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Tsvetkov Leonid

The modern construction industry is unthinkable without such a simple and uncomplicated invention of mankind at first glance - the brick. On the pages of the Internet portal on low-rise construction http://site you will find a huge amount of materials and articles covering, to one degree or another, the issues of building houses and cottages made of brick or using modern ceramic products - porous blocks and stones. In this article we want to tell you about the history of brick construction, which dates back to the times of Ancient civilizations, Egyptian pharaohs and Roman emperors.

Making bricks in ancient Egypt

Numerous archaeological excavations allow us to say with confidence that first bricks They were used as a building material by humans about 5 thousand years ago. But who exactly invented brick It’s impossible to say for sure. Most likely, the brick in the understanding that we put into this word was not the invention of one person, but the fruit of the evolutionary development of the very technology of building a strong and inexpensive home from scrap materials. Scientists were unable to accurately indicate and find the place where the first brick structure was built, but the fact that these buildings were erected in Mesopotamia, the territory between the Tigris and Euphrates (Interfluve), is not at all accidental. The fact is that in these places there was always plenty of water, clay and straw. And all this grace was illuminated by the hot sun almost all year round. It was from these natural materials that the local residents built their homes. The buildings were built from straw coated with clay.

The clay dried under the sun's rays and became hard, but at the same time it did not allow moisture to pass through and protected well from bad weather. People noticed this, and since they sought to make their work easier, they invented this, simple at first glance, block of straw and clay, which we call brick. The technology for making the first bricks was simple: sticky clay was mixed with water, straw was added for strength and strength, and the bricks already formed in this way dried out under the hot rays of the sun and became hard as stone.

Manufacturing of raw bricks

It was still adobe or raw brick. Raw brick and now in our time it is widely used in many countries around the world as the main building material.
The ancient Egyptians were the first to master the technology of firing bricks in a kiln.. The images preserved from the times of the pharaohs clearly show how brick was made, and temples and houses were built from it. For example, the city walls of Jericho were made of brick, which had a shape similar to today's loaves of white bread.

Brick became the main building material in Mesopotamia and almost all cities during the heyday of this civilization were built from it. For example, in Babylon, the most beautiful city of the ancient world, all buildings were built of bricks.
The ancient Romans and Greeks became great masters in the production of brick and the construction of buildings and structures from it. It was from the Greek word "plinthos", which literally means "brick", that plinths got their name, a product that represented a new milestone in the history of brick production.
This is interesting: Another Greek word, keramos, translates to clay. The term “ceramics” means products made from baked clay. Once upon a time in ancient Athens, master potters lived compactly in one of the city's districts. This area became known to the Athenians as "Keramik".

Plinths- the most ancient baked bricks. It was made in special wooden forms. The plintha was dried for 10-14 days, then fired in a kiln. They were square and large in size. In Ancient Rome, the plinth was usually made in the following dimensions: 50 x 55 x 4.5 cm, and in Byzantium 30 x 35 x 2.5.
Smaller plinths were also made, but they were used as tiles. As you can see, the ancient plinths were much thinner than modern brick, but this circumstance did not in the least prevent the Romans from building famous Roman arches and vaults from them.

External arches of the Colosseum

Such bricks were easily shaped, dried and fired. They were built from them using a thick layer of mortar, often equal in thickness to the plinth itself, which is why the temple wall became “striped.” Sometimes a row of natural stone was laid after several rows of plinths. In Byzantium plinth walls almost never plastered.

Brick in Russia

In pre-Mongol Kievan Rus, which adopted a lot from the culture of Byzantium, including construction technologies, plinth became the main material for the construction of structural elements of buildings and was used in ancient Russian temple architecture of the 10th - early 13th centuries, in particular, the St. Sophia Cathedral was built from them ( Kyiv), 1037, Church of the Savior on Berestov, 1113-25, Annunciation Church (Vitebsk), Boris and Gleb Church (Grodno).
The first brick workshops in Rus' appeared in monasteries. Their products were mainly used for the needs of the temple. It is believed that the first religious building in Rus' built of brick was the Tithe Church in Kyiv.

