Kiln brick size. Choosing a stove brick: suitable types, application, rejection What is an m500 stove brick

The requirements for building blocks for laying stoves and fireplaces are quite high; only solid heat-resistant bricks with the correct geometric shape and uniform structure are suitable for these purposes. The use of low-quality material is fraught with destruction and collapse of the walls, even when the work is performed by experienced craftsmen. Blocks for stove and fireplace masonry are produced by many Russian manufacturers: Borovitsky, Kirovo-Chepetsky, Novomoskovsky, Gzhel and Tula factories; among foreign ones, the Belarusian Vitebsk KZ and the Baltic Lode are distinguished.

Varieties depending on composition and purpose

In private construction, two types are used for the construction of stove masonry: fireclay with fireproof properties for the firebox and high-quality ceramic for the second circuit, the chimney. The latter, in turn, is divided into ordinary and facing. These products are exclusively solid (no voids), with a surface without defects and edges without chips. It is important to understand that standard solid wall blocks are not suitable for laying stoves or fireplaces due to the lack of refractory clays in the composition and different firing technology.

1. Fireclay brick.

Products for internal cladding can withstand prolonged heating up to 1500 °C without loss of properties and shape. The composition includes refractory clays (up to 70%) and fireclay chips; when fired, they form aluminum oxide, which gives the material special strength. The main difficulty in their manufacture lies in proper curing: underburning leads to a decrease or loss of fire resistance, overburning leads to the formation of a film on the surface and defects. Overexposed blocks are used in construction (they do not lose strength), but not for laying stoves or fireplaces.

It is difficult to confuse it with other varieties: it has a yellow color and a structure with quartz inclusions. It belongs to porous building materials; its operation at humidity levels above 80% is not allowed. The characteristics are regulated by GOST 390-96; in private construction, fireclay bricks marked ShA and ShB are used. Its shape and dimensions depend on the intended purpose: most often, rectangular blanks 230x114x65 or wedge-shaped are found; finding and buying shaped or non-standard blocks is not difficult.

2. Stove.

In addition to refractory clay, the composition includes coke, quartz powders or pressed graphite; it is these components that impart resistance to incandescence up to 700-1000°C. It differs from ordinary full-bodied wine by using exclusively selected raw materials with fine grinding, firing technology and mandatory rejection. This variety cannot be considered as a heat-resistant brick, but it copes well with the high-temperature effects of flue gases (and protection against their penetration into the room) and heat accumulation.

A number of products are polished or face chamfered during manufacturing; these brands are recommended to be chosen for external masonry. The sizes and shapes of stove bricks vary; the standard is 250x120x65 mm. For arches and corners, shaped and radial blanks are used. The traditional color is red; facing brands come in different shades - from white and light straw to chocolate.

Performance characteristics of fire bricks

The properties and parameters taken into account include:

• Strength. The minimum acceptable grade for stove masonry is M150.
• Frost resistance. Plays an important role when selecting bricks for chimneys; for external surfaces, you should choose products that can withstand multiple freezing cycles.
• Fire resistance is the operating temperature limit.
• Water resistance - taken into account when constructing outdoor objects and sauna stoves.
• Coefficient of thermal conductivity. Characterizes the ability of stove masonry to accumulate and transfer heat.
• Dimensions, shape, weight, surface type (for facing grades).

To create reliable stove masonry, experts recommend purchasing the entire required volume from one manufacturer, ideally from the same batch. In addition to studying the characteristics and quality certificate, a visual inspection of the products is carried out; it is advisable to check their condition when broken and impacted. The following signs of correct production are distinguished:

• A good refractory brick has a uniform color throughout the entire surface and internal structure. An overly light shade indicates underburning, black spots or changes in color inside indicate a violation of the firing regime, specks indicate the presence of unnecessary impurities (does not apply to quartz chips). A clear sign of a defect is a mica-like film of metal oxides.
• Correct geometric shape, absence of external defects, chipped edges. Permissible deviation from standard dimensions is no more than 2 mm.
• Pure “singing” sound and no dents when struck by metal. Violation of this condition indicates a defect; it is not suitable for the construction of stove masonry.

All of the above factors are checked; fakes or unsuitable brands will crack and collapse the walls in the first year of service. Each element of the furnace design has its own optimal type, much depends on the operating conditions. In particular, fire-resistant bricks with high strength and frost resistance (but not necessarily the correct shape) are recommended to be chosen for foundations and external walls of chimneys. Clinker has good reviews, but it is very expensive.

The combustion space is laid out mainly from fireclay, with the exception of stoves with a relaxed thermal regime (Dutch, Russian). The chimney tooth (the area just above the main combustion zone) is made of a material with a high content of quartz, its surface reflects the maximum amount of infrared rays. The rest of the fireplace is assembled from blocks with high heat capacity.

Specialized waterproof ceramic grades (not fireclay or quartz) are used in sauna baths and outdoor structures. The best option for rooms with high humidity is clinker. Regardless of the purpose of the stove, it is recommended to choose breathable products for cladding. There are many varieties of decorative facing stove bricks, but when planning to cover the walls with plaster for the second circuit, a porous second-grade one is sufficient.

