Refractory masonry mixture and its varieties, what are they? Why is the most common not resistant to high temperatures? The answer is quite simple - cement contains combustible raw materials, namely substances that decompose when heated.

To create a unique composition with the property of heat resistance, it will be necessary to solve the only problem - to replace combustible elements with non-combustible ones with similar properties.

Details on the topic

Cost of auxiliary and refractory raw materials

Name	Manufacturing company	Packing, kg	Packing cost, rub	Cost of 1 kg, rub
Chamotte clay	"VOLMA", Volgograd	20	250	12
Polyurethane Fire Fighting Foam	FOME Pro, Germany	Balloon (690 ml)	500	—
Liquid glass №1	"MITSAR", St. Petersburg	15	420	28
Liquid glass №2	Bitumast, Belgorod	12	740	60
Base for mastic 3VMKV (prom)	Termostroy, Perm	50	35 000	695
Mertel	"TERRACOT", Kurgan	20	360	18,5

Styling mix

As already mentioned above, raw clay can be used for laying refractory bricks, but for this the wall thickness must be at least one brick (i.e. 25 cm). With such masonry, stability will be weak, the wall will not crumble due to static, and clay will help distribute the load. This is acceptable for fireplaces and stoves that are inside the house, i.e. the seams will not shrink, and as a result, the walls will not be deformed.

Another problem with clay is that after some time it will fall out from the seam.

To make the masonry durable, we suggest using a clay-cement mortar. To prepare it, do everything in the following proportions:

• Clay - 2 measures.
• Sand - 1 measure.
• Cement - 1/3 measure = 10% of the total volume

So, a small amount of cement that we will add will help the clay to hold in the seams. This solution is called heat-resistant, but only conditionally, since the composition still contains a combustible element. Such a solution of cement and clay can withstand a maximum temperature of +96 degrees.

Of course, the best solution to this problem would be to buy a ready-made masonry refractory seven Mertel. The latter is a refractory powder, which is used as a raw material to be added in proportion to the sand-cement mixture. The amount of powder added is calculated by temperature - the higher, the more powder is added. The thickness of the seam will be from 0.3 to 1.2 cm.

List of the best refractory masonry mixes

Refractory plaster

Mortars for plaster and masonry do not differ much from each other in composition, as well as mixtures for general construction purposes. The difference between a masonry mortar and a plaster mortar in functional terms is that the layer plays a protective role, and is able to perceive “blows” from the side. external environment, which means that the stability is many times higher.

The easiest and most inexpensive way to give the plaster mixture refractory properties is the silicification procedure. In practice, this looks like adding silicon glue to the mixture, or, as it is more simply called, liquid glass. To obtain properties that are enough to be used for finishing the internal surfaces of a fireplace or, you will need to add 20% of liquid glass to the mixture of the total volume. For 1 m 3 of solution, 200 liters of silicon glue will be needed.

Factory-made putties and plasters are made on the basis of kaolin clay, a binder and fireclay dust (waste from the production of fireclay products). Such a mixture can withstand up to +210 degrees.

The best refractory plasters produced in the factory

Name	Manufacturing company	Packing, kg	Packing cost, rub	Cost of 1 kg, rub
"Pechnik"	G. Perm	20	380	19
"PLITONIT-SuperFireplace"	Kirovsk LO	20	860	43
Stroyzashchita Nertex-U	Moscow	15	276	18
"Ekabud"	Saint Petersburg	25	430	7,5
"Dune" SHT-60	G. Chelyabinsk	25	230	9
BergaufBautermo	Yekaterinburg city	25	470	19,4

Tile adhesive and mastic

Mortar and silicon glue are also used to create mastic and glue. In general, mastic is just a combination of these two components. The glue can withstand temperatures up to +1200 degrees, and it is actively used when facing the hearths of fireplaces lined with heat-resistant ceramic tiles. The masonry seams that are subject to high temperatures are rubbed with mastic, since the masonry mortar has a lower heat resistance.

