The whole truth about the link: how and from what cement is made. What is cement made from? cement process

Cement is understood as a binder obtained by grinding clinker, as well as gypsum and additives. Clinker as a result of sintering the raw mass, which contains limestone and clay. Also, the clinker may contain nepheline sludge, marl, blast-furnace slag. Clinker is the main component that is part of the cement and is reflected in its quality characteristics.

The introduction of mineral additives in the amount of up to 20% by weight makes it possible to noticeably change the properties of the starting material. If the content of additives exceeds 20%, the output is pozzolanic cement.

Cement production

The production cycle consists of several stages:

• The first stage involves heating a mixture of clay and slaked lime (other components may be present depending on the type of cement) to a temperature of +1450°C, as a result of which clinker granules are formed.
• The second stage is the dismounting of the granules with gypsum (gypsum is added to regulate the setting time, it can be replaced by calcium sulfate) and grinding. Next is the introduction of additives (if necessary), which will affect the properties of cement. The average parameters of the clinker include the content of 67% - Cao, 5% - Al 2 O3, 22% - SiO 2 , 3% - Fe 2 O 3 and other components in the amount of 3%.

What is the composition of cement

• Alit(Ca 3 SiO 5) - tricalcium silicate, providing a quick reaction with water. This component plays a significant role in the curing of cement. Its content in clinker is 50-70%.
• Belit(Ca 2 SiO 4) - dicalcium silicate. When mixed with water at first, it slowly reacts, while its effect on the strength of concrete is negligible. For more later dates bleach significantly increases the strength of the structure. The content of belite in clinker is 15-30%.
• Aluminate phase(Ca 3 Al2O 6) - tricalcium aluminate. Mixing with water, the component is able to provoke a quick setting. Therefore, gypsum or similar components are added to the cement composition to control the setting process. The content of the aluminate phase in the clinker is 5-10%.
• Ferrite phase(Ca 3 Al2O 6) tetracalcium aluminoferrite. The rate of reaction with water is intermediate between that of belite and alite. The share of the ferrite phase in the composition of the clinker falls 5-15%.
• Other elements(for example, calcium oxide or alkaline sulfates) no more than 3%.

Main characteristics of cement

According to GOST 10178-76, this material can be produced with and without additives. Their content can affect such cement properties as:

• Strength- the ability of the material to perceive a certain amount of loads without destruction. There is a direct relationship between strength and the ability of cement to harden when mixed with water. The strength is marked with the letter "M" and the digital value 300, 400, 500, 550, 600, less often 700 and 800. This indicator is determined by calculating the bending strength of the sample and characterizes the load in kg per 1 cm 2.
• Seizure time. The timing of setting and hardening of cement is directly affected by the fineness of the grinding of clinker. The thinner it is, the stronger the material. The setting time of the test specimens is determined when testing the density of the cement paste. In addition to grinding, their duration is affected by water demand and mineralogical composition.

The setting time for a composition of normal density is a minimum of 45 minutes, a maximum of 10 hours. With increasing temperature, they decrease, with a decrease, on the contrary, they increase.

• Water requirement- the amount of water that is required to hydrate the composition and give a certain plasticity to the cement paste. As a rule, 15-17% of water by weight of cement is used in the hydration process. If it is required to ensure the mobility of the solution, water is taken 2 times more.

• Bulk density. In a compacted state, this indicator is 1400-1700 kg / cm 3, in a loose state - 900-110 kg / cm 3. In this case, the true density of cement is 3000-3100 kg / cm 3.
• Corrosion resistance. This characteristic depends on the mineral composition and density of the material. With an increase in the fineness of grinding clinker and an increase in the porosity of concrete, a decrease in corrosion resistance occurs.
• Heat removal. During the hardening process, the cement releases heat. If this process is slow, then the risk of cracks on the surface of the structure is minimal.

