Physical properties of clay. The use of clay in construction. What are the criteria for classifying clay

Clay is a very common rock. Complex, both in composition and in physical and technological properties. Pure rock consists of complex chemical compounds - "clay" minerals, which include aluminum, silicon and water. In mineralogy, they are called aqueous aluminosilicates.

The property of clay depends on its chemical and mineral composition. Earthy rock - clay easily dissolves in water, forming "suspensions" (turbidity) or plastic dough, which retains its shape after drying and acquires the hardness of the stone after firing. Also, another property of clay can be considered "sorption" - the ability to absorb some of the substances dissolved in it from the liquid. Since the clay contains a large amount of aluminum oxide, it is used as a chemical raw material for the production of sulfate salts.

Characteristics and types

For ease of use, all existing clay was divided into the following types:

• Kaolin - the most popular type, white, consisting of the mineral kaolinite. It is used in the porcelain and faience and paper industries.
• Fire-clay, it comes in white or gray. During firing it can withstand a temperature of about 1580 °. The composition includes minerals kaolinite and hydromica. Used for the manufacture of refractory cookware.
• Acid resistant clay is a type of refractory clay, which contains iron, magnesium, calcium and sulfur.
• Molding clay - has increased plasticity and bonding capacity. They are used as a bonding material in the manufacture of containers for metallurgical casting.
• Cement clay has a rich color palette. Part of Portland cement.
• Brick clay - low-melting, it contains a significant admixture of quartz sand. They are widely used in brick production.
• Bentonite clay - the main forming mineral is montmorillonite. Rich colors. Has the highest whitening power. This type is indispensable for refining petroleum products, vegetable and lubricating oils.
• Mineral natural clay - used in medicine and cosmetology

(The picture shows a variety of cosmetic clay)

In industrial practice, clay is divided into "fat" and "skinny" groups. It all depends on the degree of their pollution with quartz sand. In "greasy" clays there is not much sand, but in "lean" clays there is a large amount.

Field and production

Clay is widespread in nature, occurs at a shallow depth. All this contributes to low mining costs, making the raw materials cheap. Usually, brick and tile factories are built on the clay deposit itself. The largest deposits of clay are located in Ukraine and Russia. Relatively small accumulations of rock are found in Georgia, Kazakhstan, Uzbekistan, Turkmenistan and other CIS countries.

Clay application

Clay can be classified as a mineral raw material for mass consumption. It is used in a wide variety of industries, for example, in the household, where the manufacture of dishes and other products. In construction, for the production of building bricks of any color and cement. And also in industry: soap making, perfumery, textiles and many others.

Factories use a certain type of clay to refine petroleum products, vegetable oils and fats. Clay is indispensable in art, plastic colored clay is an excellent material for creating sculptures. It earned wide popularity in agriculture: for laying stoves, clay ceilings, whitewashing walls, etc.

Clay - a plastic natural material used in construction, folk crafts, treatment and improvement of the body and in other areas of human life. It is this widespread use that determines certain qualities and properties of clay. And the properties of clay are largely influenced by its composition.

Clay application

Clay is very accessible, and its benefits are invaluable, and therefore it has been used by people since very ancient times. There are many references to this wonderful material in textbooks on the history of all countries of the world.

Building... Currently, clay is used as a material for making red bricks. Clay of a certain composition is molded and fired using a certain technology to obtain a durable and inexpensive ingot - a brick. And buildings and structures are already being built from bricks. In some countries and regions, clay is still used to build a dwelling - a hut; it is widespread to use clay in the construction of brick ovens, where clay serves as a binder (as cement). The same clay is used for plastering ovens.

The medicine. Wellness and traditional medicine uses clay in the form of mud baths and masks. The whole point is to nourish the surface of the skin with beneficial clay elements. Of course, not all clay will work here.

Souvenirs and dishes... I combine two large directions into one, since many items of tableware have only a souvenir character. Plates, pots, jugs and vases are abundant in modern stores. Not a single fair is complete without the sale of clay souvenirs - hazy toys, svustulki, tablets, key chains and much more. We will try to mold many things on our own.

