg / cu. m - "M300". Up to 450 kg / cu. m gravel is marked with an interval of 50, but then the difference in designations between two neighboring grades already doubles and is equal to 100, i.e. M500, M600, etc.

This designation of brands according to the specified principle, which depends on the density of expanded clay, has a specific naming of GOST 9757-90. Of course, according to the established rules, grades of crushed stone and gravel from expanded clay have conditional lower and upper boundaries, respectively, M250 and M600. But if necessary, these standards can be adjusted at the request of the customer, use a value that exceeds M600.

In the case of expanded clay sand, the following standards apply: M500 - M1000. If the values \u200b\u200bof characteristics close to the lower threshold refer to reference values, then the highest values \u200b\u200bshould be observed. The following conclusion suggests itself: if you choose a certain fraction, then the quality indicators will be more preferable for the expanded clay, the weight of the granules of which is minimal.

What other types of expanded clay density are there?

Knowledge of the true and specific gravity of bulk insulation is necessary condition to perform calculations. Each material has its own specific gravity. For example, in the case of expanded clay gravel, it can vary from 450 to 700 kg / cu. m, and in the case of expanded clay concrete dry mix - about 800 kg / cu. m. The specific density of expanded clay crushed stone is in the range of 600-1000 kg / cu. m.

The true density is determined using a simple formula: the result of dividing the mass of a substance in a dry state by its volume (minus the volume of cells inside the granules). It follows from this that the true density of bulk insulation, which is expanded clay, belongs to the category of constant values.

The improvement of building technologies is constantly moving towards increasing the strength of materials and reducing their weight. An important aspect, both in cold and hot climates, remains a decrease in thermal conductivity. One of building materials, in which good strength and thermal insulation properties have been accumulated, is expanded clay.

General properties of the material, its structure and types

Expanded clay is made from clay by high-temperature firing, carried out at specialized enterprises. The outer surface of the clay conglomerates is melted, which ensures its smoothness and specific color. The formation of a porous structure occurs due to gases released during firing.

Clay, in various forms, is part of most important building materials - bricks, cement and a number of others. Its natural properties are characterized by high strength parameters, which are not lacking in expanded clay. Despite its porous structure, which improves thermal insulation properties, its compression resistance is sufficient for use in the composition of concrete, expanded clay blocks and conventional bedding.

Depending on the shape, appearance and technological process production, expanded clay is divided into the following types:

1. expanded clay gravel - classic oval, almost round pellets or granules with a red-brown surface color - the main form of produced expanded clay. Such gravel is used throughout the construction industry;
2. expanded clay crushed stone - represents fragments of large expanded clay conglomerates obtained by cleaving the latter. The shape of the crushed stone is angular and has sharp edges. The main application is limited to adding to the composition of concrete;
3. expanded clay screenings or sand - fine particles, which are a by-product of firing or crushing expanded clay and used as a porous filler.

Gravel and crushed stone have sizes from 5 to 40 mm, and expanded clay sand is particles less than 5 mm. Fine crushed expanded clay fractions are used in water purification (filtration) systems, as well as a bedding in terrariums and aquariums. Such use is one of the evidence of low toxic qualities, allowing you to put expanded clay "5" for environmental friendliness.

The appearance of the material is very unpresentable, but this does not matter. Expanded clay is almost never used in open form, but is a part of concrete or insulated wooden and concrete floors. The cost of expanded clay is the lowest among the available heat-insulating and structural materials, for which it deservedly receives a rating of "5".

The picture shows a photo, a general description of expanded clay and its features

Specifications

The material parameters are established by GOST 9757-90, which regulates the quality of porous building materials. Some indicators are not regulated, but still remain an important characteristic. Let's consider in more detail the main properties of expanded clay.

