The highest quality cement. Which cement is better? Dependence of concrete grade on cement grade

Cement is one of the most common building materials. Only steel can compete with it. Cement production in the world is very large. Before building a house, you need to understand the markings and types of materials in order to choose the most the best option. To determine which cement is best for the foundation, it is also recommended to carefully read the regulatory documentation.

The situation with cement is similar to what happens with other common building materials, such as rebar and concrete. New regulations oblige the use of markings that differ from the old ones. At the same time, many manufacturing plants and builders continue to use outdated names, and young specialists are studying new regulatory documents. Confusion ensues. To understand it, you need to compare the markings offered by the new and old GOSTs.

Marking according to GOST 10178-85 (1985)

According to this regulatory document, the 5 most used brands can be cited:

• ShPTs-300 was used for the production of low-quality concrete, foundation concrete blocks (FBC), trays and rings;
• PC-400 D20 was the most common cement for construction;
• PC-500 D0;
• PC-550 D0;
• PC-600 D0.

The marking PTs means Portland cement, ShPTs means slag Portland cement. For ShPC, the additive (slag) content is standardized within the range of 20-80%. If the labeling indicates the designation D0, this means that the composition contains no more than 20% additives. D0 - additive-free cements (used for the production of high-strength concrete). The number in the marking is the strength grade, the value is given in kgf per cm2.

Marking according to GOST 31108-2003 (2003)

This document is designed to bring the marks into compliance with the European standard EN-197-1:2000. The designations in these two documents are similar, therefore, knowing domestic standards, you can guess the brand of products of foreign companies. The difference is letter abbreviation, in one case they use the Cyrillic alphabet, and in the other the Latin alphabet.

The label describes the product in more detail, which is its undoubted advantage. You can create labels by moving along the columns of the table.

	Group	Subgroup	Additive labeling	Strength class*	Hardening speed
(common designation for all brands)	(additive-free Portland cement)	—	—		(normally hardening) (fast-hardening)
	(Portland cement with active mineral additives)		and (lime) mk (microsilica)
		(21-35% additives)
	Portland cement)
	(pozzolanic cement)	—	—
	(composite cement)	—	—

*Unlike the old GOST, the new one uses not a strength grade in kgf/cm², but a strength class in MPa.

When designating between a group and a subgroup (if there is one), it is necessary to put a fractional line. The last two groups are extremely rarely used in construction.

Comparison of old and new markings

When purchasing, it is important to know the compliance of cement grades, so as not to make a mistake with the choice if the manufacturer still uses outdated regulatory documents. It is important to remember that the comparison in terms of strength is approximate, since the brand and class do not match the values ​​​​in MPa. For convenience, you can use the following table of the most common cements.

Marking according to GOST 2003 is more accurate, but has one important drawback: the strength values ​​of the materials do not coincide exactly. The following comparisons can be made.

The table shows that the corresponding values ​​are lower than in the old document; this must be taken into account when designing foundations.

When pouring the foundation, it is necessary to use the correct binder. The brand required by the joint venture “Concrete and reinforced concrete structures" can be determined from the table.

For private construction, it is wiser to choose CEM II/A-sh32.5 or CEM I 32.5 (PTs-400 D0). This brand will become the most optimal solution in terms of price/quality ratio. If you want to get a foundation of increased strength for a heavy house, it is better to use TsEM l 42.5 (PTs-500 D0).

Additives to concrete

To improve the characteristics of the mixture or finished structure, in addition to cement, special modifiers are added to concrete. The most common ones include:

• Plasticizers and superplasticizers. Allows you to reduce the amount of water for mixing. This increases the strength and frost resistance of the finished structure, reduces the likelihood of cracks, and reduces shrinkage. In addition, water resistance increases.
• Antifreeze additives. They are used if it is necessary to fill at low temperatures. Allows you to perform work down to -15 degrees Celsius.
• Self-compacting additives. If you plan to fill thin-walled structures, these substances are introduced into the solution.
• Additives to accelerate strength gain. They are used to increase strength in the first day after pouring.
• Additives to slow hardening. Used if it is necessary to maintain the mobility of the mixture for a sufficiently long time.

