What happens to extruded clinker when heated. Clinker tiles through the eyes of manufacturers. What is hidden behind the phrases “clinker”, “clinker facade” and “clinker tiles”

Cladding with clinker tiles is a well-known way to improve a fireplace or stove. This tile has many textures, colors, shades. Particularly popular are tiles that imitate brick. She's different great strength and service life.

Not all types of clinker tiles are suitable for facing a fireplace. When choosing a specific material, you need to take into account a number of nuances.

What is taken into account when choosing clinker?

The main factor that most people pay attention to is appearance. From a professional point of view, this factor is not the main one. First of all, you need to look at the expansion coefficient. In order for tiles to stay in place for decades, they need to expand when heated, much like fireplace walls.

Preparation method

The expansion coefficient of clinker directly depends on the production method. Thus, classic tiles used in facade cladding are distinguished by their high density and water resistance. These qualities make it ideal for use in cold weather, but prevent expansion when heated.

Dense clinker tiles are made using the extrusion method. First, the clay mixture passes through specialized molding nozzles, after which the resulting semi-finished products are dried and baked under high temperatures.

Another method of making tiles is semi-dry molding. The clay paste is pressed into special molds and then baked at high temperature. Drying is excluded with this method. The resulting tile is more porous and has less frost resistance. It is not recommended for use on facades, but is ideal for decorative finishing fireplaces. The expansion coefficient of this tile is similar to brick.

The reverse side of extruded and molded clinker differs in relief. A relief mesh is applied to the molded clinker tiles. Small longitudinal grooves are easily visible on extruded clinker.

An example of clinker tiles for fireplaces is.

What clinker should I use for finishing stoves and fireplaces?

Many European factories produce exclusively extrusive clinker. In some factories, molding clinker is produced manually. In its production, standard semi-dry molding is used, due to which it acquires heat-resistant properties. Thanks to manual molding, each individual tile acquires its own unique appearance and relief.

Clinker tiles are used exclusively for exterior finishing. If you need to treat the inside of the fireplace, this is suitable fireclay brick or other fire-resistant material.

If the fireplace requires high-quality thermal insulation and the heat does not pass through the walls, you can use any clinker tiles for decorative finishing.

Features of clinker finishing

A fireplace lined with clinker tiles will heat up less and take longer to cool down. This is due to the characteristics of the material: low thermal conductivity prevents heat from escaping outside, high thermal capacity prevents the tile from cooling after the fireplace goes out.

This feature is important when using the fireplace regularly. If it serves for decorative purposes, this property is not critical.

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Ceramic clinker tiles are a building material that has been produced for several centuries. Today, as before, it remains popular and is used everywhere: it is used to line the steps of cottages and public buildings, floors, walls, fireplace portals, swimming pools. Recently, the production of thermal panels lined with clinker tiles has been launched. This material is practically indistinguishable in appearance from high-quality brickwork.

It is produced different textures: with a rough (matte) surface and glossy. Color palette also very different: from dark brown to light ocher or yellow. The surface of the material can be covered with glaze. Dimensions of standard tiles are 245x66x8mm.

The color palette is quite varied from dark brown to light ocher or yellow.

From the origin story

The founders of the production of clinker tiles were the Dutch, who were forced to use “sea” clay to produce this type of artificial stone due to the lack of natural material. This happened at the beginning of the 19th century.

At first this artificial stone roads were paved, but then they began to clad the facades of buildings with it.

Subsequently, the Poles picked up the baton: they learned to produce very high-quality and inexpensive tiles, which they began to export to many European countries. We have also established production, but, unfortunately, the quality of domestic material is still inferior to foreign samples.

Tiles of various shapes, for example, concave, convex or even in the form of an angle, can be made using the extrusion method, which you can read about below.

Some information about production

The process begins with mixing different varieties clay with the addition of fireclay, feldspar, quartz sand and fighting earthenware. The resulting mixture is ground and crushed to a homogeneous mass using special mills. The next stage is drying. The result is a granular substance needed as a raw material. The tiles are formed either by pressing or by extrusion.

The pressing process involves filling the mass into special forms, its compaction and pressing high pressure. Extrusion occurs with the addition of water and mixing of the raw materials until a dough-like mass is obtained. The resulting mass is passed through a special hole, the dimensions of which correspond to the dimensions of the finished product. The emerging strip-blank is cut to length.

