When talking about bulk materials for thermal insulation, the first thing we involuntarily remember is expanded clay, not always understanding what it really is. What are its characteristics, how to use it: then we will dispel all doubts and consider the material from all sides.
The essence of expanded clay
Expanded clay is light porous granules obtained from special types of clay with a high quartz content. It is fired at high temperatures, during which the balls swell and the shell melts.
The following depends on the type of raw material and the subtleties of processing:
- Expanded clay weight in 1 m3;
- Grain shape;
- Strength of granules.
The average weight of expanded clay in 1 m3 is 250…1000 kg. The mass and density of the material is determined by the bulk method; a relative value is obtained, which is influenced by the porosity, density of the granules and the quality of the feedstock.
Balls are classified according to strength into grades M250 - M1000. The specific gravity of expanded clay in each group is presented in the table:
Release form
By type, granules are divided into 3 groups:
- Expanded clay gravel is a classic form of oval pebbles without sharp corners.
- Expanded clay crushed stone is produced by breaking large pieces of sintered porous clay. The fragments have an angular shape, reminiscent of ordinary rubble. The material is used to add as a coarse filler to “warm” ones.
- Screenings/sand is a by-product of fine-fraction expanded clay production.
By fraction, the material can be:
- 5…10 mm;
- 10…20 mm;
- 20…40 mm in diameter.
Specifications
Properties of expanded clay:
- Thermal insulation. Expanded clay, whose thermal conductivity is 0.1...0.18 W/m*C, competes with many modern insulators of traditional flat shape.
- Sound absorption and expanded clay layer can dampen noise of any size. This quality is used when organizing floor coverings for noisy neighbors below.
- Frost resistance with proper waterproofing of the bulk material is high. It is not standardized by GOSTs, but expanded clay itself is not afraid of significant temperature changes.
- Water absorption is the weak side of foamed clay; its value can reach 20%, but no more.
- Absolute fire safety- clay does not burn, does not smolder and does not emit harmful substances at high temperatures.
Features to consider when choosing and installing:
- Stones are difficult to dry when intensely wet. When laying insulation, it is necessary to protect the insulation from moisture and steam;
- Fragility depending on the brand. If a load will be installed on the surface of the granules, you should select a material that matches the characteristics.
- High level dust formation during filling - a respirator is required to protect the respiratory system.
Application
Despite its apparent unpopularity, expanded clay has a widespread use:
- Insulating mass for walls, floors and attics;
- Underlayment layer under concrete floor screed;
- Filler for concrete mixtures;
- The underlying layer under ;
- Granules are used as drainage filler in gardening;
- Backfill.
The cost of expanded clay per 1 m3 is determined by its fraction and strength, the average price per cubic meter of the popular 5...10 mm is about 2,400 rubles.
It is safe to say that such material as expanded clay belongs to those types of insulation for which it is still difficult to find a replacement. This is primarily due to its harmlessness to the people present in the building.
Physical parameters of expanded clay – specific gravity and density are characterized by relatively small values. Internal structure The shape resembles 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 fraction in relation to a specific situation. But, to carry out more objective calculations, it is necessary to know the numerical values of all three parameters: specific gravity, volume and fraction size.
Expanded clay manufacturing technology
Specialized clay is used as a raw material for the production of expanded clay. In general, the process comes down to firing the raw materials. Before turning into the final product, clay must go through all technological stages of processing. At the last stage, over a short period of time, which usually takes from 20 to 40 minutes, the temperature increases from an initial value of 1050 to 250 degrees Celsius.
An interesting effect is observed - swelling of the heated mass, pores (or voids) are formed inside, i.e. cells filled with air. The result is durable granules, the surface of which melts under high temperature, forming an airtight shell. Granules are able to withstand moderate mechanical loads.
What fractions of expanded clay exist?