Most often in modern construction plasticizers are used. The use of complex additives for concrete mixture.

Important points when purchasing

At independent purchase material, you must carefully study the product. This will avoid problems during the construction and operation of the building. A few tips to help when purchasing cement for pouring a foundation:

1. The origin of the material has a very big influence. Cement is produced in many countries, but it is better to give preference to domestic brands. Climatic conditions in different regions differ, and so do the requirements for concrete. You should be especially careful about material from Turkey, Iran and other countries with warm climates. This cement does not meet Russian standards for frost resistance and moisture resistance due to differences in conditions external environment. It is better to use raw materials that are produced specifically for the northern regions.
2. To make sure that the manufacturer indicated on the packaging really is one, you need a special document - a sanitary-epidemiological report, which indicates the address of the manufacturer. The seller is obliged to provide this document upon the buyer's request. The absence of a conclusion should raise suspicion about the quality of the product.
3. A careful inspection of the packaging will also ensure quality. It should have small holes designed to remove excess moisture.
4. It is not recommended to use cement that was manufactured more than 2 months before the construction date. The quality of the material may be unsatisfactory. When purchasing, pay attention to the production date. Old cement can develop stones and hardened areas.
5. Even if the manufacturing date meets the requirements, the bag is probed for stones and seals. If the contents of the package are loose, buy cement without fear.
6. The standard weight of a bag of cement is 50 kg, the permissible deviation in both directions is 1 kg. If the condition is not met, the material is poured into the bag manually in a small factory, which cannot guarantee quality.

To avoid problems when pouring, it is recommended to buy one test bag of material and knead concrete mortar. If it works out good quality, you can purchase material for the entire scope of work. But it is very important to buy material from the same batch. For one manufacturer, the quality may vary from batch to batch.

A competent choice of binder for a concrete mixture will guarantee high reliability of the structure while complying with the technology.

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Cement refers to the most popular building materials. It belongs to the group of hydraulic binders that are used in the fastening process various surfaces. The properties of this material vary greatly depending on the required tasks. To find out which cement is better for the foundation, you need to understand the types of cement, its brands and main characteristics.

Cement is a free-flowing dark gray powder. This is the main component of concrete. It is mixed with sand, water and crushed stone, resulting in a monolithic composition that can withstand significant loads.

Features of cement for foundations

On the packaging of cement there is marking, which helps determine the percentage of additives and loads that future structures can withstand.

When choosing cement for pouring the foundation, you need to knock on the bag to determine the degree of flowability of the material. If the consistency of the composition contains fossils, then such a product is not worth purchasing. Availability lumps in powder indicates that the shelf life of the cement is too long. When choosing products you need to consider resistance to aggressive factors.

The cement must have the following characteristics:

To the advantages cement mixtures include:

Calculation of cement for the foundation

For many brands of cement, certain values ​​are already provided, which are taken as the main measure when constructing a foundation:

Certain additives influence the improvement of cement quality. There are special components that allow the solution to be used at very low temperatures. For the construction of foundations for buildings, the grade of cement for the foundation is M300 and higher.

Knowing the cement consumption per cubic meter, you can calculate how much is needed building material. Running simple calculation of the amount of sand and cement with the addition of crushed stone: For one part of cement, take three parts of sand and five parts of gravel. In this case, water must be added until the solution has a medium consistency.

When deciding what kind of cement is needed for the foundation, you need to pay attention to the quality of sand and crushed stone. There should be no clay substances in the sand, since it reduces astringent properties cement. It is also worth considering that the cement fraction does not exceed 40 mm.

Varieties

There are more than 30 types of cement in the construction industry. The most commonly used types are:

There are many types of cement, so when choosing a material for the base the most important parameter is considered the brand of cement for the foundation. Each of them has a certain strength class and frost resistance.

Brand selection

It is worth considering that damage to the packaging will cause the material to absorb moisture and become unusable within a few days. It is important to know how to calculate the cement for the foundation correctly in order to accurately calculate how many packages are needed and not buy material in reserve.

In addition to marking the cement, the bags are written additional indexes:

• D0 indicates that the cement is without additives.
• D20 indicates that the composition contains 20% additives.

