What is the expanded clay fraction 10 20. Concept and characteristics of expanded clay gravel (expanded clay). Expanded clay thermal conductivity by fractions

02.05.2020

This is a building material that looks like crushed stone or gravel, made by firing clay or clay slate for half an hour under a temperature range of 1,000 to 1,300 degrees. The result is a light and porous raw material, characterized by oval shapes. This is expanded clay, the fractions, features and characteristics of which will be discussed below.

The parameters for expanded clay are determined by GOST, which regulates the quality of building materials with a porous structure. Let's look at the main properties in more detail:

fractional composition. Three fractions were identified, varying in the ranges of 5 – 10, 10 – 20, 20 – 40 mm. Fractions that are rarely used in construction are included in a separate category. These include crushed stone and expanded clay granules with fractions from 2.5 to 10 mm, a wide mixed fraction of 5 – 20 mm. Thermal insulation layers used as bulk material are represented by a mixture of all expanded clay samples, the fractions of which are 5 – 40 mm. This is explained by the need to fill void areas in order to increase the rigidity of the structure and eliminate convection of air flows;
density grade. Seven values are established, the data of which is given in the table:

M 700 and M 800 are not produced for general consumption; this requires prior agreement with the customer. The true density indicator exceeds the bulk value by one and a half to two times. This parameter characterizes the density of expanded clay, without taking into account the intermediate areas between individual granules or fragments;

strength of the material. Expanded clay gravel has thirteen grades with different strength indicators after compression in a cylinder. For crushed stone, eleven values are standardized with the same abbreviation as for gravel grades. At the same time, crushed stone and gravel of the same brand have differences in strength. It should be noted that as the density of the material increases, its strength increases. There is also a mutual relationship between brands, regulated by standards, which completely eliminates the preparation of low-quality expanded clay with a high density indicator, but which immediately collapses under light loads;
compaction coefficient. This value is agreed with the customer and does not exceed the value of 1.15. It is used to take into account the compaction of the mass of material obtained from transportation or storage, which often happens with fine-fraction expanded clay. The need to use such a coefficient is caused by frequent shipments of materials using the bulk method, which is very convenient for selling large volumes;
thermal conductivity. An important parameter characterizing the level of thermal insulation of the material. For expanded clay this coefficient is 0.10 – 0.18. The range is quite narrow, which once again confirms the high thermal insulation qualities of the raw materials. This coefficient increases with increasing density, which is explained by a reduction in the number and size of porous areas that contain air;
moisture absorption. Another important indicator that determines the behavior of expanded clay when exposed to a humid environment. The material is considered a sustainable raw material, the water absorption value is 8 - 20 percent;
sound insulation. Like many other thermal insulation materials, expanded clay is characterized by increased sound insulation. The best results are achieved by laying a layer on a wooden floor, using expanded clay as a layer separating the outer surface of the floor and the floor pit;
resistance to low temperatures. Since the basis of expanded clay is clay, and the level of water absorption of the material is low, the raw material has a high frost resistance. In numerical terms, the standards are not standardized, because expanded clay resists low temperatures “by default.”

Types of factions

Based on their shape, external characteristics and manufacturing technology, expanded clay fractions are divided into several types.

Small

Fine particles, which are by-products obtained during firing or crushing of the material, are used as porous fillers.

Sand of fraction 0 - 5 mm has become an excellent alternative for replacing simple quartz sand in solutions, which increases the coefficient of their thermal conductivity. This means that the mortar used in masonry work, based on expanded clay material, is several times warmer than the sand-cement composition that is familiar to everyone.

Average

Expanded clay gravel is one of the most popular building materials. It is represented by rounded grains, the sizes of which reach 10 – 20 mm. Gravel is formed in pyrogenic furnaces due to the swelling of super-melting clay raw materials. The material is considered moisture and frost resistant and does not ignite in a fire.

