Currently there is a huge number various types concrete, which have their own area of ​​application and additional properties, specially selected for specific needs. However, there are situations when this material is exposed to various factors in the form of high temperature, which are not characteristic of him. Therefore, the question of how to make heat-resistant concrete with your own hands is of great interest to modern craftsmen.

Types of material by temperature conditions

To begin with, it is worth mentioning that there are many varieties of such materials. They all have their own technical characteristics, the main of which are temperature parameters. Therefore, it is necessary to understand their composition and manufacturing methods.

Temperature up to 800 degrees

First of all, it must be said that the composition of heat-resistant concrete allows the use of this material for high temperatures without changing its basic properties.

In this case, you can get different brands of such a solution depending on the proportion.

• The main role in such compositions is played by a special additive. It can be purchased in specialized stores or markets building materials. However, it should be said right away that it is the additive that is needed for making concrete, and not a composition for paint or other substances.
• It is also necessary to use other binding agents. Simply put, the same amount of Portland slag cement is added to one part of Portland cement. Moreover, both of these substances are considered as one unit of measurement when selecting proportions.

• Also composition heat-resistant concrete change in relation to fillers. Instead of ordinary crushed stone, broken bricks, blast furnace slag or rocks are used. Expanded clay, pumice, perlite, diabase, andesite and diorite are perfect for this role.
• Instead of sand, it is better to put electrocorundum in such a solution, but for data temperature conditions this is completely optional.

Advice! It is very important to follow the instructions that come with the supplement. They may differ from each other depending on the brand.

Temperature up to 1700 degrees

These types of material must retain their properties at very high temperatures, which means their composition must be approached very carefully. That is why corundum is used as sand for them, which it is advisable to further clean from various impurities.

There are also other types that can withstand high temperatures. Their price may seem too high, but they are completely worth the cost.

It is important to mention that some craftsmen recommend using other materials instead of cement as a binder. They may differ in their composition and even be liquid, but they must be selected individually.

Advice! If the area of ​​application of such solutions requires a strictly defined quality, then it is best to order them from a manufacturer who has the appropriate certificate for their product and does not violate technological processes during manufacturing.

Application area

It is important to mention that refractory concrete can be of many different grades and have different densities. This is precisely the main criterion in determining the scope of its application.

Thermal insulation material

This category presents compositions that, in their characteristics, resemble foam blocks or gas blocks. In fact, they are, but only with the inclusion of a special additive and the correct selection of components. These also include expanded clay concrete products.

Structures made from this material are used as insulation, which must withstand high temperatures without allowing the air to cool. Moreover, very often they are located inside work areas and are subject to sudden changes.

Such compositions are characterized as cellular and. However, they have a certain thermal conductivity and resistance to intense heating.

Advice! It is important to remember that such materials should not be forcibly cooled. As a result, they may crack.

Construction materials

Typically, installation instructions advise using similar grades of concrete to create supports, floor slabs or other building elements that are exposed to heat during operation. However, it is worth noting that it is not worth using reinforcement with these types of concrete. The fact is that when heated, the metal expands and can destroy the entire product.

Conclusion

After watching the video in this article, you can study in detail these types of concrete and their scope of application. Also, taking as a basis the text presented above, it is worth concluding that this material can be produced independently, but for critical areas it is better to use products from trusted manufacturers.

The need to use fire-resistant materials quite often arises during the construction of facilities. In the future, this allows you to protect structures and people from the unpleasant consequences of accidental fires. One of these materials is heat-resistant concrete, which can withstand high temperatures up to 1000 °C. At the same time, he retains useful qualities and does not lose shape.

Classification

There are several types of heat-resistant concrete, which is also called fire-resistant or heat-resistant. The material contains special fire-resistant additives. The main binding component in the production of heat-resistant concrete is Portland cement. The following can be used as fillers: blast furnace slag, rock screenings (diabase, andesite, porous rocks of volcanic origin, diorite, artificial fillers), blast furnace slag.