Overview of the offered range

Brand name, manufacturer	Strength grade	Frost resistance	Size, mm	Weight, kg	Price per piece, rubles
Fireclay SHA-22, Borovitsky refractory plant	M200	F25	230×114×65(55), wedge-shaped	3,4	63
Krasny, Vitebsk conservatory			250×120×65	3,7	27
Janka Vecais red rectangular, Lode	M500	F100		4,2	80
Fireclay smooth SHA-5, Novomoskovsk	M200	F25	230×114×65	3,5	30
Solid single stove brick, Gzhel	M300	F75	250×120×65	4,1	28
Ceramic full-bodied red, Pobeda LRS	M250	F25		3,8	19
Lotos, Kirovo-Chepetsk plant				3,9	61

Borovitsky and Novomoskovsky factories offer to buy chamotte of acceptable quality; in general, production is limited. The cost of heat-resistant blocks for furnace masonry is at least twice the price of ordinary red ones. Among the best manufacturers of ceramic refractories are Belarus, Russia and the Baltic states. In particular, Vitebsk brick M200 is considered the standard in terms of dimensional accuracy and performance characteristics. The best cladding and decorative elements are offered by Lode; their products, in addition to aesthetics and variety of shapes and colors, are valued for their unique brand of strength and frost resistance (M500 and F100, this result is achieved without the introduction of dangerous additives).

Red brick is a popular material among consumers. It has a fairly wide scope of application, which is due to its high properties, external qualities and, partly, versatility.

One of these areas is the construction of furnaces. However, this requires a brick that is not quite ordinary, since such a structure is exposed to extremely high temperatures, which not any product can withstand.

In this article we will talk about specialized material intended for the construction of such a structure. Let's figure it out, kiln red brick: how does it differ from similar materials and what are the main features of production?

What is a kiln brick?

As already mentioned, stove brick is a special product. It is distinguished mainly by its increased resistance to high temperatures. We will now consider what other differences are.

Composition and properties

Like any ceramic product, red stove brick is made from clay. This is its main component. But this clay must be fireproof. In addition to it, the composition includes, of course, water and some specialized additives that increase the properties of the finished products.

Table 1. Red stove brick: main technical and operational characteristics:

Indicator name	Meaning and Brief Description
Thermal conductivity	The numerical value is about 0.72 W*mS. The figure is, of course, quite high. However, it is worth taking into account the density of the product, which is also relatively high.
Frost resistance	The minimum value among most popular manufacturers is usually at least 35 cycles of time-based freezing and thawing. Most manufacturers are ready to guarantee durability equal to at least 75 such cycles.
Water absorption	The hygroscopicity of oven bricks is around 6%. This is a pretty good indicator.
Strength grade	For laying stoves, it is recommended to use bricks with a strength grade of 200.
Red Kiln Brick Size	The standard value is 250*120*65. For refractory products – 250*123*65
Environmental friendliness	The material does not contain any harmful or toxic substances, so it can be considered environmentally friendly. However, it is worth considering the fact that much in this regard depends on the deposit of the clay itself - the basis for the products.
Durability	If you managed to purchase a truly high-quality product, the stove will serve you for an extremely long time. It is worth noting the importance of correct, technically correct installation and subsequent finishing, as well as operating rules.
Difficulty of installation	Brick, and not just kiln brick, is quite complicated to handle. Installation requires certain skills and craftsmanship.

On a note! Some indicators of the quality of oven bricks may vary significantly depending on the manufacturer. Some products will barely meet the standard, while others will significantly exceed it. Therefore, when choosing, be sure to familiarize yourself with the characteristics of the material of a particular manufacturer.

Key Features

So:

• Several types of red brick can be used to build a stove: regular stove brick and refractory refractory brick.

• The latter is made from high-strength clay. He is not afraid of exposure to high temperatures. As a rule, it is distinguished by high strength indicators. Such products are used when laying the external and internal parts of stoves and fireplaces. It can also be used in the construction of industrial technical structures, such as, for example, a blast furnace.
• A simple red brick for a stove has its advantages: it heats up quickly enough and is able to transfer heat to the room in a short time. It is also quite resistant to temperature changes.
• For laying stoves, solid bricks without voids are used.
• The weight of a red stove brick with standard dimensions is 4.2 kg.

Owners of country houses in our time, when thinking through the issues of heating their homes, have a very wide range of choices. The range of boiler equipment and all the necessary components to create an effective heating system, in relation to the existing conditions, is extremely wide. However, many owners also want to have a real brick stove in their home. This is a kind of tribute to tradition, and the creation of special comfort, and the presence of a reliable “helper” in case of emergency.

Fireclay bricks

High-quality ceramic bricks can withstand heating up to 700 ÷ 900 °C; for clinker bricks this figure can reach up to 1200 °C, but this may not be enough for the furnace sections that are in direct contact with fire and hot afterburning combustion products. Therefore, in most ordering schemes you can find areas highlighted in a special color - this is how the masonry is made with fireproof fireclay bricks.

To produce fireclay bricks, special types of refractory clay, enriched with special mineral additives, are used. Firing is carried out at temperatures above 1500 °C, and the result is a material that can withstand heating up to 1300 – 1400 °C without losing its strength properties.

Fireclay brick is easily distinguished by its characteristic fine-grained, high-density structure and color - cream shades usually predominate. When split, such a brick does not crumble and does not crumble, and breaks up into large fragments.