The color of unglazed tiles depends on the porosity of the clay and its iron content. Clinker products undergo a much longer firing procedure and at a higher temperature than regular tiles: 1.5 days at 1500 °C.

During firing, the basic qualities inherent in this material: high density(due to complete sintering of the clay), resistance to mechanical damage, temperature changes and abrasion. Its water absorption is 5 times less than that of ordinary tiles: this ensures high frost resistance.

Features of different manufacturing methods

Each of the above methods has its own advantages and disadvantages. Pressing makes it possible to obtain clinker tiles with more exact dimensions And high quality surfaces. However, the extrusion method requires lower financial costs, which means products obtained in this way are cheaper. In addition, extrusion allows you to produce (unlike the pressing method) tiles of various shapes, for example, concave, convex or even in the form of an angle. Another feature of the extrusion method is that the resulting product has conical grooves that improve adhesion to the base.

Material advantages

Clinker tiles have a number of advantages over conventional ceramic tiles, namely:

• it is more wear-resistant;
• has greater strength;
• it has a longer service life;
• due to high frost resistance, it can be used for outdoor work;
• has a low level of moisture absorption.

This finishing material received such characteristics due to the peculiarities of production technology. During the firing process it is formed upper layer, performing protective function: thanks to this, the tiles do not become dirty, do not change their color and are easy to clean with any chemical or even abrasive agent.

What are ceramic tiles and what are they made from?

Ceramic tiles are plates made of baked clay. Most often they are square and rectangular shapes, but can be made in the form of a complex geometric mosaic. It can be used to decorate walls and floors both indoors and outdoors.

1. Wear resistance is one of the the most important qualities floor tiles, which characterizes the resistance of the tile to abrasion and the ability to maintain its appearance without changes. There is a PEI classification that includes five groups: PEI I - for walls in bathrooms, PEI II - for walls/floors in bedrooms, offices, bathrooms, PEI III is installed in any residential premises and in small offices that do not have a direct entrance from streets, PEI IV suitable for any living rooms, as well as for covering stairs, halls, corridors, PEI V is used both in private and public interiors with above average traffic (offices, shops, cafes, restaurants). For places with heavy traffic (traffic), it is recommended to use unglazed porcelain tiles (airports, train stations, shopping centers).
2. Water absorption is the ratio of the mass of water absorbed by a sample when it is completely immersed in water to the mass of dry matter. The ratio is expressed as a percentage. The water absorption of glazed ceramic floor tiles should not exceed 3%, while tiles with a water absorption of more than 10% can only be used on indoor walls. The water absorption rate of the tiles plays important role when lining swimming pools. To do this, you need to use only special tiles, such as porcelain stoneware or clinker.
   
   
3. Frost resistance - the ability of tiles to resist temperature changes. Durability ceramic tiles is determined by two parameters: the presence and number of pores. Double-fired tiles are quite porous and therefore not frost-resistant. And single-fired tiles with a water absorption of less than 3% are considered frost-resistant. Porcelain tiles, unlike ceramic tiles, have a minimum level of water absorption - less than 0.05%.
4. Cracking is the appearance of fine cracks in the enamel coating. This happens with low-quality or incorrectly selected tiles under the influence of sudden temperature changes. This defect is sometimes present on the tiles before installation. When tiles crack some time after installation, the cause may be improper installation of the tiles: the use of poor mortar or glue, too thick or thin layer these materials.
5. Slip resistance is a characteristic that determines the ability of a surface to prevent an object placed on it from sliding. This property is a basic requirement for the safety of residential and industrial premises, as well as for outdoor floor coverings. In bathhouses, saunas and swimming pools, ribbed tiles with grooves are usually laid.
6. Chemical resistance is a characteristic of tile enamel, reflecting its ability to withstand contact with acids, salts, household chemicals at room temperature. It must resist the aggressive or mechanical effects of these substances without undergoing external changes. Tiles can be protected by filling them with epoxy materials that are highly resistant to chemical attack.
7. Tone and caliber. Tone - color saturation tiles, which may slightly differ from the declared color. It is indicated on the packaging by a number or letter. Caliber is the actual size of the tile, which sometimes differs by a couple of millimeters from the nominal one. The caliber is indicated on the packaging next to nominal size. During production, tiles are sorted into batches of the same size and tone with the tolerance for differences established by the standards.
   