This is interesting: In the scientific literature, it has been suggested that, along with plinth, in Rus' already in the 12th-13th centuries. manufactured and block brick, which was used together with plinth. In fact, square brick, which is of Romanesque origin, first entered Kyiv from Poland in the very last pre-Mongol years. Block bricks together with plinths were used only in cases where they were used to repair buildings that had been built earlier. Examples include the Assumption Cathedral of the Pechersk Monastery, the Kiev rotunda, and St. Michael's Cathedral in Pereyaslavl, restored shortly after they were damaged in the earthquake of 1230. In addition, narrow format plinths were sometimes mistaken for square bricks, i.e. “halves”, especially if they had an unusually large thickness (for example, in the Novgorod Cathedral of the Anthony Monastery and the Old Ladoga Cathedral of the St. Nicholas Monastery - more than 7 cm).

Actually in Muscovite Rus' molded brick began to be widely used only from the end of the 15th century, and the first brick factory was founded in 1475. And the walls of the Kremlin in Moscow were built from this brick.
This is interesting: The history of the appearance of the first brick production plant in the Moscow kingdom is quite interesting. In 1475, he was invited to Moscow from Italy architect Aristotle Fioravanti for the construction of the Kremlin. But Aristotle began not with construction, but with the establishment of brick production with a special kiln. And very quickly this plant began to produce very quality brick. In honor of the architect it was nicknamed "Aristotle's brick". The walls of the Novgorod and Kazan Kremlin were also built from such “clay stone”. "Aristotle's brick" had an almost identical appearance to modern brick and the following dimensions: 289x189x67 mm. "Gosudarev Brick" was the first in Russia that involved ligating stitches.

Despite the exceptional popularity of brick as a building material, until the 19th century, brick production techniques in Russia remained primitive and labor-intensive. The bricks were molded by hand, dried exclusively in the summer, and fired in temporary floor kilns made of dried raw bricks or small portable kilns. In the mid-19th century in technology brick production there was a real revolution. For the first time, a ring kiln and a belt press were built, and the first brick dryers appeared. At the same time, clay processing machines such as runners, dryers, and clay mills appeared.
This made it possible to bring brick production to a qualitatively new level. The next issue arose was the quality of the products. In order to separate defectors from bona fide producers, a branding system was invented. That is each brick factory had its own brand name - a brand that was applied to the brick. The first technical description of brick, a list of its parameters and properties, also appeared in the 19th century.

This is interesting: Under Peter 1, the quality of bricks was assessed very strictly. A batch of bricks brought to the construction site was simply dumped from the cart: if more than 3 pieces were broken, then the entire batch was rejected. During the construction of St. Petersburg, Peter I introduced the so-called. "stone tax" - payment in bricks for entering the city.

Modern brick acquired the dimensions familiar to us - 250x120x65 mm - in 1927, its weight was no more than 4.3 kg.
5 thousand years have passed, but brick still remains the most popular building material and is not going to give up its primacy to anyone. The evolution in the development of technology for the production of bricks and ceramic products is somewhat akin to the evolution of man according to Darwin's theory. If we draw an analogy, then first the emergence of primitive forms (adobe huts), then primitive man (raw brick), now modern man (burnt brick and ceramic stones). The evolutionary development of man and brick production technologies go hand in hand, and this pattern indicates that as long as our civilization exists, brick will exist as the basis of the entire construction industry created by humanity over many centuries.
Construction of houses from Porotherm blocks >>>

The history of brick began a very long time ago, from the very time when people began to burn dishes. It was then that modern ceramic production began.

Ancient Egyptian brick structure

Particularly proud is the brick construction of Ancient Egypt and Mesopotamia, which created complex structural elements. Take, for example, the Tower of Babel, which is one of the seven wonders of the world. Its remains were discovered at the turn of the era (19th and 20th centuries). It was a brick building with seven tiers, the lining of its walls was made of blue glazed brick. It can be assumed that thousands of years ago in the East technologies already existed that made it possible to make and burn different types of bricks, similar to modern ordinary and facing ones. But in antiquity, poor people built their homes from sun-dried bricks, not from baked bricks. Probably, later this technique was somehow lost.

There were different bricks:

1. unfired, that is, sun-dried;
2. fired in a kiln.

The first type of bricks is raw clay. Special knowledge was not required for the manufacture of such building material. It is still used in some countries around the world.

There are different versions of its appearance.

Raw clay. Manufacturing.