Different abbreviations are also used. PC stands for Portland cement, Pl- frost-resistant and plasticized. If the soil is dry, then Portland cement is used.

The quality of the prepared concrete is influenced by the type of soil where the work will be carried out. construction works. For rocky and sandy soils you can use concrete M250 or M200. It is worth considering that the grade of cement for the foundation M400 is used to create M200 concrete. In this case, the ratio of cement, crushed stone and sand is 1 to 4.8 and to 2.8. For M250 this ratio is 1:3.9:2.1.

When building the foundation on clay soils M300 concrete is used, which has more durable properties. It is obtained from M500 cement, and the ratio of the starting material, crushed stone and sand is 1 to 3.7 and to 1.9.

Before preparing the solution, you need to check the quality of the sand. The sand is poured into a tank of water and left for a day. If during this time the water has become cloudy, then the material cannot be used to prepare the foundation. You also need to check the quality of the cement. There shouldn't be any fossils in it. This material begins to harden in the corners of the package. Therefore, first all corners are checked for softness.

The best option Portland cement without additives is used for foundation construction. Pozzolanic and slag type of material can also be used.

The foundation is the foundation for every building. The durability and reliability of the structure depends on its quality. Therefore, the choice of cement must be taken responsibly. Knowing the brands and their characteristics will help you avoid mistakes when purchasing.

Many people who are involved in construction own home, I am interested in the question of which cement is better for the foundation. This is a rather important aspect, since the quality of the foundation determines how long the building will last. This article will discuss the main nuances that should be considered when purchasing cement.

general information

Nowadays, on the shelves of construction stores you can find a huge number of various brands cement of domestic and foreign production, so many people simply do not know which cement is better for the foundation. When choosing, you should consider many factors, the main ones being:

• strength;
• compatibility with reinforced concrete structures;
• type of construction;
• weight of the future building;
• best before date;
• availability of quality certificates.

All these parameters affect the quality, strength and durability of the foundation, so they should be taken into account when purchasing materials.

What brand of cement is best for foundations? This question haunts many novice builders. Portland cement is considered ideal, since the solution prepared on its basis has high strength and excellent resistance to negative factors environment. As for choosing a specific brand, it all depends on what type of building the foundation will be poured for.

If you want to build a base for drainage system, then the use of materials with low strength is allowed, and what cement is better for the foundation of a house? For residential buildings, you should choose materials whose strength is 2 times higher than that of a concrete mixture. If you stick to everyone construction technologies, then the cement must have a strength of M400.

Review of the main brands of cement

Today there are not many brands of cement that are suitable for the construction of residential buildings. If you don’t know which cement is best for pouring a foundation, here is a list of acceptable brands:

• PC M400 D0 is a binder mixture that produces high-strength cement that can withstand very heavy loads and is highly resistant to moisture and severe frosts;
• PC M400 D20 - cement of good quality and at an affordable price. Highly resistant to aggressive environmental factors;
• PC M500 D0 is a high-quality cementitious mixture containing up to 99% cement content. Ideal for pouring foundations for heavy residential buildings and small industrial facilities;
• PC M500 D20 is a material that, in its properties and characteristics, is almost completely identical to the previous one, but has less strength.

For the foundation on which non-residential buildings will be located, you can use other brands of cement made on a slag basis, but they are not suitable for heavy buildings.

Decoding cement markings

To understand which cement is best for the foundation, the manufacturer has absolutely no importance, you need to learn to understand the markings. In addition to the brand, the abbreviation may contain the following parameters:

1. B - cement that hardens quickly. Used on construction sites with a limited construction period.
2. PL is a plasticized binder that can withstand very low temperatures.
3. SS is one of the varieties of cement that has increased resistance to negative environmental factors.
4. NC is a prestressing PC that has high resistance to moisture and high strength after hardening. Used for pouring foundations in basement, for the construction of houses on difficult soils and reconstruction of buildings.

The ability to understand cement markings will allow you to avoid many mistakes during the construction process.

