Brick pressing is one of the most important operations in technological scheme production sand-lime brick.

As a result of pressing, the raw mixture is compacted. To compact the raw material well means to minimize the free space between the sand particles, bringing them closer together so that they are separated from each other only by the thinnest layers of binder. This convergence of sand grains creates favorable conditions to obtain a dense and durable sand-lime brick. The density, strength and other physical and mechanical properties of silicate bricks largely depend on the degree of compaction of the raw mixture in the process of pressing the raw material.

At the moment of pressing the raw mixture, the sand grains resist compression. The frictional force of the mixture against the walls of the mold and the grains against each other is overcome by pressure, which must be distributed evenly over the entire area of ​​the pressed product.

When molding silicate bricks, the specific pressing pressure is 150-200 kgf / cm2.

Of great importance is the speed at which the pressure rises during pressing. Thus, the rapid application of forces during impact pressing can cause not compaction, but destruction of the product structure. Therefore, in order to overcome internal frictional forces, the pressure during pressing must increase smoothly, at a certain optimal speed.

The operation of the press and the quality of silicate bricks are greatly influenced by the moisture content in the raw mixture at the time of pressing the raw material.

The optimum moisture content of the raw mix when pressing raw bricks depends on the properties of the sand and other indicators. At each silicate brick factory, this value is established empirically. Tentatively, we can assume that the optimum moisture content of the raw mixture is about 6-7% of its total weight.

An increase in the moisture content of the mixture above the optimum does not make it possible to compress the raw material, remove it from the press table and lay it on the trolley. A decrease in humidity leads to the fact that the compressed raw material is difficult to remove from the press table; it breaks apart under its own weight.

The process of pressing raw bricks consists of the following main operations: filling press boxes, pressing the raw materials, pushing the raw materials onto the table surface, removing the raw bricks from the table, placing the raw materials on the steaming trolleys. The raw mixture prepared in silos or extinguishing drums is fed using a belt conveyor to the mixer for mixing and additional moistening, and then to the bins above the press mixers. The supply of the mixture to the press mixer is regulated so that the mixture always fills it by about 3/4 of its volume. If the incoming mixture has a lower moisture content than required, it is once again additionally moistened in a press mixer, for which a water pipe with small holes directed downward along the length. The amount of water flowing through the pipe is controlled using a valve.

The moistened mixture is mixed with the knives of the press mixer while rotating them and enters two adjacent press boxes through the holes in the bottom. When the press table rotates, the boxes filled with mass are moved at a certain angle (1/8 of the circumference) and occupy a position in which the mixture is located between the pressing piston and the counter-stamp plate. The piston gradually rises and, compressing the mixture, forms a raw brick.

During pressing, the press table remains stationary, and the knives of the press mixer, rotating, fill the next pair of press boxes with the mixture. At the end of pressing, the table is rotated so that both boxes with the pressed raw material stop above the ejection piston. The latter pushes the brick in a vertical direction; the top plates of the dies when pushed out come out of the press boxes 3 - 5 mm above the table level. The raw brick located on them is removed with an automatic machine. The ejector piston is then pushed down to its original position. After removing two bricks from the press table, the table rotates and the dies fit under a mechanical brush to clean the upper plates from the adhered mixture. The dies are lowered in the press boxes to a predetermined filling depth and the cycle begins again.

The size of silicate brick must meet the requirements of GOST 379-69. In case of deviation from the established dimensions, the raw material is considered a marriage. It is necessary to especially carefully monitor the thickness of the raw brick, periodically checking its dimensions with a caliper or a metal ruler.

The magnitude of the pressure during pressing, and therefore the density of the raw material, is regulated by changing the amount of filling the pressing boxes with the raw mixture: the higher the height, the higher the density of the raw material, and vice versa, the lower the filling height of the boxes, the lower the density of the raw material. During pressing, it is necessary to ensure that the raw material is of the same density; for this, the filling height of the press boxes must be kept the same. Press mixer knives must be fixed at the same distance from the bottom and walls (no more than 2 mm).