In principle, such a brick is suitable for any part of the furnace, but this is not practiced solely because of the high cost of the material. It is used for laying or lining combustion chambers and the initial sections of chimney channels, where post-burning of pyrolysis gases is possible.

The standard sizes of fireclay bricks are presented in a wide variety. They can fully correspond to ordinary bricks or have their own parameters, for example, narrowed or with a reduced block width. This can sometimes be very convenient when laying a firebox - it will be easier to fit it into the overall “body” of the stove, which is laid out from ordinary heat-resistant ceramic bricks.

Pay attention to the illustration above. As you can see, fireclay brick is not combined with ceramic brick in any place, and its laying requires a special solution. But the picture below is clearly illiterate work that is unlikely to give a good result.

The fact is that ceramic and fireclay bricks have completely different thermal characteristics, including the coefficient of linear thermal expansion. Such masonry is doomed to internal instability of the seams and deformation of the entire structure. On the contrary, a gasket is usually made between the materials, for example, from an asbestos sheet, to ensure the required temperature gap.

Quartz bricks can also be used as a refractory. Outwardly, they are somewhat similar to fireclay material, but differ in an even more dense and uniform structure.

This material is very expensive and does not withstand aggressive chemical environments very well, so its scope of use in household stove construction is quite limited. Quartz brick is characterized by reduced linear expansion, so it is mainly used in places where the layout suggests laying metal parts. but it is best to use it to insert a fireplace tooth - a special shaped element, due to which a powerful infrared reflection of the heat flow into the room occurs. There, quartz brick will fully demonstrate all its advantages.

ceramic brick

The chimney tooth is the place where quartz brick becomes optimal

How to evaluate a brick when choosing?

When choosing a brick, you should immediately familiarize yourself with its characteristics declared by the manufacturer - any batch of material from a bona fide supplier is always accompanied by relevant documents. It is undesirable to take the sellers' word for it, and it is better to purchase material from reputable companies, rather than on the spontaneous market - it is very easy to run into low-quality goods.

If the brand of brick meets the requirements in terms of manufacturing technology, heat resistance, brand strength and frost resistance, the quality of the batch should be assessed.

• First of all, a visual inspection and comparison of several bricks from one batch is carried out. They should not have significant differences in linear dimensions - a deviation of no more than 2 mm is allowed. Any distortion of shape, helical curvature of edges, crumbling at corners and edges, pronounced heterogeneity of the material, foreign inclusions, signs of obvious burnout are completely unacceptable.

A pronounced mica film on the surface of a brick does not mean anything good either - such a material will not show resistance to frequent temperature changes.

• Experienced stove makers always check the chosen material by ear. So, when carefully tapped with a hammer, a high-quality brick should produce a clearly audible, clear sound. If the sound is dull, then, most likely, either the raw materials were not of the best quality, or the production was carried out in violation of the technology, and the bricks turned out to be insufficiently dried and hardened.

This check also gives another result - after light blows with a hammer, there should be no chips or deep marks left on the surface of the brick.

• It is advisable to agree with the seller to conduct a crash test. The brick from the selected batch is split - it becomes possible to evaluate its strength and the density of the material itself - it should not crumble into dust, but break off in large fragments. A cut of a brick will tell you a lot - the internal structure is usually more “revealed” than the surface.

The homogeneity of the structure and the presence of voids are assessed. Large foreign inclusions, including clayey ones, must be absolutely excluded. Their presence indicates gross violations of raw material preparation technology.

Video: professional recommendations for choosing bricks for laying a stove

• The color of the cut should also be uniform throughout the entire depth (grade 1). A clear predominance of a light shade in the center indicates that the brick has not received proper firing, is not baked, and its strength will be far from the declared characteristics - usually such material is classified as grade 2. Dark spots indicate the opposite - the brick has been burned, which may result in increased fragility (grade 3). It is better not to purchase either option for the furnace, or to use them in thermally unloaded areas.

- So, moderately burnt grade 3 brick may well be suitable for laying out the foundation - it is characterized by increased resistance to compression, and nothing more is required.

— And for lining the stove, especially in cases where further finishing with plastering or ceramic tiles is planned, grade 2 brick can be used. Its heat capacity will be quite sufficient, increased porosity will even benefit the “breathing” of the stove, and a slightly rough surface will better hold the finishing material.

“But for internal channels, only first-class, properly annealed brick is used - here it will be subject to a serious thermal load. The quality of the surface is also important - there should be no large burrs left after cutting the plastic mass during the production process. The idea is that chimney ducts require as smooth a surface as possible to minimize possible areas of soot accumulation.

By the way, situations occur almost everywhere when bricks of all three types are found on one pallet. Therefore, experienced stove makers always begin work by carefully sorting the material in order to use it rationally with minimal losses.

• By the way, for some sections of the furnace it is quite possible to use the material left over after dismantling old structures - often it is even offered for purchase at a fairly favorable price. But it should be remembered that only bricks that have not experienced direct contact with extremely high temperatures are considered suitable - these are the upper and lower rows of masonry and areas located at a distance from the combustion chamber.

The material with which the firebox was lined is not suitable for reuse.