Interestingly, with a relatively low density, expanded clay has good strength. High indicators of the last parameter for granules are ensured by their specific structure. The material maintains its integrity while under enormous weight, but also thanks to this, various objects that come into contact with the granules remain protected. Due to the existing difference in granule sizes, there is reason to conditionally divide expanded clay into three types or fractions: crushed stone, gravel and sand.
Of the listed types, sand is considered the smallest fraction - the size of sand grains ranges from zero to five millimeters. Depending on the average size of the 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 fraction is called crushed expanded clay. Its particles measure no more than ten millimeters. The required density of gravel is achieved by using plastic, wet, dry and powder-plastic modes during the manufacturing process.
About bulk density and expanded clay grades
The density or bulk density of expanded clay, like all other materials, is measured in the same units - kilograms per cubic meter(kg/cubic m). When we talk about expanded clay, we mean its thermal insulation properties. The main parameters - cellularity, total volume of cells inside the granules, volumetric (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 ranges between 250 and 800 kg/m3. m.
This is because 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/cub. m, then the marking is “M250”. For densities ranging from 250 to 300 kg/cu.m. m – “M300”. Up to 450 kg/cu.m. m gravel is marked at intervals of 50, but then the difference in designations between two adjacent marks 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 the specific name GOST 9757-90. Of course, according to the established rules, grades of crushed stone and gravel made from expanded clay have conditional lower and upper limits, respectively, M250 and M600. But if necessary, these standards can be adjusted at the request of the customer, using a value exceeding M600.
In the case of expanded clay sand, the following standards apply: M500 – M1000. If the values of characteristics close to the lower threshold are reference values, then it is advisable to comply with the highest ones. The following conclusion suggests itself: if you choose any faction, then quality indicators will be more preferable for that 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 density of bulk insulation is a necessary condition to perform calculations. Each material has its own specific density value. For example, in the case of expanded clay gravel, it can vary from 450 to 700 kg/cubic meter. m, and in the case of expanded clay concrete dry mixture – about 800 kg/cu.m. m. The specific density of expanded clay crushed stone is in the range of 600-1000 kg/cub. m.
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 the 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.
Characteristics of expanded clay according to GOST.
GOST 9757-90 provides for the following fractions of expanded clay gravel by grain size: 5-10, 10-20 and 20-40 mm. and expanded clay sand fr.0-5. In each fraction, up to 5% smaller and up to 5% larger grains are allowed compared to the nominal sizes. Due to the low efficiency of screening material in drum screens, it is difficult to achieve separation of expanded clay into fractions within established tolerances.
Based on bulk density, expanded clay gravel is divided into 10 grades: from 250 to 800, and grade 250 includes expanded clay gravel with a bulk density of up to 250 kg/m3, grade 300 - up to 300 kg/m3, etc. Bulk density is determined by fractions in measuring vessels.
The larger the fraction of expanded clay gravel, the lower the bulk density, as a rule, since large fractions contain the most swollen granules.
For each bulk density grade, the standard establishes requirements for the strength of expanded clay gravel when compressed in a cylinder and the corresponding strength grades (table). Marking by strength allows you to immediately outline the area of rational use of a particular expanded clay in concrete of the corresponding grades. More accurate data is obtained by testing aggregate in concrete.