Large

This expanded clay material is represented by a filler of arbitrary shape, in most cases angular. The size of the pebbles reaches 4 cm in diameter. Expanded clay crushed stone is obtained by crushing large pieces of expanded clay mass.

Scope of application of expanded clay fractions

Sand, the average value of which does not exceed 5 mm in diameter, is mainly used for interior decoration. This fraction of expanded clay is excellent for pouring cement floor screeds. A solution prepared with such material allows not only to level the surface, but also to insulate it. In addition, the material is used in the manufacture of various concrete products and is widely used in crop production as a drainage element. In addition, hydroponic systems are made from such filler.

A larger fraction of expanded clay (5 – 10 mm) is used to create a “warm” floor using German technology. It is used as backfill material for gypsum fiber sheets. In addition, the material is an excellent insulation material for facades. In this case, a truly unique technology is used: expanded clay is mixed with a small amount of cement material, the prepared mass is poured into the space between the load-bearing walls and the cladding layer. This method of insulation is called “capsimet”. It should be noted that if you are in doubt which fraction of expanded clay is best suited for pouring concrete products and structures, you can safely use this particular type of material.

Gravel material has a small bulk area, so it is recommended to use it when backfilling attics, basements, foundations, when it is necessary to install a fairly large layer of thermal insulation. This expanded clay is the best option for constructing a drainage system for planting trees and shrubs.

Expanded clay from the same group of medium and larger fractions (10 - 20 mm) is used as an insulating material for roofing structures, floors made of wood materials, and walls if they are built with well masonry. The material is indispensable for the construction of street water supply and sewer systems and other communication lines. By using expanded clay to insulate heating mains, you can be absolutely sure that heat loss will be minimal. In an emergency, you won’t have to spend a lot of time digging to find the leak.

Having successfully completed the repair work, you can always use expanded clay again, since it will not lose its properties even if it gets wet.

As builders note, sales volumes of expanded clay material are not much inferior to sales of more common building materials. The construction of a thermal insulation layer from it is considered the main, but by no means the last useful application, because to the specified quality one can safely add reliable noise insulation. The “underlying” qualities of the material are also popular, so expanded clay fractions are quite suitable as a basis for concrete screed. In conclusion, we can add that today expanded clay material has a low cost, acceptable for any consumer.

Modern house It is impossible to imagine without insulating elements. And this determines the wide offer of necessary materials, both in form and composition.

It is suitable as insulation "from heaven to earth". Granules are used to insulate the roof and walls, poured under the floor for the same purposes, and provide thermal insulation for the foundation.

The term "expanded clay" implies several types of insulation, united by common raw materials for production. Three fractions of gravel, sand and crushed stone are distinguished.

Gravel looks like round or oval granules. It is produced by firing low-melting rocks in rotary kilns. Features of application are determined by the diameter of the fraction:

Expanded clay gravel, fraction 20 – 40 mm. Has the lowest bulk density. It is used where a thick heat-insulating layer is needed: filling foundations and cellars, backfilling floors in attics.
Expanded clay gravel, fraction 10 – 20 mm. Serves as insulation for roofs, floors in the house and walls with a well masonry method.
Expanded clay gravel, fraction 5 – 10 mm. It is used for backfilling as a base under a “warm” floor. Grains of this fraction are used when insulating the facade, when a mass of a small amount of cement and expanded clay is poured between the masonry and the facing layer.

Sand obtained by sifting fine clay and crushing large pieces of expanded clay in shaft kilns. Areas of use:

Expanded clay sand, fraction up to 5 mm. Indispensable for laying cement floor screeds.
Expanded clay sand, fraction up to 3 mm. Allows you to obtain a unique “warm” masonry mortar. The thermal conductivity of such a solution is 0.34 W/(m*C), while that of a mixture based on quartz sand is 1.15 W/(m*C).

Crushed stone also comes from crushing large parts of baked clay. It is used as a filler in the production of concrete structures with lower specific density and better heat and sound insulation.