Clay can enter composition of other materials... Chasovoyarskaya clay of fine grinding, for example, is an element of artistic paints (gouache), sauce, pastels and sanguine. Read about it in the articles "Help for the artist".

Clay properties

Colour. Clay of various compositions has many shades. The clay is called by its color: red, blue, white ... True, during drying and further firing, the color can completely change. This is worth paying attention to when working with clay.

Plastic. It was the ability to deform and keep the shape given to it that allowed a person to find the use of clay in his life. It is worth noting here that everything depends on the consistency - the ratio of the amount of water, clay and sand. Different compositions require different compositions. So, for modeling, sand may be generally unnecessary.

Hygroscopicity allows the clay to absorb water, changing its viscosity and plasticity properties. But after firing, clay products acquire water resistance, strength and lightness. The development of technology has made it possible to obtain faience and porcelain, which are irreplaceable in the modern world.

Refractoriness... A property used in construction rather than in artistic crafts, except for the firing of products. The firing technology is different for one or another clay composition. The property of clay shrinkage or compressibility is closely related to drying and firing - a change in mass and size due to the removal of part of the water from the composition.

Clay composition

The properties of clay are determined by its chemical composition. Different types of clay have different chemical compositions. For example, red clay contains many iron oxides. Clay basically contains certain substances - clay minerals - which are formed in the course of various natural phenomena. The format of the article does not provide for consideration of the chemical properties and composition of the clay, so I will not go into details.

The composition of clay suitable for use in folk crafts, as already mentioned, is determined by three essential elements: clay minerals, water and sand.

The proportions of these elements can be changed, although it is much easier to add than remove. So, for example, dry clay can be quickly dissolved, however, it is not at all easy to make clay as liquid as sour cream suitable for modeling. It is very easy to add sand, but removing it from clay is not a trivial task.

Distinguish between "skinny" and "fat" clays. The "fat content" scale determines the plasticity coefficient, and the binding properties of the clay allow you to adjust the fat content by mixing it with other natural materials, such as sand. Skinny clay has less plasticity, its binding strength is weaker, but it gives less shrinkage when drying and firing.

Clay deposits are found in various states around the world. This ensured its use by artisans of different nationalities, and served as the emergence of such a variety of products and technologies.

Craftsmen have learned to control the behavior and condition of the clay through various additives in the composition. So you can thin the clay, torture it, give it greater refractoriness, and reduce shrinkage. As a result of such manipulations, an experienced craftsman will be able to end up with a high-quality highly artistic product.

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Introduction

Many people consider clay to be ordinary. In fact, the material familiar to everyone is very interesting. Interesting to know: what is clay?

Clay is a widespread rock and by-product of the earth's crust, a sedimentary rock formed by the destruction of rocks during the process of weathering.

The main source of clayey rocks is feldspar, the decomposition of which under the influence of atmospheric phenomena forms kaolinite and which, under the influence of atmospheric phenomena, forms kaolinite and other hydrates of aluminum silicates. Some clays of sedimentary origin are formed in the process of local accumulation of the mentioned minerals, but most of them are drifts of water flows that have fallen to the bottom of lakes and seas.

Previously, clay was mined along the banks of rivers and lakes. Or they dug a hole specially for it. Then it became possible not to dig the clay yourself, but to buy it from a potter, for example. In the days of our childhood, ordinary, red clay was dug up ourselves, and noble white one was bought in shops for artists or, especially clean, in a pharmacy.

Depending on what kind of rock the clay is formed from and how it is formed, it takes on different colors. The most common clays are yellow, red, white, blue, green, dark brown and black.

Clays are widely used in industry (in the production of ceramic tiles, refractories, fine ceramics, porcelain and earthenware and sanitary items of trade), construction (production of bricks, expanded clay and other building materials), for household needs, in cosmetics and as a material for artwork ( modeling). We decided to study the composition and properties of clay and conduct experiments with it.

Relevance of work: the spread of clay in nature.

Hypothesis: Different properties of clay can be used for different applications.

Objective: researching and applying the properties of clay to create decorative crafts

Tasks:

Explore general information about clay using literature sources.

Study and observe the physical properties of clay, analyze research results.