• And finally, a few words about the manufacturer of the material. There are a great many brick factories throughout Russia and in the near abroad. You cannot indiscriminately criticize some or praise others - surely each region has its own “authorities” in the production of such products. And here we will just list a few companies whose bricks, as they say, are “well-known” and are popular with many craftsmen.

Such companies include:

- Vitebsk production - JSC Keramika, and experienced craftsmen also distinguish products by workshop. Thus, a certain difference is made between “Workshop No. 1” and “Workshop No. 2”. This difference is not so much in the performance characteristics of the products, but in the intended purpose of the products - for hidden or external masonry.

— “Borovichi Construction Materials Plant”, OJSC “BKSM”, Novgorod region. Products of the Borovichi brand have a very long, well-deserved reputation, the quality of the brick itself is excellent, although you can also come across some critical remarks regarding the sometimes “dancing” geometry of individual modules.

— Again Borovichi, but already a refractory plant, OJSC BKO. It’s interesting that the history of this enterprise has already exceeded one and a half centuries! Fireclay bricks produced by BKO OJSC are of the highest quality and enjoy unquestioned authority among furnace masters.

— A stable position in this market was won by OJSC Pobeda LSR, St. Petersburg, which united several enterprises producing construction materials. Its product line includes high-quality ceramic bricks, widely used by stove makers.

— Their foreign manufacturers include the companies LODE and Wienerberger Group. The product range includes a wide range of materials designed specifically for laying stoves and fireplaces.

Video: a brief overview of the company’s bricks for stoves and fireplaces “LODE"

For the construction of heating devices, it is necessary to use heat-resistant materials that can withstand heavy loads from flames and hot gases. These characteristics are achieved through a unique composition and the use of special technologies in the formation of finished products.

Where is kiln brick used?

Stove bricks are designed to create reliable and durable shells in stoves and fireplaces. They must prevent the spread of flames and hot gases that form in the heating system.

These products are used for the construction of:

• the inner surface of fireplaces;
• combustion chambers for furnaces for various purposes;
• smoke exhaust ducts;
• stationary barbecues or grills;
• for lining the fireboxes of solid fuel boilers.

Material requirements

Basic requirements for heat-resistant stone, which is used for the construction of heating devices:

• must withstand temperatures up to 1000°C;
• have high strength;
• withstand prolonged exposure to high temperatures;
• low thermal conductivity, which will provide an opportunity to protect surrounding structures from fire;
• resistance to frequent temperature changes.

The characteristics of a standard refractory brick provide that it must quickly accumulate heat, and then gradually release it into the environment.

What is fire brick made of?

The workshop for the production of these products must be equipped with specialized equipment, which is used to prepare raw materials and form finished products. In this case, for the manufacture of heat-resistant brick products the following is used:

• refractory clay – not less than 70%;
• powdered coke;
• graphite;
• quartz powder.

Laying fireclay bricks

The characteristics of the finished product will depend on the additives that the manufacturer uses to make the material.

Technology for the production of refractory products

The production process of standard heat-resistant bricks includes the following steps:

• Raw materials are delivered to the workshop and undergo a certain preparation - refractory clay and various additives are crushed and mixed to achieve a uniform consistency. At the same time, 10% of water from the total volume is added.
• Each brick production workshop must be equipped with a bunker into which prepared raw materials are transferred.
• After this, it moves into the forming carriage.
• The molded brick is lowered onto the lower punch of the mold.
• Using a press, the product is compacted.

The material is fired at a temperature of 1000°C in a special tunnel-type furnace, which every workshop must have.

Making bricks at home part 1

Main types of heat-resistant bricks

Depending on the composition and configuration, the following types of brick products for the construction of fireplaces and stoves are divided:

• fireclay;
• dinas;
• semi-sour;
• fireclay-semi-sour;
• mollite;
• corundum;
• mullite-siliceous;
• mullite-corundum.

These products are manufactured in different places - Vitebsk (Belarus), Ryazan, Tula and Leningrad regions, as well as in the Baltic countries.

Solid Vitebsk stove brick is considered one of the best. It can have a surface from smooth to rough and of various shapes - with cuts, rounded corners.

Making bricks at home part 2

Is it possible to use ordinary bricks for stoves?

For the construction of furnace elements that are not exposed to high temperatures, you can use red solid brick. How much does this material weigh? One standard copy of the product, which measures 250 x 120 x 65 mm, weighs 3.3-3.6 kg.

When using a standard red stone, please note that it was without external defects - chips, cracks, shells.

The color of this material must be uniform over the entire surface. The dimensions and weight of the red block may be different if non-standard material is used, but one-and-a-half or double bricks.

The mutual perpendicularity of all planes must be observed, and the geometric dimensions must comply with the generally accepted standard.

The red block must have a grade of at least M 200, which will ensure its strength at elevated temperatures.

Physical properties of kiln bricks

Heat-resistant solid material is used for the construction of stoves and fireplaces.

Main characteristics of standard refractory bricks:

• brand – M 200 – M 250;
• frost resistance – within 15 cycles of freezing and thawing;
• the amount of moisture that can be absorbed is from 15% to 30%;
• thermal conductivity - 1.8-2.8 W/(m*°C).