   
8. Bending resistance. The higher it is, the lower the water absorption of the tile. Porcelain tiles have very high bending resistance, while porous tiles have lower ones.
9. Tensile strength - the level of possible load that the tile must withstand. It directly depends on its thickness. The ability to withstand loads is especially important for floor tiles. The tile covering should be able to withstand loads such as the weight of a person or furniture easily and not break.
10. Surface hardness is a characteristic that expresses the ability of a surface to be resistant to scratches and damage. Scratches are clearly visible on a shiny tile surface, but on a matte surface they are less noticeable.

Firing - final technological operation clinker production. During the firing process from a raw material mixture of a certain chemical composition clinker is obtained, consisting of four main clinker minerals.
The composition of clinker minerals includes each of the initial components of the raw material mixture. For example, tricalcium silicate, the main clinker mineral, is formed from three molecules of CaO, the oxide of the limestone mineral, and one molecule of SiO2, the oxide of the clay mineral. The other three clinker minerals are produced similarly - dicalcium silicate, tricalcium aluminate and tetracalcium aluminoferrite. Thus, to form clinker, the minerals of one raw material component - limestone and the minerals of the second component - clay must chemically react with each other.
Under normal conditions, the components of the raw mixture - limestone, clay, etc. are inert, i.e. they do not react with one another. When heated, they become active and begin to exhibit mutual reactivity. This is explained by the fact that with increasing temperature, the energy of moving molecules solids becomes so significant that mutual exchange of molecules and atoms is possible between them with the formation of a new compound. The formation of a new substance as a result of the reaction of two or more solids is called a solid-phase reaction.
However, the rate of the chemical reaction increases even more if some of the materials melt to form a liquid phase. This partial melting is called sintering, and the material is called sintered. Portland cement clinker is fired until sintered. Sintering, i.e., the formation of a liquid phase, is necessary for more complete chemical assimilation of calcium oxide CaO by silica SiO2 and thereby obtaining tricalcium silicate.
Partial melting of clinker raw materials begins at a temperature of 1300° C. To accelerate the reaction of formation of tricalcium silicate, the clinker firing temperature is increased to 1450° C.
Thermal units of different design and operating principles can be used as installations for producing clinker. However, rotary kilns are mainly used for this purpose; approximately 95% of clinker is produced in them from the total output, 3.5% of clinker is obtained in shaft kilns and the remaining 1.5% in thermal units of other systems - sintering grates, reactors for burning clinker in suspension or in a fluidized bed. Rotary kilns are the main heating unit for both wet and dry clinker production methods.
The firing apparatus of a rotary kiln is a drum lined inside fireproof materials. The drum is installed at an angle on roller supports.
From the raised end, liquid sludge or granules enter the drum. As a result of the rotation of the drum, the slurry moves towards the lowered end. Fuel is fed into the drum and burned from the lowered end. The resulting hot flue gases move towards the material being fired and heat it. The burned material emerges from the drum in the form of clinker. Coal dust, fuel oil or natural gas. Solid and liquid fuels are supplied to the furnace in an atomized state. The air required for fuel combustion is introduced into the furnace along with the fuel, and is also additionally supplied from the furnace refrigerator. In the refrigerator it is heated by the heat of the hot clinker, cooling the latter at the same time. The air that is introduced into the furnace along with the fuel is called primary, and the air received from the furnace refrigerator is called secondary.
The hot gases formed during the combustion of fuel move towards the material being burned, heat it, and cool themselves. As a result, the temperature of the materials in the drum increases all the time as they move, and the temperature of the gases decreases.
The broken nature of the material temperature curve shows that when the raw material mixture is heated, various physical and chemical processes occur in it, in some cases inhibiting heating (flat sections), and in others promoting sharp heating (steep sections). The essence of these processes is as follows.
Raw material sludge, which has an ambient temperature, enters the furnace and is sharply exposed to the high temperature of the waste flue gases and heats up. The temperature of the exhaust gases decreases from approximately 800-1000 to 160-250 ° C.
When heated, the sludge first liquefies and then thickens and, with the loss of a significant amount of water, turns into large lumps, which, with further heating, turn into grains - granules.