Types of additives in concrete

So that the concrete or future foundation is strong and durable, and also has high performance characteristics, it contains certain additives, which can be divided into the following types:

1. Plasticizers allow you to mix the solution with less water, due to which the foundation will freeze significantly less during the cold season, will be stronger and more durable, and will not sag over time.
2. used in construction for the construction of houses in cold regions. They allow you to work normally with cement in severe frost.
3. Compactors help increase the strength of concrete and are used for the construction of thin walls.
4. Strengthening accelerators are used during short construction periods, when it is necessary for cement to gain its strength as quickly as possible after pouring.
5. Set retarders are used in cases where it is necessary to keep cement in liquid state over a long period of time, for example during transportation.

There are also universal supplements that combine all of the properties listed above.

Mixing concrete: optimal proportions of materials

Knowing which cement is best to fill the foundation with is not enough, since you also need to be able to mix it correctly. Good concrete should contain at least 25% cement, but when preparing the mixture you should follow the manufacturer's recommendations indicated on the packaging. To prepare cement for the foundation, you should choose a grade from M200 and higher, since a smaller grade is not able to withstand heavy loads and is unsuitable for building houses.

A good PC, if chosen correctly, consists of one part cement, three parts sand and five parts crushed stone. As for water, its quantity depends on the brand of building material, however, the minimum volume is 0.4, and the maximum does not exceed 0.65. It’s worth noting right away that these proportions are only suitable if you use high-quality materials.

Kneading process

So, we have already figured out which cement is best for the foundation, as well as the optimal proportions of materials required to obtain high-quality and durable concrete. Now we need to talk about what technology should be used to knead so that ready mix turned out good. All work occurs in the following sequence:

1. First, 4/5 of the water is poured into the concrete mixer.
2. Then crushed stone or gravel is added.
3. Cement and sand are poured.
4. During the kneading process, the remaining water is added in small portions.

If you are constructing in a region with difficult climatic conditions and frosty winters or on a flooded plot of land, then, in addition to the main components, special plasticizers are also added to the concrete, which significantly increase its performance properties. They must be added at the very end of the batch, strictly adhering to the proportions specified by the manufacturer.

A few words about the price

We now already know which cement is best for the foundation of a house, but how much will it cost to purchase materials? It all depends on the packaging in which you buy the materials. Cement is sold in bags, big bags and by weight. The last option is the most profitable and will allow you to save a decent amount.

As for the average market prices on the CPU, then purchasing mixtures from famous brands having high quality and excellent performance properties, will cost approximately 4000-4500 rubles. The exact amount depends on the brand of the mixture and the presence of various additives, increasing the resistance of cement to water and frost. If you buy in bulk in bags weighing 50 kg, then you will pay approximately 230 rubles per unit.

Which cement manufacturers are better?

Which cement is best for the foundation of a bathhouse, and which manufacturers produce the highest quality mixtures today? It is very difficult to give an unambiguous answer to this question, since both domestic and foreign materials are available for sale. Some experienced builders claim that American and European-made cement is better, however, given their high cost, purchasing these mixtures will not be affordable for everyone.

Among Russian companies Those involved in the production of cement are in great demand for the products of the Novgorod and Borshchevsky cement plants, as well as such companies as Sebryakovcement, Mikhailov Cement Rusean and some others. All these companies produce high-quality PCs of various brands according to affordable prices, so the foundation will not cost you too much.

The requirements for the binder when preparing concrete for pouring or assembling a foundation are high: the cement must have the correct strength grade, be suitable for reinforced concrete structures, be fresh and of high quality. Much depends on the type and weight of the building, for the foundations residential buildings PC M400 is considered the minimum; for temporary and lighter ones, a reduction in requirements is allowed. Checking the certificate and expiration date is mandatory in any case; preference is given to cement produced no later than 3 months; the material is not purchased in advance. Important technology standards include precise adherence to proportions, preparation and correct sequence of loading components into the mixer, and compaction of concrete after pouring.