Advantages and disadvantages of the material

As a result of the analysis of these varieties of expanded clay, the conclusion suggests itself that it is better to choose gravel as insulation. His advantage confirmed by a set of properties:

Durability. Retains its qualities for a long time.
Fire resistance. The material is absolutely not flammable.
Chemical inertness. Not affected by acids and other chemicals.
Biostability. Resistant to fungus formation and does not allow rodents to enter.
Frost resistance. Stable under temperature fluctuations. Tolerates more than twenty shifts of freezing and thawing.
Low bulk density. From 250 to 800 kg/m3. The larger the fraction, the lower the density.
High strength.
Good heat and sound insulation. A consequence of low thermal conductivity, about 0.16 W/m, and porosity.
Ecological cleanliness. Does not emit harmful substances.

Worth considering separately reaction of expanded clay to water. It has solid water resistance and, if the gravel is dried after wetting, all parameters will be restored.

But at the same time, expanded clay has noticeable moisture absorption. Moisture-saturated gravel gains weight and loses in insulating qualities. Therefore, do not forget about waterproofing.

Important! When insulating horizontal and inclined surfaces with expanded clay gravel using the dry filling method, use dense polyethylene film or bitumen-based roll material for vapor barrier. To ensure airtightness, the sheets are laid overlapping, and on the side walls they are folded to the level of the backfill.

Compare Table 1 will help you with the technical characteristics of various types of insulation.

Table 1. Basic technical characteristics of some popular insulation materials

Name of insulation	Specific gravity, bulk density, kg/m 3	*Thermal conductivity, W/(mS)**	Moisture absorption coefficient,%
Expanded clay (gravel)	250	0,099	10-20
Same	300	0,108	10-20
"	350	0,115	10-20
"	400	0,12	10-20
"	450	0,13	10-20
"	500	0,14	10-20
"	600	0,14	10-20
Foam glass	200-400	0,07-0,11	0,05
Fiberglass mats	150	0,061	10-130
	40-180	0,036	50-225
	40-80	0,029-0,041	18-50
	125	0,052	3-5

The table is based on the data SP-23-101-2004 and advertising sites.

Gravel consumption It is not difficult to determine, given its loose form. When filling large areas, you simply need to calculate the required volume. And 0.1 cubic meters are spent on insulating surfaces. m per layer of 10 cm per 1 m 2.

On a positive note The use of expanded clay in home insulation measures should be recognized:

We guarantee that having completed all the work correctly, the house will be insulated for its entire service life.
The material does not emit harmful substances.
The opportunity to do everything yourself. Minimal skills required.

Coefficient of thermal conductivity expanded clay gravel is slightly higher than that of modern synthetic and mineral insulation. This leads to the main disadvantage, which manifests itself in the significant thickness of the insulating layer and an increase in the thickness of the walls. It is advisable to take this incident into account at the design stage.

How work on insulation with expanded clay is carried out

Expanded clay gravel very easy to use material. It does not require any special tools. You will need shovels, buckets (stretchers), ramming beams, a building level, usually a tape measure, beacons.

Consumable materials: vapor or waterproofing, tapes, etc. for gluing seams, cement for preparing milk.

Foundation

For the foundation thermal insulation is needed to protect against annual temperature fluctuations. The technology for its protection by filling with expanded clay is as follows:

A trench is dug around the finished foundation with a depth corresponding to the amount of soil freezing. The trench width is at least 50 cm.
In the resulting cavity, formwork is placed from available materials (boards, slate sheets).
Waterproofing work is carried out on the bottom and side surfaces (film, roofing felt, etc.).
Expanded clay gravel is filled to zero level and compacted. The surface is leveled.
The insulation on top is also insulated from moisture.
Then a blind area is made around the foundation or a thin layer of soil is poured.

