Which cement in bags is better. Which cement to choose? Overview of types and main characteristics. Find out how the cement was stored

Cement is the most commonly used building material.

Not a single construction or repair can do without it. To choose a truly high-quality cement, you should understand how one brand of material differs from another and which one should be chosen for construction.

For home master accustomed to doing everything with his own hands, this problem is all the more urgent - because sometimes the fruits of many days of work nullify low-quality materials.

On the pages of our site, the issue of using cement was raised in almost every second article.

It is also used for interior finishing work, for example, for the preparation and installation of self-leveling floors.

Cement like any other construction material, differs in physical and technical characteristics, depending on the conditions under which it is supposed to be used. It is not difficult to choose it, the main thing is to understand the intricacies of marking and find a suitable supplier.

Choosing cement

Cement is labeled according to two characteristics, such as the ability to withstand a certain load and the composition of the material.

The first parameter is denoted by the letters M (PC) and a number indicating the maximum strength properties of cement. For example, the M400 marking indicates that this species cement is able to withstand a load of 400 kg / cm. The second parameter is denoted by the letter D and a number showing the amount of additives as a percentage. For example, cement labeled D20 contains 20% additives. Their number directly affects the plasticity and strength of the material.

Many people think that the numbers in the marking indicate that measure (part) of sand, which is necessary for the preparation of high-quality mortar. In fact, this is far from the case - the numbers 400, 500, etc. in the marking of cement, this is nothing more than the production characteristics of its strength. They are given when testing cement at the factory, when a cube formed from cement is subjected to weight tests - if it collapses under a pressure of 400 kilograms, then such cement is assigned grade 400, 500 - respectively M500.

On the front side of the bag, the name of the product, the trade mark and the relevant state standards must be indicated. On the back, look for weight, density and others specifications product, as well as the address and telephone number of the manufacturer.

In private and agricultural construction, cement is most often used, or, as it is also called, Portland cement grades M (PC) 400 / D20 and M500 / D20. The first has increased frost and water resistance. It is usually used in the manufacture of precast concrete, wall slabs, foundations, etc. The second one is ideal for plastering, masonry, other repair and construction work and the preparation of various mortars. In addition to good water and frost resistance, this type of cement has a reduced resistance to corrosive effects.

Before buying cement, carefully study the packaging in which the material is packaged. In addition to the brand and weight, the manufacturer must be indicated on it - the name of the company, country and city. Remember that when buying a bulk batch of loose cement, you run the risk of purchasing low-quality or expired goods. Also ask under what conditions the material was transported and stored: the quality of cement is greatly affected by the environment, especially high humidity.

We offer several practical advice, which will help you choose really high-quality cement, as well as properly transport and store it.

Check not only the integrity and labeling of the package, but also the cement itself - whether it is prone to pelletizing. To do this, take a little substance and squeeze it in a fist. Fresh cement will easily seep through your fingers, but one that has been sitting in a warehouse for a long time is likely to turn into a lump.

In addition, the quality of cement can be determined by the date of its manufacture and expiration date. The longer the cement is stored, the more its quality indicators decrease. So, after six months, its activity decreases by almost a third.

To preserve all the qualities of cement, it must be transported in compliance with certain requirements. Cement is a pulverized cargo, the loss of which as a result of spraying during transportation and loading and unloading operations on non-specialized rolling stock reaches 5-10%. In addition, cement hardens when even a small amount of moisture gets on it, and when the shelf life increases, it becomes caked. Cement dust is harmful to humans and the environment, so this material must be transported in closed, sealed containers - cement trucks.

It is best to use cement immediately after purchase. If for some time it needs to be stored, it is better to do this in a well-ventilated and well-protected room from moisture. For the winter, paper bags with cement are recommended to be additionally placed in plastic bags. Loose cement can be stored in barrels tightly wrapped in plastic wrap. And be sure to ensure that the shelf life of cement does not exceed six months.