If accelerated heat removal is noted, it is not recommended to use this material in the creation of massive structures. It is possible to regulate such an indicator as the heat removal of cement by introducing inert and active additives into its composition.

• Frost resistance- the ability to withstand a certain number of thaw and freeze cycles in fresh or salt water.

Recipe of cement M500

Despite the impressive selection of building materials and mixtures, M500 cement still does not lose its high popularity. Like decades ago, it is used almost everywhere in foundation pouring and concrete production.

Such a high demand for the material is explained by its environmental friendliness (produced on the basis of clay rocks), high resistance to aggressive environments and corrosion (used in the construction of dams and other hydraulic structures). On its basis, concrete, reinforced concrete, sand concrete, asbestos cement, building mixtures and mortars are produced.

The cement group includes:

• BTC - fast hardening,
• BPC - white,
• SPC - sulfate resistant,
• TsPTs - color,
• HPC - hydrophobic cement.

Plasticized PC is obtained by introducing 0.25% sulfate-alcohol stillage into the dry composition. When this component is added, frost resistance indicators increase, the mixture acquires increased mobility. The gray color of the mixture is due to the iron compounds contained in it. Like any other building material, it differs in the number of additives introduced.

Cement M500 - M (strength grade), 500 - load (kg) per 1 cm 2. The percentage of additives can be determined by the number next to the letter D in the cement marking.

The chemical composition of cement M500 (PC 500 D0) (%)

• 21.55 - silicon oxide
• 65.91 - calcium oxide
• 5.55 - aluminum oxide
• 4,7 - iron oxide
• 1,9 - sulfuric anhydride
• 1.46 - magnesium oxide
• 0.35 - potassium oxide
• 0.49 - loss on ignition.

Quality indicators of cement M500:

• activity during steaming - 35.3;
• setting time, 155 minutes - start and 250 minutes - end;
• compressive strength, on the third day - 34.1 MPa and 51.3 MPa - on the 28th day;
• fineness of grinding - 92.3%.

The chemical composition of clinker:

• magnesium oxide,% - 1.26
• SO 3 content, % - 0.1
• chlorine ion % - 0.0001
• insoluble residue,% - 0.41

Mineralogical composition of clinker (%):

• C 2 S (2CaO * SiO 2) dicalcium silicate - 16.7
• C 3 S (3CaO * SiO 2) three calcium silicate - 59.8
• С 4 AF (4CaO*Al 2 O3*Fe 2 O 3) four-calcium aluminoferrite - 14.3
• C 3 A (3CaO * Al 2 O 3) three-calcium aluminate - 6.7

The main types of material:

• M500 D0- powder composition without impurities and additives, is able to give concrete high strength, frost and water resistance. It is used in industrial construction, it is effective in restoration, emergency and repair work due to high initial strength;
• M500 D20. The composition of the mixture contains 20% additives. It is characterized by high rates of water and frost resistance, practically not subject to corrosion. It is used in various branches of construction, in the production of foundations, reinforced concrete, beams, etc. This building material is widely used in the manufacture of masonry, plaster, building and concrete mortars, in repair and construction work.

The main characteristics of cement M500:

• Long operating period.
• Speed ​​(setting occurs a few hours after mixing).
• Excellent adaptation to the environment.
• Ease of preparation and use of the composition.
• High quality finished structures, low wear and deformation.

The use of M500 cement can significantly reduce the construction cycle and provide structures with high strength.

The cement industry is one of the most important branches of material production. The importance of this sector in the national economy is determined primarily by its inextricable connection with the progress of capital construction. Cement is one of the most important building materials intended for the manufacture of concrete, reinforced concrete products, as well as for fastening individual parts of building structures, waterproofing and many other purposes.

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. The fuel is natural gas.

The history of Portland cement begins on October 21, 1824, when the English bricklayer 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 joint fine grinding of 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 the ability to harden when interacting with water. It is characterized by the brand 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: obtaining clinker (the most time-consuming and energy-consuming stage) and its grinding with appropriate additives.