Preference is given to Portland cement; concretes with it have the necessary strength and resistance to external influences. The choice of brand for foundations directly depends on the type and purpose of the mixture construction staff. To fill the drainage base, it is allowed to use cement with a low strength grade (the final concrete is from M75 to M150), in all other cases the rule applies: the grade of binder must be twice as high as the expected grade of the concrete mixture. Taking into account the minimum allowable for foundation structures M200, the solution is mixed with Portland cement with a strength of M400 (about this brand of cement).

The maximum proportion of foreign impurities in the binder is 20%; their introduction reduces the cost, slightly reducing frost and water resistance. As a consequence, to suitable types cement for pouring the foundation include:

• PC M400 D0 – can withstand loads of up to 400 kg/cm2 after curing, providing good durability, water resistance and frost resistance. Concrete based on it can withstand low temperatures, contact with ground and atmospheric moisture and exposure to aggressive environments. Cement M400 D0 is suitable for any type of foundation, including reinforced and prefabricated (it is used for mixing masonry mortar).
• PC M400 D20 - combining fairly good resistance to moisture and freezing and a reasonable price. The best option for the construction of foundations for light residential buildings in the absence of serious soil requirements.
• PC M500 D0 is recommended to be chosen when constructing critical objects; this brand consists only of cement clinker, the proportion of foreign additives (in in this case- gypsum) does not exceed 1%. This has a positive effect on frost and moisture resistance; the variety is considered elite. Its use when mixing concrete for the foundation will pay off economically during construction in problem areas (in particular, flooded ones).
• PC M500 D20 is a similar brand of cement to the previous one, slightly inferior in terms of resistance to moisture and freezing (but not in strength), but in its characteristics it still surpasses M400.

Slag or pozzolanic based cements withstand the effects of sulfates dissolved in ground moisture well, but for laying monolithic or prefabricated foundations it is better to choose a different type. main reason– slow strength gain and low frost resistance. As a result, their use is permissible only on the advice of professionals and with the acceptance additional measures to protect foundation structures from frost heaving of soils. If there is the slightest doubt, it is better to choose Portland cement without impurities or specialized brands:

• B is a fast-hardening binder, which is recommended for limited work periods.
• PL is a plasticized variety with increased frost resistance. Its introduction allows you to save up to 8-10% of cement, but it is important to remember that it cannot be used with any other types except PC.
• SS – special sulfate-resistant PCs.
• NC – tensile cement. Concrete based on it has a compacted structure after hardening, preventing moisture from entering. NC is recommended to be chosen when laying the foundation of a house with a basement or erecting a monolith on flooded soils. They are also well suited for repairing and restoring existing structures.

Cements below M400 are allowed to be used in the construction of bathhouses and light panel or wooden one-story buildings on dry and stable soils. To eliminate mistakes, they start from the grade of concrete; when selecting it, they must take into account such criteria as the expected weight load (weight of load-bearing structures, including the foundation itself, roofing system, snow cover and objects in the house) and soil parameters (level of freezing, rising water, structural composition and homogeneity of the soil), timing of filling and hardening conditions.

Cooking proportions

The minimum acceptable grade of concrete for pouring a foundation is considered to be M200 (more is better); when concreting the foundations of residential buildings within 1-2 floors, M250 is most often chosen. The recommended proportions of components when preparing the M250 solution are 1:3:5 (cement, sand, gravel or granite crushed stone, respectively). The W/C ratio does not exceed 0.65, it depends on the expected grade of concrete: the higher it is, the lower the volume of introduced water, minimum 0.4.

Concrete grade	Ratio (C:P:SH)	Volumetric composition per 10 liters of cement for sand and crushed stone, l	Concrete yield per 10 liters of cement, l
PC M400
M100	1:4,1:6,1	41:61	78
M150	1:3,2:5	32:50	54
M200	1:2,5:4,2	25:42	64
M250	1:1,9:3,4	19:34	43
M300	1:1,7:3,2	17:32	41
M400	1:1,1:2,4	11:24	31
M450	1:1:2,2	10:22	29
When using PC M500
M100	1:5,3:7,1	53:71	90
M150	1:4:5,8	40:58	73
M200	1:3,2:4,9	32:49	62
M250	1:2,4:3,9	24:39	50
M300	1:2,2:3,7	22:37	47
M400	1:1,4:2,8	14:28	36
M450	1:1,2:2,5	12:25	32

The indicated proportions are relevant when using the correct components: clean and dry quartz sand with a fraction size of at least 2 mm, washed and dried crushed stone with a strength grade of at least M1200. The activity of the binder plays an important role, reviews in this regard are clear: for the foundation of a house it is better to take cement no earlier than 1-2 weeks before the start of work, checking the release date and certificate is mandatory. Fresh powder has no lumps and is easily passed through your fingers.