Preparation of the simplest cement mortar:

1. Cement is poured first, and then water is added (average 1 part water to 3 parts cement).
2. The finished solution is a homogeneous mass of sour cream consistency.
3. The mixture is stirred with a special mixer.
4. Trowel and spatula prepare the portions necessary for a particular type of work.

WHAT CEMENT?

It is difficult to imagine a more indispensable in construction and decoration than cement. It is used both in its pure form and as a component for the manufacture of masonry, plaster, concrete and other mixtures. There are many varieties of this material, but usually Portland cement is understood as cement, which, in turn, is also divided into several types, each of which has its own purpose.

WHAT IS CEMENT. PRODUCTION TECHNOLOGY

In the manufacture of cement, either a mixture of natural materials (75-78% limestone and 22-25% clay) or limestone marl is used - a sedimentary stone-like rock that already contains both of these components, which greatly facilitates the process. The raw material is ground to raw meal and then continuously fired in rotary kilns at around 1450 °C.

If necessary, auxiliary components are added to improve sintering: quartz sand and substances containing iron oxide. In this way, cement clinker is obtained, which is then crushed to the final product. When grinding, additional components can be introduced into the composition in various proportions to obtain cement with certain characteristics. The qualitative and quantitative composition of these additives underlies the classification of cement types.

TYPES OF BUILDING CEMENT AND THEIR MARKING

Currently, there are two GOSTs in Russia at once, which regulate the classification and quality of cement produced, so the labeling of different domestic manufacturers can vary significantly. In accordance with the Soviet GOST 10178-85, according to the material composition, cement is divided into the following types:

7 PCDO - Portland cement (without mineral additives);

7 NTs D5 or D20 - Portland cement with additives (no more than 5% or 20% of active mineral additives);

7 ShPTs - Portland slag cement (with the addition of granulated slag over 20%). Also, this GOST establishes strength grades (300-600), which are determined by the average compressive strength. In addition, the standard provides for the labeling of fast-hardening cement (B), the abbreviations PL and GF are used to denote the plasticization and hydrophobization of cement, respectively.

In 2003, a new GOST 31108-2003 was put into effect, which is harmonized with the pan-European standard EN 197-1 and contains requirements for the 12 types of general construction cements most suitable for use in construction conditions in the CIS countries. In accordance with this standard, according to the material composition, cements are already divided into five types:

7 CEM (CEM) I - Portland cement (without mineral additives);

7 CEM (CEM) II - Portland cement with mineral additives (not more than 35%);

7 CEM (CEM) III - slag port land cement (36-65% mineral additives);

7 CEM (CEM) IV - pozzolanic cement;

7 CEM (CEM) V - composite cement.

According to the content of Portland cement clinker and additives, cements of types CEM II - CEM V are divided into subtypes A and B. Instead of grades, this standard introduces compressive strength classes (22.5; 32.5; 42.5; 52.5), similar to those specified in EN 197-1. The values ​​of strength classes, in contrast to the average values ​​of strength grades, are probabilistic in nature and are established with a confidence level of 95%. According to the hardening rate, each class of cements (except for class 22.5) is divided into two subclasses: normally hardening (N) and fast hardening (B).

All European and many Russian manufacturers label their products in accordance with this pan-European classification. However, the former marking is still used by some domestic manufacturers (table).

To avoid unnecessary problems, costs and most accurately choose the type of cement you need, you need to know what exactly it will be intended for and in what conditions it will be used.

Having an accurate idea of ​​the future construction work, you can choose.

Portland cement without additives (CEM I / PC DO)

Pure Portland cement is characterized by very high performance and, accordingly, high cost. In private construction, such cement is used quite rarely, mainly for the manufacture of prefabricated and monolithic structures, since it has excellent frost resistance and an average degree of deformation during shrinkage. Most often, in such cases, cement with a strength class of 32.5 (M400) is used.

More durable cements are usually used for the construction of large industrial structures, airfield pavements and bridge structures.