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

6. After pre-processing, source materials are fed to the Hydrofol wet self-grinding mill, where they are processed into sludge. Then the sludge is ground in raw mills and averaged in sludge pools.

7. There is a special laboratory at the plant, which performs constant quality control and dosage of raw materials and additives. And including testing 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, the particles of raw materials are fused together, forming clinker.

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

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

15. Electrostatic 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 production area. It is simply impossible to be in the workshop without headphones.

21. Cement is obtained by joint fine grinding of Portland cement clinker, mineral additives (10-15%) and gypsum (3-7%), which serves to regulate the setting time. The grain size of cement lies in the range from 1 to 100 microns.

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

25. Various mineral additives serve to impart special properties to concretes, mortars, and other products based on cement (hardening rate, 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 by car in the following form: in bulk, in special MKR containers weighing up to 1 ton, in paper bags weighing 50 kg.

Cement is an astringent substance that tends to harden in water and in the open air. Let's figure out what cement is made of, however, everything is still jealous of. It is formed by grinding clinker, gypsum and special additives. Clinker is the result of firing a raw mixture that includes limestone, clay and other materials (blast furnace slag, nepheline sludge, marl). The ingredients are taken in a certain ratio, which ensures the formation of calcium silicates, aluminoferrite and aluminate phases.

The first patent for cement was registered in 1824 in England by D. Aspind. Then the author of the patent mixed lime dust with clay, processed the mixture by means of high temperature. The result was gray clinker. Next, the material was ground and filled with water.

What is cement made of today? As before, clinker is the main component that is part of the cement. It is on him that the properties and strength depend. building material. In addition, the composition includes active mineral additives (15%) in accordance with production standards. They slightly affect the basic properties and technical characteristics of the building material. If the amount of additives is increased to 20%, then the properties of the cement will be somewhat changed, and it will be called pozzolanic cement.

In a scattered state, it is 900-1300 kg / cubic meter, compacted - up to 2000 kg / cubic meter. m. Calculating the capacity of warehouses for storage, the weight of cement is 1200 kg / cu. m. The production of cement without additives is regulated by GOST 10178-76, with additives - GOST 21-9-74.

Main characteristics of cement

Depending on what cement is made of, the material has different properties. The main ones include:
1. Strength. This is a parameter that is responsible for the destruction of the material under the influence of certain conditions. Depending on the mechanical strength, there are four types of cement: 400, 500, 550 and 600.
2. . It is determined by laying a cement paste of normal density on a flat surface - the cement should evenly change its volume when it dries. Otherwise, it cannot be used in construction due to possible destruction of the coating as a result of excessive stress. Changes in volume are checked by boiling hardened cakes of cement.
3. Grit size. The parameter affects the drying rate and strength. The finer the grinding, the better and stronger the cement, especially in the first stage of hardening. Grinding granularity is determined by the specific surface of the particles that are part of 1 kg of cement, and ranges from 3000-3200 kg / cu. m.
4. Density. The cost of water to create a mixture. This is the amount of water during mixing, necessary for normal installation and drying of the material. To reduce its consumption and increase the plasticity of cement, plasticizing organic and inorganic substances. For example, sulfide-yeast brew.
5. Frost resistance. The parameter allows you to determine the ability to withstand temporary freezing of water, as a result of which its volume increases by 8-9%. Water presses on the walls of the cement (concrete) coating, and this, in turn, disrupts the structure of the solution, gradually destroying it.
6. Armature bonding.
7. Heat dissipation- heat is released during the curing of cement. If this happens slowly and gradually, then the coating hardens evenly, without cracking. The amount and rate of heat release can be reduced by using a special mineralogical composition that is added to the solution.

Many types of cement are produced today. What is cement made of? more affects its properties. Depending on the raw material basis, the following types of cement are distinguished:

• lime;
• marly;
• clay cement with additives of slag and bauxite. Its feature is water resistance, frost resistance, fire resistance.