Almost no building in our country has been built without the use of bricks for many decades. This reliable and affordable material is made from artificial stone, nowadays it is still popular in construction production like many years ago.

The overwhelming majority of the population lives in private brick houses, and from my own experience I was convinced of all the advantages of walls from brickwork... Such structures are distinguished by their super-resistance to any atmospheric precipitation (rain, hail, strong gusts of wind, snow) and immunity to mold.

About mechanical resistance brick wall and it's not worth reminding once again, most likely, too, about its strength and long service life. In addition, the material is immune to the destructive effects of aggressive environments and, which is very important, does not pose any environmental hazard to humans.

Due to its excellent building performance, facing brick has earned its due distribution among domestic consumers. In this case, it is the products that are meant Russian manufacturer in all its diversity and varieties.

The most popular type, as before, is a single facing brick with standard parameters: 6.5 cm high, 12 cm wide, 25 cm long. The production of one-and-a-half, double and non-standard bricks is also gaining momentum. In accordance with the strength indicator, all these products are subdivided into grades - the higher the brand number, the more strength the brick has.

Although a dozen years ago we had the opportunity to observe brick structures of exclusively white or red color, today the color scheme is more extensive. There are several dozen of various colors and tones, approximately the same number of variants of product textures. All this huge assortment, combined with excellent operational characteristics, make facing brick the most profitable building material in the construction of residential suburban buildings.

All brick faces have their own names: large - "bed", small side - "poke", long side edge - "spoons". There are four main types: clinker, silicate, ceramic, hyper-pressed.

Clinker brick

It's gorgeous construction material with a lot of positive performance characteristics... It is resistant to moisture and adverse climatic conditions, provides high heat and sound insulation. Due to its dense structure, it wears out little over time and practically does not get dirty.

Clinker bricks are made from special, refractory types of clay, fired in special ovens at temperatures above 1000 degrees Celsius. Thanks to this method of production, the material acquires homogeneity, strength and durability.

This type is universal - it can be used in any type of construction. New buildings are erected from it, with its help old buildings are reconstructed. Window openings are decorated with clinker bricks, columns are laid out of it, etc.

When finishing the facades, a special facade clinker, including glazed - multi-colored. Colored clinker bricks can be matte or glossy depending on the glazing method. And the easiest way is to cover the finished clinker in two layers with paint of the desired shade, and then send it to the oven. Secondary firing is carried out at a temperature of about 1200 degrees, and the applied paint is tightly sintered with the "original" brick surface.

Glazed multi-colored clinker brick does not lose its brightness for a long time. They are laid out, for example, facade mosaics.

Ceramic brick

The second common class of such building materials. Currently practiced different ways manufacturing, development innovative technologies contributes to the emergence of new methods. It is noteworthy that in factories with the same professional equipment clay or raw materials can vary significantly. However, a constant requirement for the raw materials used is its uniformity.

As a rule, red clay is used for the manufacture of this type, therefore the brick received the corresponding name - "red". Clay of other colors is used less often, depending on the color of the clay used, a brick of a certain color is obtained. Practice shows that when erecting large construction projects, it is advisable to use bricks of the same batch due to the fact that it is almost impossible to choose a similar color for different batches.

Sometimes in the process of construction comes across a ceramic brick of black or mustard color. This is a marriage: burned out or unburned, which cannot be used for laying walls. When struck, a defective product emits a dull sound.

During the production process, it is possible to add various pigments to the feedstock, which makes it possible to obtain different colors. Nowadays, ceramic bricks are usually made by plastic molding.

The optimal raw material in this case is clay containing up to 30% sand. The content of sand in the raw material prevents significant shrinkage during installation. When clay of a certain composition is mined in the required amount, it is moistened with steam and thoroughly mixed until a lamellar, homogeneous mass is obtained. This mass is used to form a raw brick.

It should be noted that it initially has a larger volume (by about 10-15%), since the subsequent shrinkage is taken into account. The formed raw material is sent to drying, where it reaches a moisture content of 6-8%, then the products are sent to the kiln for firing, the temperature in the kiln is 1000 ° C. Sometimes some additives are used to speed up the combustion process.