Floor

Insulate the floor on a concrete base from the cold from below will result from the step-by-step implementation of the following operations:

The surface is carefully prepared. All rubbish is removed and any unevenness is leveled out.
Vapor barrier is provided. The perimeter film is folded onto the wall to the height of the expanded clay layer.
Beacons indicate a given level. You can fix the beacon slats with small lumps of solution.
Expanded clay is poured when the solution under the beacon strips sets. It's better to take granules of different fractions, to obtain a more durable layer.
The embankment is leveled along the beacons with a lath or rule. And then it pours from above "cement milk".
The final stage is cement screed. It is advisable to lay a reinforcing metal mesh on the expanded clay in front of it. The thickness of the screed is selected to be at least three centimeters.

Walls

Exterior walls in the house are responsible for maintaining heat to the greatest extent. But the technology for insulating them with expanded clay is more complicated than for the floor or ceiling. Such walls must be erected by a professional mason.

Masonry is underway in two layers: internal (main) and external from facing bricks. The gap between the masonry is about ten centimeters, where the expanded clay is poured. Between the masonry, jumpers-ligaments are required.

Ceiling

Wooden ceiling can be insulated with various materials, including expanded clay. First, the ceiling must be prepared. Check beams and ceiling boards. Replace unusable ones and, if necessary, rebreak the boards more tightly. After all, with insulation, the load will also increase.

Procedure then like this:

We cover the structure with a vapor barrier material. The joints need to be glued. Bend the edges to the height of the backfill.
Pour expanded clay to the height of the beam.
Apply a cement screed to the gravel layer or, in extreme cases, cover it with waterproofing.
If the attic will be used as a living space or for storing things, lay a floorboard on top.

From all of the above, we can conclude that expanded clay rightfully occupies one of the leading places among insulation materials.

How environmentally friendly expanded clay insulation is produced and used - look at the video:

When choosing expanded clay for various construction works, it is advisable to familiarize yourself with its main characteristics in advance. The physical and mechanical properties and application of this environmentally friendly material are largely determined by the size of the granules. Where to use expanded clay of different fractions and how it differs - this is what we will talk about next.

Porous clay granules, expanded under the influence of high temperatures, acquire a whole range of useful qualities, while remaining as natural as possible. Expanded clay of any fraction is characterized by a high level of heat and sound insulation, strength, resistance to frost and fire, and low volumetric weight. At the same time, the material has its own characteristics, depending on the “caliber” of the particles. You will find a detailed description of the expanded clay manufacturing method.

Description and characteristics

Granules are made in sizes from 0.05 to 4 cm, they are divided into 4 categories - expanded clay sand 0-5 mm and three types of gravel:

small – 5-10 mm;
average – 10-20 mm;
large – 20-40 mm.

Table 1 shows the main technical characteristics of the named varieties.

Comparing expanded clay fractions with each other, it is worth noting that the heat-saving capacity of medium and coarse gravel is somewhat greater. Taking into account their low bulk density, it is better to use them for insulating unloaded areas. And, conversely, fine-grained material is more durable - such expanded clay is most often chosen for floor screed. All types are characterized by a high level of moisture absorption (from 8 to 20%), and therefore require reliable waterproofing.

Application of expanded clay

Due to the variation in the values of physical and technical parameters, the use of bulk material from baked clay has its own nuances.

1. Expanded clay sand (0-5 mm).

There are two types of technology for producing fine-grained expanded clay. The first method is firing small particles of clay in special kilns with active aeration. This is an ineffective technique because small granules stick to large ones. Higher-quality small-caliber expanded clay is obtained by crushing expanded clay gravel on special roller crushers. The price of crushed expanded clay is much higher than granulated.

Fine expanded clay is used for thermal insulation of floors and wall masonry.

Wet screed. In order to achieve real insulation with its help, small granules should not be introduced into the solution. As a result, their pores become clogged with cement, and thermal insulation deteriorates. It is better to backfill the floor layer by layer with expanded clay (4 cm each), distributing the cement-sand mixture between them. This technique allows you to install screeds with a maximum thickness of 200 mm.
Warm solution. From the point of view of thermal resistance, the most vulnerable point in the masonry is the seams. A conventional sand-cement composition has a thermal conductivity coefficient of 1.15 W/m o C (more than that of sand-lime brick). This figure can be reduced several times if you use fine expanded clay sand (0-3 mm). By blocking the “cold bridges”, the wall is insulated.