Clay and carbonate compounds are mainly used in the manufacture of cement. Sometimes - artificial raw material(waste, slag) or other natural materials (alumina residues).

Distinguish. Portland cement hardens quickly and may contain mineral additives from 10 to 15%. Clinker and gypsum (the main components) included in its composition are fired at a temperature of 1500 degrees Celsius. Portland cement is actively used for modern construction work. Its main property is the ability to turn into a solid block of stone even when interacting with water.

In addition to Portland cement and Portland slag cement, the following types of cement are distinguished:

• hydraulic;
• straining - tends to quickly set and dry;
• grouting - designed for concreting gas and oil wells;
• decorative (white);
• sulfate-resistant distinguishing feature– low hardening rate and increased frost resistance.

Areas of use

Very often, cement is used in construction to create concrete and reinforced structures. Grade 400 is used for pouring foundations and constructing floor beams in high-rise buildings.

It is difficult to imagine an area of ​​construction where cement would not be used. It is necessary at all stages of any construction process starting from the arrangement of the foundation and ending interior decoration premises. Until now, analogues of this building material have not yet been found, which indicates the unique properties of cement.

What is cement made of, description

Cement is a crushed clinker powder in which modifying additives and fillers are introduced. In dry form, it is a free-flowing homogeneous mass gray color. When diluted with water, a paste-like binder is obtained, which is easily applied to any rough surfaces.

After the cement hardens, a strong connection is formed, which is not inferior in its density to the stone. No wonder artificial stones are made from cement.

Chemical composition and formula

When limestone and clay are heated to a temperature of about 1450 degrees, the structure of these materials changes, resulting in the formation of clinker granules. These granules are mixed with gypsum and ground to a powder. The chemical formula of the finished cement is as follows: 67% calcium oxide (CaO), 22% silicon dioxide (SiO2), 5% aluminum oxide (Al2O3), 3% iron oxide (Fe2O3) and 3% other components.

quite complex and labor intensive. It requires special equipment and compliance with technological norms and conditions.

Specifications

The main technical characteristic is brand of cement. It is designated by the letter "M" and a digital indicator. The numbers indicate the maximum load in kilograms for a certain volume of hardened cement, i.e. its compressive strength.

In practice, this means the weight that the cement can support without breaking. For example, if it can withstand a weight of 200 kg, then the cement is assigned the M200 grade.

On the package, in addition to the brand, the percentage is also indicated composition of additives. It is denoted by the letter "D" and shows what it consists of. this species cement. For example, the symbols "D10" mean that 10% of additives have been added to the dry mix.

Such additives are introduced to improve water resistance, corrosion resistance, frost resistance and other qualities of cement. Consider also other characteristics of cement, which should be paid attention to in the production of construction work.

M400. Its strength is 400 kg/cm2. This is the most popular brand of cement used worldwide for all types of construction and finishing works. This is the construction of buildings, monolithic construction, the manufacture of concrete slabs, blocks, stair structures, foundations, well reinforced concrete rings, paving slabs and a range of other products.

M500. The strength is 500 kg/cm2. This brand of cement is characterized by rapid hardening and high strength. Cement is used for the monolithic construction of high-rise structures, the manufacture of load-bearing elements, floor slabs, prefabricated reinforced concrete structures, beams, as well as in other cases requiring increased strength and durability of structures.

In addition to brands, classes, types and degrees of grinding, which differ from each other by a combination of individual components and composition.

According to GOST. The production of general construction cements should be based on the requirements of GOST 31108-2003. The standard regulates the ratio of the necessary components in the composition of the dry mix and the cement manufacturing technology. This does not include special formulations.

Activity. This is the strength of a single sample cement mortar for compression. The obtained indicators of activity are compared by specialists with the standards and appropriate brand is assigned to this cement. The activity indicator depends on several factors: the activity of the clinker granules, the grinding intensity, the presence of additives. For example, active additives will significantly increase the activity of the cement itself.