In this case, two types of mortar are used - thermal hardening and hydraulic. The latter solidifies according to the principle of a conventional cement mortar, and the thermal one begins to harden during firing, creating a continuous ceramic surface.

Name	Manufacturing company	Packing, kg	Packing cost, rub	Cost of 1 kg, rub
KPD-50 (UNIVERSAL)	Yekaterinburg city	25	270	10,4
NEOMIDSupercontact	Saint Petersburg	4	380	85
XT-7200	City of Samara	75	1500	20
NullifireF0100	Saint Petersburg	3	190	62
triumph	Novosibirsk city	15	690	48

Refractory cement

This type of mineral binder contains calcium aluminate, due to which the strength of the mortar and concrete is maintained.

Its distinguishing features are:

It is impossible to make such cement on your own, but it can be easily found on sale. This will allow the creation of refractory concrete, which will help move away from the established methods of laying fireplaces and bring to life the most interesting ideas of designers.

Dry mixtures, in addition to kaolin clay, can be given refractory properties by additives based on barium, silicon, asbestos or other materials. When reacting with water or a catalyst in the form of a solvent, the mass acquires the desired properties. We also note such a property that comes as a bonus, namely waterproofing. This is of particular relevance to solutions using liquid glass, which, when the standard proportion is reduced to 10-15%, gives waterproofing properties.

Refractory cement

Name	Manufacturing company	Packing, kg	Packing cost, rub	Cost of 1 kg, rub
Kemeos SECAR 38R	France	25	550	22
GTs-40	Novosibirsk city	40	950	23,5
ISIDAS 40	Türkiye	25	650	26
Lakka Tulenkestava	Finland	25	1400	54
VHC-I-35, VHC-I-50	Novosibirsk city	20	2000	100

Mixes for brickwork stoves and fireplaces are designed not only to fasten building elements, but also to ensure the tightness of the structure. A high-quality composition guarantees a long service life of the stove or fireplace.

Peculiarities

For the construction of stove and fireplace structures, only refractory bricks or natural stone are used. To ensure the solidity of the structure allows the use of a special mixture for laying furnaces, which has heat resistance and increased strength. In addition, such mixtures are characterized by medium plasticity, the absence of toxins and unpleasant odors when heated. Their feature is that they fill the entire space between the elements without forming voids. This ensures the tightness of the furnace - no draft-violating air enters it, carbon dioxide and toxins released during the combustion process do not escape.

Such compositions can be purchased ready-made or knead with your own hands. In the first case, we are talking about dry mixes consisting of the necessary ingredients in the right volume. Before use, it is enough to fill them with water and mix with a mixer or a special nozzle on a drill until a homogeneous consistency. Self-preparation of the solution involves the purchase of the necessary ingredients and mixing them in the prescribed proportions. Hand-made mixtures are often inferior to ready-made ones in their qualities, since it is not always possible to correctly calculate the required ratio of products, to find the right ingredient.

When it comes to oven mixes, professionals refer to terms such as refractory, heat-resistant and heat-resistant. Despite the similarity, these concepts have different semantics, which should be understood before mixing the mixture.

Heat-resistant is a composition that can withstand high-temperature heating and at the same time retain its load-bearing capacity. When cooled, such a mixture retains chemical and structural features and does not deform. The heat-resistant version differs in mechanical and physical characteristics. But in short, it withstands higher temperatures, and can also be used as part of mechanisms.

Refractory is a heat-resistant or heat-resistant composition that can withstand, in addition to high temperatures, the impact of aggressive components contained in flue gases without loss of strength.