Portland cement with mineral additives (CEM II / PC D5 or D20)

This is the largest and most widely used group of cements. Replacing expensive cement clinker with various mineral additives will reduce; em cost ceme

improves its individual characteristics, but at the same time, resistance to aggressive environmental influences also decreases. However, you can safely use such Portland cement for private, construction and household repair, since its performance characteristics are sufficient for such types of work.

Just like pure Portland cement, cement with additives varies in strength classes. Most often, cement of class 32.5 (M400) or 42.5 (M500) is used for conventional construction. As additives, granulated blast-furnace slag (Sh), pozzolan (P), fly ash (3), gliezh or burnt shale (G), microsilica (M) or limestone (I) are used. These components are designed not only to compensate for the main properties of clinker while reducing its content in the final product, but also to improve some of its characteristics, such as plasticity or resistance to various influences.

Portland slag cement (CEM III / ShPTs)

This type of cement contains more than 35% blast-furnace slag, which determines its low cost. The process of curing it, unlike Portland cement, takes much longer, but over time, Portland slag cement shows better results. Best Properties it acquires during prolonged solidification in a humid, warm environment.

Portland slag cement also loses in resistance to environmental influences, especially low temperatures; therefore, in private construction it is often used for interior finishing work. At the same time, it is resistant to fresh and sea ​​water, can be used in conditions of variable humidity.

Pozzolanic cement (CEM IV)

This cement is used for the construction of underwater and underground reinforced concrete structures, since it is highly resistant to fresh and sulfate waters. It is recommended to use it in conditions of constant high humidity.

But in ground structures in conditions of air hardening, as well as for structures that are in conditions of alternate moistening and drying, freezing and thawing, it is not recommended to use pozzolanic cement. The fact is that it has a rather low frost and air resistance.

Composite cement (CEM V)

It is obtained by adding gypsum stone and a complex additive consisting of several mineral components to cement clinker.

This is the youngest type of Portland cement, which was invented in order to reduce CO2 emissions into the atmosphere, as well as resource and energy saving. Composite cement is expected to eventually replace conventional Portland cement as new (hybrid) mineral additives can take cement performance to new levels. However, so far, precisely because of the novelty, composite cement is not very popular. In addition, the combined effect of various mineral additives is still poorly understood, so domestic manufacturers prefer to produce classic types of Portland cement.

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How to cheat in the markets when buying cement, and how to choose high-quality cement from a reliable manufacturer.

The start of the construction season is just around the corner, and building a house is a very costly process and people are looking for ways to save money. Cement is one of the main building materials, and its quality significantly affects the final result of the work performed, whether it is foundation pouring, screed or masonry. Unfortunately, when choosing Portland cement in bags, the consumer rarely thinks about possible risks buying a defective product. However, it is low-quality cement that can cause a burst foundation, cracked screed or efflorescence on the wall.

The tips in our article will help you minimize the risk of purchasing low-quality products.

• How consumers are deceived when buying Portland cement
• Tips for choosing bagged portland cement
• How to properly store cement, and what is its shelf life

How to cheat when buying cement

Competition in the building materials market is quite high, so there are such "entrepreneurs" who offer "Portland cement" packaged in bags at a price below the market. The number of such products especially grows during the season of active construction.

How to understand whether such a product is of high quality? And how can a consumer distinguish counterfeit goods?

When erecting multi-storey buildings, cement-based building materials or ready-mixed concrete are brought to the site directly from the factory. In private housing construction, the situation is different: the consumer purchases products on his own, so he risks being deceived. At the same time, the price range for the product from the manufacturer and from the handicraft packer can vary significantly. They lower the price in different ways: from a banal body kit to a change in the composition of cement.

Therefore, private homeowners are interested in the question of how not to be deceived?

Dima4 FORUMHOUSE User

I'm building a foundation. Wondering what kind of cement to buy? There are so many manufacturers - domestic and imported - that it's just dizzying.