The material is divided into separate classes according to:

1. Structure (heavy, light, porous).
2. Purpose (thermal insulation, structural).
3. The nature of the fillers.
4. The binder components used.

Specifications

Fire-resistant concrete prepared using Portland cement as a binder has a classic strength index. When conducting a compression test, the limit values ​​are in the range from 200 to 600 MPa/cm2.

Manifestations of thermal stability are observed when temperatures reach no more than 500 °C. Prolonged exposure to an open flame or prolonged contact with hot surfaces significantly reduces the strength properties of cement and often causes defects.

The most fire-resistant concretes prepared on the basis of alumina are able to withstand any household temperatures. Aluminous coatings saturated in composition are characterized by thermal stability of about 1600 °C and higher. A gradual increase in temperature leads to in this case to an increase in heat resistance, since the cement mass is converted into a ceramic state.

However, despite the high resistance to the effects elevated temperatures, aluminous refractory concrete has relatively low strength. The material made using such components can withstand mechanical pressure of up to 25-35 MPa/cm2.

Primarily, refractory material is used in the manufacture of thermal structures, industrial furnaces and household use, foundations, collectors, combustion chambers. However, it cannot be said that such concrete is used only in structures that are susceptible to thermal influences.

Thus, the specific composition of refractory concrete contributes to its widespread use in the chemical industry, in the production of building materials, and to meet the needs of the energy sector.

Heat-resistant material is used in the construction of floors, floating structures, and purlin bridges. They give preference to this construction basis due to the need to lighten structures, taking into account high strength and reliability indicators. The refractory composition makes it possible to reduce the weight of structures by approximately 40%. This is explained by the use of a significant volume of porous fillers in the mixture.

Preparation of the composition

How to create fireproof concrete by making your own mixture? For this purpose water is used, binders and various heat-resistant fillers. The manufacturing process has its own distinctive features. The components used must be of particular purity. In addition, clogging of refractory and refractory components with sand, limestone or granite is eliminated.

Making such mistakes in production technology often leads to rapid destruction of the material.

Manufacturing techniques

There are several ways to produce heat-resistant concrete with your own hands. First of all, you can obtain the material using a ready-made dry mixture, which has all the necessary components. A more complex option involves mixing the components yourself in the required proportions.

The optimal solution is to use the first method, since the best components are used in the production of heat-resistant mixtures in the factory. In addition, in this case, manufacturing technology is carefully observed. As a result, the consumer gets the opportunity to use a ready-to-use mixture highest quality. You just need to add solvent or water.

When making it yourself, in order for the material to acquire fire-resistant properties, it is advisable to add following components fine grinding: andesite, fireclay, chromite ore, magnesite cement. The result of the correct selection of ingredients and compliance with proportions is a material that can withstand elevated temperatures without collapsing.

Tools and materials

By resorting to doing it yourself, you can save significantly by refusing the services of masters. However, before you start making the mixture, it is recommended to prepare necessary tools and materials. Here you will need the following:

• equipment for mixing concrete components;
• spatula-trowel;
• wheelbarrow for transporting materials;
• shovel;
• water spray;
• wooden formwork, casting molds;
• sand, gravel, slaked lime, heat-resistant components;
• Portland cement.

Manufacturing Features

When producing refractory cement, pre-prepared dry components are placed in a concrete mixer (cement-sand ratio is 1:4). After forming a homogeneous mixture, water is added in the amount necessary to achieve a dough-like consistency. Since refractory building bases have specific viscosity characteristics and quickly harden by adding water, it is better to follow the recommendations of the cement manufacturer.

The finished mixture is distributed into molds, poured into formwork or used as a binding material when laying refractory bricks. When using aluminous fillers, after adding water they act extremely quickly, which avoids premature setting of the solution.

If it is necessary to prepare small volumes of mortar using Portland cement, the components can be mixed manually. It is convenient to use wide containers for this - deep basins, bathtubs, troughs.