Crushed sand is also used in the production of expanded clay concrete. Small particles mix well with cement and sand concrete, so the blocks are stronger and harder than those made from expanded clay gravel (but less warm).

2. Fine gravel (5-10 mm).

The material of this fraction is used in several directions.

2.1. Expanded clay for leveling floors - dry screed. It provides insulation and ideally levels the plane for subsequent installation of gypsum fiber sheets (gypsum fiber sheets). If the screed is 10 cm thick, then for backfilling you should buy fine gravel at the rate of 35-40 kg per 1 m2. First, the floor is covered with polyethylene film, a screed level is applied, expanded clay insulation is poured into sectors, it is leveled with a rule, GSP sheets are laid, and the cracks are filled with polyurethane foam.

2.2. Insulation of facades. Gravel of the 5-10 mm fraction is used to create thermal insulation layers during the construction of walls. The following options are possible:

filling cavities with lightweight well masonry;
filling the space between the internal brick wall and the external structure made of sand-lime or facing bricks, as well as concrete blocks for plaster;
thermal insulation of a frame or block house - backfilling fine gravel between the wall and the facade material (for this purpose, leave a gap of 10 cm).

In all cases, the insulation is compacted and poured with cement laitance. To protect porous granules from dampness, a ventilation gap is installed. Fine gravel is widely used in the production of expanded clay concrete blocks, characterized by low thermal conductivity.

3. Medium gravel (10-20 mm).

Like its smaller analogue, it is suitable for filling the space between external and internal walls. Another area of application is the insulation of a flat roof or a pitched roof with a slight slope. First, the rafters with the sheathing are lined with a vapor barrier, then the bulk building material is laid in a layer of 20-30 cm. To evenly distribute the granules along the length of the slope, transverse stops are secured between the rafters. Expanded clay is poured in portions, covered with rolled waterproofing, the joints of which are sealed with bitumen mastic. The roofing material is installed step by step.

When carrying out work, the weather must be dry. The roof structure requires additional strengthening to support the weight of the insulation. The flat roof is reinforced with a reinforced concrete slab. For a pitched roof, the cross-section of wooden elements is increased, additional stops, struts, and bars are installed.

4. Coarse gravel (20-40 mm).

The material of this fraction has a low bulk density, and therefore has found application as insulation for attic floors, basements, and foundations.

Thermal insulation of the attic. Due to the low weight of expanded clay of large fractions, the load on the floors is reduced, so the thickness of the insulating layer in the attic can be increased to 16 cm. First, the beams are protected with a vapor barrier (Izospan, aluminum foil, polyethylene film). Next, a layer of crushed clay is laid, and coarse gravel is poured on top. To increase the strength of the surface, a wet screed is applied to the expanded clay (if the floors allow).
Insulating the floor in the basement. A sand cushion is placed on the earthen base and compacted. Lay polyethylene film over the walls, cover with a layer of expanded clay 10 cm thick. Reinforce it with steel mesh on top and lay a cement screed. If the floor is already covered with concrete, longitudinal and transverse joists are mounted on it. The resulting cells are filled with gravel, after which the frame is sheathed with wooden flooring.
Thermal insulation of the finished foundation with expanded clay. This method is quite old, but is still popular. The technology involves digging a trench along the perimeter of the foundation to a depth of soil freezing, with a width of at least 50 cm. Formwork is constructed from available materials (slate, used boards or bars). Its inner surface is lined with roofing felt for waterproofing. After this, fill the space with gravel of a fraction of 20-40 mm, cover it with roofing felt. Sand is poured on top and a concrete blind area is made.