• Fractional composition. In total, three fractions of the material have been installed, having a size range of 5-10 mm, 10-20 mm, 20-40 mm. A separate category includes factions that are rarely used in construction works... These include expanded clay granules and crushed stone with sizes from 2.5 to 10 mm, as well as a wide mixed fraction from 5 to 20 mm. Heat-insulating expanded clay layers, used in the form of a bulk mass, represent a mixture of all fractions - from 5 to 40 mm. This is due to the need to fill the voids in the heat-insulating layer, which increases the rigidity of the structure and eliminates convection air currents.
• Expanded clay grades by bulk density (bulk bulk density). In total, seven values \u200b\u200bhave been established: up to 250 kg / m3 - grade 250, from 250 to 300 kg / m3 - grade 300, similarly - grades 350, 400, 450, 500, 600. Grades 700 and 800 are not produced for general sale and are produced only upon agreement with the consumer. True density (true bulk density) is 1.5-2 times greater than bulk density. This parameter characterizes the density of the material without taking into account the gaps between the granules or fragments of the material;
• Expanded clay grades by strength. For gravel, there are 13 grades that differ in pressure strength in the cylinder. For crushed stone, 11 grades are standardized, having the same designations as gravel grades. The strength of crushed stone and gravel of the same brand is different. So, for grade P100, the compressive strength of gravel is from 2.0 to 2.5 MPa, while crushed stone is from 1.2 to 1.6 MPa. There is a connection between the grades of expanded clay in terms of density and strength - an increase in density leads to an increase in strength. The relationship between brands is also regulated by the GOST 9757-90 standard, which excludes the production of low-quality expanded clay high densitywhich collapses under low load.
• Compaction factor - the value agreed with the consumer, which does not exceed the value of 1.15 and is used to account for the compaction of expanded clay mass as a result of transportation or caking. The use of the coefficient is associated with the frequent shipment of material in bulk, convenient for the sale of large batches.
• Thermal conductivity - is the most important parameter characterizing thermal insulation properties. For expanded clay, the thermal conductivity coefficient is from 0.10 to 0.18 W / (m? ° C). The range of values \u200b\u200bis rather narrow, which indicates the high thermal insulation properties of the material. With increasing density, the thermal conductivity coefficient increases. This is due to a decrease in the number and volume of pores containing the main heat insulator - air.
• Water absorption Is an important parameter showing the behavior of a material when exposed to water. Expanded clay refers to relatively resistant to materials and is characterized by a water absorption value of 8-20%.
• Soundproofing - like most thermal insulation components, expanded clay has increased sound insulation. The best results are achieved when soundproofing a wooden floor, in which expanded clay acts as a layer between the outer part of the floor and the interfloor slab.
• Frost resistance - due to low water absorption and clay, which is the basis of the material, expanded clay has sufficiently high frost-resistant properties. Numerical values \u200b\u200bare not standardized by standards, since expanded clay is frost-resistant "by default". Only the indicators of building stones are normalized, which contain expanded clay - expanded clay blocks.

Disadvantages - individual parameters

The advantages of expanded clay (good strength, low thermal conductivity) are practically not influenced by its individual disadvantages. Unlike numerous heat insulators, the disadvantages of expanded clay are very conditional.

These include the following:

1. increased tendency to dust formation, which is especially noticeable when working indoors. A respirator helps to solve the problem, which should always be at hand at a construction site;
2. prolonged drying of wet material - how hard expanded clay absorbs moisture, it is so difficult to get rid of it later. To prevent high humidity in rooms containing expanded clay, reliable moisture and steam protection should be provided in advance.

Minor shortcomings, together with high performance indicators, make it possible to assess the practicality of expanded clay at 4 points.

The main properties and characteristics of expanded clay gravel, as well as its pros and cons, to a greater extent depend on the correctness of the stages of its implementation.

Alternative to expanded clay - expanded polystyrene and vermiculite

Expanded polystyrene (polystyrene) is an effective insulation material that is successfully used in interior decoration. Its thermal conductivity is about 3 times lower than that of expanded clay. This creates, at first glance, a real alternative to choice.

In reality, the methods of using these materials differ, which is caused by the high fragility of the foam boards. Insulation with expanded polystyrene is very effective, but cannot be used in places subject to mechanical stress. That is why the thermal insulation properties of foam and expanded clay do not compete with each other.

Another disadvantage of polystyrene is its fire hazard... In the event of a fire, expanded polystyrene will not only support the fire, but also release toxic gases.

Vermiculite refers to minerals expanded under the influence of high temperature and has high heat and sound insulation properties. The material is an effective replacement for expanded clay when used in the form of interlayers or bedding. For the production of composite blocks, expanded clay is still out of competition.

Another obstacle to the use of vermiculite is its price, which is 4-5 times higher than the cost of expanded clay. Despite the high thermal insulation properties of vermiculite, its use will be much more expensive.

Let's summarize. Expanded clay can be used for a wide range of construction tasks, including the construction of private houses and thermal insulation of apartments. High performance and the relatively low price makes expanded clay optimal for a modest budget. The use of substitutes for expanded clay is possible, but justified only in a few cases.

Expanded clay gravel has high heat-saving and sound-insulating performance, which allows it to be ubiquitous and insulating of various structures.