Conduct practical experiments with clay.

Craft a decorative clay product.

Research methods:

Working with sources of information. Theoretical research.

Experimental methods.

Observation and photography.

Analysis of the results obtained.

1. The theoretical part. Clay basics.

1.1. Rock formation - clay

Clays and clayey rocks make up about half of all sedimentary rocks of the earth's crust. Clay is a fine-grained sedimentary rock, dusty in a dry state, plastic when moistened. Clay consists of one or more minerals of the kaolinite group (derived from the name of the Kaolin area in China), the rock-forming mineral in the clay is kaolinite, its composition: 47% (wt) silicon oxide (IV) (SiO2), 39% aluminum oxide (Al 2 O 3) and 14% water (H 2 O).

Aluminum oxides and silicon oxides - make up a significant part of the chemical composition of clays of yellow, brown, blue, green, purple and even black colors. Clay is everywhere. Which, in general, is not surprising - clay, sedimentary rock, is a stone, worn by time and external influence to the state of a powder. The last stage of stone evolution. (Stone-sand-clay.)

Clay appeared on earth many thousands of years ago. Its "parents" are considered rock-forming minerals known in geology - kaolinite, spar, some types of mica, limestone and marble. Under certain conditions, even some types of sand are transformed into clay. All known rocks that have geological outcrops on the earth's surface are subject to the influence of the elements - rain, vortex storm, snow and flood waters.

Changes in temperature day and night, heating of the rock by the sun's rays contribute to the appearance of microcracks. Water gets into the formed cracks and, freezing, breaks the surface of the stone, forming a large amount of the smallest dust on it. The cyclone crushes and grinds the dust into even finer dust. Where the cyclone changes its direction or simply dies down, over time, huge accumulations of rock particles form. They are compressed, soaked in water, and the result is clay.

1.2. Clay properties

Clay properties: plasticity, fire and air shrinkage, refractoriness, sinterability, color of the ceramic shard, viscosity, shrinkage, porosity, swelling, dispersion. Clay is the most stable waterproofing agent - water impermeability is one of its qualities. Due to this, clay soil is the most stable type of soil, developed in wastelands and wastelands. The water impermeability of clay is useful for maintaining the quality of groundwater - a significant part of high-quality artesian sources lie between clay layers.

The clay is colored by the creator stone and the salts of iron, aluminum and other similar minerals that are nearby. Various organisms multiply, live and die in clay. This is how you get red, yellow, blue, green, pink and other colored clays.

Dry clay absorbs water well, but when wet it becomes waterproof. After kneading and mixing, it acquires the ability to take various forms and keep them after drying. This property is called plasticity. In addition, clay has a binding capacity: with powdered solids (sand) it gives a homogeneous "dough", which also has plasticity, but to a lesser extent. Obviously, the more sand or water impurities in the clay, the lower the plasticity of the mixture.

By their nature, clays are divided into "fat" and "skinny". Clays with high plasticity are called "greasy" because they give the tactile sensation of a greasy substance when wet. "Oily" clay is shiny and slippery to the touch (if you take such clay on your teeth, it glides), contains few impurities. The "dough" made from it is tender. A brick made of such clay, when drying and firing, cracks, and in order to avoid this, the so-called "emaciated" substances are added to the batch: sand, "skinny" clay, burnt brick, potter's battle, sawdust, etc. Low-plastic or non-plastic clays are called "skinny".

An important property of clay is its relation to firing and, in general, to elevated temperatures: if soaked clay in air hardens, dries and is easily erased into powder, without undergoing any internal changes, then at high temperatures chemical processes occur and the composition of the substance changes.

Clay melts at very high temperatures. The reflow point (the beginning of melting) characterizes the refractoriness of the clay.

The color of clays is varied: light gray, bluish, yellow, white, reddish, brown with various shades. The quality of the bricks produced does not depend on the color of the clay.

The most important properties of clay are:

1) the ability, when mixed with water, to form thin "suspensions" (cloudy puddles) and viscous dough.

2) the ability to swell in water.

3) the plasticity of clay dough, i.e. the ability to take and maintain any form in its raw state.