Kinds

Clay compositions are ready-made and diluted independently. Dry compositions, in turn, are divided into simple and improved. The first options contain only clay and sand cleaned of impurities and are used for units that do not experience sharp temperature fluctuations. To increase strength, cement is sometimes added to the finished simple mixture. Simple clay compositions are affordable. Their heat resistance is about +1100 degrees, fire resistance is 100% (it dissolves only in fluorine-antimony and hydrofluoric acid). Such a composition is not used for laying outdoor fireplaces and bath stoves, since it becomes sour at high humidity. When used indoors with a normal level of humidity, this feature is an advantage - if necessary, you can sort out the oven.

Improved analogues include, in addition to clay and sand, plasticizers, which provide increased strength, elasticity, and fire resistance of the solution. It is suitable for joints exposed to sudden changes in temperature and humidity, so it can even be used for outdoor fireplaces. Such mixtures are more plastic, which allows the formation of a thin layer, and also have a water-retaining property, so that pre-soaking of the bricks can be dispensed with.

Depending on the place of use, the compositions are cement, clay and lime. Cement is a cement-sand, with the addition of clay, a composition used to fill the base of furnaces. The furnace part, as well as surfaces subject to high heat, are built using clay mixtures (or clay-chamotte), lining is made using compositions containing lime. In addition, there are universal finished products.

The foundation of the furnace is not exposed to heat, so a cement-lime mixture is suitable for pouring it, which can withstand temperatures of 200-250 degrees. For the furnace part and elements in direct contact with an open flame and exposed to elevated temperatures, a heat-resistant mixture is used. It is also a repair, since the composition is used to repair structures and mechanisms that are exposed to high-temperature effects.

The heat-resistant solution can be heated up to 1300 degrees, while it only becomes stronger. This is due to its composition, which includes clay and fireclay filler. The material has a higher price compared to the price of clay mortar. If necessary, to increase the strength of the firebox, a cement-chamotte mixture is used. It has strength indicators characteristic of the cement-lime analogue and typical of the clay-chamotte modification with increased heat resistance. The fire resistance values ​​are considered sufficient for the firebox.

The lime mixture contains lime dough (purchased in a store, has a ready-made look) or quicklime-boiling lime in the form of pieces. The latter should be broken and extinguished before use. If even a small amount of unslaked grains remains, then when heated, they will damage the integrity of the seams. Such a composition has a lower heat resistance compared to clay analogues - about 450-500 degrees, withstands the influence of flue gases. The mixture is non-hygroscopic, therefore suitable for outdoor use. As a rule, lime mortar is used when laying the part protruding above the roof chimney. To speed up the setting of the mixture allows the addition of gypsum to it. Cement is used to increase strength.

The advantage of ready-made mixtures is not only ease of mixing and accuracy (accuracy to grams of component content), but also the ability to choose a product for each type of work - this allows the characteristics of the mixture to fully manifest itself and ensure the reliability and durability of furnace structures. Most manufacturers share compositions for structures operated indoors and outdoors, and also offer separate modifications for bath units used at elevated temperatures and humidity.

In addition to masonry and plaster mixtures, analogues for pouring the base and repair work, laying firebox and tile adhesive, also emit grout mixtures. They allow you to give the finished oven a more aesthetic appearance, hide small defects in masonry joints. It is important to use a special refractory grout. As a rule, it is sold in devices that work on the principle of a glue gun or polyurethane foam, and is a container with a thin tube from which a semi-liquid mixture flows.

Product overview of popular brands

The mixture should be bought from well-known manufacturers, having previously requested certificates of conformity from the seller. Among the manufacturers that enjoy the trust of experts, there are several brands.

"Borovichi"

Under this brand, you can find refractory masonry mortar for fireboxes, as well as mortar for chimneys. Professional stove-makers often add clay pulp to these compositions, which is clay diluted to a semi-liquid state, which increases the adhesion of the mixture.

Scanex

Domestic company producing mixtures for ceramic bricks under the TERM SA brand, fireclay - TERM TK. The latter are masonry, because they have a refractory property due to the clay-silicate composition. The option for ceramic bricks is cement-sand, so it is only suitable for making the outer walls of structures. Finally, the same manufacturer offers a mixture of TERM AL, which is a plaster for exterior walls.