Application of an automatic cement activity meter CEMENT-PROGNOZ:

Density. The lowest density is fixed in freshly prepared cement. Electrostatic forces act on its individual particles, repelling particles from their counterparts. Then, during transportation and storage, the mixture is caked and compacted.

The density also depends on the degree of grinding of the clinker granules. When making calculations, the indicator medium density cement is taken equal to 1300 kg per cubic meter. But in practice, the density depends on the storage conditions of the material.

Specific and volumetric weight. The specific gravity of cement is determined by the ratio of its weight to the volume it occupies. This concept is necessary for the correct compilation of the proportions of cement mortars. The specific gravity of cement can vary considerably depending on the state of the mixture. So, fresh powder can have a specific gravity of about 1000 kg/cubic meter, and a caked mixture - 1500 kg/cubic meter.

Volume weight calculated from the average cement density. The average density is approximately 1300 kg / cu. Therefore, a bag weighing 50 kg will have about 0.04 cubic meters. Bulk density increases when cement is caking or transported.

Best before date. Cement is characterized by a limited shelf life. Manufacturers guarantee its safety under normal conditions for 2 months. If sealed storage conditions are provided, the cement can lie without problems for a year.

It should be borne in mind that the higher the brand of stored cement, the faster it can lose some of its properties. So, cement M500, after being in a warehouse with high humidity, in a month will correspond in quality to cement M400, and after 2 months - M300.

Bulk density. This is the ratio of the mass of loose cement to its volume. That is, it is practically the same as the specific gravity, if we take a loose mixture. It is determined by experience. Cement is poured into a measuring container from a certain height. After filling the container, weighing is carried out. Knowing the weight of the empty container, determine the value of the bulk density. For fresh mixtures, this figure is about 1200 kg / cu. In compacted cement, the bulk density is about 1500 kg / cu.

Freeze time. The prepared cement mortar sets and hardens in a few hours. In summer, this process can occur in 2-3 hours. In cold weather, the setting process is delayed up to 10 hours. So, at a temperature of 0 degrees, the solution can harden only after 20 hours. Additives introduced into the solution can speed up or slow down the solidification process.

With the help of cement, they equip the foundation, plaster the walls, make the floor screed. Each of these operations requires, which in any case must be prepared with high quality.

Grinding fineness. The smaller the size of the crushed cement particles, the faster the mortar hardens, and the more reliable it will be in the solidified state. The fineness of grinding directly depends on the equipment used for this. The recommended particle size should be between 40 and 80 µm.

Certificate of conformity

Certification of cement in Russia is carried out according to GOST 10178-85, 30515 97, but more often according to GOST 31108-2003. All major Russian enterprises have already switched to the new GOST 31108-2003, which was adopted in 2004. It spelled out more stringent criteria for the quality of cement, as well as its testing. The new requirements fully comply with European quality standards.

What is the difference between cement and concrete

Cement is a dry mixture that is used specifically for the preparation concrete mortar. Concrete is cured fake diamond, consisting of cement, water and fillers. Gravel, sand, screenings, slag, expanded clay and other materials are usually used as fillers. Until the moment of solidification, concrete is a mobile concrete mix.

Not only in construction and repair work. If you want to make something solid and strong, cement is indispensable.

Strength class of cement and strength test methods

According to GOST 31108-2003, such a term as "cement grade" is transformed into the term "strength class". Therefore, the digital marking of cement means its strength class.

Strength tests of cement are carried out in factory laboratory conditions using modern equipment and progressive methods of analysis. At the same time, the fineness of grinding, the density of the cement paste diluted with water, the setting time of the cement mortar are determined. The compressive or bending strength of the hardened samples is also determined.