In concrete on liquid glass, the binder is an aqueous solution of sodium silicate at Na 2 O* nSiO 2 * mH 2 O, which, as a result of physicochemical interaction with sodium silicofluoride or other additives (hardening reagents), decomposes with the release of Si(0H) 4, coagulates and glues aggregate grains together into a monolithic conglomerate. Liquid glass has high adhesive properties in relation to all materials used in the refractory industry. Its adhesive ability is 3-5 times higher than cement, which ensures the production of high-quality heat-resistant concrete based on it.

Unlike concrete with hydraulic binders, hardening of concrete occurs not as a result of hydration of minerals, but as a result of the formation of colloidal glue Si (OH) 4, which acquires maximum strength after drying and recrystallization into Si0 2 with the release of water. Concrete hardens in air-dry conditions at an air temperature of at least 15 °C. At lower temperatures, the hardening process practically does not occur; the most favorable hardening temperatures are 25–50 °C. The most satisfactory properties are possessed by liquid glass, in which the silica module (molar ratio of SiO 2 and Na 2 O) ranges from 2.5 to 3. The silica module is also called the glass module. The process of setting and hardening of concrete occurs only at the moment of separation of silica gel from the colloidal solution:

The setting and hardening of concrete on liquid glass with the addition of sodium silicofluoride or other hardening reagents is a complex colloidal adsorption process caused by the colloidal chemical interaction of the hardening reagent with alkali sodium silicate. In a simplified form, the chemical interaction of sodium silicofluoride with alkali sodium silicate, whose silicate modulus is two, can be expressed by the following scheme:

Na 2 SiF 6 + 2 (Na 2 O * 2SiO 2) + 10H 2 O = 5Si (OH) 4 + 6NaF;

Sodium silicofluoride, due to its low solubility in water (0.6%), reacts with liquid glass slowly.

The process of setting and hardening depending on the amount of added silicofluoride, temperature and modulus liquid glass starts after 30-60 minutes. During this time, the freshly prepared mass is quite plastic and well shaped. The amount of sodium fluoride silico should ensure normal setting and hardening times for concrete, as well as the required strength of concrete at the time of formwork. It should not be forgotten that sodium fluoride is a highly active flux that reduces the fire-resistant properties of concrete based on liquid glass.

In addition to sodium silicofluoride, nepheline sludge, ferrochrome slag, and calcined serpentinite are sometimes used to harden concrete on liquid glass, which is also used as a filler to produce refractory concrete with faster hardening times (10-30 minutes).

When heating hardened liquid glass with the addition of sodium silicofluoride, the main part of the moisture (80%) is removed at 100 °C; when heated to 200 °C, another 12% of the moisture is removed. Residual moisture (8%) is removed by heating to 300 °C, due to dehydration of helium silicic acid during crystallization of Si0 2. As a result of the removal of moisture in concrete, shrinkage occurs, which, when correct selection concrete composition does not exceed 0.8%, and when using concrete with finely ground magnesite 0.25%.

Heating to 800–900 °C leads to partial sintering of concrete. With the introduction of refractory finely ground additives, concrete sintering occurs at higher temperatures, its fire resistance increases.

To prepare finely ground additives, chamotte, magnesite, chromite, chromomagnesite, quartz, dunite, serpentinite, talc, andesite, diabase, etc. are used. The degree of grinding of all types of additives must be such that at least 50% of the mass of the material passes through a 0.09 mm sieve (4900 holes/cm2).

The choice of one type of additive or another depends on the required fire resistance of the concrete and the service conditions of the lining. The use of finely ground magnesite and chromium magnesite increases the fire resistance to the greatest extent.

The lower the density of liquid glass, the lower the strength of concrete, for example, when using liquid glass with a density of 1.25, the tensile strength is only 50% of the compressive strength of dried concrete (25-30 N/mm2) prepared with liquid glass with a density of 1. 36 g/cm 3 .

As the consumption of liquid glass increases, the amount of water in concrete increases, as a result of which its porosity increases and its strength decreases. Thus, when the liquid glass content increases from 400 to 500 kg per 1 m 3 of concrete, the compressive strength decreases in proportion to the Na 2 O content.