The disadvantage of such raw brick is the impact of rain on it. According to scientists, such bricks were made from a clay mass that clumped into lumps after the river flooded the banks. As the water dried out, clay, mud and straw, clumped together, remained at the edge of the shore, and the sun dried them out. It happened that resin was also added to the mass. Such bricks could contain from 20 percent clay to seventy-five.

Modern brick factories extract clay from the depths, carefully mixing it with sand. But before, people preferred deposits on the surface; they already contained both clay and sand in a certain ratio. Brick makers then tested the clay by tasting it. The decision to carry out construction in a particular area depended on the availability of brick clay.

When a suitable type of clay was found, it was freed from stones so that they would not make it difficult to cut brick products and would not burst during firing. When the clay was ready, it was mixed with water and molded.

Thanks to firing, the bricks became durable and acquired the qualities of stone. But they differed in that it was easier for them to give the desired shape.

Brick firing is a complex production process

After firing, the bricks become water resistant. Firing is not such a simple process. If you place a brick in a fire, it will not become strong. Before achieving a specific degree of sintering, there must be a constant temperature (900-1150 degrees Celsius) for several hours (8-15). The temperature depends on the type of clay that is used. To avoid cracks, slow cooling is required after firing.

Brick firing

If the bricks are not fired enough, they become soft and crumble. If it is too strong, they lose their shape during firing and can melt into a glassy substance. For proper firing there must be a furnace in which the required temperature is constantly maintained.

The most common brick shape was a square, with sides of 30 and 60 centimeters, and a thickness of 3 to 9 centimeters. They were called plinths (the word came from Greek). In Ancient Greece and Byzantium they were in great demand. The plintha looked like a flat block. In our perception it looks more like tile than brick.

When did brick appear in Rus'?

Ancient Rus' learned about bricks thanks to Byzantine culture. Builders from Byzantium brought and revealed the secret of brick production. They arrived together with other masters, scientists and priests in 988 after the baptism of Rus'. The first brick building here was the tithe church in Kyiv. The first brick buildings in Moscow appeared in 1450, and only 25 years later the first brick factory in Russia was built (1475), producing bricks. Before this, bricks were made mainly in monasteries. In 1485, the reconstruction of the Moscow Kremlin began, where brick was used. The construction of the Kremlin walls and temples was supervised by Italian masters. The next stage was the construction of the brick Kremlin in Nizhny Novgorod (1500). A similar one was built in Tula in 1520.

Peter I, St. Petersburg and brick factories

In St. Petersburg, among the first brick houses were the chambers of the Admiralty Councilor Kikin, built in 1707. Three years later, on Trinity Square - the house of Chancellor G.P. Golovin (1710). The next year, the palace of Natalya Alekseevna, princess, sister of Peter I, was built. Next - the construction of the Winter and Summer palaces of Peter I himself (1712). For quite a long time, for seven years, the construction of the Menshikov Palace was carried out. It was rebuilt several times. But, despite everything, its original appearance was preserved. Today it is a museum, a branch of the State Hermitage.

The first Russian bricks. Peter 1

Peter I, by decree, allowed the construction of new brick factories, in which manufacturers had to put stamps on their bricks in order to make it easier to find defectors. After all, the strength of this building material was determined very simply. The entire batch of products was thrown off the cart. If at least three bricks were broken, then all products were considered to be of poor quality. Brick production developed, and craftsmen were gathered throughout Russia. At the same time, there was a ban on the construction of stone buildings in other cities. Those who violated this decree were threatened with exile and confiscation of property. Many masons came to St. Petersburg in search of work. Anyone entering or entering had to leave a brick, the so-called pass to the city. This is exactly what Peter I was counting on. There is an assumption that Kamenny Lane was built from brought and brought bricks.

How did the brick industry develop?

Technological production of bricks continued to remain primitive and labor-intensive until the 19th century. The bricks were molded by hand, dried only in the summer, and fired in temporary floor ovens, which were lined with dried raw bricks.

Another branded brick

In the mid-19th century, the brick industry began to actively develop. Modern factories appear that produce the bricks of our time. Today we can say with confidence that the production of bricks is wide and varied: over fifteen thousand different combinations, shapes, sizes, surface textures and colors are produced. And also the brick can be hollow, ceramic, with heat-insulating properties, ordinary, shaped, front, fireplace, single, double, thickened and others. And accordingly, you can build anything from it: from a simple pillar to a high-rise building of an unusual shape... It is convenient to work with it, it is considered a strong material, durable, beautiful and environmentally friendly.