"Plitonite"

Product of German-Russian production. Sold in several versions.

Of the most popular products, it is worth noting the following compositions:

• "Thermolay". These are products used for the outer walls of stoves, fireplaces. Differs in economy of material.
• "Fireproof". The material is intended for heat-resistant bricks.
• "Thermoglue". Adhesive for oven lining, e.g. ceramic tiles.

"Vetonite"

The products of this brand are available in three versions: for chimneys - the SVL series; for combustion chambers, as well as surfaces in contact with open fire, TM compositions are suitable; casting of elements exposed to ultra-high temperatures (1200-1300 degrees) allows the TV composition.

"Terracotta"

Another Russian manufacturer that has received many positive customer reviews. It produces mixtures based on fireclay and kaolin clay, thanks to which the finished product can withstand heating up to 1300 degrees. Differs in plasticity that causes convenience of application.

RATH

Austrian company specializing in the production of heat-resistant refractory kiln mixtures. The high price, according to buyers, is justified by the high quality of the product, ease of application (allows you to put thin seams) and quick drying.

Furnace house "Makarov". It is one of the leading Russian manufacturers, whose products are well known outside the country. Mixtures of this brand are widely used by professional stove-makers, which indicates their high quality. At the same time, due to the ease of breeding and elasticity, they can also be used by people who do not have professional building skills. The composition is based on varieties of blue and red Cambrian clay.

How to do it yourself?

When mixing the solution for the oven on your own, remember that each part of it requires a special composition. For example, the underground part can be performed using conventional cement mortar. However, surfaces in contact with an open flame and exposed to heat must contain clay. The mixture for the base is kneaded from cement and sand, taken in a ratio of 1: 3. It is also permissible to add fine gravel to the solution. It should be diluted with water to a consistency resembling wet earth. Sand for the composition is better to take mountain. Being rough, these sand grains provide higher adhesion than wave polished river sand.

The solution sets in half an hour, complete solidification occurs in a day, after which laying can be done.

Masonry is carried out using burnt chamotte clay, which is filled with water and kneaded to the consistency of thick sour cream. You can increase the strength of masonry joints by adding cement to the mortar, and speed up drying by adding lime. When adding cement, 2 parts of clay, 1 part of sand and a third of cement are taken. Cement should not exceed 10% of the total volume of the mixture. Chamotte is called pre-baked refractory high-alumina clay, which also includes compounds of the mineral pomegranate and chicory. Fireclay can be found on sale under the name "mortar". It is important that the clay has an average fat content. This indicator can be determined as follows: a ball or sausage should be rolled out of clay, after which it should be compressed or stretched. If cracks appear on the surface, this means that there is a lot of sand in it - the fat content of such raw materials is low, and it is not suitable for adding to the mixture.

You can also place a rolled ball between two small boards that need to be squeezed slowly. The optimal composition is one in which cracks on the ball appear only after it is compressed by a third. If these phenomena appear earlier, then the fat content of the clay is not enough. If cracking is not observed for an excessively long time, then the clay is too liquid. In the case of using lean or overly fatty raw materials, the seams crack and sag unevenly, so it is not suitable for use. In some cases, too fatty raw materials can be corrected by adding sand to it.

Clay must be well sifted to remove impurities. For purification, you can use the method of experienced stove-makers - clay is poured into the upper part inclined surface in a uniform layer of no more than 30 cm. Water is poured down so that it does not reach the clay. Then waves are created with a trowel or hands that wash the clay. After some time, pure raw materials remain in the liquid, which is then separated from the water and filtered through a sieve. The next step is soaking the resulting raw material in clean water for 24 hours. After the specified time, the composition is stirred again, if necessary, pour in water.