4) the ability to maintain this shape after "drying out with a decrease in volume".

5) stickiness.

6) binding ability.

7) water resistance, i.e. the ability, after saturation with a certain amount of water, not to pass water through itself. From clay dough they make various products - jugs, jugs, pots, bowls, etc., which after firing become completely solid and do not allow water to pass through.

Not all clays and not to the same extent have the listed properties.

1.3. The meaning and application of clay

Clay of a certain color helps with various diseases.

With the help of white clay, they treat bowel diseases, obesity, hair loss, and strengthen nails. Red clay is used for diseases of the cardiovascular system, hypotension, varicose veins, nervous and endocrine diseases. Yellow clay is used for stroke, diseases of the stomach and intestines, migraines, headaches, osteochondrosis. Black clay is used to reduce temperature, with various types of heartbeat, inflammation of the skin and internal organs, and helps to rejuvenate the body. Blue clay well heals obesity, hypothyroidism, relieves muscle weakness and provides joint mobility. Cosmetically, blue clay is used for oily skin. If there is no clay of the desired color, then any clay can be used.

Practical use

Produced from expanded clay clays by annealing with expansion expanded clay and sand are widely used in the production of building materials (expanded clay concrete, expanded clay concrete blocks, wall panels, etc.) and as heat and sound insulation material. It is a lightweight porous building material obtained by firing low-melting clay. Walls made of expanded clay concrete are durable, have high sanitary and hygienic characteristics, and structures made of expanded clay concrete, built more than 50 years ago, are in operation to this day. The largest producer of expanded clay is Russia.

Many doctors recommend using blue clay in the form of powders, pastes, ointments for skin diseases (ulcers, burns, diaper rash). Inside, adults are recommended to take 20-30 g at a time and no more than 100 g per day for gastrointestinal diseases (colitis, enteritis, food poisoning).

In folk medicine, blue clay is used to treat: stomach ulcers, diarrhea, bloating, jaundice, liver cirrhosis, asthma, pulmonary tuberculosis, anemia, metabolic disorders, atherosclerosis, paralysis, epilepsy and even alcoholism, gall and urolithiasis. Take 20 g of clay, dilute in 150 ml of warm water, take 15-20 minutes before meals.

Clays are classified as mineral raw materials for mass consumption. They are used in a wide variety of sectors of the national economy for a variety of purposes.

Brick production

Widespread fusible sandy ("skinny") clays of any color are used to produce building bricks.

Cement production

Portland - cement is a finely ground powder of a mixture of clay and limestone.

Art

Plastic green, gray-green and gray clays are widely used in sculpture. Usually, all sculptors initially create their works from clay, followed by casting them from plaster or bronze. Industries

These include, for example, soap, perfume, textile, abrasive, pencil and a number of others.

Life and agriculture.

Clays, in addition, are widely used in everyday life, especially in agriculture: for laying ovens, clay currents, whitewashing walls, etc. The use of swelling bentonite-type clays in the construction of dams, reservoirs and other similar structures has great prospects. Clay is an important and necessary mineral for many sectors of the national economy.

2. Practical part

2.1. Selection and preparation of materials and equipment for work

Equipment: beaker, glass rod, glass slide, spatula, muffle furnace, stacks, oilcloth, foam sponge. (Appendix 2, photo 5).

Practical experience 1. Familiarization with a clay sample

Work plan: familiarization with a clay sample.

goal - study the appearance of the clay.

Result familiarization with clay samples is set out in the form of a table

Table 1. Properties of clay

(Appendix 1, photo 2).

After carefully examining the sample, I wrote down my observations in a table

Table 2. Description of the physical properties of clay

Clay properties	Observations
State of aggregation
	Gray green
	Absent
	Earthen
Hardness (Mohs scale, handbook)
Plasticity, fragility, elasticity
Water solubility	insoluble
Melting point (reference)
Density (reference)
Thermal conductivity (reference)
Electrical conductivity (reference)

Output: properties of substances are signs by which some substances differ from others. Knowing the properties of substances, a person can use them with great benefit for himself.

Practical experience 2. Study of the solubility of clay

Goal:study the process of clay dissolution.

Raw materials: clay; water.

