Firebrick: production, characteristics and properties. Types, sizes and examples of use
Low-rise residential buildings to this day it is customary to heat different designs that are made of kiln bricks. Its properties guarantee high temperature resistance of the material. But not only this characteristic made the material so popular. It is able to protect structures from negative impacts and acts as a heat accumulator. This circumstance allows you to save on fuel.
Examples of using
These products are used to form elements that isolate an open flame and protect the structure from destruction. Refractory bricks are used for lining the internal walls of household stoves, chimney ducts, fireplaces and pipes. The process of laying it is called lining.That is why the brick is sometimes called lining.
The construction material described in the article is suitable for the construction of stationary outdoor facilities for barbecues and barbecues. Fireclay is also designed for lining the combustion chambers of heating boilers and solid-fuel water heaters.
The composition of the furnace brick
When solid fuel is burned, special conditions are created that must be able to withstand furnace brick. Therefore, it is made heat-resistant, heat-resistant and is given the quality of low thermal conductivity. The material must tolerate temperatures of 1000 ° C and more, without losing its strength and withstanding the long-term exposure to negative factors.
The brick should have a low thermal conductivity, because of its functions should be allocated protection of building structures. As for heat resistance, it is required for the material to be able to undergo an impressive number of cooling and heating cycles. The refractory brick acts as an energy accumulator, it is able to quickly heat up and release heat to the room.
These products are manufactured according to the technology stipulated by GOST 390-96.The raw material that forms the basis of the products is refractory clay of special varieties, up to 70% of it should be contained among the ingredients.
To obtain blocks with different characteristics, some types of charge are introduced into the molding mass, namely:
- fine coke;
- large fractions of quartz powder.
Production technology involves the use of semi-dry pressing method. At the first stage, the raw material is prepared, the clay is crushed and kneaded thoroughly, the mixture is introduced, and the mixture is mixed until homogeneous. In the process water is added to the composition in an amount of from 8 to 10%, this allows to achieve the required level of humidity.
The finished mass is placed in a hopper, from where the mixture enters the metering carriage, moving back and forth. As soon as the products are molded, they arrive at the lower punch of the mold, which descends simultaneously with the workpiece. At the next stage, the upper part of the press is lowered onto the brick, and the products are under pressure to achieve compaction.
The lower punch at the final stage pushes the brick out of the mold, at this moment the carriage moves with the next batch of raw materials,transferring the workpiece to the conveyor belt. Pressing is repeated, the raw material is sent for firing at a temperature of 1000 ° C. When a refractory brick is manufactured using this technology, the need for drying is eliminated, which reduces time. This method is cheaper compared to the plastic molding method.
Types and characteristics of refractory bricks
After reviewing the building materials market, you can find a wide range of refractory bricks. He can be:
- mullite siliceous;
Specifications will depend on the brand and type of brick. If there is a fireclay brick in front of you labeled SHAK, then you should know that its fire resistance is 1,730 ° C, whereas the porosity is 23%, but the tensile strength is 23 N / mm2. These products contain an additive in the form of Al2O2in the amount of 33%. If it is a fireclay brick in front of you with the marking of ShA, then it will have several other indicators of refractoriness - 1690 ° C. The porosity is slightly higher - 24%, while the tensile strength is 20 N / mm2. Al2O2brick contains in the amount of 30%.
Chamotte brick SB has a refractoriness of 1650 ° C, the porosity remains the same as in the above brand. But Al2O2contained in the amount of 28%. Fireclay bricks under the marking of high-voltage materials have a fire resistance of 1630 ° C, the limit of its strength is 22 N / mm2but Al2O2contained in the amount of 28%.
The semi-acid refractory brick under the label PB has a fire resistance of 1670 ° C, its porosity is 24%, and the tensile strength is 20 N / mm2. Al2O3may be contained as an additive in a volume of from 14 to 28%, whereas SiO2used in volumes from 65 to 85%.
Dimensions of refractory bricks
The refractory brick for the kiln is manufactured according to strict dimensional requirements. The accuracy of the forms is governed by GOST 8691-73. For refractory bricks 11 sizes are provided, each of which has a certain ratio of height, thickness and length. Deviations from dimensions have the following meanings:
- thickness - up to 2 mm;
- length - up to 5 mm;
- width - up to 3 mm.