After that, you will need to take five liter jars, two of which are completely filled with purified clay. The third jar needs only a third to be filled with clay, filling the rest with sand. The next jar should contain even less clay - a fourth of it, and the remaining parts are also covered with sand. The last jar should only contain sand.

The next step is to mix the dry ingredients from all the jars and fill them with water. It is more convenient to knead the composition with your hands. By consistency, it should resemble sour cream and not stick to your hands. Professional craftsmen usually check the strength of the composition by rolling a ball with a diameter of about 5 mm from it. Then the ball is completely dried (about 10 days), after which it is thrown from a height of 1 m. If the ball does not crumble and does not deform, then the composition is considered strong and of high quality.

If there is no time to wait for the clay ball to dry out, then two bricks can be fastened with the prepared mortar. After that, you should wait 5 minutes and lift the bricks by the upper part - the lower brick should not fall or “crawl”. A quality mixture can withstand several such uplifts.

The oven is usually plastered using a mixture based on lime and water, and gypsum or cement is also added to increase the strength characteristics of the layer. Lime is pre-sifted, breaking lumps. Then all dry ingredients are thoroughly mixed and poured with warm water. The resulting solution in its consistency should resemble thick sour cream. When a strong heating of the plastered surfaces is expected or the use of a facing composition from inside the furnace, silicon glue is placed in it, which provides heat resistance. This additive is usually bought in a specialized store - it is better known as liquid glass. In the finished solution, its content should be less than 20%.

A recipe with liquid glass may look like this: 3 parts of clay and sand are combined with 1 part of liquid glass and the same amount of tooth powder.

traditional recipe of plaster mortar includes 1 part of lime, 2 parts of sand and a tenth of asbestos. You can get a stronger composition by taking the same amount of sand and cement (together they form 1 part), add 2 parts of sand and a tenth of asbestos. If it is necessary to tile the furnace with tiles, the following composition is prepared: 1 part of the clay-cement mixture (consists of an equal amount of clay and cement), 2 parts of sand. Salt is sometimes added to increase strength and prevent cracking of the seams.

Some masters refuse to add clay to the solution, kneading the composition of cement, salt and sand. The ingredients are taken in equal volumes. However, for this mixture, the tiles should be soaked in water for about 2 hours in advance. Strengthen adhesion and prevent peeling tiles allows the deepening of masonry joints.

Dry ingredients are poured into warm water, thoroughly mixed, after which the composition should be left to “rest” for an hour. The consistency should be a mixture resembling thick sour cream. If it breaks, then water should be added. If, when raking the composition with a trowel, a trace of it remains on the surface, then there is too much liquid - when raking the solution with a trowel to the side, it should keep its shape well and not tear.

When using ready-made solutions, it is possible not to soak the bricks additionally, since dry mixtures are characterized by water-retaining capacity, which makes it possible to reduce the installation time of the furnace and reduce the drying time of the masonry.

The solution is applied with a trowel 10-12 mm thick. Dry mixes allow you to form a thin (from 2-4 mm) seam, which allows you to avoid cracking, save composition and get a more attractive result. Work should be carried out at temperatures from +10 to +35 degrees Celsius. The composition should be stored undiluted, in sealed original packaging, in a dry and warm place.

Despite the fact that manufacturers of ready-made mixtures indicate the required amount of water, its volume also depends on the temperature of the room. At an elevated room temperature, a little more water is required, and at a lower one (within the normal range, but not lower than +10 degrees) - a little less. Experienced stove-makers sometimes add table salt to the refractory mixture, which makes it possible to increase the strength of the seam. For 10 kg of dry composition, 150 grams of salt is taken. Instead of salt, 1 kg of cement can be added to the same volume of solution - the M400 brand will be enough.

It is recommended to choose different compositions for the fireplace, due to the difference in their design and operation. The elements of the fireplace heat up less (in fact, only the furnace part is exposed to high temperatures), so increased heat resistance is not needed here, but strength and moisture resistance are important. In this regard, experts recommend diluting a lime-cement mortar for fireplaces, and a clay-chamotte composition for a firebox.