Determination of the normal density of cement paste in a virtual laboratory:

The most common bonding material in construction is cement, which is made on the basis of magnesia or carbonate-silicate rocks. The latter variety occupies more than 90% of the market and is called Portland cement. The production process includes several stages, the range of produced mineral binders is wide, it will be useful for every builder to find out by marking the scope of the powder.

What is cement made of - the main raw material

The starting materials for production are solid minerals, near which cement plants are located. Used in the manufacture of clinker - a product of joint firing of rocks - carbonate stones and clays. The first category of mineral formations is consumed in larger quantities and is represented by limestone varieties of an amorphous or crystalline structure, these are:

• chalk is a soft rock white color, consists of calcium carbonate with an admixture of magnesium, metal oxides and quartz grains;
• marl - a natural mixture of 50-75% calcite derivatives with 25-50% silicate clay formations, well suited for production;
• shell rock is limestone from the shells of marine animals, its metamorphosed by pressure at high temperature the variety is called marble;
• dolomite - in addition to calcium carbonate CaCO3, it contains a magnesium component: MgCO3.

Clay rocks that introduce silicates into the clinker are loess, loams and shale. To reduce the cost of production and give cement special properties, alloying additives are used in the technology - alumina, iron, silicon, waste from metallurgical plants.

What is cement clinker

This is a product obtained by sintering at a temperature of 1450 ° C two rocks: 75% limestone and 25% clay. The clinker comes out of the kiln in the form of granules Ø10-60 mm.

By chemical composition the calcined crushed stone of each of the manufacturers may differ, the average alignment is given as a percentage:

• CaO - 67;
• SiO2 - 22;
• Al2O3 - 5;
• Fe2O3 - 3.

Crushed stone from the kiln is not the only component in the production of Portland cement. To slow down the setting time of the final product, the grinding of granules to a finely dispersed powder is carried out with the addition of up to 6% calcium sulfate CaSO3 contained in gypsum or gypsum stone to the clinker.

Grinding of ingredients is carried out by ball mills with pumping of the finished product into multi-ton silos by pneumatic transport.

The production of cement is regulated state standards: GOST 30515-2013 - general technical conditions, GOST 10178-85 and 31108-2003 for building Portland cements. Separate standards have been developed for special types.

Product Main Features

Cement density indicators: bulk - 900-1100 kg / m³, with compaction - 1400-1700. True values specific gravity reach 3 t/m³. There are several specifications, by which the quality of the binder powder is judged:

1. Grinding fineness - determines: the smaller the particles, the larger the surface in one layer they cover. Control measurements are carried out by scattering on a sieve with a cell of 80 microns.
2. Water requirement - the amount of moisture required to hydrate the cement and give the dough plasticity. Excess water in the solution leads to the formation of pores and cracks, reducing strength.
3. Frost resistance is the ability of products based on cement powder to withstand repeated freezing and thawing without destruction. The required indicator is achieved by special additives when mixing the solution.
4. Setting time - depending on the density of the batch is in the range of 0.7-10 hours. The indicator also depends on the amount of gypsum added to the clinker during grinding.
5. Strength is determined by the destruction of a sample made of cement from each batch of released mortar. The age of the cubes is set by the standard - 28 days.

For all volumes shipped by the cement plant, quality certificates are filled out, in which the listed characteristics are entered. Consumers independently conduct input control to confirm the integrity of the supplier.

What is the brand of cement

The strength characteristic of Portland cement is its brand, which is established by the results of tests of cubic samples with a face of 10 cm for compression. The composition of the solution for filling forms: for 1 part of the binder powder, 3 measures of pure quartz sand.

After adding water, the mass is mixed and left to harden for 28 days. 6-10 metal molds are poured simultaneously.

Of these, 6 samples are randomly selected and crushed under pressure. The arithmetic mean pressure is calculated from the 4 cubes that collapsed under the greatest load. Values ​​measured in kg / cm² will indicate the brand of cement in accordance with GOST 10178-85. The display of stress in the metric system of units is performed in accordance with GOST 31108-2003 in MPa. Here, the distribution is carried out according to the cement strength class.