Brick is the oldest building material. Its history goes back several thousand years, but no one can say for sure who and when the first copy was made. The oldest objects made of baked clay were found at an Old Stone Age (Paleolithic) site in Slovakia; their age is 25 thousand years.

The first mention of brick as a building material dates back to the 5th – 4th millennium BC. e. in the architecture of the Predynastic period (Ancient Egypt).

During excavations in Jemdet Nasr, traces of construction from the late 4th – early 3rd millennium BC were discovered. e. made of thin flat bricks (so-called “rimchens”).

At the beginning of the 3rd millennium BC. e. hand-made one-sided convex bricks were replaced by bricks made in wooden forms, initially oblong (20 x 30 x 10 cm - Old Babylonian brick).

The binding material during construction was clay, sometimes mixed with ash and bitumen. Lime mortar began to be used only from the middle of the 1st millennium BC. e.

The next step in the history of brick production was the appearance of plinth. The Greek word “plinthos” actually means “brick”. The term "ceramics" refers to products made from fired clay. In Greek, keramos means clay. In ancient Athens, master potters lived compactly in one of the city's districts. This area became known to the Athenians as "Keramik". Since then, the universal name “ceramics” has been assigned to any objects made of clay and fired in a kiln. In addition to pottery, the most important product of pottery was the well-known brick.

Brick did not bypass the no less famous Roman civilization. Here, for the first time, arches, vaults and other complex structures began to be built from bricks measuring 45 x 30 x 10 cm.

In the Ancient East, bricks were shaped like clay bottles and resembled modern, well-known loaves of white bread.

In ancient Rus', brick production began in the 10th century, this is due to the influence of Byzantine culture. As a result of the baptism of Rus' in 988, not only priests arrived here from Byzantium, but also builders who brought with them the secret of brick production. Since that time, the active use of brick as a building material began. It is believed that the first building in Rus' built of brick was the Tithe Church in Kyiv.

Brick production in Prussia
Brick production in Prussia began during its conquest by the Teutonic Order at the beginning of the 13th century. After securing the newly conquered territories, the Order began building castles and fortifications from natural stone and baked brick, for the production of which there were huge reserves of clay.

At the initial stage, these were rampart fortifications with wooden walls, towers and blockhouses for the garrison. After securing the territory and stabilizing the situation, the administration of the Order began rebuilding the castles using stone and baked bricks. It is impossible to determine exactly when the Order first began to use brick in the construction of castles. German researchers indicate different dates, but most likely this happened after the suppression of the first Prussian uprising, presumably in 1250-55.

Prussia was poor in stone supplies; there were no quarries on its territory. But there were huge reserves of clay necessary for the production of bricks. Therefore, the main building material for Prussian castles was

and later the church and residential buildings were hand-molded baked bricks.

Its production was quite expensive and labor-intensive. The extracted clay was placed in shallow but spacious pits, then filled with water and left in this state for 1.5-2 years, and sometimes more, depending on the quality of the clay. Then the clay was kneaded and teams of molders began to work. Each of them had a wooden form of approximately the same size. It was manually filled with prepared clay, carefully compacted and laid out directly on the grass or prepared area. For this purpose, large clearings were chosen near housing. It took some time for the clay to dry. During this time, dogs and other domestic animals could run across the still wet forms, leaving their paw marks on them. But not only animals left their “facsimiles”. Often, small children, unattended, wandered into the forms prepared for drying. There are still bricks with “fingerprints” of children’s feet.

After drying, the bricks were fired in temporary kilns built nearby. With imperfect firing technology, there were often cases where the brick loaded into the kiln was burned out, and it turned out to be black in the usual red hue.

Black brick, if it had a sufficiently strong base, was used to decorate the masonry of walls. These could be diamond-shaped patterns (the castles of Insterburg and Saalau, order churches in the village of Gvardeiskoye, Bagrationovsky district, and the village of Rodniki, Guryevsky district), which have survived to this day, patterns showing the features and variety of brickwork (Brandenburg Castle) and some figures in the form Cross - Order Church in Kreuzburg.