After 3-4 days after laying the furnace using dry mixes, you can start heating the device. This should be done actively for another 3-4 weeks, after which cladding can be done. If, after a trial heating of the oven, efflorescence has formed in the area of ​​\u200b\u200bthe seams (which is considered the norm), then they can be removed with a damp cloth after the oven has cooled down.

For information on how to prepare a mixture for laying bricks, see the following video.

The refractory mixture is a special composition that is used for laying and plastering structures, the temperature of which can rise significantly. These materials are indispensable in the manufacture of fireplaces, boilers, stoves and other products.

Most often, the mixture for refractory masonry contains clay in its composition. This material is environmentally friendly, it perfectly withstands high temperatures. The main feature of masonry mixtures is the ability to endure elevated temperatures and maintain their own specifications. For each material, the maximum thermal regime may differ. However, a high-quality refractory mixture must withstand temperatures up to +1200°C. The materials can be used indoors and outdoors.

Advantages of refractory mixtures

Modern fire-resistant compositions have valuable advantages:

• high elasticity - facilitates the use of mortars and allows you to get an aesthetically attractive masonry;
• resistance to cracking - achieved due to the fact that the expansion coefficient of the mortar is the same as that of the brick, therefore, when the temperature rises, the mortar behaves in the same way as the base material;
• ease of application - to prepare a solution, it is enough to close the composition with a liquid, its use is in many ways reminiscent of classic masonry compositions;
• high environmental friendliness - there are no toxic substances in the composition of the solutions;
• good adhesion - the solutions hold materials well, which allows the structure to withstand severe mechanical loads;
• thermal stability - even with strong heating, substances retain their performance characteristics;
• incombustibility - the material does not ignite at the highest temperatures;
• acceptable cost - the price of refractory mixtures is at a low level, which makes them affordable for a wide range of consumers.

Features of storage and operation of refractory mixtures

In order for the composition to maintain its parameters, it is necessary to take care of the appropriate storage conditions. In this case, the humidity index should not exceed 4.5%. When preparing the solution, a liquid should be used at a temperature of +15°C and above, but it can be applied at a temperature of +5°C. If these requirements are not met, the quality of the solution and the structure being constructed will decrease. It is also forbidden to use third-party additives.

The Slavdom company offers to buy a refractory mixture from the world's leading manufacturers. You can get to know the products better in one of our offices, which are located in Moscow and St. Petersburg. However, it is not at all necessary to visit them - delivery is carried out to all cities of Russia. Contact us! We will help you choose the most suitable refractory mixture for your purposes!

Conventional mixtures cannot be used for laying and plastering stoves and fireplaces, since exposure to high temperatures will lead to cracks, unreliability and fragility of the structure.

To choose a heat-resistant mixture, we suggest understanding what varieties exist.

Types of mixtures for furnaces

And plaster can be industrially produced, it can be purchased in specialized stores, as well as made by hand.

Industrial mixtures

Such a mixture for the stove and fireplace is high temperature composition, which combines with water until a homogeneous mass is formed. The volume of water is usually indicated in the instructions. In addition to the usual ingredients (cement and sand), components are added to the composition, increasing heat resistance.

Benefits of using industrial mixes for masonry and oven plastering and the fireplace are:

• Proven by experience and time composition. Manufacturers experimentally identify the most stable proportions and make the best recipes.
• hard to reach components. Specific substances added to the mixture are sometimes difficult to find in stores, and acquiring them in small quantities is too expensive.
• Multifunctionality. In many cases, the compositions can be used both for laying furnaces and for lining them.
• Attractive look. Not a practical criterion but also important.

The main disadvantage of industrial compositions is their value. For this reason, making a solution with your own hands is more rational and economical.