| BULK BRAND DENSITY | HIGH CATEGORY QUALITIES | FIRST CATEGORY QUALITIES |
||
|---|---|---|---|---|
| Brand by strength | Tensile strength when squeezed in a cylinder MPa, not less | Brand by strength | Tensile strength when squeezed in a cylinder MPa, not less |
|
| 250 | P35 | 0,8 | P25 | 0,6 |
| 300 | P50 | 1 | P35 | 0,8 |
| 350 | P75 | 1,5 | P50 | 1 |
| 400 | P75 | 1,8 | P50 | 1,2 |
| 450 | P100 | 2,1 | P75 | 1,5 |
| 500 | P125 | 2,5 | P75 | 1,8 |
| 550 | P150 | 3,3 | P100 | 2,1 |
| 600 | P150 | 3,5 | P125 | 2,5 |
| 700 | P200 | 4,5 | P150 | 3,3 |
| 800 | P250 | 5,5 | P200 | 4,5 |
Characteristics of expanded clay - strength of porous aggregate
The strength of porous aggregate is an important indicator of its quality. Only one method for determining the strength of porous aggregates outside concrete has been standardized - by squeezing the grains in a cylinder with a steel punch to a given depth. The value of stress recorded in this case is taken as the conditional strength of the filler. This technique has fundamental disadvantages, the main one of which is the dependence of the strength indicator on the shape of the grains and the voids of the mixture. This distorts the actual strength of the aggregate so much that it makes it impossible to compare different porous aggregates and even aggregates of the same type but from different factories. The method for determining the strength of expanded clay gravel is based on uniaxial compression testing of individual expanded clay granules in a press. The granule is first ground off on both sides to obtain parallel supporting planes. At the same time, it takes on the appearance of a barrel with a height of 0.6-0.7 diameters.
The greater the number of granules tested, the more accurate the average strength characteristic. To obtain a more or less reliable characteristic of the average strength of expanded clay, a dozen granules are enough.
Testing expanded clay gravel in a cylinder gives only a conditional relative characteristic of its strength, and a greatly underestimated one. It has been established that the actual strength of expanded clay, determined when tested in concrete, is 4-5 times higher than the standard characteristic. Based on experimental data, V. G. Dovzhik, V. A. Dorf, M. Z. Weinstein and other researchers came to the same conclusion.
The standard technique involves loosely pouring expanded clay gravel into a cylinder and then squeezing it to reduce the original volume by 20%. Under the influence of load, first of all, the gravel is compacted due to some displacement of the grains and their more compact placement. Based on experimental data, it can be assumed that due to more dense laying of expanded clay gravel, a reduction in the volume of free backfill by an average of 7% is achieved. Consequently, the remaining 13% of the volume reduction is due to grain crushing (Fig. 1). If the initial grain height is D, then after crushing it decreases by 13%.
Rice. 1. Diagram of compression of expanded clay grains during testing
Fig.2. Scheme of laying expanded clay grains
, which has high strength, is usually characterized by relatively smaller, closed and evenly distributed pores.
It contains enough glass to bind the particles into a dense and durable material that forms the walls of the pores. When sawing granules, the edges are preserved and the crust is clearly visible. Cutting surface as the material is small
The water absorption of aggregate is expressed as a percentage of the dry weight of the material. This indicator is standardized for some types of porous aggregates (for example, in GOST 9757-90). However, a more clear idea of the structural features of aggregates is provided by the indicator of volumetric water absorption.
Surface melted crusts on expanded clay grains in the initial period (even with a lower volumetric mass in the grain and greater porosity) have almost two times lower volumetric water absorption than crushed stone grains.
Therefore, a technology of gravel-like fillers with a surface fused crust made from perlite raw materials, slag melts and other by-products of industry (thermal power plant ash, coal preparation waste) is needed.
At first, the surface crust of expanded clay is able to delay the penetration of water deep into the grain (this time is comparable to the time from the production of the lightweight concrete mixture to its laying). Fillers without a crust absorb water immediately, and in the future its amount changes little.
In some cases, there is a close correlation between water absorption and grain strength. The greater the water absorption, the lower the strength of porous aggregates. This manifests itself as a defect in the structure of the material. For example, for expanded clay gravel the correlation coefficient is 0.46. This relationship is revealed more clearly than the relationship between strength and bulk density of expanded clay (correlation coefficient 0.29).
To reduce water absorption, attempts are being made to pre-hydrophobize porous aggregates. So far they have not led to significant positive results due to the impossibility of obtaining a non-separating concrete mixture while maintaining the hydrophobization effect.
Characteristics of expanded clay - deformative properties.