Progress: A small amount of water was poured into a beaker and a small piece of clay the size of a pea was placed. The clay was stirred in water with a glass stick.

Result: The water became cloudy, the clay settled to the bottom.

Output: Clay is poorly soluble in water, forming a two-component system of clay and water. (Appendix 2, photo 4).

Practical experience 3. Studying the plasticity of clay

Goal:explore the plasticity of clay.

Raw materials: clay; water.

Progress: Moisten a piece of clay with a damp foam sponge until it becomes soft and pliable.

Result: clay becomes soft and easy to mold when moistened.

Output: clay, when moistened, acquires new properties - plasticity and softness. (Appendix 1, photo 3).

Practical experience 4. Research on drying raw clay

Goal:to study the process of drying raw clay.

Raw materials: clay

Progress: A piece of moistened raw clay was used to make a decorative clay craft. Clay is easy to mold, it is soft and plastic, so you can mold any product. In the course of practical work, a dog figurine of 10x10 cm was sculpted. The dog figurine was left out of raw clay in a room to air dry. Drying time was one day.

Result: after drying, the earthenware has changed its color. Wet clay is gray-green in color and dry clay is light gray in color.

Output: When wet clay dries, excess water slowly evaporates. A clay product acquires properties: color change, hardness.

Practical experience 5. Firing clay

Goal:study the process of firing clay.

Raw materials: dried clay craft.

Progress: The dried clay craft was placed in a muffle kiln for firing. The firing process takes place at a temperature of 900-1010 0 C. The firing time is 8 hours.

Result: After firing, the clay product has acquired a different color and has become more solid. Dry clay is light gray in color and fired clay is brown-orange in color.

Output: during firing, the clay loses almost all moisture and acquires new properties: strength and water resistance. (Appendix 1, photo 1).

Practical experience 6. Coating clay crafts with varnish and paints.

Goal:creating a painted creative clay craft.

Raw materials: fired clay crafts, paints, varnish.

Progress: paint and varnish the baked clay craft.

Result: After painting with paints, we got a beautiful decorative craft.

Output: fired products can be coated with paints and varnishes, glazed to give these products new properties: waterproof, hygienic, decorative.

Conclusion

In the course of my work, I learned a lot of new interesting information about clay, its extraction, application and properties.

Clay is a widespread rock and by-product of the earth's crust, a sedimentary rock formed by the destruction of rocks during the process of weathering. It comes in different colors, it depends on the creator stone. It is used for cosmetics, health and rejuvenation. The production of building materials from clay is of great industrial importance: brick, cement, etc.

In the work, the following properties of clay were studied and used in order to create decorative crafts: plasticity, water resistance, moisture evaporation, drying and firing.

The hypothesis was confirmed: different properties of clay can be used for different applications. Knowing the specific properties of clay, you can use it for various needs. Useful properties of clay: it is used for cosmetics, health and rejuvenation. The production of building materials from clay is of great industrial importance: brick, cement, etc.

conclusions

1. Using literary sources, general information about clay, its properties, meaning and application were studied.

2. In the practical part of the work, we studied and observed the physical properties of clay.

3. In the course of the work, experiments and observations were carried out with photographic recording of the results obtained. The physical properties of clay were investigated: softness, plasticity, brittleness, heat capacity, hardness, strength, color, water resistance. All of the above properties of clay have been studied and applied in practice in the manufacture of clay crafts.

4. In the practical part of the work, a decorative clay product was made in the shape of a dog, 10x10 cm in size.

Bibliography

Gabrielyan O.S. Chemistry. Grade 8: textbook. for general education institutions - M .: Drofa, 2013 - 267 p.

Kritsman V.A. Reading book on inorganic chemistry. A student manual. - M .: Education, 1975 - 303 p.

Nachtigall V. Big series of knowledge. - M .: OOO "TD" Publishing House of the World of Books ", 2005 - 128 p.

Electronic resource: article Clay on www.xHYPERLINK "http://www.xumuk.ru/"umuk.ru.