If you doubt the integrity of the supplier, it is worth checking the quality of the material in advance: the correct cement sets well within 45 minutes.

In addition to the use of components required quality the sequence of their loading into the concrete mixer is observed. Recommended scheme: 80% of the total share of water → crushed stone → sifted cement and sand → the rest of the water in small portions. Most plasticizers or hardeners are added at the end with strict adherence to proportions. These include liquid soap(added along with the main portion of water), factory specialized additives, fiber, inhibitors, substances that affect the setting time of concrete. Their use requires caution; exceeding their proportion worsens the structure of the artificial stone.

Material cost

Products are sold in bags, big bags and in bulk; wholesale purchases are the cheapest. The prices in this case are:

Cement marking	Manufacturer	Price for 1 ton, rubles
		With delivery within Moscow by cement truck	pickup
PC M500 D0	JSC Lipetskcement CJSC Belarusian Cement Plant	4500	4250
PC M500 D20	JSC Maltsovsky Portland Cement	4350	4100
PC M500 D0B (fast-hardening)
PC M500 D0N (standardized clinker)		4650	4450
PC M400 D0	JSC Maltsovsky Portland Cement JSC Mikhailovcement JSC Lipetskcement	4300	4150
PC M400 D20		4200	3950

When building a foundation on your own and delivering it using your own transport, it is more convenient to use bags (the proportions are easier to adjust to the measured weight). High-quality cement is offered by many domestic factories and manufacturers of dry cement. building mixtures: Novgorod Central Plant, Borshchevsky Central Plant (Lafarge), Mikhailovcement, Maltsovsky Portland Cement, OJSC Voskresenskcement, Mordovcement, Sebryakovcement, Rusean. The cost when purchasing it in packaged form is.

Cement is used everywhere: from laying the foundation to brickwork and carrying out work on interior decoration. Such a wide and even immense scope of use of cement has led to the emergence of materials with different compositions and characteristics. You can’t just buy the first cement you come across and start work - first it’s important to make sure that the composition matches the task. Going to hardware store, It is important to know theoretical basis, so it’s time to figure out how to choose cement, find out what brands and types of cement exist, where certain compositions are used, and also what to take into account when choosing.

No. 1. Main types of cement

Cement is an inorganic binder. Cement powder, when interacting with water, forms a plastic mass that quickly sets and forms a stone-like body. It is often used for the manufacture of mortars. The composition of cement can vary greatly. Accordingly, the properties and scope of use will differ.

Today the following main types of cement are produced:

• Portland cement– the most popular type of cement in construction. It is made from Portland cement clinker, gypsum and special additives. Clinker is produced from limestone, clay and additives by firing. Ready-made Portland cement consists of 70-80% calcium silicates, the rest is gypsum (regulates the setting speed) and corrective additives. Portland cement is produced in grades M400-M600 and is used to create mortars, asbestos-cement and other materials. Not suitable for the construction of structures exposed to sea water;
• white portland cement are made on the basis of gypsum, diatomite and clay-sand rocks with a minimum content of coloring substances. The result is a composition with high strength, weather resistance and rapid setting. Only two brands are produced: M400 and M500. Often the composition is used for external finishing works, as it has an aesthetic appearance and is not susceptible to cracking. Used for the manufacture of decorative elements (statues,), when organizing self-leveling floors, in road construction, V . Made from white Portland cement color compositions;
• sulfate resistant Portland cement produced on the basis of Portland cement clinker and gypsum. The composition is characterized by a reduced content of calcium aluminates, which ensures resistance to sulfates. Cement can be without additives or have additives in the form of granulated slag. Brand M400 and M500. It is used in the creation and construction of structures that will be operated under the influence of mineralized waters. This cement is used in the manufacture of piles, bridge supports, and in the construction of external elements of hydraulic structures;
  
