What is cement made from? The whole truth about the connecting link: how and from what cement is made. How to make cement from clinker

Today it is impossible to imagine the construction of any object without the use of cement. It is used at all stages of the construction process. Without it, it is impossible to carry out the foundation, laying walls, as well as interior and exterior decoration. To date, no analogues of this building material have been invented, which indicates the unique properties of cement. Do you know what cement consists of?

What is cement

Cement is a building material, which is presented in the form of crushed powder obtained from clinker. Its composition may contain modifying components and fillers.

According to GOST

The process of obtaining general construction cements must be carried out taking into account the requirements of GOST 31108-2003. It is the standard that is able to regulate the proportions of the necessary ingredients included in the dry mass and the production technology of the material. But this standard does not include special-purpose material.

The specific gravity of cement grade M 500 is described in this

Definition of species

Today, the definition of the most common materials includes:

• aluminous;
• lime-ash;
• waterproof.

Aluminous

The process of obtaining such material is carried out using the melting method when exposed to temperatures of 1380 - 1600 degrees. In this case, there is no need to use fine grinding of the charge. The process of obtaining this type of material is carried out in various types of furnaces. The most commonly used are blast furnace and electric.

The composition of this material involves the following components:

1. Aluminium oxide.
2. Calcium oxide.
3. Silicon oxide.
4. Iron oxide.

How dry cement-sand mixture M 150 is used is described

In addition, the composition of aluminous cement is rich in dicalcium silicate. It allows for delayed curing. To increase certain properties, the composition can be supplemented with aluminates and ballast admixtures. This mixture will allow you to obtain a reliable and durable structure.

Airtight

This cement contains finely ground blast furnace slag and gypsum stone in a 2:1 ratio. A structure laid out on the basis of such material acquires the necessary hardness in water and air. If hardening was carried out in water, then the percentage of shrinkage is minimal.

The setting process occurs after 10 minutes, and for complete drying you need to wait 3 days. The resulting solutions based on airtight material are characterized by such properties as waterproofness, fire resistance, durability, and stability. Compared to Portland cement, this material has any fire resistance rating. In addition, the hardening process occurs faster than that of aluminous.

What is the bulk density of cement M 500 described

Lime-ash

To obtain this composition, components such as fuel ash and slag with lime are used. After mixing these elements, they are finely ground. To improve the properties of lime-ash cement, add 5 g of gypsum. It allows for rapid hardening and increases the strength of the structure.

When constructing a structure for a specific purpose, it is necessary to purchase the required brand of cement, which would contain all the necessary components. If all proportions are strictly observed by the manufacturer, then the resulting product will have excellent strength, durability and resistance to various aggressive environments. Read about what this is in our article.

In our article we would like to talk about the amazing building material from which numerous concrete structures, house walls, bridges, foundations, small architectural forms and similar structures are made. We're talking about cement. As you know, cement is not a natural building material.
The production of this sought-after material is a very expensive and energy-intensive process, but what comes out is worth it in the end. Cement, as a rule, can be used separately, or can be a component of another building material, for example, concrete. Production plants are usually located right where the raw materials needed for the preparation process are obtained, so as not to incur transportation costs.
The production of cement has two stages: the first is the production of clinker, the second is that the clinker is processed into a powder and gypsum or other additives are added to it.
The first stage of the process is the most expensive, it consumes about seventy percent of the cost of cement preparation, because at this stage the main raw materials are extracted. The upper part of the limestone mountain is carried down, and as a result, the limestone layer is exposed. It occurs four to five times at a depth of ten meters (no more), each such layer reaches a thickness of seventy centimeters.
The extracted limestone is crushed so that the largest piece does not exceed ten centimeters in circumference. Then the material is dried, ground again and mixed with other components (such as active mineral additives). Then the resulting mixture is fired. The clinker is ready.
The second stage also consists of many operations: crush the clinker, dry the mineral additives, crush the gypsum, mix the clinker along with the other components. Raw materials will not always be the same in composition and texture. Each type of raw material implies its own production method. There are three methods used in the production of cement: dry, wet and mixed. Each method has its own unique technologies and equipment, and each has its own pros and cons.
With the dry production method, the raw materials are pre-dried before grinding, and after grinding they are obtained in the form of a powder (charge). The wet method is used when making cement from chalk, clay using various additives containing iron (carbonate component, silicate component, converter sludge, etc.). The moisture in clay should not be more than twenty percent, and in chalk more than twenty-nine percent. This method is called wet because the mixture is ground in water, resulting in an aqueous suspension, in other words, sludge. Next, it is fired in a kiln, releasing carbon dioxide, then the clinkers in the form of balls are processed into the finest powder - this is cement.
With a mixed method, both of the previous ones are involved. This method has two types. In the first, the raw materials are prepared with water - in a wet way, obtaining sludge, then the moisture is removed with filters to fifteen to eighteen percent and fired in ovens in the form of an almost dry mass. In the second method, dry raw materials are used, gradually diluted with water and turned into granules ranging in size from ten to fifteen millimeters and fired.
In each of the listed methods, it is very important to maintain proportions, special equipment and a clear sequence of actions. Ready bulk or packaged cement in bags weighing fifty kilograms is loaded onto road or rail transport and sent to its destination.
Not a single construction project can be completed without such an important building material as cement, which indicates its high performance characteristics.

