There are many advantages that make brick one of the most popular building materials. In addition to standard sizes and simple shapes, this artificial stone boasts strength, durability and beauty, which is why it has been used for a very long time and almost everywhere.
Technologies with the help of which they make bricks also deserve attention - as a set of processes allowing to obtain material with all the characteristics necessary for the customer.
Composition by type
Among all types of bricks, two are most popular - ceramic and silicate, also referred to as red and white, respectively.
They differ in the following features.
- The main component of ceramic bricks produced by firing is clay. Such material has an aesthetic appearance, dampens noise and perfectly stores heat in the room.
- The composition of silicate brick, manufactured under the action of high pressure and steam, provides for the presence of sand and lime. Adherence to technology allows you to get durable and inexpensive products that can withstand changes in temperature and humidity.
It is also necessary to highlight refractory bricks made of fireclay with the addition of coke or graphite - components that significantly increase its strength.
Another topical variety is facing, the production of which involves the use of cement, limestone and pigment ingredient. Such a brick, manufactured by pressing technology, has not only an aesthetic appearance, but also an impressive operational resource.
Given the greatest importance of the red and white varieties, they should be considered in more detail - which will be done later.
The main ingredient of this type of brick is ordinary clay. It is a mineral mass that:
- becomes plastic when water is added to it;
- stores the form during the drying process;
- hardens as a result of firing, gaining strength comparable to natural stone.
The origin of the clay used deserves special attention. Depending on the depth, it can have various properties - both suitable for brick production and not meeting established requirements.
If you select the component that most often forms the basis of clay, then this is kaolinite - one of the aqueous aluminum silicates. Montmorillonite, illite, quartz and other minor ingredients may also be part of the raw materials used.
In addition to clay, ceramic brick consists of other components that are additives. They are used to impart certain properties of manufactured products, and the main ones are the following .
- Sinking - ash, sand, slag. Contribute to better mass formation and less shrinkage.
- Burn-out - sawdust, powdered coal or peat. They increase the porosity of the material, which naturally reduces its density.
- Coloring - as a rule, metal oxides. Give products the desired color or shade.
In addition, it is worth mentioning iron ores and sandstone, the use of which allows you to effectively control the firing temperature.
Plasticizers can also be used - additives that minimize the likelihood of cracking of the ceramic material. The specific amount of each of these ingredients is determined by customer requirements and / or manufacturer's policies.
The production of white brick involves the use of three mandatory components, a list of which is as follows.
- Sand . It can have both natural and artificial origin. It is desirable that the grains used be uniform and have a size of 0.1 to 5 mm. No less important are the surface features of the grains of sand (in the presence of acute angles, they provide better adhesion). A prerequisite is the preliminary cleaning of the material from impurities.
The recommended proportion of sand in the composition of silicate brick is from 85 to 90%.
- Lime To obtain this component, raw materials are used, which are characterized by a high content of calcium carbonate (90% or more) - primarily limestone and chalk. Before firing at a temperature of about 1150 ° C, the prepared rock is crushed to a size not exceeding 10 cm. Upon completion of the above procedures, lime is added to the composition of silicate brick (optimal value is 7%).
- Water . This ingredient is needed to solve two main problems - slaking lime and giving plasticity to the formed mass. It is used at all stages of the manufacture of silicate brick.
Often, the production of the described products involves the use of additional components necessary to give the product the desired characteristics.
- Chemical compounds . An example is titanium dioxide, due to which silicate bricks remain white for as long as possible.
- Components that increase frost resistance . Most often, industrial products are used to solve this problem, which reduce the thermal conductivity of the material by 10-12%.
- Dyes . They are used in situations where the manufacturer needs to give products a specific shade or tone.
Ceramsite sand is also worth mentioning - an additive that can simultaneously solve two problems at once. In addition to a marked increase in the thermal efficiency of silicate products, it gives them a beautiful coffee color, thanks to which they look more solid.
Depending on the type of bricks made, their production has its own characteristics. This is due to the specifics of the ingredients used, requiring the use of various technological processes.