Average cost of expanded clay

The price of bulk insulation depends on the size of the granules and the grade of strength, as well as on the form in which it is supplied - packaged in a bag or loose. Expanded clay in bulk of any fraction is cheaper than the same expanded clay in bags. You can buy the material in Moscow at retail and from the manufacturer (directly or through official dealers). The absence of an intermediary, as well as purchasing in bulk, can significantly reduce construction costs. The average cost of a cubic meter of insulation is shown in Table 2.

Type of delivery	Price, rub/m3
Fraction	0-5	5-10	10-20	20-40
In bags	2200	2050	1400	1400
in bulk	1900	1750	1100	1100

Buyers are often interested in... This depends on the fraction of the material and the container capacity: it comes in 50-, 40- and 25-liter sizes. Table 3 will help you compare the cost of packaged insulation.

Fraction	Bag, volume, l (m3)	Number of bags in 1 m3	Price per bag, rubles
0-5	40 (0,04)	25	88
5-10	40 (0,04)	25	82
10-20	25 (0,025)	40	35
10-20	50 (0,05)	20	70
20-40	25 (0,025)	40	35
20-40	50 (0,05)	20	70

Expanded clay has different technical characteristics of fractions 20-40 and 10-20. In this article we will consider its properties and varieties, application in construction and in the production of building materials. Despite the emergence of new materials for thermal insulation, this insulation is still in demand. It is impossible to imagine modern construction without the use of expanded clay.

Expanded clay is a natural and environmentally friendly thermal insulation material with a fraction of 10 to 40 mm. The material is obtained by firing special types of clay in high-temperature ovens. This clay swells when heated sharply, resulting in a durable bulk thermal insulation material with low weight, but with a low thermal conductivity coefficient - this property applies to all fractions from 10 to 40 mm.

Expanded clay has some advantages over mineral wool. Most mineral insulation materials decompose and cake over time. Expanded polystyrene emits harmful substances and is a fire hazardous material. Expanded clay is environmentally friendly, does not decompose, is resistant to moisture and open flame, and has good heat and sound insulation.

This porous material is one of the most effective for thermal insulation, which is in great demand in the production of building materials (expanded clay concrete, lightweight concrete, etc.) and for insulating residential buildings (floors on the first floor of a house, etc.). The main properties are: grain fraction, bulk density and strength. See the photo below for the use of the material.

Varieties of expanded clay

Expanded clay sand has a fraction size from 0.14 to 5 mm. It is used as a filler for concrete and mortars, for thermal insulation of floors and interfloor ceilings with low backfill thickness (up to 50 mm).

Expanded clay gravel has fraction sizes from 5 to 40 mm. It is used as a filler in the production of lightweight concrete, for thermal insulation of horizontal surfaces on roofs and floors.

Expanded clay crushed stone has fraction sizes from 5 to 40 mm. The material is obtained by additional crushing of large pieces of expanded clay, because of this the crushed stone has an irregular and angular shape.

Technical characteristics of expanded clay

In appearance, expanded clay is a round-shaped porous material granules of various sizes. It is used extremely widely in construction today; the main purpose of the material is to insulate structures during construction, as well as to reduce the weight of building materials during their production without loss of strength. See the characteristics of bulk thermal insulation in the table below.

Expanded clay thermal conductivity by fractions

Expanded clay is divided into gravel fractions: 5-10 mm; 10-20 mm; 20-40 mm and sand (0-5 mm). Based on density and strength, gravel is divided into grades from M300 to M700. These numbers indicate bulk density, but do not indicate the strength of the material or its thermal conductivity. Technical characteristics of expanded clay in terms of strength and bulk density:

Fraction 20-40 mm (M300 - M380) - gravel strength grade P50 - P75
Fraction 10-20 mm (M400 - M450) - gravel strength grade P75 - P100
Fraction 5-10 mm (M500 - M550) - gravel strength grade P100 - P125
Fraction 0-5 mm (M600 - M700) - gravel strength grade P50 - P75

Expanded clay thermal conductivity characteristics

Use of expanded clay in construction

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

When laying expanded clay, it should be protected from getting wet and absorbing moisture with a waterproofing film (polyethylene, roofing felt, etc.).