Last summer I filmed at the Lafarge (Uralcement) plant located in the village of Pervomaisky, Chelyabinsk region. The plant has been producing cement using the wet method since 1957 and is among the ten largest cement plants in Russia in terms of production volumes. Clay and limestone are used to produce cement. Natural gas is used as fuel.

The history of Portland cement begins on October 21, 1824, when English mason Joseph Aspdin received a patent for a substance he called “Portland cement” because its color resembled the gray color of the rocks around the city of Portland.

Portland cement is a hydraulic binder obtained by jointly finely grinding Portland cement clinker, gypsum and special additives. The properties of Portland cement depend on the composition of the clinker and the degree of its grinding. The most important property of Portland cement is its ability to harden when interacting with water. It is characterized by a grade of Portland cement, determined by the compressive and bending strength of standard samples of cement-sand mortar after 28 days of hardening in wet conditions.

2. Cement production consists of two main technological processes: producing clinker (the most labor-intensive and energy-consuming stage) and grinding it with appropriate additives.

3. To make cement, limestone and clay are first extracted from a quarry.

6. Having undergone pre-treatment, the raw materials enter the Hydrofol wet autogenous grinding mill, where they are processed into sludge. Then the sludge is ground in raw mills and averaged in sludge basins.

7. The plant has a special laboratory in which constant quality control and dosage of raw materials and additives are carried out. And they also test the final product for strength.

11. Then the finely ground raw sludge is introduced into a rotary kiln (about 200 m long and 4 m in diameter) and fired at a temperature of 1450 degrees Celsius.

12. During firing, particles of raw materials are fused together, forming clinker.

13. The kiln is a rotating metal cylinder, which is inclined to the horizontal plane at an angle of 3-4 degrees to allow the material to move along the kiln.

14. The resulting clinker is cooled in refrigerators, crushed and fed by conveyors into the bunkers of cement mills for grinding.

15. Electric precipitators on rotary kilns can reduce dust emissions into the atmosphere by 10-30 times.

18. The cooled clinker is fed into the mill.

20. This is the noisiest area of ​​production. It is simply impossible to be in the workshop without headphones.

21. Cement is produced by jointly finely grinding Portland cement clinker, mineral additives (10-15%) and gypsum (3-7%), which serves to regulate the setting time. The size of cement grains ranges from 1 to 100 microns.

24. Procedure LOTOTO (LockOut / TagOut / TryOut). A set of actions to improve safety at work.

25. Various mineral additives are used to give concrete, mortars and other cement-based products special properties (hardening speed, stability in natural waters, frost resistance).

28. The resulting Portland cement is transported from the mills to storage silos.

29. Cement is shipped from silos by rail cars and road transport in the following form: in bulk, special MKR containers weighing up to 1 ton, paper bags weighing 50 kg.

At all times, people have been engaged in construction for their needs, starting with ancient buildings and ending with modern technical masterpieces. In order for buildings and other structures to remain reliable, a substance is needed that will prevent the component parts from disintegrating individually.

Cement is a material that serves to bind building elements together. Its application is great in the modern world. It is used in various fields of human activity, and the future fate of all structures depends on it.

History of origin

They began to use it in ancient times. At first it was unfired clay. Due to its ease of production and prevalence, it was used everywhere. But due to its weak viscosity and stability, clay has given way to heat-treated materials.

The first high-quality building materials were obtained in Egypt. These are lime and gypsum. They had the ability to harden in air, which is why they were widely used. These building materials met the requirements until navigation began to develop. A new substance became necessary that would resist the action of water.