As a result of firing, the compressive strength of concrete changes insignificantly compared to the strength of dried concrete. Heating to 300–400 °C causes strengthening of its structure due to dehydration of the gel; at 400–600 °C there is some decrease in strength; with an increase in temperature to 800–1000 °C, the strength for most compositions does not change or increases slightly.

Types of finely ground additives affect the strength of concrete when heated. It is highest for concrete with finely ground magnesite and fireclay additives. The addition of finely ground quartzite significantly reduces the strength due to its modification transformation at 575 °C.

The degree and methods of its compaction have a great influence on the strength of concrete. To ensure the mobility of concrete during compaction by vibration, at least 16% of liquid glass from the total mass of concrete must be added to concrete with fireclay fillers. It is impossible to reduce the consumption of liquid glass with this compaction method, since concrete has high viscosity and is not compacted by vibration.

To obtain high-strength, non-shrinkable concrete with a liquid glass content of 10-14%, it is necessary to use compaction with pneumatic tampers. In this case, the size of the aggregate in concrete should not exceed 5 mm, since coarsening leads to crushing by tamping and a decrease in the strength of concrete.

When using compaction of semi-dry mixtures, the compressive strength of concrete on liquid glass increases by 1.5-2 times. At the same time, shrinkage during the drying and heating process is almost not observed; this is of great importance when lining induction melting furnaces for aluminum melting.

Increasing the sodium fluoride content in concrete reduces fire resistance and strength at high temperatures, since it is a strong flux.

The highest application temperature is for liquid glass concrete with finely ground additives and fillers from broken magnesite bricks (1300-1400 °C). Such concrete begins to soften under a load of 0.2 N/mm 2 at 1250-1300 °C and collapses at 1400-1450 °C.

Liquid glass concrete with finely ground magnesite and fireclay fillers is widely used in induction furnaces for melting aluminum. This concrete has high heat resistance and is resistant to the reducing action of molten aluminum due to the fact that the fireclay grains in this concrete are covered with a shell of magnesite cement stone.

Refractory concretes are mixtures of refractory aggregates and cements, which, when hardened, turn into a stone-like material capable of maintaining specified mechanical properties under prolonged exposure to high temperatures. Recently, the refractory industry has been producing non-firing refractory products in increasing quantities. They can be considered as fire-resistant concrete on the grounds that, by analogy with ordinary concrete, they consist of a fire-resistant filler, inert at ordinary temperatures, and a binder of mineral or organic origin.

Refractory concrete differs from ordinary concrete, firstly, in its fire resistance and sufficient strength under service conditions at high temperatures; secondly, they acquire their operational properties during operation when exposed to high temperatures. Refractories of this type are widely used because their production technology does not require complex and expensive technological process- firing.

Refractory concrete is produced in the form of large blocks or monolithic lining structures, which makes it possible to industrialize the construction and repair of industrial furnaces.

Refractory concrete has some advantages over fired refractory products:

1) there are no seams in a monolithic concrete lining, and in the case of using large concrete blocks, the number of seams is significantly reduced;

2) firing of traditional refractory products, as a rule, occurs in an oxidizing environment and the phase composition of the fired products is characterized accordingly by the oxide forms of certain components. These refractories serve in most cases in a reducing environment at temperatures at which the oxide forms become unstable. Therefore, in fired products of any type under service conditions, changes in the phase composition occur, often accompanied by a change in the volume of minerals, which leads to a loss of strength of the products. In refractory concrete, the change in phase composition occurs only in the inert filler;

3) during the manufacture of fired products, crystallization of minerals occurs from the liquid phase formed at high temperatures. In service conditions it is observed reverse process- dissolution of these minerals in the liquid phase. Since the specific volumes of the substance in the liquid and solid states are different (the volume of the melt of oxide substances is approximately 10% greater than the volume of the solid substance), the crystallization of minerals is accompanied by submicroscopic porosity, which causes an increase free energy refractory and, consequently, its increased reactivity.