Features of deformative properties are predetermined by the porous structure of the fillers. This primarily relates to the elastic modulus, which is significantly lower than that of dense aggregates. Intrinsic deformations (shrinkage, swelling) of artificial porous fillers are, as a rule, small. They are one order of magnitude lower than the deformations of cement stone. When studying the deformations of expanded clay, all samples show swelling when saturated with water, and shrinkage when dried, but the magnitude of the deformations is different. After the first cycle, half of the samples show residual expansion, after the second - three quarters, which indicates a change in the structure of expanded clay. The average shrinkage value after the first cycle is 0.14 mm/m, after the second - 0.15 mm/m. Considering that gravel in concrete is saturated and dried to a lesser extent, the actual deformations of expanded clay in concrete are only a part of these values. Porous aggregates have a restraining effect on the shrinkage (and creep) deformations of cement stone in concrete, as a result of which lightweight concrete has less deformation than cement stone.
Other important properties of porous aggregates that affect the quality of lightweight concrete are frost resistance and resistance to decay (silicate and ferrous), as well as the content of water-soluble sulfur and sulfuric acid compounds. These indicators are regulated by standards.
Frost resistance (F, cycles) - GOST standardizes that this indicator should be at least 15 (F15), and the weight loss of expanded clay gravel in % should not exceed 8%. - as a rule, manufacturing plants maintain this standard.
Artificial porous aggregates, as a rule, are frost-resistant within the requirements of the standards. The insufficient frost resistance of some types of aggregates outside of concrete does not always indicate that lightweight concrete based on them is also not frost-resistant, especially when it comes to the required number of cycles of 25-35. Fillers of lightweight concrete intended for severe operating conditions do not always meet the requirements for frost resistance and therefore must be carefully examined.
Characteristics of expanded clay - thermal conductivity.
The thermal conductivity of porous aggregates, like other porous bodies, is affected by the quantity and quality (size) of air pores, as well as humidity. The phase composition of the material has a noticeable effect. The anomaly in the thermal conductivity coefficient is associated with the presence of a glassy phase. The more glass, the lower the thermal conductivity coefficient for filler of the same density. In order to stimulate the production of aggregates with better thermal insulation properties for concrete enclosing structures, it is proposed to normalize the content of slag glass (for example, for high-quality slag pumice 60-80%).
Depending on the manufacturing technology and the properties of the raw materials, the thermal conductivity index may vary among different manufacturers, but on average it is 0.07 - 0.16 W/m oC, where a correspondingly lower value corresponds to the density grade M250. (It should be noted here that the M250 brand is rare and is often made to order. The usual density of the material is M350 - M600, respectively, then K 0.1-0.14).
Artificial porous sands are mainly products of crushing porous lump materials (slag pumice, agloporite) and granules (expanded clay). Specially made expanded sands (perlite, expanded clay) do not yet occupy a dominant position.
The great advantage of crushed sand is the possibility of its production in conjunction with the production of crushed stone. However, this circumstance also causes significant shortcomings in the quality of sand. Being a by-product when crushing material into crushed stone, sand in some cases does not correspond to the required granulometric composition for the production of lightweight concrete. Very often, the sand is too coarse and does not contain in sufficient quantities the most valuable fraction for ensuring cohesion and mobility of the concrete mixture with a size of less than 0.6 mm.
The bulk volumetric mass of porous sands, to an even lesser extent than coarse aggregates, characterizes their true “lightness”. The low volumetric mass of sand is often achieved due to intergranular rather than intragranular porosity due to the specific grain composition (the predominance of grains of the same size).
When introduced into a concrete mixture, such sand does not lighten the concrete, but only increases its water requirement.
Obviously, to improve the quality of porous sand, a special technological stage of crushing the material into sand of a given granulometry is necessary, and not the associated production of sand by crushing it into crushed stone.
The production of crushed expanded clay sand, especially when large fractions predominate in it, cannot be considered rational. Large fractions (1.2-5 mm in size) of crushed sand do little to improve the workability of the mixture, but cause an increase in its bulk density due to the presence of open pores and increased voids. Expanded expanded clay sand (in fluidized bed furnaces) is still produced in small quantities. In terms of physical and technical indicators, it is better than crushed sand. First of all, its water absorption is lower.