The process of evaporation of mechanically mixed water from sludge (drying of sludge) lasts up to approximately a temperature of 200 ° C, since the moisture contained in the thin pores and capillaries of the material evaporates slowly.
Due to the nature of the processes occurring in sludge at temperatures up to 200 ° C, this zone of the furnace is called the evaporation zone.
As the material moves further, it enters the region of higher temperatures and chemical processes begin to occur in the raw material mixture: at temperatures above 200-300 ° C, organic impurities burn out and the water contained in the clay minerals is lost. Loss of clay minerals chemically bound water(dehydration) leads to the complete loss of the clay's binding properties and pieces of sludge crumble into powder. This process lasts up to temperatures of approximately 600-700° C.
Essentially, processes occurring in the temperature range from 200 to 700 ° C, this zone of the furnace is called the heating zone.
As a result of the presence of the raw material mixture at this temperature, calcium oxide is formed, therefore this zone of the furnace (up to a temperature of 1200°) is called the calcination zone.
The temperature of the material in this zone increases relatively slowly. This is explained by the fact that the heat of flue gases is spent mainly on the decomposition of CaCO3: to decompose 1 kg of CaCO3 into CaO and CO2, 425 kcal of heat is required.
The appearance of calcium oxide in the raw material mixture and the presence of high temperature determines the beginning of the chemical interaction of the oxides of silicon, aluminum and iron found in the clay with calcium oxide. This interaction occurs between oxides in the solid state (in solid phases).
Reactions in solid phases develop in the temperature range of 1200-1300 ° C. These reactions are exothermic, that is, they occur with the release of heat, which is why this zone of the furnace is called the exothermic reaction zone.
The formation of tricalcium silicate occurs already in the next section of the furnace in the region of highest temperatures, called the sintering zone.
In the sintering zone, the most fusible minerals melt. In the resulting liquid phase, 2CaO-Si02 is partially dissolved and it is saturated with lime to 3CaO-Si02.
Tricalcium silicate has a significantly lower ability to dissolve in the melt than dicalcium silicate. Therefore, as soon as its formation has occurred, the melt becomes supersaturated with respect to this mineral and tricalcium silicate falls out of the melt in the form of tiny solid crystals, which are then, under given conditions, capable of increasing in size.
The dissolution of 2CaO-Si02 and the absorption of lime by it does not occur immediately in the entire mass of the mixture, but in its individual portions. Consequently, for more complete assimilation of lime by dicalcium silicate, it is necessary to keep the materials for a certain period at the sintering temperature (1300-1450°C). The longer this exposure is, the more completely the binding of lime will occur, and at the same time they will become larger crystals 3CaO-Si02.
However, it is not recommended to keep clinker at the sintering temperature for a long time or to cool it slowly; Portland cement, in which ZCaO - Si02 has a fine-crystalline structure, has higher strength.
The duration of clinker exposure depends on the temperature: the higher it is in the sintering zone, the faster clinker is formed. However, with an excessively high, and most importantly a sharp increase in temperature, a lot of melt quickly forms and the fired mixture can begin to clump. The large grains formed in this case are more difficult to heat up and the process of transition of C2S to C3S is disrupted. As a result, the clinker will be poorly burned (it will contain little tricalcium silicate).
To speed up the process of clinker formation, as well as in cases where it is necessary to obtain clinker with a high content of 3CaO-Si02, certain substances are used (calcium fluoride CaF2, iron oxide, etc.) that have the ability to reduce the melting point of the raw mixture. The earlier formation of the liquid phase shifts the process of clinker formation to the region of lower temperatures.
During the sintering period, sometimes all the lime in the mixture does not have time to be completely absorbed by silica; the process of this assimilation proceeds more and more slowly due to the depletion of the mixture in lime and 2CaO Si02. As a result, in clinkers with a high saturation coefficient, which require maximum assimilation of lime in the eide ZCaO Si02, free lime will always be present.
1-2% free lime does not affect the quality of Portland cement, but more high content causes uneven changes in the volume of Portland cement during hardening and is therefore unacceptable.
The clinker from the sintering zone enters the cooling zone (VI), where flows of cold air move towards the clinker.
The clinker leaves the cooling zone at a temperature of 1000-1100 ° C and for final cooling it is sent to the furnace refrigerator.