There are two main methods for the production of ceramic bricks - semi-dry molding and plastic. The latter, which is more popular, involves a step-by-step solution to the following problems.
- Preparation of the main component - clay. It is allowed to include additives in the mixture - no more than 1/3 of its total amount. The fraction of the main ingredient should not exceed 1.2 mm.
- Moving the prepared mass for further molding.
- Division of the general array into standard sizes.
- Drying ceramic bricks.
- Perforation of products (relevant in situations where products need to be made hollow).
- Burning. This type of processing involves a smooth change in temperature in the furnace (first upward, and then vice versa). Following this rule allows you to avoid the appearance of cracks on the bricks due to sharp temperature changes.
As for the production of ceramic bricks by the method of semi-dry molding, it implies the following procedure:
- preparation of raw materials and its grinding;
- drying and regrinding;
- slight moisture with steam;
- removal of the last traces of moisture from ceramic products.
It is reasonable to mention the production of red brick at home: in this way it is quite realistic to make a full-bodied “raw” variety of this material.
To solve this problem, you must:
- make a ball from a homogeneous piece of clay, previously moistened with water;
- thoroughly inspect the sample after 4 days - for the presence of uneven shrinkage and cracks;
- provided there are no visible defects, the ball must be dropped to the ground;
- if the sample does not pass the strength test, its composition must be strengthened with appropriate additives.
Upon completion of all preparatory procedures, the mixture should be distributed according to the forms made of wood. Finished ceramic products will remain to dry in the shade, after which they can be used for the construction of light one-story buildings.
To make surfaces more durable, it is advisable to cover them with paint or high-quality cement mortar.
One of the main features of the manufacture of silicate bricks is the complexity that does not allow to solve this problem at home. In particular, this is explained by an impressive list of necessary equipment - conveyors and conveyors, crushers and batchers, mixers and autoclaves, cranes and loaders.
There are two main production methods for the products under consideration - drum and silo.
The technology for manufacturing silicate brick involves the following steps:
- checking and preparing the main components - sand and lime (the first is separated from large inclusions, and the second is crushed);
- mixing the components with subsequent sedimentation in the hopper;
- grinding the mixture and adding water to it;
- lime slaking, carried out in a drum or silo (determined by the selected production method);
- removal of moisture from sand;
- molding using a press;
- steam treatment in an autoclave (recommended temperature - 180-190 ° С, pressure - 10 atmospheres).
At the final stage, temperature and pressure are gradually reduced. Upon completion of all procedures provided by the technology, the finished silicate bricks are packed and sent to the customer.
Types of firing
The heat treatment of ceramic bricks, called firing, deserves a separate consideration. It represents the final stage of production of these products and provides for the presence of 3 stages - heating, actually firing and cooling.
- Bricks are heated to 120 ° C to remove residual water from them.
- To eliminate inclusions of organic origin and the last traces of moisture, the temperature is increased to 600 ° C, and then to 950 ° C, which gives the products extra strength.
- Upon completion of the hardening, the bricks are cooled, gradually lowering the temperature.
Subject to technology, a product with a uniform structure and an orange-red tint will be obtained.
I would also like to mention two types of devices used to solve the problem described above.
- Tunnel It is a long airtight furnace, consisting of 3 chambers, inside which rails are laid for transporting ceramic bricks. In the first chamber, the products are dried, in the second - firing using burners, and in the third - cooling.
- Roundabout . The design of this furnace assumes the presence of a large number of separate sections having their own heat source and placed in the form of a ring. Its feature is that bricks go through all stages of firing, without leaving the limits of one chamber. So, the neighboring compartment provides initial heating, the calcination is carried out thanks to its own heat source, and the cooling of the product occurs under the influence of the next section.
Thus, knowledge of the technology of brick production allows you to get a strong, aesthetic and wear-resistant material from brittle and malleable raw materials, initially not of any value to the builder.
The intricacies of modern brick production are described in detail in the video below.