In the 18th century, a material was invented - romancement. This is a product that could harden both in water and in air. But the increased development of industry required higher quality materials and binding properties. In the 19th century, a new binding agent was invented. It was called Portland cement. This material is still used today. With the development of mankind, new demands are placed on binders. Each industry uses its own brand that has the necessary properties.

Compound

Cement is the main component of the construction industry. The main components in it are clay and limestone. They are mixed with each other and subjected to heat treatment. Then the resulting mass is ground to a powder state. The gray fine mixture is cement. If you mix it with water, the mass will become like a stone over time. The main feature is the ability to harden in air and resist moisture.

Preparation of cement mortar

In order for the building mass to be of the required quality, the composition must contain at least 25% liquid. Changing the ratio in any direction leads to a decrease in the performance properties of the solution, as well as its quality. Setting occurs 60 minutes after adding water, and after 12 hours the mixture loses its elasticity. It all depends on the air temperature. The higher it is, the faster the mass will harden.

To obtain the solution, sand is needed, to which cement is added. The resulting mixture is thoroughly mixed and filled with water. Depending on the work performed, the solution can be ordinary or enriched. The first consists of proportions 1:5, and the second - 1:2.

Types and production of cement

At the moment, many types of binder material are produced. Each has its own degree of hardness, which is indicated in the brand.

The main types include:

• Portland cement (silicate). This is the founder of all types. Every brand uses it as a foundation. The difference is the amount and composition of additives that give the cement the necessary properties. The powder itself is gray-green in color. When liquid is added, it hardens and becomes stronger. It is not used separately in construction, but is used as a basis for creating
• The plasticized composition reduces costs, has the ability to reduce the mobility of the solution and has excellent resistance to the effects of cold.
• Slag cement. This is the result of clinker crushing and the addition of active additives. Used in construction for the preparation of mortars and concrete.

• Aluminous. It has high activity, speed of setting (45 minutes) and hardening (complete occurs after 10 hours). Also a distinctive property is increased resistance to moisture.
• Acid resistant. It is formed by mixing quartz sand and sodium silicofluoride. To prepare the solution, sodium is added. The advantage of such cement is its resistance to acids. Disadvantage: short service life.
• Color. Formed by mixing Portland cement and pigment substances. The unusual color is used for decorative work.

Cement production consists of 4 stages:

• Extraction of raw materials and their preparation.
• Firing and production of clinker.
• Grind to a powder.
• Addition of necessary impurities.

Cement production methods

There are 3 methods that depend on the preparation of raw materials for heat treatment:

• Wet. With this method, the required amount of liquid is present at all stages of cement production. It is used in situations where the main components cannot participate in the technological process without the use of water. This is chalk with a high moisture content, plastic clay or limestone.

• Dry. All stages of cement production take place with materials containing a minimum amount of water.
• Combined. Cement production includes both wet and dry methods. The initial cement mixture is made with water, and then it is filtered as much as possible using special equipment.

Concrete

This is a building material that is formed by mixing cement, filler, liquid and necessary additives. In other words, it is a hardened mixture that includes crushed stone, sand, water and cement. Concrete differs from mortar in its composition and filler size.

Classification

Depending on what binding material is used, concrete can be:

• Cement. The most common type in construction. The basis is Portland cement, as well as its varieties.
• Plaster. Has increased strength. Used as a binding material
• Polymeric. They are based on Suitable for working on horizontal and vertical surfaces. It is an excellent material for finishing and landscaping work.
• Silicate. The binding material is lime and siliceous substances. Its properties are very similar to cement and are used in the production of reinforced concrete structures.

Depending on the purpose, concrete can be:

• Ordinary. Used in industrial and civil construction.
• Special. It has found its application in hydraulic structures, as well as in road, insulation and decorative works.
• Special purpose. resistant to chemical, thermal and other specific influences.

Cost of cement

Manufacturers produce products packaged by weight. The weight of cement bags is 35, 42, 26, and 50 kg. It is most profitable to buy the latter option. It is most suitable for loading and allows you to save on packaging. Depending on the facility where repair work will be carried out, various grades of cement are used, which have their own cost. Each bag of cement is taken into account when paying. Its price is fixed and may fluctuate depending on the requirements of the seller.

Before you start calculating cash costs, you need to decide on one more nuance. Sometimes you can see an advertisement that indicates a price lower than the standard one. You shouldn't fall into such a trap. In such cases, expensive cement is diluted with cheaper cement. By winning a few rubles, you will lose the quality of the building material.