How much does a stove stone weigh? The weight of the bar is 3.5-4 kg, while its size is 250 x 120 x 65 mm.

Appearance and geometric shape of stove stone

The characteristics of red heat-resistant brick depend on its shape, which can be not only standard:

• side wedge: dimensions – 230 x 114 x 65 x 45, weight – 3.3-3.5 kg;
• end wedge: dimensions and weight of the material are identical to the side wedge;
• plate: size – 460 x 230 x 75 mm, weight – 15.5-16 kg.
• With dimensions 600 x 230 x 90, the weight of the plate is 24-25 kg.

In this case, all material must be solid, regardless of how much it weighs. Standard material grade M 200 is used for laying the walls of the firebox or chimney.

Using a side wedge, you can lay shaped elements, and an end wedge is used in the case of a narrowed butt.

Slabs of different sizes are used to cover fireboxes.

Permissible deviations in size

Solid brick M 200 may have less than ideal dimensions, which is provided for by building standards. In this case, the permissible deviations are the following values:

• length – no more than 5 mm;
• width – less than 3 mm;
• thickness – no more than 2 mm.

These parameters are monitored at the enterprise where solid brick material is produced. If, upon examination of a batch, a large percentage of spoilage is revealed, all copies are removed from sale.

How to choose quality products?

For the construction of heating devices, it is important to use materials that meet building standards.

When choosing, follow the following rules:

• check what types of work this material is used for;
• there should be no visible defects on the ceramic bars;
• for laying the firebox, use material of the same size;
• For construction, use solid stone from one batch. In this case, the product parameters will be approximately the same.

When constructing critical structures that are exposed to high temperatures, it is important to use high-quality fireproof material, which will be the key to the reliability and durability of the structures.

Video: Masonry with fireclay bricks

When starting to build a stove, the owner of the house will have to think through many questions that inevitably arise during the preparation process. If the stove or fireplace is not planned to be tiled or covered with plaster, then the choice of brick comes to the fore.

Laying a furnace under jointing will not look ideal if you use low-quality brick, so you need to approach its purchase with the utmost responsibility. To know which brick is best to use for a stove, you need to study the characteristics of its various types and shapes. In addition, you should learn to distinguish quality products from mediocre ones.

Main types of bricks

Nowadays, there is a wide range of different types of bricks on sale, which differ from each other in several key parameters.

• According to manufacturing materials:

- ceramic;

- silicate;

— hyper-pressed;

- fireclay.

• For use in construction:

— construction downtime;

— clinker;

- fire-resistant (stove).

• According to the internal design:

- full-bodied;

- hollow.

Brick marking

You can often find out about the properties of the selected brick by markings, in the symbols of which some information is encrypted:

• Brick size.
• Product name or manufacturer abbreviation.
• Material of manufacture (silicate, ceramics or fireclay ).
• Brick geometry (thickened - U, hollow - P, with horizontal voids - G, solid bricks are not designated ).
• Strength grade, showing what kind of mechanical impact the product can withstand, kilograms per square centimeter (kgf/cm²). Denoted by the symbol M, it can range from M-25 to M-500.
• Frost resistance, that is, the estimated minimum number of deep freezing and thawing cycles without compromising the strength properties. It is designated by the letter symbol F. The usual range for brick is from F-15 to F-75.

For the construction of fireplaces and stoves, solid stove bricks, marked M-150, or better yet M-200, M-250, are usually selected.

Methods for determining brick quality

In addition to becoming familiar with alphanumeric markings, you must be able to independently determine the quality of the material. There are several proven ways to verify the integrity of the manufacturer, and you should definitely use them when choosing a brick:

• Appearance. To build a stove, you need a brick that has the correct shape and size. High-quality material may have a dimensional error of no more than 2 mm. If an irregular shape or curvature of surfaces or ribs is visually determined, it is better to discard such products immediately.
• If a mica-like film is found on the surfaces of the brick, then you need to know that this material will not withstand serious temperature changes.
• Sound check. This method of determining the quality of building materials can be called the most reliable and affordable. If small distortions cannot be noticed during inspection, then the sound will immediately indicate a defective product.

A high-quality brick, when carefully struck with a hammer, should produce a clear and ringing sound. In addition, there should be no traces left at the impact site - dents or chips. Don't stop your choice on the brick that has a dull sound - this indicates that it is poorly dried and hardened, or low-quality raw materials were used for its manufacture.

Video: checking the quality of bricks “by ear”

• Chips. When choosing a brick, you need to purchase one piece from the lot and split it in two. It is easier to determine quality by the internal structure than by examining a solid brick. The uniformity of the material on the chip indicates its quality. The structure should not contain any foreign inclusions, including pieces of clay. Their presence indicates a violation of the product manufacturing technology.