Applications

1.Plasticity - this is the ability of clays in a wet state to take the required shape and size under the influence of external influences and keep it without breaks and cracks during drying and firing. Plasticity depends on the mineral composition and fineness of the clay particles. Plasticity can be increased:

the introduction of plasticizing additives

elutriation - cleaning clay from sand impurities

soaking in a water-saturated state for several months.

Plasticity can be reduced by the introduction of lean additives.

2 clay shrinkage - this is a decrease in the linear dimensions of the raw clay during drying (air shrinkage) and firing (fire shrinkage). Shrinkage is expressed as a% of the original size of the product.

Air shrinkage has a value equal to 2 to 12% of the original size of the product

Fire shrinkage – 2-8%

Full shrinkage is added up as the sum of air and fire shrinkage.

3.The sintering capacity of claysor the behavior of clays when exposed to high temperatures.

At temperatures above 100 ° C, physically bound water is removed from the ceramics, then burn-out and pore-forming additives burn out, in the temperature range of 450-750 ° C, chemically bound water is removed - this process is accompanied by an irreversible loss of plasticity.

In the temperature range 900-1000 0 С, a new phase is formed from the remains of aluminosilicates mullite, which gives the ceramic a stone-like state.

General scheme for the production of ceramic products

The production of ceramic products includes the following steps:

Career work,

Mechanical processing of clay mass,

Forming products,

Drying them,

Firing and surface decoration.

Career work. These include the extraction of clay from open pit mines, transport to pottery factories and the storage of an intermediate stock of clay. During storage, the so-called. Clay aging is a technological operation, as a result of which, under the influence of variable temperature and humidity, clay particles break down into smaller aggregates.

Mechanical restoration clay mass... It is carried out with the help of clay-processing machines and has the purpose of separating or grinding stony inclusions, homogenizing the ceramic mass and introducing the necessary additives.

The separation of stony inclusions from clay is carried out by passing it through screw stone separating rollers or using other specialized machines. Almost complete separation of stones from clay can be achieved by hydraulic separation. The clay is dissolved in clay pots, and then passed through a sieve and dehydrated. Clay grinding is carried out after separation of stony inclusions. After grinding, the clay with the required amount of water and additives is pounded in special pug mills, which are a cylindrical structure, in the center of which a shaft with blades rotates. The result is a homogeneous (homogeneous) ceramic mass.

Forming ceramic products. The task of molding is to give the clay mass the geometric shape and dimensions of the future product. As a result, a raw ceramic product is formed. Molding is done in three ways:

- plastic molding ... Wall ceramics are formed from plastic (with humidity 18 - 28%) clay masses on belt auger presses, which can be vacuum and non-vacuum at pressures up to 7 MPa;

- semi-dry pressing. It is produced in molds for one or more ceramic products. Ceramic products are molded on hydraulic or mechanical presses by semi-dry pressing under a pressure of 15 - 40 MPa from ceramic press powders with a moisture content of 8 - 12%.

- casting method (or slip ). This method is used to produce mainly thin glazed tiles on automated conveyor lines, as well as products of complex configuration (for example, sanitary ware). In the production of tiles, raw material with moisture 40 – 60% is poured onto porous ceramic trays and covered with a glaze layer. Moving along the conveyor, the ceramic mass dries quickly on a porous pallet and goes first to a stripping device, and then to a cutting device, which cuts the dried mass into tiles of a given size. Plaster molds are used in the production of complex ceramic products.

Drying of raw materials. The molding moisture content of products made by different molding methods is different. Before firing, the product must be dried to moisture content no more than 5% to avoid uneven shrinkage and cracking during firing. Drying is carried out in tunnel dryers, in which, according to the principle of counterflow, the raw material moves towards the flow of hot air or flue gases. Drying takes place at t about \u003d 120-150 about C for 16-36 hours. In modern automatic factories, tunnel slot dryers are used, in which the drying time is reduced to 5-7 hours.