Let's take one 50 kilogram bag of cement. The price of the M400D0 brand will be 220 rubles. The cost of others may vary, but on average it is:

• M400D20 - 240 rubles.
• M500D0 - 280 rubles.
• M500D20 - 240 rubles.

If you only need to use a couple of bags of cement, then it is most profitable to buy them at your local building materials store. And if you need a large quantity, you should contact the manufacturer.

Cement consumption

Before carrying out any construction work, the question arises of how much cement is needed and what consistency the solution should be. Ideally, strength should be maintained and the proportionality of the components should not be exceeded.

When important and serious work lies ahead, mixing cement and sand “by eye” is unacceptable. If you do not spare the binding material, then in large volumes it will cost huge amounts of money.

So how much cement is needed for the work being done? Construction standards (SNiP) will help you answer. All reasons influencing the production of the mixture are taken into account here. Focusing on the brand of the composition and taking into account all the factors, you can clearly find out the rate of cement consumption per 1 cubic meter of solution.

The main feature that many developers do not take into account is that the cement is distributed in the voids between the sand particles. Remember that the composition is active. If stored indoors for a long time, the 500 brand will become 400 in a few months. Therefore, when purchasing, you should always ask for a certificate with the date of issue.

Master of Architecture, graduated from Samara State University of Architecture and Civil Engineering. 11 years of experience in design and construction.

Without this material it is impossible to imagine a modern construction site. For more than a hundred years, cement has made it possible to build the strongest structures, it is used for repair work, it is used to decorate premises, but few people think about what cement is made of.

So what is cement? This material is a powder based on inorganic compounds. Interacting with water, this powder begins to harden and acquire the strength of a monolithic, strong material, filling a pre-prepared form.

The reaction occurs when sufficient moisture is provided. After gaining strength, cement structures can serve for a long time without changing their basic properties. Plants involved in the production of this material try to be located in close proximity to the source of raw material extraction, since the volume of processing and transportation of materials for the production of cement is quite high.

To understand what cement consists of, it is enough to show the chemical composition of the cement most used in construction - Portland cement. It is made using the following proportions:

• calcium oxide – at least 60%;
• silicon dioxide – not less than 20%;
• alumina – no less than 4%;
• iron oxide – not less than 2%;
• magnesium oxide – not less than 1%.

The formulas of other types of cement are similar, only the amount of each ingredient is adjusted.

Main characteristics of cement

Construction materials, including cement, are most often tested for compliance with the following characteristics:

• Strength. To check this characteristic, you will need to make a concrete cylinder, which is subsequently subjected to compression tests. The duration of exposure to the sample is at least 28 days. This is the period required for the material to fully gain strength. After checking and comparing the indicators in MPa, you can determine the grade of this cement, which is designated: M200, M300, M400, M500, M600;

• Resistance of the material to corrosion. Being in a humid environment, concrete structures that are not treated with special compounds are subject to corrosion. To eliminate this process, it is recommended to use special additives when forming a solution for concreting. The same applies to protection from the effects of active substances and various household chemicals. For work in aggressive environments and high humidity, a special brand has been developed - pozzolanic cement;
• Frost resistance. This characteristic is determined in cycles of freezing and thawing of the material, during which it is able to retain its original properties. When moisture freezes, expansion occurs in the pores and microcracks of the concrete base, which affects the quality of the concrete and leads to its destruction. To strengthen the structure of concrete, it is necessary to use special additives that allow the concrete to withstand sudden temperature changes. Additives are also used to organize work in winter;
• Water demand. Expressed as a percentage relative to the total volume of the solution of the required plasticity. The maximum water requirement in Portland cement is 28%. It should be understood that a mixture that requires a minimum amount of water produces stronger and more reliable concrete, while a solution saturated with water produces a porous concrete structure, which is characterized by lower strength;
• Setting time. This indicator is important for the organization of work. It should not be too long or short so as not to disrupt the process of pouring the base or masonry. This characteristic is regulated by the amount of gypsum in the dry mixture. If the volume of gypsum is higher, setting occurs faster, if lower, it sets more slowly. Optimally, the cement setting process occurs within 10 hours, and the beginning of setting is within 40-50 minutes.