Characteristics of expanded and crushed sand by fraction:
50% is the fraction of 1.2-5 mm. Therefore, in lightweight concrete it is necessary to reduce the consumption of expanded clay gravel, which is irrational (replacing gravel with sand).
With a decrease in the volumetric mass of porous aggregates (bulk and in grain), their porosity and water absorption increase. However, water absorption attributed to grain porosity decreases, indicating an increase in “closed” porosity in lighter materials.
Radiation quality, Aeff., (Bq/kg) - for expanded clay this indicator is at the level of 200-240, which does not exceed 370 Bq/kg, therefore there are no restrictions on the scope of its application.
Expanded clay is already catching up with brick and cement in sales volumes, while its production is constantly growing. It just seems that it is rarely used. And all because where can you see it openly if the material is either in the composition of lightweight concrete or in the insulation of floors? Advantages: environmentally friendly, easily tolerates any natural conditions, fire-resistant and does not rot, that is, the qualities necessary for construction.
It would be wrong to estimate this value only using the school formula, where the mass should be divided by the volume. After all, this material is bulk, and the geometry of the granules is very different, as is the number of pores, therefore, the indicators will differ greatly. Therefore, for calculations and for convenience, several parameters are used.
Bulk density is one of the most important characteristics when using expanded clay. This value is determined by pouring the product into a unit volume and then weighing it. That is, if 500 kg of balls fit in 1 m3, then the bulk density will be equal to 500 kg/m3, and the grade will be M500.
The true density of expanded clay characterizes the mass of dry matter per unit volume, if the voids between the balls and the pores inside are removed from it; this is what was calculated using the school formula as specific gravity. But there is also the specific density of expanded clay, which is determined only without voids between the granules. The difference between them is that the first is a constant value, the second is a variable, depending on the size of the particles.
| Brand | Bulk density, kg/m3 |
| M250 | 250 or less |
| M300 | 250-300 |
| M350 | 300-350 |
| M400 | 350-400 |
| M450 | 400-450 |
| M500 | 450-500 |
| M600 | 500- 600 |
| M700 | 600-700 |
| M800 | 700-800 |
| M900 | 800-900 |
| M1000 | 900-1000 |
And one more thing: if 1 m3 had a mass of, for example, 310 kg, then the brand will still be M350, that is, upward. Rounding methods are not taken into account in this situation. It is clear that the fewer pores and voids there are in a building material, the heavier it is. This is possible if the particles are small. That is, an inversely proportional relationship is obtained: the smaller the geometric dimensions of the elements of bulk and porous materials, the higher the density of expanded clay. On the contrary, expanded clay with low density has large granules.
Insulation fractions
The grains of the material initially have different sizes. After sifting through sieves, the grains are separated into expanded clay sand (particles smaller than 5 mm are considered sand) and expanded clay gravel of three sizes:
- small - 5-10 mm;
- average - 10-20;
- large - 20-40.
Sand is obtained either by firing clay fines, or from the remains of crushing large particles of gravel into crushed stone. The size of the crushed stone is 5-40 mm, but the shape is no longer rounded, like gravel, but angular.
Thus, the material enters the construction market in three fractions: sand, gravel and crushed stone. The density and strength of the resulting lightweight concrete largely depends on the size of the granules. Correct selection of granules reduces cement consumption, since small ones fill the voids between large ones. But the ratio of the largest granule to the smallest should not exceed 1.5. In this case, the strength of concrete is reduced by a quarter.
Application in construction
Expanded clay sand. For the production of lightweight concrete blocks. The strength of its adhesion to the solution due to the rough surface is great, and the high density increases the strength characteristics of the blocks. It can also be suitable instead of regular sand for floor screeds, even under linoleum. The screed will be quite dense, strong and even. And for floor insulation they use fine, sandy expanded clay. Water and heat supply pipelines are also equipped (filled) with fine expanded clay. There is such a property as flowability, the ability to fill empty spaces between pipes.