It turns out that the old and new classifications are simultaneously used to assess the strength characteristics. Digital range of brands: M200, M300, M400, M500, M600. Corresponding hardness class values: B15; B22.5; B32.5; B42.5; B52.5.

Marking

The given designations of the strength indicators of Portland cement are only a small part of the information about the properties of the manufactured cement encrypted in the full marking.

In the context of the simultaneous use of standards with the previous designations and from 2003, many codes carry identical information.

Cement manufacturers are trying to convey information about the quality and properties of products, using the terms of both standards.

What does the marking of cement by type of additive mean?

In addition to the main components, additives are introduced into the composition of the binder mineral substance, which make it possible to use cement in special-purpose concretes. Information about special properties included in product labelling. The letters encode the powder and additives:

• PC - Portland cement without improving additives;
• ShPTs - when grinding clinker, slag is added in an amount of ≥20%, the product is called Portland slag cement;
• PPC - used for concreting in flooded conditions (pozzolans are products of volcanic activity: ash, tuffs, pumice);
• SPTs, SSPTs, SSSHPTs - sulfate-resistant binders, anticorrosive;
• B - fast hardening powder;
• BC -; clinker for its production is made from kaolin and light grades of limestone;
• G - quick-setting alumina powder, raw materials for firing are carbonate rocks and bauxites;
• HF - hydrophobic cement for concrete products in water;
• PL - plasticized, provides ease of laying the solution even at low temperatures;
• VRC is a moisture-proof expanding cement that hardens in any environment.

In the GOST 10178-85 marking, the amount of additives is indicated by a letter and a percentage: D0, D5, D20. At the end of the code, the standard according to which the product is made is indicated. Example: PC 400-D20-B-PL GOST 10178-85 - Portland cement with a strength of 400 kg / cm² with additives in the amount of 20%, fast-hardening, plasticized.

Deciphering the marking of cement according to new standards

The coding of product information in accordance with GOST 31108-2003 is based on the division of cement types into 5 groups, denoted by Roman numerals. The first 3 letters are taken from the name of the powder - CEM.

Each association has signs indicating manufacturing features:

• I - Portland cement without additives, consists of 95-100% of cement clinker;
• II - this group is subdivided into subclasses A with additives of 6-20% and B - 21-35%. There are also pozzolanic cements containing<20% пуццолана, и композитные, в которых присадки суммарно не превышают того же значения;
• III - slag Portland cement with a slag content of 36-65%;
• IV - pozzolanic cement with the addition of 21-35%;
• V - composite powder, including 11-30% slag and pozzolan within the same range.

Each of the additives has its own letter in the designation: I - limestone, Z - fly ash, MK - silica fume, K - composite additive, G - glieg, Sh - slag, P - pozzolan. This is followed by the number of the strength class, followed by the letters: H - normal hardening time, B - quick setting. Example: Portland slag cement CEM III / A 32.5N GOST 31108-2003. It is deciphered as follows: cement strength is 32.5 MPa, it is normally hardening, contains 36-65% slag.

Grades of cement and their application

Portland cements are used in accordance with the labeling, which directly indicates special conditions, if any. For construction work, when choosing a brand, pay attention to the indicator of the strength class or brand of cement.

Arrangement steps depending on the hardness of the binder powder:

• M200 - cement is intended for plastering, manufacturing;
• M300 - corresponds to the M200 monolith, is used for concreting underlying surfaces for foundations, pouring foundations for low-rise buildings;
• M400 - construction of reinforced concrete structures with a strength of M300, road surfaces, paving slabs, supporting structures;
• M500 - all types of external concrete work, the manufacture of airfield slabs and hydraulic structures from the monolith M400.

The compositions of the solutions may vary and are set according to the conditions of the facility being built. The recipe of mixtures is determined by the project.