From these patterns one can judge the time of laying. This is usually the end of the 13th century or 14th century. The dimensions of the manufactured bricks varied quite a lot, sometimes the difference reached several centimeters:

2900 x 1400 x 900 mm – Schaaken Castle

3000 x 1350 x 1000 mm – Preussisch-Aylau castle

3050 x 1450 x 950 mm – Brandenburg Castle

3200 x 1550 x 1000 mm – Balga castle.

The largest brick from the Order period found in the Kaliningrad region today can be considered a brick from the Balga castle, 3350 x 2150 x 900 mm and weighing 10 kg 720 g.

In Russia, bricks of this size are called “monastic” bricks.

In addition to ordinary bricks, shaped (shaped) bricks were also required for the internal surfaces of vaults, windows, doors and for vault supports. Such bricks gave uniqueness and individuality to each room.

It is safe to say that square slabs were also made from clay, which were used to lay the floor of the first (basement) floor, or the arched ceilings of basements (Preussisch-Aylau Castle).

During the 14th century, more than 100 expensive castles were built. The pinnacle of this considerable military-economic enterprise was the reconstruction of Marienburg from the Komtur castle into the residence of the Grand Master (beginning of the 14th century).

Today it is the largest medieval complex built of brick in Europe.

After the secularization of the Order in 1525, due to the lack of government orders, the volume of brick production decreased sharply, but the need for it was still noticeable. In order to save on building materials, some of the castles were dismantled into bricks (Balga, Brandenburg, Kreuzburg, Laptau, Lochstedt, Povunden, Thirinberg, Fischhausen, etc.). This situation continued until the 18th century.

Brick production has always been highly developed in Prussia. Material for it was available in abundance both before and now.

Authors: head of the department of local history literature S. M. Postnikova, creator of the brick museum D. Shilov photo of the largest brick, “matryoshka dolls”, church, Kreuzburg castle - D. Shilov drawing of Brandenburg castle: A. P. Bakhtin

December 2009
http://gorodkanta.ru/print.php?newsid=4085

Standard baked brick has been used in Rus' since the end of the 15th century. A striking example was the construction of walls and temples of the Moscow Kremlin during the time of John III, which was supervised by Italian craftsmen. " ... and a brick kiln was built behind the Andronikov Monastery, in Kalitnikov, in what to burn the brick and how to make it, our Russian brick is already longer and harder, when it needs to be broken, they soak it in water. They ordered to mix the lime thickly with hoees; once it dries in the morning, it’s impossible to split it with a knife.».

Dimensions

• 0.7 NF (“Euro”) - 250x85x65 mm;
• 1.3 NF (modular single) - 288x138x65 mm.

Incomplete (part):

• 3/4 - 180 mm;
• 1/2 - 120 mm;
• 1/4 - 60-65 mm.

Face names

Types of bricks and their advantages

Today, two main types of bricks are used in modern construction: ceramic and silicate bricks.

Sand-lime brick

Sand-lime brick is made from a mixture of quartz sand, airborne lime and water. The molded brick is subjected to autoclave treatment - exposure to saturated water vapor at temperatures of 170-200 ° C and high pressure. As a result of using this technology, artificial stone is formed. :

Advantages of sand-lime brick

• Environmental friendliness Sand-lime brick is made from environmentally friendly natural raw materials - lime and sand, using technology familiar to mankind for several centuries.
• Soundproofing. This plays an important role in the construction of inter-apartment or interior walls. Sand-lime brick is used for laying walls and pillars in civil and industrial construction.

Compared to ceramic brick, sand-lime brick has a higher density.

• High frost resistance and strength. Sand-lime brick is significantly superior to lightweight concrete grades in strength and frost resistance. Builders give a 50-year guarantee on facades built from it.

• Economical. The cost of sand-lime brick is lower than that of its ceramic analogues.

• Reliability and wide range. The reliability and wide range of sand-lime bricks allows it to be used both in new construction and during reconstruction. Textured, colored silicate brick will decorate the facades of both public and residential buildings, as well as country cottages and dachas.

• Type of painting. Colored sand-lime brick is colored in the same way as ceramic brick. But, unlike ceramic bricks, silicate bricks can be colored only with the help of special artificial dyes, and ceramic bricks acquire a certain color as a result of mixing different types of clay or also by adding special dyes.

• Unpretentiousness. Structures made of sand-lime brick are unpretentious and resistant to external factors. The vagaries of nature do not have a significant impact on its appearance. The facade retains its color and does not require additional care, except for cases of use in aggressive environments or in conditions of high humidity.