Markovkin FORUMHOUSE Member

I want to know why cement in bags of the same brand, from different factories, costs differently? Looked at several manufacturers. One has good packaging. Cement does not wake up during transportation and, most importantly, it costs 40 rubles. cheaper than a brand from a company located in my own region.

Etsnova FORUMHOUSE Member

I wanted to buy cement. To navigate, I studied the prices on the Internet in advance. Went to the market. I had to choose. The seller told me the price for a bag of 100 rubles. higher than indicated on the websites of other offices. Who to believe? I called my friend for advice on what to do. He said that it is generally better not to take cement on the market, because. many fakes. Now I sit and think, where to buy high-quality Portland cement, and not a surrogate?

The bag must contain the following information:

1. type and class of cement;
2. number of the valid certificate of conformity;
3. GOST;
4. contacts and address of the manufacturer's plant.

2. Check the documentation

Each batch of factory cement is accompanied by appropriate documentation confirming its quality and origin. The list includes the following documents:

• quality certificate for cement with the date of shipment;
• conclusion about its physical and chemical properties.

At the slightest suspicion, ask the seller for these documents!

3. Make an examination

If you bought a suspicious batch of cement, contact a special laboratory for an independent examination. This is much more profitable than discovering flaws during the construction process, or then racking your brains on what to do with a cracked foundation or a delaminated screed, where underfloor heating pipes have already been laid.

4. Control your weight

The weight of a bag of cement cannot differ from that declared by the plant by more than 1 kg. Hand-packed bags tend to be lighter.

If the batch of packaged cement is large, selectively weigh it before buying.

5. Find out how the cement was stored

The seller of packaged cement must comply with the rules for its storage. Factory cement, as a rule, is packaged in special multilayer paper bags. Buy bags of cement without mechanical damage, because. When exposed to moisture in the air, Portland cement deteriorates. Check that paper bags of cement are stored on pallets, not lying in bulk on the floor of the warehouse and wrapped in plastic wrap. Only dry and well ventilated rooms are suitable for cement storage.

The shelf life of cement and the rules for its storage

Cement is a perishable building material. If you bought Portland cement in bags and did not immediately use it in construction, remember that:

• According to GOST, the manufacturer guarantees the quality of cement within 60 days from the date of shipment from the plant. However, with proper storage, most cements can be stored for more than six months without significant loss of quality characteristics.
• An open bag of cement should preferably be used as soon as possible.

For long-term storage, wrap an unopened bag of cement, provided that it has not been saturated with moisture, in a sealed plastic bag. Store packages indoors on pallets, not outdoors. Change bags every 2-3 months. Check the quality of cement when buying Can visually. Open the bag. Scoop it up with your hand. Clench your fist. Good cement will flow through your fingers like water without clumps. The color of quality cement is gray or light gray. The mixture should be homogeneous, without foreign inclusions.

conclusions

The desire to save money and buy cheap cement in bags is understandable. But, in the race for low prices, it's easy to lose, especially when it comes to building materials. Bagged cement is no exception. there is a risk of running into a fake. Approach the choice wisely, analyze the information. Manufacturers' websites contain addresses and contacts of authorized distributors. Purchase packed cement directly from the plant or from its official representatives, who guarantee the quality by providing the consumer with all the necessary documentation.

The article tells how to independently produce self-mixing concrete of excellent quality.

In the video - How to choose high-quality sand concrete and determine its quality.

This question is usually asked by amateurs. Because it all depends on what it is going to be used for. It is used mainly as a binder in a variety of works: the manufacture of plaster mixtures, mortars, concrete for various purposes, etc.

Therefore, when choosing good cement, you should not use rumors or advice, since when purchasing a specific material, you need to know in advance for what purposes it is intended. Private home builders are interested in the category of general purpose products. These include the fairly popular Portland cement or Portland slag cement. Let us briefly consider which varieties, for which it is preferable to use.