Selection criteria based on technical characteristics

In addition to fire resistance, which is the main characteristic of a brick intended for laying a furnace, since the temperature in the firebox sometimes reaches very extreme values, it must have a number of other qualities that you should pay attention to when purchasing it:

• Strength is the already mentioned ability to withstand mechanical loads and stresses without deformation or damage.
• Frost resistance, which was also mentioned above. It would seem that for a stove installed in a residential building, this parameter is not so important, but still, the higher this indicator, the greater the resistance the brick will show under any temperature changes.
• Hygroscopicity (water absorption) is a parameter that is indicated as a percentage: how much moisture in relative terms from its total mass the material can absorb. This indicator must be taken into account, since brick with a high percentage of water absorption is not suitable for every part of the building. For example, for the foundation of a furnace, you should choose a material with the lowest indicator.
• The size and weight of the brick are necessary to calculate its quantity for the future structure, and to determine the massiveness on which the load on the base will depend.
• The thermal conductivity of the material is very important when choosing bricks for laying stoves, since bricks that poorly accumulate and release heat are not suitable for them. Therefore, the coefficient must be at least 0.61 W/(m²×°K).

Main types of bricks by material of manufacture

In order not to make a mistake when choosing a brick, and to purchase exactly the one that is best suited for building a stove, it would be nice to have information about what types of this building material there are.

To begin with - types of bricks based on base material and additives, which were used for its manufacture.

Sand-lime brick

Sand-lime brick is made from purified sand and lime additives. The composition is usually mixed in a percentage ratio of 90 to 10%, but some manufacturers change the proportions slightly, depending on the quality of the components used.

To ensure that the products are of high quality, conscientious manufacturers pre-clean the sand from clay inclusions, manganese and organic impurities, and choose lime with a low calcium oxide content.

Prices for sand-lime bricks

Silicate brick

The brick is made under high pressure, so its structure is quite dense. Thanks to the materials from which this type of brick is made, it is “warmer” compared to the ceramic version. Partitions and walls are most often built from sand-lime brick, but it is practically not used for laying stoves. Firstly, such bricks fit very poorly on clay refractory mortar, and secondly, when temperature changes occur, they begin to absorb moisture abundantly, literally like a sponge, which leads to rapid destruction. The only acceptable exception is the use of sand-lime bricks for that part of the chimney that is located above the roof. But in this case, the brand of brick should be at least M-150 in strength, and not less than F-35 in frost resistance.

Sand-lime brick is marked as follows:

Hyperpressed brick

Hyper-pressed bricks are made from screenings of shell rock, limestone, dolomite and marble, which are mined during the development of open quarries.

These ingredients of the brick making mortar are about 90%, and Portland cement is used as a binder. The amount of water with which the mortar is mixed is of great importance for the quality of the brick, and if manufacturers do not follow the technology, the building material will not meet the necessary requirements.

The bricks undergo a pressing process under high pressure in compliance with a special temperature and humidity regime, and after this they must have ideal sizes and shapes. The surface of this type of brick can be absolutely smooth or textured, imitating natural rock - for example, “torn stone”.

Manufacturers often assign high performance characteristics to this material, including as a material for masonry or oven lining. However, this is not entirely true. Hyper-pressed brick is perfect for cladding the outside of buildings, but is in no way suitable for kiln work. It is known that limestone does not withstand high temperatures well, and, moreover, when heated, it begins to release carbon dioxide, and then quickly collapses. If we talk about stove work, then hyper-pressed brick can be used for outdoor barbecue stoves, and for indoor heating buildings, such as, it is better to choose fire-resistant solid fireclay brick, especially for those parts that are in direct contact with fire.

Ceramic brick

This type of material is made from high quality clay with a minimum amount of undecomposed calcites and does not contain foreign impurities such as sulfates and marl.

The most common and in demand are fired ceramic bricks.

The clay is cleaned, soaked and kneaded, then it goes through the process of molding and drying, and only after that it is fired at a temperature of 1000 degrees or more in a special oven.

High-quality ceramic bricks must be in the kiln for a time strictly determined by the technology - it cannot be under-burnt or over-burned. If the brick has not been burned, it will have a light shade, but if it is overexposed it will be too dark.

Proper firing makes the surface of the brick semi-matte. When you hit a block with a hammer, it makes a ringing sound, and when chipped it has a uniform, without inclusions, porous structure.

Prices for ceramic bricks

Ceramic brick

Unfortunately, modern ceramic material is not able to withstand too high temperatures - manufacturers define its limit as only 700 degrees. With regular firing of the furnace, the brick gradually deteriorates over several years. If you still decide to use it, then at least for the firebox you need to use fireclay bricks. Brick for laying stoves or fireplaces must withstand temperatures of at least 1000 degrees - this is very important to consider when choosing it.

The ceramic type of brick is divided into two subtypes - construction (ordinary) and facing. Ordinary is mainly used for laying the base of the furnace. It may vary slightly in size and have a heterogeneous structure. The front version is used for external masonry of the stove and fireplace - it can have different curly shapes and a three-sided chamfer.

Experienced craftsmen recommend choosing solid brick samples for stoves - they can withstand high temperatures more easily and retain heat longer. The service life of this type of material is much longer, since the brick body is evenly heated.

Sometimes sellers pass off ordinary ceramic bricks as refractory bricks, but this is a misconception. Yes, it is used for the construction of stoves, smoke channels, decorative elements and outer walls are made from it, but it is not suitable for laying fireboxes.

Fireclay brick

To make fireclay bricks, special fireclay clay is used, which has high refractoriness and fire resistance. Fireclay brick is also called alumina brick, since the mixture for it consists of 70% clay, and the remaining 30% are various natural additives.

High-quality fireclay brick has a golden-straw hue, and if it is poorly fired, then its color is almost white.