Disadvantages of sand-lime brick

• A serious disadvantage of sand-lime brick is its reduced water resistance and heat resistance, so it cannot be used in structures exposed to water (foundations, sewer wells, etc.) and high temperatures (furnaces, chimneys).

Application of sand-lime brick

Sand-lime brick is usually used for the construction of load-bearing and self-supporting walls and partitions, one-story and multi-story buildings and structures, internal partitions, filling voids in monolithic concrete structures, and the outer part of chimneys.

Ceramic brick

Ceramic bricks are usually used for the construction of load-bearing and self-supporting walls and partitions, single-story and multi-story buildings and structures, internal partitions, filling voids in monolithic concrete structures, laying foundations, the inside of chimneys, industrial and household furnaces.

Ceramic brick is divided into ordinary (construction) and facing. The latter is used in almost all areas of construction.

Advantages of ceramic ordinary bricks

• Durable and wear-resistant. Ceramic brick has high frost resistance, which is confirmed by many years of experience in its use in construction.
• Good sound insulation- walls made of ceramic bricks, as a rule, comply with the requirements of SNiP 23-03-2003 “Noise Protection”.
• Low moisture absorption(less than 14%, and for clinker bricks this figure can reach 3%) - Moreover, ceramic bricks dry quickly.
• Environmental friendliness Ceramic brick is made from environmentally friendly natural raw materials - clay, using technology familiar to mankind for dozens of centuries. During the operation of buildings constructed from it, red brick does not emit substances harmful to humans, such as radon gas.
• Resistant to almost all climatic conditions, which allows you to maintain reliability and appearance.
• High strength(15 MPa and above).
• High density(1950 kg/m³, up to 2000 kg/m³ with manual molding).

Advantages of ceramic facing bricks

• Frost resistance. Facing bricks have high frost resistance, and this is especially important for the northern climate. Frost resistance of a brick is, along with strength, the most important indicator of its durability. Ceramic facing bricks are ideal for our climate.
• Durability and stability. Due to its high strength and low porosity, masonry constructed from facing products is distinguished by its high strength and amazing resistance to environmental influences.
• Various textures and colors. The range of different shapes and colors of facing bricks gives you the opportunity to create an imitation of ancient buildings when building a modern house, and will also allow you to replace lost fragments of the facades of ancient mansions.

Disadvantages of ceramic bricks

• High price. Due to the fact that ceramic brick requires several stages of processing, its price is quite high compared to the price of sand-lime brick
• Possibility of efflorescence. Unlike sand-lime brick, ceramic brick “requires” a high-quality mortar, otherwise efflorescence may appear.
• The need to purchase all the required facing bricks from one batch. If facing ceramic bricks are purchased from different batches, problems with tone may arise.

Production technology

Until the 19th century, brick production techniques remained primitive and labor-intensive. The bricks were molded by hand, dried exclusively in the summer, and fired in temporary floor ovens made of dried raw bricks. In the middle of the 19th century, a ring kiln and a belt press were built, which led to a revolution in production technology. At the end of the 19th century, dryers began to be built. At the same time, clay processing machines such as runners, rollers, and clay grinders appeared.

Nowadays, more than 80% of all bricks are produced by year-round enterprises, among which there are large mechanized plants with a capacity of over 200 million pieces. per year.

Organization of brick production

Ceramic brick

It is necessary to create conditions to ensure basic production parameters:

• constant or average clay composition;
• uniform production operation.

In brick production, results are achieved only after lengthy experiments with drying and firing regimes. This work must be carried out under constant basic production parameters.

Clay

Good (facing) ceramic brick is made from clay extracted in a fine fraction with a constant composition of minerals. Deposits with a homogeneous composition of minerals and a multi-meter layer of clay suitable for mining with a single-bucket excavator are very rare and almost all have been developed.

Most deposits contain multi-layered clay, so bucket and rotary excavators are considered the best mechanisms capable of producing medium-composition clay during mining. When working, they cut the clay to the height of the face, crush it, and when mixed, an average composition is obtained. Other types of excavators do not mix the clay, but extract it in blocks.

A constant or average clay composition is necessary to select constant drying and firing conditions. Each composition requires its own drying and firing regime. Once selected modes allow you to obtain high-quality bricks from the dryer and kiln for years.