For example, the first size has the following parameters: 230 x 65 x 65 mm. For the fourth standard size the following parameters are 230 x 114 x 75 mm. The sixth standard size has the following dimensions: 230 x 114 x 40 mm.The eighth and tenth sizes have the following parameters: 250 x 124 x 65 mm and 345 x 150 x 75 mm, respectively.
Main properties: corpulence, density and strength
The size of the refractory brick is not the only parameter that interests the consumer. It is also important to know about other physicochemical characteristics, which are determined by the method of production and the raw materials used. For the construction of fireplaces and stoves for industrial and domestic purposes, it is common to use solid products. Their density acts as one of the important parameters controlled in the walls of factories. The check is made in accordance with GOST 24468-80.
The inner walls of fireplaces and stoves are exposed to high temperatures and open fire. The refractory brick, the characteristics of which are specified in the article, has the ability to resist these factors. The tensile strength depends on the brand, production technology and adherence to the formulation. The maximum strength of fireclay bricks, which is produced under the brand name ShAK, this parameter in this case is 23 N / mm2. Such products are widely used for laying furnaces for various purposes.Use similar products for the construction of existing fireplaces in private homes.
Thermal conductivity of bricks
Fire-resistant bricks used for laying chimney ducts and fireboxes protect adjacent structures from high-temperature exposure. In order to achieve this goal, the product must have a not so high thermal conductivity. Depending on the type, this indicator may vary. For example, in fireclay bricks it varies in the range of 1.8 - 1.9 W / (m * ° C), whereas in the silica brick it ranges from 1.9 to 1.95 W / (m * ° C).
As for magnesite, this value varies; it varies from 2.6 to 2.8 W / (m * ° C). Whereas the chromo-magnesite has from 2.75 to 2.85 W / (m * ° C). Thus, the smallest degree of thermal conductivity is characteristic of fireclay bricks, which thanks to this today is most widely used in construction. Such products are able to protect the building structure from impressive temperatures. An additional ability is the accumulation of heat.
The stability of fireclay refractory bricks against aggressive media
The refractory material of the refractory brick is sufficiently resistant when it comes into contact with fire and combustion products.However, during operation it is important to eliminate the effects of alkalis, acids and other corrosive media. If this requirement is neglected, then the product may begin to collapse prematurely.
The production of refractory bricks involves the use of clay, which is burned. In the process, pores are formed in the products, and the presence of voids contributes to water absorption from the atmosphere. Depending on the type of brick material will be able to accumulate moisture in the amount of from 15 to 30% of the total. This figure is considered to be quite high.
This property should be considered in the process of storage and storage of bricks. Products should not be in open areas for a long time, this is especially true for areas that are not protected from snow and rain. Otherwise, the brick can absorb water in significant quantities, which will adversely affect the performance and strength.
Properties and weight of refractory red brick
The red refractory brick has a rather impressive fire resistance and excellently tolerates exposure to temperatures ranging from 1400 to 1800 ° C.Such products are used for laying fireplaces, internal parts of furnaces, as well as for the construction of technical and industrial structures like blast furnaces.
The refractory refractory brick has the following dimensions: 250 x 123 x 65 mm. The standard product weighs 3.4 kg. However, to calculate the carrying capacity of the vehicle and the characteristics of the foundation, it is necessary to use more accurate data. The weight of the red refractory brick, which is also called refractory, can vary from 3.6 to 3.8 kg, this is true if the dimensions are 228 x 115 x 64 mm.
Fireclay refractory brick is used for the construction of fireplaces and stoves in industrial and residential buildings. Such products have outstanding technical characteristics, but they are not distinguished by increased frost resistance, which is caused by the raw materials and structure used.
For example, for products of the ShAK, ShV, ShA and ShB brands, this indicator does not exceed 15 cycles. Therefore, refractory bricks are not recommended for the formation of basement structures and exterior cladding of buildings. When operating stove or stone heating equipment, positive temperatures should be maintained in the premises.This is explained by the fact that frequent cooling of structures to extreme temperatures may ultimately cause destruction.