Deciphering the marking of cement

The first symbols of cement marking:

Old GOST: PC - Portland cement, Portland slag cement with the addition of slag, is marked as ShPTs. Symbols can follow, for example, D20 - the percentage of additives.

New GOST: CEM I - without additives, CEM II - with additives. Further letters A and B are the number of additives, and the subsequent ones are their type.

A table of correspondence between the old, sometimes previously denoted by the letter “M” (for example, M400), and the new value is given below.

The first column is the value in kg / cm?, the second in MPa, the third is the recommended replacement.

300 = 29,4 – 22,5

400 = 39,2 – 32,5

500 = 49,0 – 42,5

550 = 53,9 – 52,5

600 = 58,8 – 52.5

The correspondence of other values ​​is easy to calculate using arithmetic. For example, 200 = (400/2) = (39.2/2) = 19.6.

Application of cements

For the vast majority of applications in individual housing construction, the above parameters are sufficient. Consider which grades are recommended for specific construction work.

1. Foundation

It should be massive and reliable, because it holds the load of the entire building.

The following brands are commonly used:

M200 - foundation for small buildings - garages, verandas, hedge base;

M400 - for residential 1 storey houses, since according to SNIP, concrete for residential buildings is needed at least M200:

M500 - for 2-story.

2. Walls

The required properties of the masonry mortar depend on their purpose. Each type has its own brand of cement:

M200 - walls of the veranda, gazebo, garage, barn;

M300 - interior bulkheads of a residential building;

M400 - load-bearing structures of the walls of buildings.

3. Homemade building materials

Cement or expanded clay concrete blocks, paving slabs or facing - M300.

4. Plaster

Interior decoration - M300,

Outdoor work - M400 5.

Screed, blind areas

A grade of 50-150 is usually used. When choosing the tensile strength of the screed for the floor, take into account the load, permeability, the intensity of the movement of weights, the weight of the furniture.

For filling gaps, cracks, grouting the surface, as well as other minor work, an arbitrary grade is used.

What to look for when buying?

1. Packaging

It is undesirable to buy cement in bulk, since it is not clear how it was stored. This option is possible only with a large amount of work, when the entire batch is purchased directly from the manufacturer or from a reliable supplier. If the products are packaged, then the bags must be double-layer, hermetically sealed, without damage. Too thin-walled packaging is most likely due to the fact that it lacks a moisture barrier, which can adversely affect the safety of the contents. Therefore, each bag should be controlled - there should be a feeling that there is a loose substance, and not a compacted monolith or cobblestones.

2. Quality

Good cement complies with the European standard ISO 9000, which is usually indicated on the label. If the products are not packaged, then often such designations are absent, or it is impossible to find them. Sometimes the origin of even packaged goods, not to mention loose goods, raises strong doubts, especially when there is also no certificate. It is worth paying attention to the excessively low price. If the material is supposed to be used for critical structures, then it makes sense to refuse such an acquisition.

3. Additives

They play an important role when a binder with special properties- plastic, frost-resistant, with accelerated curing, etc. Conventions There is no need for a non-specialist to know various additives, since you can always check with the manager of the trading company on the spot how this or that brand differs.

4. Release date

It is indicated on the packaging and documentation for the batch. It is advisable to purchase cement produced no more than a month ago, since the additives, as well as the cement base itself, lose about 20% of their initial properties in 3 months, and up to 40% in six months. Therefore, to ensure the required strength, the consumption also increases.

5. Brand

Quality can be determined by the popularity of the manufacturing company throughout the country or region. A good sign is that the trading organization has some assortment from this company. The presence of the contact phone number and address of the manufacturer on the package is also a good sign.

6. Price

Before buying cement, check the price of a similar product in the available market via the Internet or by driving through stores. Too low a price, most likely, indicates a substandard product.

Some remarks

It is believed that cement is the worse, the lower the strength characteristics. That is, M600

better than M500. However, it is not. For a building of 1-2 floors, there are enough characteristics that meet the M500 standard, and even then only for load-bearing wall structures, piles or some foundation elements. Purchasing brands with higher rates is a waste of money.