Semi-dry and dry pressing

Brick produced by the method of semi-dry or dry pressing, as a rule, is used to create products with more strict clear forms, it is characterized by less frost resistance. For the specified production method, clay (raw material) is selected in accordance with other parameters. So, the moisture content of low-lamellar clay for dry pressing is 7-8%, and for semi-dry pressing - 8-12%. In this case (as opposed to plastic molding), the clay is ground to a powder. The resulting powder is molded in special presses and, with a greatly reduced drying time (semi-dry method) or without drying at all (dry method), is converted into a raw brick, which is then fired.

Silicate brick

It consists of 90% quartz sand and 10% lime and various additives. The shape is formed using dry pressing, and then, using a temperature of 170-200 degrees, it is subjected to water vapor. With the development of new building technologies a wide range of colored silicate bricks appeared on the building materials market.

The color coating of silicate bricks differs from ceramic. This is due to the fact that the coloring material is added initially to the mixture, due to which the finished product has the same color throughout the volume.

However, the disadvantages of silicate bricks are in the prohibition of its use, for example, in the construction of a building foundation or basement structures, because the long-term influence of soil salts can damage the building material. It is also strictly prohibited in the construction of home stoves, fireplaces and pipes, since the maximum operating temperature is no higher than 550 ° C. On top of that, it is heavier than the rest, which significantly reduces the range of applications.

Hyper-pressed

The production of hyper-pressed bricks is carried out by the method of semi-dry pressing. The basis for the manufacture of the material is crushed limestone, it makes up from 82 to 83% of the finished product. For adhesion of limestone, cement is used, approximately in a proportion of 12-15%. A spectacular color is achieved through the use of a coloring pigment, it is present in about a proportion of 2-3%. Dyes are usually iron oxides.

After thorough mixing of all components, they begin to manufacture. The finished mass is always homogeneous. It acts as a solvent in production plain water... The prepared composition is sent under the press. The process requires exposure of the material to elevated temperatures. In this case, the smallest particles of the mixture are, as it were, welded together, and the finished composition becomes much denser and turns into a dense brick.

The essence of the method is that at ultrahigh pressure the structure of the material is rearranged and the final product is significantly improved. physical properties... After pressing, pallets with densely packed bricks are moved to the next chamber, where steaming takes place.

The working temperature here is 70-90 degrees. Drying takes about 10 hours. From this workshop, the products are sent for rustication. You can start laying newly produced bricks after five days.

Technical characteristics are superior to those of traditional ceramic or silicate. It is distinguished by increased strength, correct geometry cuts, as well as high color fastness. Taking into account that limestone acts as a raw material, and persistent natural pigments are used for coloring, the brick retains its natural natural color for a long time. The products are characterized by environmental safety.

Wasps new technology hyperpressure is the use natural materials... The manufacturing process is absolutely harmless to environment, as a result of production, no harmful waste is generated. Due to the absence of firing and drying processes under the influence high temperatures, production is characterized by low energy consumption.

Technological standards of production provide for the content in the pressed brick of at least 8-10% of cement, which is three times lower than the parameters of the production of vibro-pressed bricks, where 20-25% of cement is required.

And yet, pressed bricks are not without certain disadvantages. Standard sizes products 250 x 120 x 65 with a weight of 4 kilograms, which can lead to shrinkage of the foundation. It is also distinguished by more long terms manufacturing. They are characterized by a higher thermal conductivity than ceramic or silicate ones. However, all these "disadvantages" are successfully leveled by the merits of this building material.

The properties of bricks are divided into the following types:

• By a set of physical and mechanical indicators: frost resistance, strength, water absorption. In this category, the leading position is occupied by clinker, followed by hyper-pressed facing, and in third place - by ceramic. The greatest attention to calculating the strength and durability of the facade will require silicate brick.
• Thermal properties. In this category, ceramic is in the first place. It is he who will best maintain the indoor climate.
• According to the load on the foundation. And again, the leader is ceramic cladding. Average values ​​are for clinker and silicate. And if you use hyper-pressed, then the load on the facade will be the strongest.