Firing products. Firing is the most important and final stage in the production of building ceramics. For firing use ring and tunnel ovens ... In ring kilns, firing continues for 1.5–3 days, in tunnel kilns from 18 to 24 hours, passing through the heating, firing and cooling zones. The maximum firing temperature is:

For bricks and ceramic stones - 950 - 1100 about FROM;

For facing ceramics - 1000 - 1200 o C;

For sanitary ware - 1150 - 1300 o C;

For acid-resistant ceramics - 1200 - 1300 о С;

For refractory ceramics - 1350 - 2000 о С;

Decoration of products... It occurs either during the molding process (applying a relief structure to the front surface, gunning, engobing), or after drying or after firing the products (glazing, staining with special paints). Surface painting is carried out with underglaze and overglaze paints. Underglaze paints are applied to unglazed products, which are covered with glaze and fired. Overglaze paints are applied to glazed fired products and set by subsequent firing. Paints are applied in various ways: by spraying with or without a stencil, using decals, seriography (pressing colored mastics through a stencil mesh, followed by their glazing and firing).

Natural clay is a sedimentary type of rock. In a dry state, it is lumps or dust, which, when wet, acquire plastic properties. This fossil is formed under the influence of forces of nature during the destruction of rocky massifs.

The main material of clayey strata is fossil, for example, feldspar. The prevalence of clay and its readiness make this material ubiquitous. Clay materials are rocks that represent the drifts of water currents that accumulate on the bottom of water bodies.

Typical composition

For more than one century, the most common and popular material in construction is rightfully occupied by clay. Natural clay is formed due to the fact that there is a splitting of clayey rocks of the earth in a natural way, as well as due to the assistance of mechanical influences.

The material has a variable structure, so the composition of the clay is varied. It is a complex compound of particles of water, aluminum and silicon. Water in clay can play a binding role; it is in a chemically bound state between particles of interlayers. A rock without impurities is a mass with a minimum particle diameter. This material is very flexible.

The composition of clay includes impurities of the following substances: quartz, magnesium oxide, iron sulfide, and so on. According to the mineral composition, the following clay materials can be distinguished:

• kaolin;
• halloysite;
• illite;
• montmorillonite.

Raw materials are named based on how the clay material will be used. An important characteristic of the material is the percentage of impurities (for example, the content of quartz sand). The refractoriness of clay is determined by the percentage of alumina.

Kinds

The above properties, of course, cannot be inherent in all types of clay at the same time. The most valuable types of natural building material are:

• refractory;
• kaolin;
• brick;
• acid-resistant;
• cement;
• bentonite.

The first two types of material are one of the main raw materials for the production of porcelain. At the same time, refractory clay can be used for the manufacture of a wide range of refractory products.

Molding clay is characterized by unique bonding properties and is also refractory. Therefore, the use of this variety is absolutely justified in the production of casting molds.

As for acid-resistant clays, they include magnesium, calcium, and iron. Mostly earthenware is made from such material.

An excellent building material is obtained from cement and brick clays. Filtration of oil products is carried out by using bentonite clay, which, by the way, swells strongly upon contact with water.

In production, a distinction is made between clay with a high content of quartz sand (an impurity prevailing in clay) and with a low content of it. The first is called "skinny" and the second - "fat".

Clay properties

Clay is a versatile natural material. Diverse in composition, as well as physical properties, it is used everywhere for the production of household items and building materials, among which it is considered in its pure form.

The properties of clay directly depend on its composition. So, she can behave in different ways, coming into contact with water. In some cases, when mixing the material with water, a dough-like mass is formed. In other cases, the result of this procedure is the formation of a suspension. In the first case, the clay has unique properties and can take any shape and retain it when it dries.

The prevalence of clay and its readiness make this material ubiquitous. At the same time, due to the inexpediency of transporting heavy material over long distances, production complexes are located directly in the place of clay deposits.

Colour

Multi-colored clay is a material that contains metal oxides or pigments and is a homogeneous mixture:

1. Natural pigments give the clay one shade or another, they are divided into two categories: oxides of metallic elements and the actual dyes.
2. During the firing process, the red clay turns red or white, depending on the process conditions and the type of firing equipment. This variety can withstand heating up to 1100 degrees.
3. Low-melting black majolica clay. After firing, the mass resembles ivory products in color. Thanks to the use of glaze, products made from raw materials become unusually durable and have high water resistance.
4. To give the material a blue color, oxygen-containing cobalt compounds are used. Chromium compounds provide the color of olives, while magnesium and nickel compounds provide brown and gray, respectively.
5. Coloring components are added to raw materials in an amount of 1 to 5%. Higher pigment contents can lead to undesirable effects during the firing process.