Do not buy cement in reserve - do not forget about the expiration date. It is advisable to take the quantity needed for a certain completed stage of work from one batch in order to exclude the heterogeneity of the resulting structure, and, as a result, reduce its reliability. For the next stage of work, fresh material is purchased.

If you had to purchase loose goods, then the approximate quality is determined as follows: a handful of cement is taken, and then squeezed by hand. If after that the material did not become lumpy, remained fluid, flowing freely through the fingers, then the product is of high quality. Note that a dark color is a clear sign that the product is too wet and is undesirable to buy.

The requirements for a binder in the preparation of concrete for pouring or assembling a foundation are high: 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 of residential buildings, the M400 PC is considered the minimum; for temporary and lighter ones, reduced requirements are allowed. Checking the certificate and expiration date is mandatory in any case, preference is given to cement released no later than 3 months, the material is not purchased in advance. Important technology standards include the exact observance of proportions, the preparation and correct sequence of loading components into the mixer, and the 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 mixed building composition. For pouring the drainage base, it is allowed to use cement with a low strength grade (final concrete - from M75 to M150), in all other cases the rule applies: the binder grade must be twice as high as the expected grade of concrete mix. Taking into account the minimum allowable M200 for foundation structures, the mortar is mixed with Portland cement with a strength of M400 (about this brand of cement).

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

• PC M400 D0 - withstanding loads up to 400 kg / cm2 at the end of curing, providing good durability, water resistance and frost resistance. Concretes based on it perfectly tolerate low temperatures, contact with ground and atmospheric moisture, and exposure to aggressive environments. Cement M400 D0 is suitable for foundations of any type, including reinforced and prefabricated ones (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 requirements for the soil.
• PC M500 D0 is recommended to be chosen during the construction of critical facilities, this brand consists only of their cement clinker, the proportion of extraneous additives (in this case, gypsum) does not exceed 1%. This has a positive effect on frost and moisture resistance, the variety belongs to the elite. Its use when mixing concrete for the foundation will pay off economically during construction in problem areas (in particular, flooded).
• PC M500 D20 - similar to the previous brand of cement, slightly inferior in terms of resistance to moisture and freezing (but not in strength), it still surpasses M400 in its characteristics.

Slag-based 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 variety. The main reason is the slow curing and low frost resistance. As a result, their use is permissible only on the advice of professionals and with the acceptance additional measures for the protection of foundation structures from frost heaving of soils. At the slightest doubt, it is better to choose Portland cement without impurities or specialized brands:

• B - fast-hardening binder, which is advised for limited periods of work.
• PL is a plasticized variety with increased frost resistance. Its input 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 other than PC.
• SS - special sulfate-resistant PCs.
• NC - tension cement. Concretes based on it have a compacted structure after solidification, without letting moisture in. NTs recommend choosing when laying the foundation of a house with a basement or erecting a monolith on flooded soils. They are also well suited for the repair and restoration of already operated structures.

Cements below M400 are allowed to be used in the construction of baths and light panel or wooden one-story buildings on dry and stable soils. To eliminate errors, they are repelled from the brand of concrete; when choosing it, such criteria as the expected weight load (mass load-bearing structures, including the foundation itself, the roofing system, snow cover and objects in the house) and soil parameters (freezing level, water rise, structural composition and soil homogeneity), pouring time and solidification conditions.

Cooking proportions

The minimum acceptable brand of concrete for pouring the foundation is M200 (better - more), when concreting the foundations of residential buildings within 1-2 floors, M250 is most often chosen. The recommended proportions of the components in the preparation of the M250 solution are 1:3:5 (cement, sand, gravel or crushed granite, 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 water introduced, at least 0.4.