If you are going to veneer an already finished building, be sure to seek the advice of specialists in order to strengthen the existing foundation as best as possible.

When drawing up design and technical documentation, it is imperative to take into account:

• The use of clinker and ceramic brick does not imply the implementation of thin-walled partitions, which are carried out by laying in a half-brick, due to the presence of only one front facet. To obtain a wall with a thickness of 120 mm with two front facades, it is recommended to use hyper-pressed bricks. The same result can be achieved when performing double masonry with "American" bricks (250x60x65), combining them with the back sides.
• The use of hyper-pressed bricks involves additional hydrophobization. finished wall(impregnation waterproofing materials to increase the strength of the structure). This is necessary to prevent the formation of microcracks, which have a destructive effect on the facade of the building, fence.
• The use of any type of "American" brick allows for an economical erection of facades due to its cheapness relative to other materials with similar parameters. Due to the capacity of this thin brick, transportation costs are halved.
• Implementation of an individual architectural design possible when using facade bricks contrasting shades or plain bricks with different texture obverse faces.
• The main classification depends on the intended use. For example, when creating facades, a facing (front) brick is used. For the construction of a high-quality structure, it is necessary to take into account its type. In accordance with the manufacturing technology and the nature of the materials used, ceramic, clinker, silicate, and hyper-pressed bricks are distinguished.

Hollow and solid brick

As a rule, everyone is familiar with solid brick, which is a briquette with little or no voids (less than 13%). It is used for the construction of internal and external walls, the construction of pillars, columns and other structures, which, in addition to their own weight, also carry an additional load.

Requirements for solid bricks are high compressive strength, bending strength, and frost resistance. Porosity is determined by the absorption of moisture by it when changing weather conditions, as well as its heat-insulating properties. Solid brick does not have a high resistance to heat transfer, therefore, if the external walls are made of of this material, then, as a rule, they need to be additionally insulated.

Hollow brick is capable of having up to 45% of voids from the total volume, its weight is much less than that of ordinary brick, which greatly simplifies the work with the material. As a rule, it is used when laying partitions, lightweight external walls, as well as filling the frames of high-rise buildings. Voids can be closed on one side and through, square, round or rectangular, depending on the location - horizontal and vertical.

The presence of voids leads to savings in raw materials required for the manufacture of hollow bricks (compared to the manufacture of solid bricks). That is why this type is also called "economical" because of its affordable cost. It should be noted that the presence of closed volumes of dry air contributes to an increase in the heat-insulating qualities of the building material, so you can save material by making the walls thinner. When laying, it is necessary to apply a sufficiently thick masonry mortar that will not fill the voids. V otherwise the main advantage of hollow bricks will be reduced to zero.

The original facade of the building is the dream of the owners who have good taste... For this purpose, it is necessary to choose high-quality and often decorative building materials. Hyper-pressed brick is one of them. In terms of its properties, it differs little from natural stone, but outwardly has enough variety to embody the most daring and original design solutions.

The brick, created by the new technology, possesses the best characteristics than the analog obtained by firing:

• strength ranges from 100 to 400 kg / cm2, depending on the brand;
• density - up to 2200 kg / m3;
• thermal conductivity up to 1.0 W / (m · ° C);
• water absorption - 6-7%;
• strength grades up to F300;
• not flammable;
• can be used for buildings of any number of storeys.

Of the types of products, the following are distinguished:

1. private - smooth;
2. facing - angular, narrow, figured and spoon decorated like a stone.

Just like clay, it can be full-bodied and hollow.

There is also the so-called Lego brick, which is assembled using grooves and does not require mortar - you can simply lay it on construction glue. It differs in a slightly lower density - 1 600 kg / m3 and durability - it is applicable up to 150 freezing and thawing cycles.

Manufacturing technology

Its properties facing brick obliged to hyper pressing, a method in which a finely dispersed moist building material is formed under high pressure, as a result of which cohesion arises - adhesion of particles on molecular level... In fact, this is cold welding.