Expanded clay gravel. It has a density lower than that of sand, but due to the different caliber parameters, the application is more extensive. Such expanded clay is often used for flooring, that is, pouring it, especially with 5-10 mm granules. This size of expanded clay particles is also suitable for floor screeding under any floor coverings. If you need a thicker floor screed, you will need larger gravel. If the particles are 10-20 mm, this is a good expanded clay for filling floors and insulating the inter-ceiling space. Here is an approximate table for gravel of different fractions:
Expanded clay crushed stone. It is a secondary product of expanded clay gravel. Therefore, if the size and angular shape allow, you can use it in the same way as gravel: in ceilings, roofs, basements, and attic floors. But most often it is used for insulating foundations, since it is the only one among crushed stones with a porous structure. Gravel with granules of 20-40 mm has the lowest density, so its thermal insulation properties are high. But because large sizes particles, such material is used for thermal insulation of floors located directly on the ground or roofs.
Price
The cost of building materials is affected by labor, raw materials, and energy costs. But demand is also important in pricing. And demand depends on the performance properties and qualities of this material. Let's see what prices for expanded clay consist of. Raw materials for production are relatively inexpensive. But the labor and energy costs are quite high.
The larger the granules, the lower the density. Thermal insulation qualities increase, but, paradoxically, the price decreases. And the reason is that the true volumetric weight of fine sand is greater than that of gravel.
Which is better to buy: in bulk or in bags? Depends on the specific case. Granules packaged in bags are purchased for small needs; for large construction projects it is more economical to buy in bulk. Otherwise, you also have to pay for the bags: a lot of bags means a lot of wasted money. The granules are packaged both in regular bags with a volume of 0.04-0.05 m3, and in ICB bags with a capacity of 1 m3.
Also, prices also depend on the volume of purchase. The first rule of wholesale: large batch - lower price. Naturally, products from different factories may differ in price. The proximity of raw materials, energy sources and places of consumption will reduce the cost of goods.
Average prices for expanded clay products:
Thus, density is an important characteristic of expanded clay. It affects heat and noise insulation, strength of concrete, load on the foundation, and cost of the material.
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 fairly light and porous material with a cellular structure, similar in appearance to gravel, sometimes crushed stone. It is obtained by firing clay fusible rocks, which can be pressed with 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.
Depending on the grain size, expanded clay is divided into fractions: 20 – 40, 10 – 20, 5 – 10 mm. If the grain size is less than 5 mm, then the material is expanded clay sand.
Material of different fractions has different purposes
Depending on the volume of bulk weight, measured in kg/m3, expanded clay gravel is divided into grades 150 - 800. Expanded clay has a water absorption range from 8 to 20%.
What is it for?
Today expanded clay is quite in demand 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 strength.
- Frost resistance, fire resistance and certain moisture resistance.
- Durability.
- Inert to chemical influences, including resistance to acids.
- Environmentally friendly.
- Excellent price/quality ratio.
How much does expanded clay weigh?
The weight of expanded clay directly depends on its dimensional characteristics and can vary between 300-600 kg/m3. When determining the average value, its weight will be 400 kg per 1 m 3.
Based on the ratio of its weight to volume, that is, the volumetric bulk density, it is determined from the brand of expanded clay, which is in the range of 150-800. Brand 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 mostly used due to its thermal insulation characteristics. Therefore, when choosing expanded clay, you should take into account its thermal conductivity. The best expanded clay for insulation will be the 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 grain decreases, then the voids will be smaller, the bulk density will increase, and the thermal conductivity will also increase.
Production of expanded clay
- Raw materials are mined in a quarry and transported to the clay storage facility.
- The initial raw materials are processed to obtain the appropriate raw granules of the established sizes.
- The granules undergo heat treatment. It includes drying, firing, and cooling of the finished material.
- Sorting occurs, if necessary, separation by density and partial crushing.
- Warehousing and shipping for sale.
Insulating the floor with expanded clay - 5 steps step by step
Expanded clay is used in many areas, but its main use is related to floor insulation.