This phenomenon is absent in refractory concrete.

Refractory concretes are always more heat-resistant and less thermally conductive than their corresponding chemical composition fired products. At the same time, refractory concrete is always less durable, especially against abrasion.

Refractory concrete must: harden quickly enough at normal temperatures; gradually lose strength when heated to decomposition temperatures of hardening products, and then increase it at higher temperatures as a result of partial sintering; have sufficient thermal stability and fire resistance; have low shrinkage during drying and firing, and a fairly high deformation temperature under load.

Thus, only the first two requirements are specific to concrete. The rest are common to any type of refractory.

The technology of refractory concrete uses terminology that is somewhat different from the terminology used in the field of refractory ceramics.

Refractory powders, divided into fractions, used for the production of refractory concrete, are called aggregate (coarse, fine, thin). Refractory powders containing all the fractions necessary for the production of concrete and dry binders are called dry concrete mixtures. Mixtures together with water or liquid binders are called concrete mixtures. Refractory concretes are classified according to the type of products made from them, the type of binders and inert fillers used in their production.

Product type:

1. non-firing products;

2. large blocks;

3. monolithic linings made of printed or molded masses.

Based on the type of binders used, they are distinguished:

Based on the type of filler, refractory concretes are divided into:

1. dinas (actually dinas, quartz, etc.);

4. corundum;

The variety of concrete in terms of aggregate composition is great.

Any fireproof, non-shrinking material can be used as a filler.

Fillers are obtained by crushing and sifting the refractory starting material into fractions. Fine-grained aggregate is produced in ball and tube mills. Concrete mixtures are prepared in conventional concrete mixers.

IN monolithic structures the concrete is placed using inertial vibrators, and the blocks are formed on vibrating platforms.

Depending on the ultimate compressive strength, concrete is divided into grades 100, 150, 200, 250, 300 and 400. The loss of strength of refractory concrete when heated to certain temperatures, caused by the decomposition of the binder, is determined by the ratio of the tensile strength of concrete after heating to the tensile strength of this concrete before heating. The greatest loss of concrete strength is observed at temperatures from 900 to 1100°C. Above this temperature, the concrete components sinter and strength increases again (Fig. 23).

The process of formation of the structure of refractory concrete can be conventionally considered as consisting of three sequential interrelated processes:

1) hardening - a process occurring at low temperatures (up to 300°C);

2) softening (or hardening) - processes occurring at average temperatures (about 300-1100°C);

3) sintering - a process that occurs at high temperatures (>1000 °C).

Rice. 23. Change in compressive strength of refractory concrete when heated depending on the type of finely ground additive

1- Portland cement with ground granulated slag; 2- the same, with fireclay; 3- the same, with ground quartz; 4- the same, without additives; 5- the same, with chromite

A joint study of these processes makes it possible to select optimal binder compositions and determine the most rational technology that ensures high properties of refractory concrete at different temperatures under operating conditions.

The hardening process of concrete is determined by the chemical interaction of components, recrystallization of chemical compounds or their hydration. The first and second processes are typical for air-hardening binders, the latter for hydraulic binders.

The softening of the structure of concrete with hydraulic binders in the range of average temperatures is associated primarily with dehydration and decomposition of calcium hydrosilicates. Binder decomposition processes are also observed in most concretes made with air-hardening binders (liquid glass, magnesia, sulfate, etc.).

Phosphate bonded concrete has recently become widespread. This is explained by the fact that they have fairly high strength at temperatures of 400-1000°C, i.e. in the temperature range in which the strength of conventional concrete is low.

Bonds for refractory concrete. Currently, a number of binders are known based on orthophosphoric acid (H3PO4): aluminophosphate (a.f.e.), magnesium-, calcium-, chromium-, iron-, zirconium phosphate.