The qualitative and quantitative composition of the deposit is determined as a result of exploration of the deposit. Only exploration reveals the mineral composition: what kind of silty loams, fusible clays, refractory clays, etc. are contained in the deposit.

The best clays for brick production are those that do not require additives. For the production of bricks, clay is usually used, which is unsuitable for other ceramic products.

Chamber dryers

The dryers are fully loaded with bricks, and the temperature and humidity gradually change throughout the entire volume of the dryer, in accordance with the specified drying curve of the products.

Tunnel dryers

Dryers are loaded gradually and evenly. Trolleys with bricks move through the dryer and pass successively through zones with different temperatures and humidity. Tunnel dryers are best used for drying bricks made from medium-composition raw materials. They are used in the production of similar building ceramic products. They “hold” the drying mode very well with a constant and uniform loading of raw bricks.

Drying process

Clay is a mixture of minerals, consisting by weight of more than 50% of particles up to 0.01 mm. Fine clays include particles less than 0.2 microns, medium clays 0.2-0.5 microns and coarse clays 0.5-2 microns. In the volume of raw brick there are many capillaries of complex configuration and different sizes, formed by clay particles during molding.

Clay produces a mass with water, which, after drying, retains its shape, and after firing it acquires the properties of stone. Plasticity is explained by the penetration of water, a good natural solvent, between individual clay mineral particles. The properties of clay with water are important when molding and drying bricks, and the chemical composition determines the properties of products during firing and after firing.

The sensitivity of clay to drying depends on the percentage of “clay” and “sand” particles. The more “clay” particles in the clay, the more difficult it is to remove water from raw bricks without cracking during drying and the greater the strength of the brick after firing. The suitability of clay for brick production is determined by laboratory tests.

If at the beginning of drying a lot of water vapor is formed in the raw material, then their pressure may exceed the tensile strength of the raw material and a crack will appear. Therefore, the temperature in the first zone of the dryer must be such that the water vapor pressure does not destroy the raw material. In the third zone of the dryer, the strength of the raw material is sufficient to increase the temperature and increase the drying speed.

The operating characteristics of drying products in factories depend on the properties of the raw materials and the configuration of the products. The drying regimes existing in factories cannot be considered as constant and optimal. The practice of many factories shows that the drying time can be significantly reduced by using methods of accelerating the external and internal diffusion of moisture in products.

In addition, one cannot ignore the properties of clay raw materials from a particular deposit. This is precisely the task of factory technologists. It is necessary to select the productivity of the brick molding line and the operating modes of the brick dryer, which ensure high quality raw material with the maximum achievable productivity of the brick plant.

Firing process

Clay is a mixture of low-melting and refractory minerals. During firing, low-melting minerals bind and partially dissolve refractory minerals. The structure and strength of a brick after firing is determined by the percentage of low-melting and refractory minerals, the temperature and duration of firing.

During the firing of ceramic bricks, low-melting minerals form glassy and refractory crystalline phases. With increasing temperature, more and more refractory minerals pass into the melt, and the content of the glass phase increases. With an increase in the glass phase content, frost resistance increases and the strength of ceramic bricks decreases.

As the firing duration increases, the process of diffusion between the glassy and crystalline phases increases. In places of diffusion, large mechanical stresses arise, since the coefficient of thermal expansion of refractory minerals is greater than the coefficient of thermal expansion of low-melting minerals, which leads to a sharp decrease in strength.

After firing at a temperature of 950-1050 °C, the proportion of the glassy phase in the ceramic brick should be no more than 8-10%. During the firing process, such firing temperature conditions and firing duration are selected so that all these complex physical and chemical processes ensure maximum strength of the ceramic brick.

Sand-lime brick

Sand

The main component of sand-lime brick (85–90% by weight) is sand, so sand-lime brick factories are usually located near sand deposits, and sand quarries are part of the enterprises. The composition and properties of sand largely determine the nature and features of sand-lime brick technology.

Sand is a loose accumulation of grains of different mineral composition with a size of 0.1 - 5 mm. Based on their origin, sands are divided into natural and artificial. The latter, in turn, are divided into waste from rock crushing (tailings from ore dressing, crushed stone quarries, etc.), crushed waste from fuel combustion (sand from fuel slag), crushed waste from metallurgy (sand from blast furnaces and water jackets). slags).