Insulation of the floor of a private house is carried out in different ways, depending on how the floor is laid. In private houses, the floor can be compacted soil, on joists, on top reinforced concrete slab or concrete screed. In city apartments, the floor is most often made on top of a concrete slab. It is also possible to insulate the floor with expanded clay in bathhouses and garages.
1. On the ground on joists
- Preparation for insulation includes removing the floor covering.
- If the logs are removed, the soil surface is completely cleaned and compacted. After this, waterproofing material is laid on it in 10 cm increments based on bitumen (glassine, roofing felt, etc.).
- The waterproofing layer is backfilled with gravel fraction of expanded clay, followed by a layer of coarse sand (expanded clay or river sand).
- Reinforcing mesh is laid.
- The screed is poured.
If the logs are left, then the order of work changes slightly:
- After removing the floor covering, bitumen waterproofing material is laid between the joists.
- Expanded clay about 15 cm thick is poured onto it.
- A vapor barrier is laid on top of the expanded clay.
- Next come the insulation boards.
Then you can do different things:
- a mesh for reinforcement is laid on the slabs and a screed is poured;
- beams are laid on top of the slabs on the logs, and a subfloor is created from boards or fiberboard slabs.
2. Floor on joists, made on brick supports
Often a similar floor construction is used in private, especially log houses.
- In this case, the space up to the joists laid on posts is filled with expanded clay.
- Then skull blocks are nailed to the joists and boards or wood slabs are laid.
- A layer of vapor barrier and insulation is laid.
- Next, a cement-sand reinforced screed or wood subfloor is laid, followed by the finishing floor.
3. Floor laid on top of a concrete slab
Such insulation is used when there are high ceilings, and they allow the floor level to be raised. It can also 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 you can insulate with expanded clay, even if there is a loss of height.
A cold concrete floor can be insulated with expanded clay backfill
Initially, you need to remove the floor covering and make sure the floor is in good condition. If there are rusts and cracks, they must be foamed using polyurethane foam. After this, it is necessary to apply waterproofing. Fine expanded clay no more than 5 - 10 cm thick is laid on it, and then a mesh for reinforcement is laid on top and a rough screed is created.
You can also put a vapor barrier on top of the expanded clay cushion, a layer of slab insulation on top, then the bars and then a subfloor on them.
4. Creation of concrete-expanded clay floors in bathhouses and garages
This insulation option will be the simplest in design.
Installing a garage floor from scrap materials
+ filling with expanded clay
- Waterproofing in the form of dense polyethylene or bitumen material is spread on the ground so that it extends onto the walls.
- Next, the beacons are mounted exactly on a horizontal surface using a level. They are strengthened with quick-drying gypsum or thick cement-sand mortar.
- Then, using a concrete mixer, mix the solution (cement + sand in a ratio of 1:2, 1 part water and 3 parts expanded clay). Most often, the gravel fraction is used to provide a reliable and denser solution.
- The expanded clay concrete mixture is then poured onto the floor surface, observing the beacons. The mixture must be compacted, removing all air bubbles. As soon as the surface hardens, it needs to be leveled and cement laitance used to “ironize” it.
5. Application of dry expanded clay screed
This insulation option can be used over concrete base or directly on the ground - the only difference will be in height: on the ground, the expanded clay layer can reach 20-25 cm, when laid on concrete - no higher than 10 cm.
- First, you should prepare the ground surface, that is, glue the damper tape slightly above the line to which the expanded clay will be poured.
- Then you need to lay a thick plastic film on the ground.
- Next, beacons are installed, and expanded clay is laid over them: if the layer is up to 10 cm, it is recommended to use a fine fraction, if 20 cm, first gravel, then sand.
- The layers are compacted using a small fiberboard boards, providing a flat surface along the beacons.
- Next, two-layer GVL sheets are laid. They are strengthened with self-tapping screws.
- Any finishing coating can then be laid on the gypsum fiber sheets.