It is high-quality fireclay material that is used for the furnace, since it not only withstands high temperatures, but also perfectly accumulates, retains and releases heat. A stove structure made of this type of brick will last a long time without requiring repair work. In addition, some experienced stove makers claim that the heat from fireclay bricks has healing properties, which is why they are often used to make bricks.

The fireclay version of the brick is selected according to the same criteria and testing methods as the ceramic one. Additionally, it should be noted that when splitting, the block should fall apart into large pieces, and not into small crumbs.

Low-quality fireclay brick will not have heat-accumulating properties, but will actively absorb and accumulate moisture, evaporating it poorly, which will quickly lead to the destruction of the material.

Most common standard fireclay dimensions brick, in accordance with GOST – 250×124×65; 230×114×65; 230×114×55 mm.

Prices for fireclay bricks

Fireclay brick

This type of brick is marked with the letter “Ш”. The second letter following it indicates the class of the material - there can be two of them, “A” and “B”. The difference between them is their ability to withstand maximum temperatures. For example, “A” can be used without problems when heated at 1400, and “B” at 1300-1350 degrees. In combination with the letters there are numbers that indicate the size of the brick.

If we consider all the characteristics of this material as a whole, then it can safely be called the best option for laying heating structures - stoves or fireplaces, for example, such as.

Types of bricks by functionality

In addition to the mentioned classification of bricks according to the material of manufacture, they are also divided according to their area of ​​application.

Construction (ordinary) brick

This type of brick (GOST 530–2007 dated 01. 03.08. ) can be used for the construction of internal and external walls for finishing with insulating and decorative materials. This is a working type of brick, so it does not have a special aesthetic appearance; there may be small flaws and chips that do not in any way affect the strength of the material.

This brick is not suitable for laying the main heated sections of the furnace, as it will not withstand the thermal load. However, the foundation and departments located away from the firebox can be built from it. However, this option is only possible if the building is finished with tiles or covered with plaster.

Brick oven finishing options

Not everyone likes a stove simply made of brick - many prefer other types of its external decoration. For a long time, the method of further whitewashing has been used. Another variant - .

Facing brick

Brick for finishing or cladding is also called facade or facing. The material has an ideal appearance without even small defects; deviation of dimensions from the norm is allowed according to GOST by a maximum of 2 ÷ 3 mm.

This type includes silicate, ceramic and hyper-pressed bricks. If a silicate version is used for exterior finishing, it should be coated with an antiseptic and then with colorless varnish, since this type of brick has increased hygroscopicity.

Facing bricks are divided into two subtypes - shaped and textured.

• Shaped bricks can have different shapes. It is used for laying arches, window sills, pillars, as well as for external laying of individual elements of stoves.

Another aesthetic quality of this finishing material is the variety of shades in which it is produced.

• Textured brick can have a perfectly smooth surface, or one that imitates chipped rock, natural stone and other relief patterns of natural materials.

Brick with a textured surface is made from all materials; it can be ceramic, silicate or hyper-pressed. Of these, it is recommended to use only the ceramic version for the stove.

Some people use hyper-pressed brick for decorative finishing of the stove, but it has been used recently, and few people use it to decorate the stoves. Thus, it is not known for certain how the material will behave under the influence of elevated temperatures. If it can be used, it is only for the external cladding of individual areas of the building remote from the firebox.

Clinker brick

Ceramic clinker bricks are made from high-quality refractory clay, which is sintered to a homogeneous mass during firing. The clay must have ideal purity from alkali metal salts and chalk, as well as high plasticity - only in this case, after heat treatment, the brick will acquire good density, moisture resistance and strength. Clinker brick can be called a deliberately burned material - it is fire-resistant and durable, can withstand temperatures up to 1200 degrees and conducts heat well.

"Aristocrat" among other bricks - clinker

Thanks to these qualities, it is used for finishing not only the internal and external walls of houses, but also for stoves and fireplaces. Brick can be produced in a very wide range of colors and shades, so it can be matched to any room interior.

Clinker bricks are very expensive, so furnaces are often lined with clinker tiles that fully imitate brickwork.

However, it should be noted that this material is quite expensive in price, and therefore it is not used very often.

Fireproof Kiln Brick

The most ideal option for constructing a furnace is refractory fireclay brick. However, many craftsmen, in order to save money, use it only for laying the combustion chamber, since it has a fairly high price.

The material tolerates high temperatures well without damaging its structure, warms up well and transfers heat to the room. If they are used to line the firebox, it acts as a heat-resistant shell for ceramic bricks, protecting it from indoor fire and hot coals.

Fireclay refractory bricks can be made not only of regular shape, but also wedge-shaped - these samples are marked ShA-25 and ShA-47.

Video: examples of refractory bricks for stoves and fireplaces

Types of bricks according to internal structure

As mentioned above, the brick can be solid or hollow. Which one you choose will depend on what will be built from it.

This version of the brick has no internal voids and is suitable for the construction of load-bearing walls of any buildings. A solid fireclay brick for the firebox is perfect for laying the stove, and a ceramic facing option for the walls.

In solid silicate brick, voids are present only in the form of pores, and do not exceed 10–12%. Porosity in clinker products is no more than 5%, and in hyperpressed products it is about 4–5%.