Clinker tiles and brick - the most durable, reliable, status, prestigious solution for facade finishing country house or administrative building. It’s worth admitting right away that clinker is far from the most cheap option, however it will not only increase the market value of your home, but will also give you a feeling that is difficult to measure in money. confidence, prosperity And superiority that will stay with you forever.

Pressed or extruded tiles?

By entering the query “clinker tiles” or “clinker facade” into Google or Yandex, you will receive more than 100,000 articles and proposals where you will be offered clinker facades of Polish, Russian, Belgian, German and even Belarusian production. and so as not to get lost in these proposals, we suggest you understand the issue once and for all:

What is hidden behind the phrases “clinker”, “clinker facade” and “clinker tiles”?

Essentially the word CLINKER- this is a derivative of the description of the characteristics of brick, which came to us from the Middle Ages. It came from the word KLINK, which describes the ringing sound emanating from a burnt brick after being struck. For builders, before the era of certificates and technical tests, this sound was one of the few criteria for assessing the quality of the material from which walls were laid. The louder a brick sings, the higher its strength, the fewer impurities it contains and the greater the load it can withstand. This is where the derivative KLINKER comes from – a sign of reliability, durability, and high quality.

Now, in the era of technological progress, measurement accuracy, precise regulation of production processes and the use of construction and finishing materials, word CLINKER turned more into a beautiful marketing story accompanying completely different Construction Materials. And in order to choose a reliable and durable material To cover a facade, it is not enough to hit two tiles against each other. You need to dig a little into production technologies. manufacturers and sellers facade materials Clinker is any facing tiles, having the appearance of a brick.

That is why we need to figure out what production technology facade tiles guarantees us the durability and status of that same “Clinker”

The dilemma is whether to prefer only aesthetic aspects or to take into account technical ones as well. IN this moment There are two technologies for the production of ceramic facades: And cold pressing.

They differ both in production method and in functions, which have a direct impact on cost and efficiency of use. Some of them have, for example, smaller tolerances, others are more resistant to adverse weather conditions. By providing this information, we hope that the investor will be able to make informed decisions based on it, taking into account not only his own preferences and expectations, but also technical aspects in order to enjoy the end result in the form of beautiful and durable facades for many years.

Ceramic facade tiles can be produced using two technologies:

1. Technology extruded clinker.

This traditional technology used in the production of clinker, bricks and cobblestones.

Blanks made from plastic masses of refractory purified clay with a moisture content of 15 to 30% are passed through an extruder, which, without creating supernatural pressure and without disturbing the molecular structure of the raw material, gives future tiles or bricks geometric shape. Then the raw workpiece is cut into individual products, and decorative elements are applied using soot mixtures and natural pigments. After which the blanks enter a tunnel kiln and are fired for 48 hours at a temperature of 1300 degrees C. Firing gives the final shape, creating porosity sufficient for vapor permeability and burning out all kinds of organic impurities from the structure of the raw material.

The output, after mandatory two-stage quality control, is extruded clinker tiles. clinker with a unique front surface created by the elements of fire, water and earth. Each extruded tile is unique. And about the strength of the material fired at extreme high temperatures and there is nothing more to say.

2. Semi-dry pressed clinker.

The tiles are produced using the semi-dry pressing method. When pressing, a powdery mass with a moisture content of 4 - 6% is compressed in two directions, usually under a pressure of about 200-400 kg/cm2. Under pressure, the granules move and partially deform, due to which the unfired tile acquires the strength necessary for subsequent operations. During the pressing process, the molecular structure is compressed, reducing the pores that discharge steam and creating additional internal stress in each individual tile.