Types of products by area of ​​use

To carry out various types of work, certain qualities of the solution are required. Portland cement is widely used and can be used for most types of work. But for special conditions other brands are required:

• White Portland cement. This material is distinguished by finer grinding and a higher gypsum content. It is used for the installation of self-leveling floors, since white cement allows you to achieve a high quality base and an attractive appearance. If necessary, various pigments can be added to the cement composition, which makes it possible to obtain a colored solution.
• Sulfate-resistant Portland cement. Designed for the construction of structures exposed to repeated exposure to aggressive and humid environments. This material is used in the manufacture of piles and piers for bridges.
• Slag cement. Used for casting structures and elements intended to work underwater or in the ground.
• Pozzolanic cement. It is characterized by excellent resistance to fresh water and is used for the installation of hydraulic structures.
• Aluminous cement. This material is used for the construction of structures operating in sea water, as well as for repair work at subzero temperatures.

Raw materials for preparation

They try to plan the location of cement production near the main reserves of raw materials. The raw materials are natural rocks mined by open-pit mining. So, what is cement made from?

• Carbonate rocks. These include: chalk; shell rock and other limestones; dolomite; marl. Limestone rocks are mainly used in industrial production. This material makes it possible to increase the efficiency of interaction during the firing process.
• Clay rocks. These include: clay; clayey shales; loams; loess. This material is necessary to achieve the plasticity of the mixture and is used mainly in the production of cement using the dry method.
• Supplements To obtain certain qualities of a cement mortar, it is necessary to add substances to the base composition that can adjust the properties of the material. Additives include: alumina; silica; fluorspar; apatites.

How cement is prepared in production

The main substances from which cement is produced are limestone and clay. From these two components, clinker is prepared in a special way, which is subsequently mixed with other additives that determine the quality, brand and properties of the solution. Mandatory additives include: gypsum, dolomite, cementite.

In nature there is clinker in its pure form - marl, but due to the small reserves of this mineral, it is not possible to use it on an industrial scale, so domestic and foreign manufacturers prepare clinker from traditional materials.

Cement production is divided into the following stages:

• To prepare clinker, you need to thoroughly mix the ingredients in special large-capacity drums.
• At the next stage, the prepared mass enters the oven, where firing occurs for 3-4 hours at a temperature close to one and a half thousand degrees. As a result, clinker is formed in the form of small fractions (up to 5 cm in diameter).

• Next, the resulting clinker grains are crushed in drums using ball screens. During the processing of the material, it is necessary to achieve a powdery state of the mixture.
• At the final stage, the necessary additives are added to the finished cement and sent for packaging in bags or hoppers.

There are three ways to make cement. They differ in clinker processing techniques.

1. Wet method. Clinker is produced using water, chalk and clay. As a result of mixing substances in the drum, a wet mass is formed - a mixture. It is sent for firing, after which the resulting granules are crushed and mixed with the necessary additives. This method is considered quite expensive, so other methods are now more often used.
2. Dry method. Allows you to shorten the stage of mixing the finished mixture with additives, since the whole process comes down to preparing, crushing and mixing ready-made ingredients. This technology is becoming increasingly popular, as it can significantly reduce production costs and the final price of the product.
3. Combined method. This technology uses various forms of clinker production, combining the production steps used in dry and wet methods.

How to make cement at home

First of all, you should immediately understand that it will not be possible to obtain a high-quality product at home or in the garage. It’s not enough to know how to make cement yourself, because in addition to this you will need to purchase special equipment, or make maximum muscular efforts, which ultimately turns out to be quite costly and tedious. It is much easier to purchase a finished product in a store.

The easiest way to obtain a solution at home suitable for cementing small cracks is to prepare a mixture based on the following ingredients: water, aqueous lime and stone ash. These substances are mixed until a homogeneous, viscous mass is obtained, which must be used immediately, since the shelf life of this solution is no more than two hours.

Other options for making cement yourself include a kiln for firing the material and a mill for grinding clinker into powder.

How to make cement mortar

To prepare cement mortar, you will need cement itself, water and filler (for plaster and masonry mortars, river or quarry sand is used).

The ratio of ingredients in the solution depends on the use of the material, but in most cases it is recommended to use the formula: 3 parts sand to 1 part cement. Water is added based on the need to obtain a more plastic or viscous solution.

If you want to obtain a structure with higher strength characteristics, increase the proportion of cement. It is correct to start preparing the solution by mixing the dry fractions, and only after obtaining a homogeneous mass do they begin to pour in water in small portions, gradually achieving the required consistency.