The shape and nature of the surface of sand grains are of great importance for the formability of the silicate mixture and the strength of the raw material, and also affect the rate of reaction with lime, which begins during autoclave treatment on the surface of the sand grains.

When coarsely mixing sand in a quarry, they check the proportion in which trolleys or dump trucks are loaded with sand of varying sizes in each face. If there are several receiving bins for different sand fractions, it is necessary to check the specified proportion of sand in the charge by the number of feeders of the same capacity, simultaneously unloading sand of different sizes.

Sand coming from the face before it is used in production must be screened out from foreign impurities - stones, lumps of clay, branches, metal objects, etc. During the production process, these impurities cause brick defects and even machine breakdowns, so sand bunkers are installed above sand bunkers. drum rolls.

Lime

Lime is the second component of the raw material mixture necessary for the production of sand-lime brick.

The raw materials for the production of lime are carbonate rocks containing at least 95% calcium carbonate CaCO3. These include dense limestone, limestone tuff, shell limestone, chalk, and marble. All these materials are sedimentary rocks, formed mainly as a result of the deposition of waste products of animal organisms on the bottom of sea basins.

Limestone consists of lime spar - calcite - and a certain amount of various impurities: magnesium carbonate, iron salts, clay, etc. The color of limestone depends on these impurities. It is usually white or various shades of gray and yellow. If the clay content in limestones is more than 20%, then they are called marls. Limestones with a high content of magnesium carbonate are called dolomites.

Marl is a calcareous-clayey rock that contains from 30 to 65% clayey matter. Consequently, the presence of calcium carbonate in it is only 35–70%. It is clear that marls are completely unsuitable for making lime from them and therefore are not used for this purpose.

Dolomites, like limestones, belong to carbonate rocks consisting of the mineral dolomite (CaCO3 * MgCO3). Since their calcium carbonate content is less than 55%, they are also unsuitable for lime firing. When burning limestone for lime, only pure limestone is used that does not contain large amounts of harmful impurities in the form of clay, magnesium oxide, etc.

Based on the size of the pieces, limestones for firing into lime are divided into large, medium and small. The content of fines in limestone is determined by sifting the rock through screens.

The main binding material for the production of silicate products is building air lime. The chemical composition of lime consists of calcium oxide (CaO) mixed with a certain amount of magnesium oxide (MgO).

There are two types of lime: quicklime and slaked; In sand-lime brick factories, quicklime is used. When fired, limestone decomposes under the influence of high temperature into carbon dioxide and calcium oxide and loses 44% of its original weight. After burning limestone, lump lime (boiling lime) is obtained, which has a grayish-white, sometimes yellowish color.

When lump lime interacts with water, hydration reactions occur: CaO+ H2O = Ca(OH)2; MgO+H2O=Mg(OH)2 or, in other words, lime slaking. The hydration reactions of calcium and magnesium oxide produce heat. Lump lime (boiling) during hydration increases in volume and forms a loose, white, light powdery mass of calcium oxide hydrate Ca(OH)2. To completely slak the lime, it is necessary to add at least 69% water to it, i.e. For every kilogram of quicklime, about 700 g of water. The result is perfectly dry slaked lime (fluff). It is also called air lime. If you slak lime with excess water, you get lime paste.

Lime should be stored only in covered warehouses that protect it from moisture. It is not recommended to store lime in air for a long time, since it always contains a small amount of moisture, which extinguishes the lime. The content of carbon dioxide in the air leads to carbonization of lime, i.e., a combination with carbon dioxide and thereby a partial decrease in its activity.

Silicate mass

The lime-sand mixture is prepared in two ways: drum and silo.

The silage method of preparing the mass has significant economic advantages over the drum method, since when ensiling the mass, steam is not consumed to slak the lime. In addition, the technology of the silo production method is much simpler than the drum method. Prepared lime and sand are continuously fed by feeders in a given ratio into a continuous single-shaft mixer and moistened with water. The mixed and moistened mass enters silos, where it is kept for 4 to 10 hours, during which the lime is slaked.

The silo is a cylindrical vessel made of sheet steel or reinforced concrete; The height of the silo is 8 - 10 m, the diameter is 3.5 - 4 m. In the lower part, the silo has a cone shape. The silo is unloaded using a disc feeder onto a conveyor belt. In this case, a large amount of dust is released.