Mixes of self-preparation

Depending on the operating conditions of the stove or fireplace, as well as on the purpose, mixtures are:

• clay,
• cement,
• calcareous.

In the composition of home-made refractory mixtures for laying the furnace without fail includes clay and sand. To increase plasticity, milk of lime is added, while asbestos is used as a reinforcing substance. Depending on the needs of the furnace owner, and other components.

Read also: Doors for stoves and fireplaces

The disadvantages of such solutions are:

• Insufficient strength. As you know, clay has a low level of resistance to mechanical stress, for this reason, a solution based on it is suitable only for masonry, but not for finishing work, in particular, plaster. In addition, the composition of the clay itself is also different, which in the end can affect the result.
• Unattractive appearance. For stoves and fireplaces located in residential premises, where the aesthetic aspect of the result is important, it is better to use the purchased mixture for plastering. For utility rooms, where the appearance of the furnace does not play a key role, a clay-based solution can be used.

Some aspects of the use of ready mixes

After purchasing the mixture for the oven, you must carefully read the instructions and manufacturer's recommendations. The main generally accepted rules are the following: the masonry and plastering process must take place at ambient temperature not lower than + 5 degrees and should be stored in a warm, dry place. Before purchasing, it is necessary to inspect the packaging: it must not be damaged, otherwise the chemical characteristics of the composition may be violated.

To prepare a solution, the most frequent proportion of the amount of water and the mixture is 1 kg. composition per 0.27 l. ordinary tap water. Before direct laying, to ensure greater strength, the bricks must be moistened with water.

Making your own solution

For do-it-yourself cooking for the oven, raw clay is used as the main component, which has the necessary properties so that the seams of the structure do not shrink. So that the clay does not crumble, cement is added in the proportion of 2 parts of clay, 0.3 parts of cement and one part of sand.

In addition, the consistency of the clay should be checked. To do this, it is kneaded and intensively kneaded in the hand. From the resulting mass, a ball with a diameter of ~ 5 cm is formed, which is placed between two surfaces, for example, planks. The boards are gradually compressed, flattening the ball. The Perfect Blend cracks when compressed by 1/3. If cracks appear earlier, this indicates a missing fat content, otherwise - about its abundance. Low-fat clay should not be used at all for the preparation of the solution; when using excessively oily clay, the proportions should be changed by adding more sand.

In this article, you will learn what gives ordinary mortars refractory properties. We will give examples of making heat-resistant mixtures from ordinary ones with our own hands, indicating the proportions of the ingredients. The article presents prices for raw materials and finished compositions of various domestic manufacturers.

Why can't ordinary cement withstand high temperatures? The answer is simple - combustible raw materials are used in its composition. More precisely, substances that decompose when heated. To create compositions with heat-resistant properties, scientists had to solve only one problem - to replace combustible raw materials with non-combustible ones with similar properties.

Raw materials for refractory compositions

Clay. For the manufacture of 80% of refractory materials widely used in private construction, ordinary clay is used. Even in the form of raw materials taken from the bowels, it has refractory properties that are several times superior to those of industrially produced Portland cement. At the same time, raw clay does not have the ability to reliably bind surfaces. Our ancestors perfectly studied the properties of clay and used it for laying Russian stoves and plastering the walls of the house.

Chamotte, expanded clay. This is clay that has undergone heat treatment. When baked in an oven, clay evaporates moisture and loses the ability to accumulate it again. Refractory bricks, blocks and rings for laying fireplaces, chimneys, and stoves are made from fireclay. When ground, both of these materials form the basis of most refractory factory mixes.

Prices for refractory and auxiliary raw materials

masonry mixture

As mentioned above, raw clay can be used for laying refractory bricks, but the thickness of the wall must be at least one brick (250 mm). Such masonry has poor stability, the wall does not crumble due to the static nature of the brick, the clay only distributes the load. This is quite acceptable for stoves and fireplaces inside the house, because the seams do not shrink, and the walls do not deform.