Hollow brick

Hollow bricks have a different percentage of voids from the total mass of the product. Thus, sand-lime brick has cavities that make up 24–30% of the total volume. Ceramic building materials can include up to 45% voids of one configuration or another.

Brick with internal voids - it is usually not used for stoves

The cavities inside the brick do not make it defective at all, but only increase its sound and thermal insulation. The cells trap heat and create an air cushion that prevents sound penetration. Very useful properties for the walls of houses, but these qualities are absolutely not in demand for laying stoves and fireplaces.

Hollow brick is not suitable for heating structures, as it is afraid of thermal shocks due to temperature changes with a large amplitude. They contribute to the creation of stress around internal voids, which leads to the inevitable destruction of their walls. In addition, as already mentioned, the low thermal conductivity of the material for the furnace is not at all a good thing.

Selection of ceramic bricks according to manufacturing method

Since ceramic bricks are most often used to build the walls of the furnace, one more point needs to be taken into account. There are two main technologies for the production of such bricks - semi-dry pressing and plastic molding.

And what material is more suitable for furnace work?

• With semi-dry pressing, the prepared clay mass is first brought to the humidity required for the process, which is only 8-14%, and only then is pressed into molds. After this, the raw bricks are sent to special kilns, where they are fired. The low humidity of the composition allows you to obtain clear edges of the product and the correct shape, but bricks made using this method are not suitable for building a stove. Therefore, when purchasing material, you need to ask what technology was used to produce this building material.
• During plastic molding, a clay mass is used, which has a much higher humidity - 18 ÷ 21%. The manufacturing process is carried out using the method extrusion - pressing plastic mass through special molding dies of screw presses.

For this purpose, conventional and vacuum installations are used. The solid version of the brick is pressed using conventional equipment, without the use of vacuum, and hollow products only on vacuum presses.

After this, the molded bricks are fired. At the same time, the increased humidity of the clay mass not only gives the composition plasticity, but also participates in the chemical reactions that occur during firing. In this case, the molded clay composition is sintered dry, forming a large number of pores, which allow the product to “breathe” and withstand thermal loads.

Many owners of private houses, where a stove is already installed, but there is a need to replace it, have a question about whether it is possible to use old bricks to build a new heating structure.

It must be said that old bricks can be used, but not all of them, but only from certain areas of the building - these are the first and last rows of masonry, as well as those that were located away from the combustion chamber.

The old stove is carefully dismantled, whole bricks are cleaned of mortar and soot. After this, they can be used again, laying them with the smoked side inward so that the remaining traces of soot do not appear through the decorative plaster. Naturally, a stove built from old bricks will need to be put in order by applying plaster to the walls or covering them with tiles.

Bricks installed in the firebox of an old furnace cannot be reused.

If you are purchasing a new brick, it is better to give preference to trusted manufacturers who have already earned credibility for their quality products. These tables show some of them. In addition, the main characteristics of the ceramic bricks they produce are given:

Manufacturer	JSC "Keramika" Vitebsk	JSC "BCSM"
Product appearance
Type of brick	Full-bodied, ordinary, single	Full-bodied, ordinary, single smooth	Full-bodied, regular, single, corrugated “Berezka”
Options
Size	250×120×65	250×120×65	250×120×65
Frost resistance	25 cycles	25 cycles	25 cycles
Water absorption	No more than 8%	9-11%	9-11%
Brand	M-200	M 150-200	M 150-200
Weight	3,6-3,8	3.9	3.9
Thermal conductivity W/(m K)	0,615-0,635	0.59	0.59

Manufacturer	OJSC "Pobeda LSR"
Product appearance
Type of brick	Full-bodied, facial	Full-bodied, facial, figured R-60	Full-bodied, front “Stained Oak”	Ceramic, chipped, front, full-bodied “Legend”	Ceramic facing for fireplaces and stoves
Options
Size	250×120×65
Frost resistance	F35	F35	F35	F50÷75	F75
Water absorption,%	8,5	8,5	8,5	8,0	6,0
Brand	M-250	M-250	M-250	M-200	M-200
Weight (kg)	4,0	4,0	4,0	3.8÷4.0	4.1
Thermal conductivity W/(m²×°K)	0.61	0.61	0.61	0.72	0.72

Manufacturer	JSC "LODE"
Product appearance
Type of brick	Janka		Brunis R-60
Options
Size	250×120×65		250×120×65
Frost resistance	F35	F35	F35	F35
Water absorption,%	8 ÷ 9	8 ÷ 9	8 ÷ 9	8 ÷ 9
Brand	M-500	M-500	M-500	M-500
Weight (kg)	4.2	4.4	3.4	3.5
Thermal conductivity W/(m²×°K)	0.65	0.65	0.71	0.71

When choosing a brick for a stove or fireplace, you need to remember that these heating structures must stand and fully serve for decades. Therefore, it is not worth purchasing just for the sake of it, focusing only on appearance and financial gain. It is necessary to approach the issue of choosing material for masonry with all responsibility, since not only the durability of the stove, but also the safety of the residents of the house will depend on the correct approach.

Video: high-quality LODE kiln bricks

Evgeniy AfanasyevChief Editor

Author of the publication 05.09.2015