TABLE 28. COMPOSITION AND PROPERTIES OF REFRACTORY CONCRETE

Aggregate	Finely ground additive		Fire resistance, °C	Deformation temperature under load 2 kgf/cm1 (0.02 kN/cm2)	Limit service temperature for one-sided heating, *C
4% compression	destruction
Highly refractory concrete
High-alumina fireclay	Absent	High alumina cement
Break of magnesite-chromite brick		Periclase cement
	Chromite and magnesite	Portland cement I >1770
Corundum or high-alumina fireclay	Alumina hydrate
Refractory concrete
	Absent	Aluminous cement
Chromite I Chromite	Liquid glass 1700
Break of magnesite brick	Break of magnesite brick
Refractory concrete
ShB class fireclay	ShB class fireclay	Portland cement
		Liquid glass with additives

The most widely used in the production of refractory concrete are aluminophosphate and magnesium phosphate binders.

Aluminophosphate binders are colloidal solutions of aluminophosphates obtained as a result of the interaction of alumina hydrate with dilute phosphoric acid. Three types of aluminophosphate binders are used depending on the degree of replacement of hydrogen with cations:

1.Solution of sodium-substituted aluminophosphate Al(H2PO4)3. It is prepared from a mixture of 14% alumina hydrate Al(OH)3 (an intermediate product for the production of alumina grades GO and ΓΟΟ) and 86% technical 60% orthophosphoric acid. The density of the solution is 1.54-1.55 g/cm3.

2. A solution of disubstituted aluminophosphate Al(HPO4)3 is prepared from a mixture of 21% alumina hydrate and 79% technical 50% orthophosphoric acid. The density of the solution is 1.49-1.51" g/cm3.

3. A solution of trisubstituted aluminophosphate Al3(PO4)3 is prepared from a mixture of 22% alumina hydrate and 78% technical 50% orthophosphoric acid.

These solutions are prepared at the site of production of refractory concrete. To do this, technical alumina hydrate is ground in ball mills to obtain particles with a size of less than 60 microns and poured into an acid-resistant reactor with dilute orthophosphoric acid, stirring continuously. The solution can be stored for up to two months.

Magnesium phosphate binders are prepared similarly to aluminophosphate binders.

It is recommended to use only highly refractory materials as filler: corundum, broken corundum and high-alumina refractories, chromite and chromium magnesite. The grain composition of the filler is selected based on general requirements technologies of concrete and refractories (Table 28).

Rice. 24. Lining the walls of a blast furnace air heater made of large blocks

1- heat-resistant concrete; 2- fireproof masonry

The scope of application of refractory concrete is quite extensive. For example, Portland cement concrete can be used to install walls and vaults in the heating and cooling zones of tunnel kilns for the production of ceramics, in flameless combustion furnaces of oil refineries, and in the furnaces of steam boilers. Concretes based on alumina and high-alumina cement with fireclay are used to insulate coolers on the roofs of steel-smelting furnaces; concretes based on periclase cement are used in individual units of open-hearth furnaces. Refractory concrete with phosphate binders is used as a lining for air heaters in blast furnaces (Fig. 24), front walls of vertical channels of open-hearth furnaces, induction furnaces for smelting silver, zinc, copper and aluminum alloys etc.

Heat-resistant concrete is used for the construction of stoves, fireplaces and chimneys. This type concrete is used in both residential and industrial construction. In order for the material to perform its function at the proper level and guarantee safety and protection, strict compliance with all technological requirements during its manufacture is necessary. The material can be cellular, light or dense. This factor depends on the area of ​​its application and purpose. Such concrete can serve as reliable thermal insulation.

To prepare refractory concrete, liquid glass, asbestos, barium or alumina cement should be added to the composition.

Working with heat-resistant concrete is similar to working with ordinary concrete material, which allows you to reduce costs for construction works. you can successfully make this material with your own hands. It is resistant to temperature changes and does not lose its properties when heated, and is also the best option for the construction of specialized facilities of various kinds.

Choosing heat-resistant concrete

To make fireproof concrete with your own hands, you will have to add liquid glass, asbestos, barium or alumina cement to the composition.

Characteristics of heat-resistant concrete.