• pozzolanic Portland cement obtained from Portland cement clinker, gypsum and additives of sedimentary origin, part of which is 20-30%. The composition is resistant to fresh and sulfate-containing waters and waterproof. Among the disadvantages are low frost resistance and low hardening speed. Used in pouring and laying basements of industrial and civil buildings, in the construction of subways, mines, canals, sluices, water supply lines;
• slag cements– a group of cements that includes slag Portland cement (SPC) and lime slag cement (ISC). The first is produced on the basis of Portland cement clinker, gypsum and blast furnace slag, part of which is 21-60%. The composition is characterized by a slow increase in strength, increased resistance to aggressive environments, but is not resistant to temperature changes. Used in hydraulic engineering construction. ISC is obtained from a mixture of slag and lime (its part is about 30%), small additions of gypsum and Portland cement are allowed. The composition hardens slowly, is most resistant in fresh and sulfate waters, can be used for the production of low-quality concrete, in mortars for and masonry;
  
• rapid hardening Portland cement, as the name suggests, is characterized by a rapid increase in strength in the first hours of hardening. These properties are explained by the precise selection and dosage of special additives. As a result, the composition reaches its ultimate strength within 3 days, which speeds up the production process of reinforced concrete structures;
• aluminous cement also different high speed hardening and strength gain. It is produced on the basis of bauxite or alumina with the addition of limestone. Based on the alumina content, ordinary (up to 55% alumina), high-alumina (up to 65%) and high-purity high-alumina cements are distinguished. The compositions are highly resistant to fire, corrosion and rapidly increase in strength. This cement has found application in emergency work, high-speed construction and winter concreting;
• expanding cements– a group of cements that are characterized by an increase in volume during hardening. A similar effect is achieved through a reaction between the powder and water, resulting in the formation of calcium hydrosulfoaluminate, a substance that can bind large amounts of water. The group of expanding cements includes waterproof, tensile, gypsum-alumina compounds and expanding Portland cement. Let's look at them all separately;
  
• waterproof expanding cement made from gypsum, aluminous cement and calcium hydroaluminate. The composition begins to set after 4 minutes, and after 10 minutes the hardening process ends. Used in underground and underwater construction, to seal cracks and to create monolithic structures from individual prefabricated reinforced concrete elements;
• tensile expansive cement made from Portland cement clinker, lime, aluminous slag and gypsum stone. The composition hardens relatively quickly and is waterproof. Used in concreting bowls, producing pressure pipes;
• gypsum alumina expanding cement made from aluminous blast furnace slag and gypsum. The composition sets within 4 hours, expansion ends after 3 days. Cement is characterized by high frost resistance, strength and deformation resistance. It is used to carry out waterproofing work;
• expanding portland cement is a mixture of Portland cement clinker, slag with a high alumina content, gypsum and mineral additives. Depending on the composition, the expansion ranges from 0.3 to 2.5%. The expansion period is long, so the volume is filled evenly. Used in arranging road surfaces and repair of hydraulic structures;
• well cement used only when plugging oil and gas wells in order to isolate them from groundwater. Made from clinker and gypsum;
• hydrophobic cement in its composition, in addition to gypsum and clinker, it contains oleic acid or other hydrophobic substances, which make it possible to create a waterproof film on the surface of dried cement. This cement is ideal for foundations;
• magnesia cement differs in the content of magnesium oxide, which increases the elasticity of the composition and its resistance to aggressive substances. Used in arranging;
  
• waterproof non-shrink cement obtained from aluminous cement, gypsum and slaked lime. The composition sets quickly and is not afraid of water;
• acid resistant quartz cement– a product of mixing quartz sand, sodium silicofluoride and liquid sodium glass. The composition is resistant to aggressive substances, but loses strength in water;
• cement with surfactants has increased mobility and is used when working on complex objects from an architectural point of view.