The technological process is complex - it is necessary special equipment for the production of hyper-pressed bricks. Crushers, presses, batchers, mortar mixers, conveyors, screens, double-arm chutes are not included.

Suitable as the main material for the product:

• limestone;
• sand;
• crushed granite;
• marble chips;
• the battle of ceramic bricks;
• iron ores;
• enriched coal;
• blast-furnace slags.

In addition, water and a bonding solution are used - concrete or lime.

After pressing finished brick matures in a steaming chamber at a temperature of 70 ° C for 3 days, gaining strength. The final shape - a surface in the form of chips - is given after this procedure. If it is possible to lay "fresh" brick in warm weather, then it is able to ripen for another month, becoming stronger.

Application

Hyper-pressed facing brick is used for construction and decoration load-bearing walls, columns, decoration of the basement, gazebos, facade, installation of fences, curbs, elements landscape design... Private - used to build a foundation, garden paths, parking places.

Dignity

Unfired hyper-pressed brick has durability, it can serve up to 200 years, while maintaining aesthetic appearance... It is used in any climatic conditions, since it does not absorb moisture and does not deteriorate under the influence of heat or frost. It has good sound insulation properties. When using hyper-pressed bricks, reliable structures are obtained that do not require maintenance, so it can be laid in areas of increased seismic activity. It will not collapse from the blast wave either.

The masonry is notable for its lightness, since its dimensions are very precise, like that of silicate. And adhesion to concrete is better than with other types of bricks, which saves mortar when laying. In addition, it is available in a variety of colors, which allows you to create a unique architecture. And the calculation of the project using this product is obtained with the smallest error, so you can save on the purchase.

disadvantages

The price of hyper-pressed decorative bricks is twice as high as usual. But even if the funds allow you to make a multi-storey cottage, do not forget that corpulent material gives a large load on the foundation, since it is as heavy as granite stone. For the same reason, it is not advisable to use it as interior partitions, especially in multi-storey construction.

Average prices in Moscow

You can buy hyper-pressed Lego bricks at a price of 11 rubles / piece.

DIY styling

First you need to check and adjust the base / plinth surface using a spirit level. Then prepare cement-sand mortar, in which there should be no large fractions. It is better to mix it in portions, as needed, and it is advisable to prepare the adhesive material itself sufficiently dense.

Masonry hyper-pressed solid brick with your own hands will differ little from a professional one if used for a solution river sand, high grade cement - from M 500, good equipment - a concrete mixer, and be careful during construction, carefully removing accidental contamination immediately.

And the main thing is to make the first row well, starting to align the blocks from the corners. The next rows are laid with an offset. It is important to check each level with a thread, avoiding the slightest deviation. Openings of windows and doors can be highlighted in a different color. After every 4 rows, jointing should be done until the mortar dries. This process is generally laborious, but the result is amazing.

Pressing, as one of the methods of forming construction piece elements, due to the compaction of raw materials, allows you to obtain products with flawless geometry and an even surface. Compression of the pressed mass with a low coefficient of moisture content is practiced in the production of bricks from clay and from a cement-mineral mixture. - cheaper modification of ceramic artificial stone, because, in contrast to plastic molding, this technology makes it possible to refuse from drying the raw material, which is due to the initial presence of moisture in the molding mixture of no more than 8%.

In spite of obvious advantage in the clarity of the form and the infallibility of size, it has a very significant "minus" that limits the use of the material in question in construction practice. The maximum frost resistance of the product corresponds to the F-50 brand, which informs about the ability to withstand only 50 cycles of alternating freezing and thawing without destructive structural changes. Thus, molded clay brick is unacceptable in the construction of structures designed for wet operating conditions.

A similar technology for molding products is practiced in the production of hyper-pressed bricks. However, in contrast to a clay sample formed under a pressure of up to 0.0015 MPa, a hyper-pressed stone is compressed during the manufacturing process with a force from 20 to 35 MPa. In this case, not clay is taken as a raw material, but crushed limestone with the addition of 12-15% cement, 2-3% iron oxide dyes and a small amount of water for chemical reaction... As a result of powerful squeezing, molecular splicing of the components occurs, and the density of the monolith structure excludes the presence of air voids in the form of pores.