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%.

Improvements in construction technologies are 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 the building materials that has accumulated good strength and thermal insulation properties is expanded clay.

General properties of the material, its structure and types

Expanded clay is produced from clay by high-temperature firing, carried out at specialized enterprises. The outer surface of 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 found in most important building materials - brick, cement and a number of others. Its natural properties are characterized by high strength parameters, which expanded clay is not without. Despite the porous structure, which improves thermal insulation properties, its compression resistance is sufficient for use in concrete, expanded clay blocks and conventional backfill.

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

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;
expanded clay crushed stone– are fragments of large expanded clay conglomerates obtained by splitting the latter. The shape of the crushed stone is angular and has sharp edges. Primary use is limited to addition to concrete;
expanded clay screenings or sand– small particles that are a by-product of firing or crushing expanded clay and are used as a porous filler.

Gravel and crushed stone range in size from 5 to 40 mm, and expanded clay sand has particles smaller than 5 mm. Small crushed fractions of expanded clay are used in water purification (filtration) systems, and also as bedding in terrariums and aquariums. Such use is one of the evidence of low toxic qualities, allowing expanded clay to be given a “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 part of concrete or insulated wooden and concrete floors. The cost of expanded clay is the lowest among available thermal insulation and structural materials, for which it deservedly receives a “5” rating.

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 take a closer look at the main properties of expanded clay.

Factional composition. In total, three fractions of material have been established, having a size range of 5-10 mm, 10-20 mm, 20-40 mm. A separate category includes fractions that are rarely used in construction work. 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. Thermal insulating expanded clay layers used in the form of bulk mass are a mixture of all fractions - from 5 to 40 mm. This is due to the need to fill voids in the heat-insulating layer, which increases the rigidity of the structure and eliminates convection air currents.
Expanded clay grades by bulk density (volumetric bulk density). A total of seven values are 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 volumetric weight) is 1.5-2 times greater than bulk density. This parameter characterizes the density of the material without taking into account the gaps between granules or fragments of the material;
Expanded clay grades by strength. For gravel, there are 13 grades, differing in strength when compressed in a 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 varies. Thus, 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 relationship between expanded clay grades 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 eliminates the production of low-quality high-density expanded clay that breaks down under light load.
Compaction factor– a value agreed with the consumer, which does not exceed 1.15 and is used to take into account the compaction of the expanded clay mass as a result of transportation or caking. The use of the coefficient is associated with frequent shipment of material by bulk volume, which is convenient for the sale of large quantities.
Thermal conductivity– is the most important parameter characterizing thermal insulation properties. For expanded clay, the thermal conductivity coefficient ranges from 0.10 to 0.18 W/(m?°C). The range of values is quite 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– an important parameter showing the behavior of a material when exposed to water. Expanded clay is a relatively resistant material 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 fairly high frost-resistant properties. Numerical values are not standardized by standards, since expanded clay is frost-resistant “by default.” Only the indicators of building stones that contain expanded clay - expanded clay blocks - are standardized.

Disadvantages - individual parameters

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

These include the following:

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

Minor shortcomings, combined with high performance indicators, allow us to rate the practicality of expanded clay at 4 points.

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

An alternative to expanded clay - expanded polystyrene and vermiculite

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

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

Another disadvantage of polystyrene foam is its fire hazard. If a fire occurs, polystyrene foam will not only support the fire, but also release toxic gases.

Vermiculite belongs 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 layers or bedding. For the production of composite blocks, expanded clay is still unrivaled.

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 the thermal insulation of apartments. High performance and relatively low price make expanded clay optimal for a modest budget. The use of expanded clay substitutes is possible, but justified only in a small number of cases.

Expanded clay gravel has high heat-saving and sound-proofing properties, which makes it suitable for insulating various structures everywhere.