No. 2. Cement grades by strength

The most important characteristic of any type of cement is its strength. This indicator is determined experimentally: a solution is prepared from cement and in a ratio of 1:3, a sample is created in the shape of a parallelepiped with sides of 40*40*160 mm. The resulting sample is subjected to gradually increasing load. The experiment is slightly different only for some types of cement.

The data obtained during laboratory research is reflected in the stamps. If the sample can withstand a load of 300 kg/cm2, then it is brand M300, 500 kg/cm2 - M500, etc. The grades are designated by the letter M and the subsequent index from 200 to 600 in increments of 50 or 100. The higher the grade, the more durable the composition we have, and the more durable and high-quality concrete it will produce:

Today, next to the classification of cement by strength grade, a division has appeared into strength classes. If the brand is an average indicator, then the class is more accurate and provides a 95% guarantee of compliance with the specified data. Strength classes vary from 30 to 60:

• 52.5 – cement withstands pressure of 52.5 MPa, corresponds to cement grade M600;
• 42.5 corresponds to M500 cement;
• 32.5 corresponds to M400 cement;
• 22.5 corresponds to M300 cement.

No. 3. Labeling of additives in cement

In addition to the strength mark, on the packaging you can see markings of the percentage of various additives in the cement. This indicator is denoted by the letter D, followed by a numerical indicator in percentage. For example, D20 cement means that it contains 20% additives. The higher the number of additives, the lower the price of the composition.

No. 4. Marking by speed of strength gain

The time it takes for cement to reach its maximum strength is another important compositional indicator. In some cases, it is required that it hardens instantly, in others, on the contrary, an excessive rate of strength gain will only cause harm. According to this parameter, cement is divided into the following types:

No. 5. What else could be in the marking of cement?

In the characteristics of the composition, after the designation of the cement brand and the percentage of additives, there may be various abbreviations indicating the specific qualities of the cement:

No. 6. What to look for when choosing cement?

The demand for cement is huge, which has given rise to the emergence of many unscrupulous manufacturers who often mix additives into cement that greatly reduce the quality ready-made composition. To avoid making mistakes when choosing cement and buy a really high-quality product, you need to know something about what good cement looks like and what properties it should have:

• cement is sold in bags and in loose form. It is better to take cement in bags, since this way it is protected from external influence, retains its qualities longer, and on the packaging of the bag you can always find out information about the composition, production date, characteristics of the cement and its manufacturer. The bags are usually made of two layers of paper, the inner one protects the cement from getting wet. By the way, the absence of any information on the packaging is also a sign that you may have low-quality material;
  
• if you buy cement in bulk and it is packaged in bags, then it is better to check carefully best before date on each, since in general they can sell you stale goods. The activity of cement drops several times after 6 months from the date of production;
• check freshness of cement It can also be done experimentally. It is enough to hit the bag - the sensation should not resemble hitting a stone. The cement in the corners of the bag hardens first, so it doesn’t hurt to check them either. Naturally, if there is no production date on the packaging at all, then it is better not to buy such a product;
• cement should be stored in dry and well-ventilated areas, otherwise it will quickly turn to stone;
  
• color of quality cement– gray, more precisely from light gray to dark gray and even greenish. Dark and marshy shades are not allowed. Good cement should crumble in your hand and not crumple into a lump when squeezed;
• The fineness of grinding affects the curing process. The finer the particle fraction, the faster the composition will harden and the higher its price. Too fine a fraction increases water consumption, so ideally it is better to take cement where fractions from 40 to 80 microns are found;
• does not interfere with carrying out assessment of cement composition and characteristics. This is not difficult to do, but you need to prepare sodium bicarbonate water in advance (Borjomi will do) or sodium bicarbonate chloride water. Gas must be released from the water. Next, we use it to knead cement dough and form it into a cake with a diameter of 15 cm. It should be thicker in the center (5 cm), narrower towards the edges (1 cm). High-quality cement should begin to set no later than after 10 minutes, and the thickened part will noticeably heat up. If setting does not occur even within 30 minutes, then you have a composition of low quality.

No. 7. The best cement manufacturers

Finally, we once again emphasize the need for information on the packaging about the brand of cement, its properties, production date and contact details of the manufacturer.