Another problem with clay is that it eventually spills out of the seam. To give such masonry strength, you can use a cement-clay mortar. Its proportions:

1. Clay - 2 parts.
2. Sand - 1 part.
3. Cement - 0.3 parts or 10% of the volume of the mixture.

A small amount of cement will help hold the clay in place. Such a solution can be conditionally called heat-resistant, because combustible material is still present in its composition. Cement-clay mortar will withstand a temperature of no more than 80-90 ° C.

Of course, the best solution for do-it-yourself refractory masonry will be factory mixes. Up to 90% of their composition is mortar - ready-made refractory powders, which are introduced into the cement-sand mixture in different proportions. The amount of mortar is calculated depending on the temperature - the higher it is, the greater the percentage of powder. The thickness of the seam is from 3 to 12 mm.

Refractory masonry mixtures

Refractory plaster

As in mixtures for general construction purposes, mortars for masonry and plaster differ little in terms of ingredients. The functional difference between a masonry mortar and a plaster one is that the plaster layer is protective, perceives the “shocks” of the external environment, and therefore must be more durable (stable).

The easiest and most affordable way to give plaster refractory properties is silicification. In practice, this means adding silicon glue, colloquially "water glass". To achieve properties sufficient for use on the inner surface of a stove or fireplace, 20% of liquid glass is required by volume of the solution. For 1 cu. m (1000 l) solution needs 200 l of liquid glass.

Factory refractory plasters and putties are made from kaolin clay, fireclay dust (waste from the production of fireclay products) and a heat-resistant binder. They are guaranteed to withstand temperatures up to 200°C.

Factory refractory plasters

Tile adhesive and mastic

For the manufacture of glue and mastic, mortar and liquid glass are also used. At its core, such a mastic is these two components mixed together. The glue can withstand up to 1100 ° C, it is used for facing the visible hearths of fireplaces with heat-resistant ceramic tiles. Mastic is used for filling (grouting) masonry joints exposed to high temperatures, since the masonry mortar has a much lower heat resistance (up to 200 ° C).

Mortar can be of two varieties - hydraulic and thermal hardening. Hydraulic hardens like a regular cement mortar. Thermal hardens during firing, forming a continuous ceramic surface (like earthenware).

Factory heat-resistant adhesives and mastics

Name of mastic, glue	Manufacturer	Packing, kg	Package price, rub.	Price 1 kg, rub.
KDP-50 (UNIVERSAL)	Ekaterinburg	25	240	9,6
NEOMID Supercontact	Saint Petersburg	4	330	82,5
XT-7200	Samara	75	1400	18,5
Nullifire F0100	Saint Petersburg	3	180	58,8
triumph	Novosibirsk	15	675	45

Refractory cement

In this type of mineral binder, calcium aluminate is used, which retains the strength characteristics of concrete and mortars. Distinctive features mortars and concretes on heat-resistant cement (in addition to refractory):

1. Corrosion resistance. This property is achieved through the use of inorganic raw materials - calcium aluminate - which is not subject to rapid natural decomposition (unlike marl and lime in conventional cement).
2. Early dates hardening due to the displacement of moisture from the solution.
3. Technological application. According to the method of use and proportions, it does not differ from Portland cement.
4. Dielectric properties due to the absence of moisture.

It is impossible to make refractory cement on your own, but it is easy to find it on the open market. It allows you to prepare refractory concrete, which helps to move away from the canons of masonry fireplaces and embody the most daring design ideas.

Refractory cement prices

In addition to kaolin clay, special additives based on silicon, asbestos, barium or other alumina materials give refractory properties to dry mixes. By reacting with water or a catalyst solution, the mass acquires the necessary properties. It should be noted one more property, which is "attached as a bonus" to heat resistance. This is hydrophobization or waterproofing. This is especially true for solutions using liquid glass, which in smaller proportions (10-15%) provides the waterproofing properties of a conventional solution.