What is affected by the difference in technological processes?

if we ignore aesthetic features appearance between tiles produced by pattern pressing and natural firing methods

At this stage we can distinguish 2 fundamental differences between extruded clinker and semi-dry pressed facade tiles

1. Adhesion. Ability to set and hold time on adhesive solutions when performing outdoor work

Semi-dry pressed tiles pressed against a dry, almost glassy and smooth surface without any open micropores formed after aggressive pressing. The glue is not able to penetrate deep into the structure of the plate. This certainly limits the possibilities of communication with adhesive solution and to obtain sufficient connection strength, specialized adhesive mixtures. Especially when the tiles are used on outdoors: not only in frost in winter, but also in summer - the sun and large daily temperature fluctuations can lead to separation of the tiles from the substrate (load-bearing wall).

Surface of pressed tiles, magnified

In case they have a porous and rough structure, which provides a large contact surface of the adhesive mortar. The glue penetrates easily and deeply into micropores open system, which leads to special strength of the glued tiles.

Magnified surface of extruded tiles

2. Vapor permeability. The ability to quickly remove wet vapors from the façade during natural and extreme temperature changes

Have low water absorption, so it may seem that they are more stable and durable. The reality is completely different. It is worth considering the internal structure of two materials that have a direct impact on the performance and ease of use of the stove. In the technology of producing a dry compressed body of tiles with a structure of compressed chaotic material particles, between which the micropores are closed with very thin capillary channels. This results in low water absorption and also very slow water flow. It is assumed that no water has entered such products. However, this assumption is purely theoretical. Water remaining in the tile due to closed structure and compacted material cannot be removed and this will lead to expansion when frozen in the cold. Consequently, this may cause damage to the tiles. Additional risks of moisture escaping from glued tiles. Dry pressed boards do not have the ability to remove water outside the substrate. Water partially enters the tile and, remaining under it, can weaken the bond with the substrate, the supporting frame.

Structure and behavior of water in pressed tiles

Facade clinker Structure and behavior of water in.

The internal structure of tiles obtained using extrusion technology is completely different. During production process extrusion, the microstructure is not damaged and retains its natural, homogeneous character. A network of interconnected capillary channels makes it possible to quickly remove moisture out; they have less absorbing capacity than, but water easily flows back into environment. The microporous structure makes the facade tiles resistant to freezing of water remaining in the tiles. In addition, due to its structure, tiles made using extrusion technology easily get rid of water between the tile and the adhesive layer, which prevents the possibility of its accumulation in the tile area. Thus, extruded tiles have higher adhesion to the base and, accordingly, the tiles are less likely to come off the base. There is less water absorption due to the internal structure, the tiles are more durable and more resistant to extreme weather conditions.

Structure and behavior of water in extruded tiles

Facade tiles. Aesthetics.

As already mentioned, the aesthetics of the tiles are pressed and completely different. Of course, there is no way to say which one is better, because both groups have their supporters and opponents. For some, the smooth, repeating surface of the pressed tiles from element to element has a plastic artificial appearance, for others - the surface is too “strict”. Pressed products are produced in molds so that the structure of the model is repeatable and their surface is highly reproducible. They are characterized by greater accuracy than extruded, fired products, and have smaller tolerances and color. The surface is very smooth, often covered with engobe, therefore, it is a stretch to say that they are artificial, plastic, and only the size resembles a brick. The pressed plates have a thickness of 6-7mm and, therefore, the small space between the tiles and the base is filled with a fugue (joint filler), which reduces the water resistance of the wall. The structure of such joints in pressed tiles is smooth and unlike the joints used in a brick facade.

When gluing pressed tiles, the tile cannot be pressed too hard to create a successful brick look. Thin mortar is also less durable and, as a result of wind due to air suction, can crack and crumble.

Clinker is made in exactly the same way as clinker bricks, from the same raw materials and using the same technology. So the surface looks similar to the surface traditional products from clinker. They are not as smooth as pressed tiles, they also have higher frost resistance. They are so perfect that after covering the facade, no one can say whether it was faced with tiles or bricks. The range of products produced using extrusion technology is rich in natural colors and surface structures, like clinker bricks. Often facade tile manufacturers offer the same or similar colors of tiles and bricks needed to complete associated elements such as facades, chimneys, fences and landscape design. Due to the fact that they are produced in thicknesses of 9-14mm, they can use the same grouts as for sealing joints for bricks, therefore, their particle size and structures are identical to the surface of masonry mortars. We hope that based on the above information, the investor, considering the technical and aesthetic aspects, will be able to make informed decisions and have tiled walls with trouble-free operation.