These additives make concrete suitable for use in areas of high temperatures. Ordinary material includes elements that undergo a process of dehydration and dehydration during the heating process. The structure collapses very quickly when going through such a test, and the restoration process is not possible. To avoid such situations, heat-resistant concrete is used. By examining the heat-resistant concrete mixture in detail, it is possible to identify a high content of various impurities. Each of them plays its role and increases strength by bonding materials under conditions of elevated temperatures. To make heat-resistant concrete with your own hands, you need the presence of binders in the base of the material.

For these purposes you can use:

• Portland slag cement;
• Portland cement;
• high alumina cement;
• aluminous cement;
• periclase cement;
• liquid glass.

Return to contents

Selection of composition for heat-resistant concrete

Various finely ground impurities are usually added to Portland cement and liquid glass. Heat-resistant concrete can be regular or light, depending on the volumetric weight indicators. A material is considered light if its volumetric weight (in a dried state) does not exceed 1500 kg/m³.

For mixing heat-resistant concrete mixture Magnesium sulfate (aqueous solution) is used on periclase cement. In order for heat-resistant concrete with an admixture of liquid glass to harden, it is necessary to introduce sodium silicofluoride, granulated blast furnace slag or nepheline sludge into the mixture. These additives are introduced into concrete at normal temperature.

Fine additives can be finely ground or dusty materials such as:

• broken magnesite brick;
• broken fireclay bricks;
• lump fireclay;
• pumice;
• Cemyanka;
• chromite ore;
• fly ash;
• andesite;
• loess loam;
• granulated blast furnace slag.

Suitable for heat-resistant light mixtures:

• broken diatomaceous brick;
• broken fireclay bricks;
• Cemyanka;
• fly ash;
• expanded clay

Small (0.15-5 mm) and large (5-25 mm) aggregates can be crushed materials, such as: broken magnesite and magnesite-chromite bricks, broken high-alumina and fireclay bricks, broken clay, semi-acid or talc bricks, titanium-alumina and blast furnace waste slag.

These also include dunite, balsate, diabase, andesite, Artik tuff, and lump chamotte. For lightweight and refractory concrete, it is better to use vermiculite, expanded clay or expanded perlite as additives. The type of binder, temperature and service conditions of the concrete determine the choice of finely ground additives and fillers. The use of refractory concrete reduces the cost of work, labor costs, and reduces construction time.

Return to contents

Step-by-step preparation of heat-resistant concrete with your own hands

For this process you need to have tools and materials:

• concrete mixer;
• wheelbarrow;
• Master OK;
• shovel;
• spray;
• hose or other water supply;
• formwork;
• plastic sheet;
• sand;
• refractory cement;
• gravel;
• slaked lime.

The concrete mixer or wheelbarrow should be located in close proximity to the water supply. Water will be needed to add to the composition, wash tools and the site. The materials must be mixed in proportions 3:2:2:0.5, for example - 3 parts gravel to 2 parts sand and 2 parts refractory cement to 0.5 parts slaked lime. The volume of heat-resistant composition should not affect these parameters and the ratio of materials; they should remain unchanged. Gravel and sand are placed in a concrete mixer, fire-resistant cement and slaked lime are added, and using a shovel, all ingredients are thoroughly mixed so that the components are distributed evenly. Then water is added to the mixture and mixed again. Water is added until the mixture reaches the required consistency (working thickness). To check, try making a lump from the resulting mixture. If there is enough water, the lump will not fall apart and will not spread in your hands.

Data concrete mortar formwork or a special form is filled. This process is carried out using a shovel, the excess is removed with a spatula, after which the surface is leveled. The hardening process of the material is accompanied by increased moisture loss. Spray the surface with water periodically to prevent cracking. Wet concrete can be covered with plastic wrap for a couple of days. After this period, the film must be removed and the concrete allowed to dry. Before removing the formwork, the concrete must dry for at least 2 days. After this, the concrete stands and gains strength within 3 weeks. The surface can be used after this period.