A worthy place among the many building materials is occupied by semi-dry pressed brick. Understanding all the advantages and disadvantages of a particular material, you can optimize the construction process, reducing the total cost without losing quality. Due to the availability of raw materials and the simplicity of production technology, you can make a ceramic brick with your own hands.

Advantages and disadvantages of semi-dry pressed brick

The advantage of manufacturing products by the method of semi-dry pressing is:

• Lower cost price. This indicator is influenced by cost savings:
  • Electricity and gas for drying. As a rule, raw brick has little moisture due to the use of low-plasticity clay press powders, so the time pre-drying is significantly reduced. More often this technological stage pass, then it is a "dry-pressed brick".
  • Labor costs. Due to the elimination of the stage of transferring from drying to roasting trolleys. The raw material is placed directly in the oven.
  • For the purchase of raw materials. For production, the use of leaner, and, accordingly, cheaper clays is recommended.
• High quality products, right angles and perfectly straight edges and edges.
• High production speed.
• Good thermal conductivity, strength.
• Variety of color palette.

The disadvantages of the semi-dry pressing method include:

The corpulent material is quite heavy.

• Increased gas and water permeability due to the low density of the product compared to plastic molded products.
• Lower frost resistance.
• Relatively large weight of a full-bodied product. The creation of hollow bricks is possible, but difficult due to the flowability of the starting material.

What to make of?

Semi-dry pressed bricks are made from special highly concentrated dispersed clay systems with the following properties:

• Lack of cohesion, flowability.
• Uniformly fine granule composition.
• Humidity 9-12%.
• Compliance of the powder to pressing.

Methods for making clay substances

Drying and grinding production of ceramic bricks consists of the following stages:

1. Roller crushing. A basket disintegrator of the SMK 211 type is used.
2. Drying in drums at temperatures from 600 to 800 ° C. In airborne mills, crushing and drying processes can be combined.
3. Sifting through string, rocking or vibrating sieves, drum screens.
4. Humidification is best done with steam, but finely dispersed water can also be used with constant stirring. Then the clay is sent to the bunker, where it lays for 24-30 hours.

With the slip method of production, the raw material is more uniform and equally moist, practically does not contain dust, all granules are homogeneous and small, air is easily removed during the pressing process, the product is pressed more densely and efficiently without increasing the pressure force. The slip method involves going through the following stages:

1. Dissolving clay hot water in a mud block. The humidity should be brought to 40-45%.
2. Pumping and cleaning under pressure through arc screens.
3. Pouring the mixture into open slurry tanks for mixing.
4. Pumping to a spray dryer, where the clay is finally brought to a moisture content of 10%.

Manufacturing and equipment required

The powder, by compression in 15-40 megapascals, is formed into dry-pressed bricks. Presses of the type SMK 491, 503 are often used in production. Compression technology is divided into 3 stages:

1. Partial extraction of air from the clay mixture.
2. Compaction, during which all moisture from the deep layers of clay grains is squeezed onto their outer surface, which provides a better grip.
3. Finishing, in which the product to be pressed receives maximum compression and internal adhesion due to the strong development of the contact surfaces.

For any powder, there is a boundary pressure, exceeding which no longer gives any additional compaction. Pressing modes can be:

• percussion and smooth;
• one-sided and two-sided directions of efforts.

Drying, if necessary, is carried out in tunnel dryers by placing bricks on oven trolleys. Drying time - 20-25 hours at a temperature of 120-150 ° to a humidity of 4-6%. Firing is similar to spot welding... This explains the decrease in the compressive-flexural strength of such products. A good alternative to the tunnel kiln would be a ring kiln with removable vaults to reduce the cost of brick production. Before firing, it is necessary to load 400 pieces at once through the vaults without the use of trolleys. Such ovens consume less electricity and gas. Construction of a ring furnace is 2-3 times cheaper than construction of a tunnel furnace.

Increasing the temperature to 1200 ° C and the firing time will help to avoid excessive brittleness.