Plastic

As it dries, the clay will retain the shape that it is given, but will decrease in size. When fired, it will become as hard as stone. It is often used in the manufacture of dishes and other kitchen utensils. Bricks are often made from fired clay; they have a fairly good strength in case of mechanical damage.

The clay has a binding capacity as well as good stickiness. When the clay has absorbed enough water, it will no longer let it through, that is, it will become waterproof.

The material has a high hiding power. This property determines the use of the material as a whitewash for walls of houses and stoves.

Hygroscopicity

Non-waterproof raw materials, when they get into water, they begin to soak, they are divided into parts, a mushy mass is formed.

It can absorb compounds dissolved in an aqueous medium (sorption capacity). This property determines the use of the material for the purification of petroleum products, treacle syrups, juices, vegetable fats.

Refractoriness

Refractory clay has good strength. Clay in its raw state can take on all kinds of configurations. These types of clays are called "greasy" because they appear greasy when touched. Clays, which are less plastic, are called "skinny". A brick made from such clay will be very crumbly and fragile.

Useful and medicinal properties of clay

Undoubtedly, clay has a positive effect on the human body. Each type of clay affects the body in a different way due to its different chemical composition.

Clay, which is a natural material, has a beneficial effect for the reason that, in fact, it is a sedimentary rock that was formed as a result of the destruction of rocks and has absorbed all kinds of trace elements for a long time.

Of all the varieties, the most ancient is Cambrian blue clay. Since ancient times, people have been quite successfully using its healing properties in medicine. This clay owes its name to the period in history during which it was formed.

Other clay materials are considered secondary. They are formed as a result of the destruction of rocks by water flows. For the most part, secondary varieties contain silicate particles.

One of the main reasons clay is used for medicinal purposes is its ability to retain heat. For this reason, clay is so common in thermotherapy. In most cases, before using the clay, it is brought to the consistency of sour cream, diluted with water.

By the amount of added water, one can judge the heat capacity and thermal conductivity of clay.

White clay

At the moment, there are about forty types of clay. White clay or kaolin is the most studied in our time:

1. This clay is widely used not only in treatment, but also in the manufacture of porcelain, it is widely used in the chemical industry, perfume making and the like.
2. White clay is enveloping as well as absorbent. Therefore, it is actually used in the treatment of burns, diaper rash, ulcers and other skin diseases.
3. This variety has not only external use, but also internal. Inside, it is taken for problems with the gastrointestinal tract, as well as for poisoning. This clay is cooled and covered with bruises or dislocations on the body.
4. Popular clay compresses are often used. People simply sprinkle clay on places of wounds and injuries. It can also be used as baby powder. But, in spite of all the useful properties of white clay, its blue counterpart is more popular among the people. Because, according to the majority, it is the most plastic and has the highest heat capacity.

Scope of application

The most common use of clay is in the production of porcelain and building materials. The most important stage in the production of clay items is their firing. So, upon completion of this procedure, the object acquires strength and moisture resistance. A building material made from clay has an amazing resistance to mechanical stress.

The hiding power of the clay, as well as its coloring properties, are no less important. Clays are found in nature in a wide variety of colors. White, for example, is great for whitewashing surfaces, and colored for painting them.

Some types of clay are suitable for filtering petroleum products as well as vegetable oils. This property of the material lies in its sorption capacity.

Place of Birth

Clay is ubiquitous, this is natural, since it belongs to sedimentary rocks, and is, in fact, rock crushed to a powdery state.

Mineral extraction sites are often located along the banks of water bodies. There are numerous outcrops, but not all deposits are suitable for commercial production.

The most famous deposits are Kashtymskoe, Astafyevskoe, Palevskoe. It should be noted that refractory and kaolin clays are much less common. Often, refractory varieties coexist with refractory varieties.

Currently, clay is mined in a quarry way. Clay pits can be of different depths. Often different types of clays can be produced in the same quarry.