Concrete brand	Ratio (C:P:SCH)	Volumetric composition per 10 l of cement for sand and gravel, l	Output of concrete per 10 l of cement, l
HRC 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, the reviews in this regard are unambiguous: it is better to take cement for the foundation of the house no earlier than 1-2 weeks before the start of work, checking the release date and certificate is required. There are no lumps in the fresh powder, it is easily passed through the fingers.

When in doubt about the integrity of the supplier, it is worth checking the quality of the material in advance: the right cement sets well within 45 minutes.

In addition to the use of components the right quality the sequence of their loading into the concrete mixer is observed. Recommended scheme: 80% of the total share of water → crushed stone → screened cement and sand → the rest of the water in small portions. Most plasticizers or hardeners are introduced at the end with strict observance of 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, bulk purchases are the cheapest. The rates 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 Portlandcement	4350	4100
PC M500 D0B (quick hardening)
PC M500 D0N (normalized clinker)		4650	4450
PC M400 D0	JSC Maltsovsky Portlandcement JSC Mikhailovcement JSC Lipetskcement	4300	4150
PC M400 D20		4200	3950

When building a foundation on your own and delivering it on your own transport, it is more convenient to use bags (it is easier to adjust the proportions to the measured weight). High-quality cement is offered by many domestic factories and manufacturers of dry building mixes: Novgorodsky CZ, Borshchevsky CZ (Lafarge), Mikhailovcement, Maltsovsky Portlandcement, OJSC Voskresenskcement, Mordovcement, Sebryakovcement, Rusean. The cost when buying it in packaged form is.

When buying cement, many of us know very little about this building material. As a result brickwork, foundation and mortar screeds are of poor quality and crack under the influence of load, frost and groundwater.

Ignorance of the specifics of the application various kinds cement, its grades and characteristics lead to an overrun of this material.

Untimely use and improper storage leads to damage and loss of invested funds.

In order to confidently navigate when choosing cement for repair, improvement or new construction, we will consider in more detail its classification, as well as strength and price indicators.

Cement is a powdered building material consisting of a binder base - clinker, filler and modifying additives. Upon contact with water, it turns into a plastic mass called cement paste. Hardening, it turns into a durable stone.

Unlike other binders (gypsum, lime), all types of cement harden and gain the necessary strength not only in air, but also in water.

The main characteristic of any cement is its brand. This is a numerical designation of its strength in the solid state, expressed in kg / cm2. The brand is determined in accordance with the GOST standards by testing the samples for bending and compression after 28 days of exposure. Fast-hardening types of cements are tested for strength 3 days after the preparation of the solution.

Brands of this group of binders are designated in numbers from 100 to 900(in increments of 100 or 50 kg/cm2). Today, cement grades below 300 are not produced. The most popular on the market are M400 and M500. High-quality cements (from M600 and above) are used in military, mine, airfield and hydraulic engineering construction.

When buying a bag of cement in a store, you will see on it not only the brand name, but also other abbreviations, the meaning of which we will now explain. In the retail network, Portland cement is most often sold, marked with the letters - PC.

To regulate the setting rate, increase frost resistance and water permeability, special additives are introduced into the cement composition. They are denoted by the letter D, after which the percentage of additives is indicated (0, 5, 10 or 20%). For example, Portland cement grade 400 with 20% chemical additives is marked as follows: PC 400 D20.

Slag Portland cement

In addition to Portland cement, Portland slag cement is used in construction. In addition to clinker, granulated blast-furnace slag is added to it in the amount of 30 - 65% of the total weight.

It is marked with the letters ShPTs and differs from Portland cement in several important parameters:

• resistant to soft river and aggressive sulphate ground water;
• low resistance to low temperatures;
• slowly gaining strength during the first 4 weeks;
• withstands action without loss of strength high temperatures(from +600 to +800 C).

The listed technical characteristics of cement using slag allow us to draw two important conclusions: concrete should not be made on it, which will be operated at low temperatures or subjected to periodic freezing and thawing.

In the cold season, it is better to use it for the preparation of mortars and concrete laid in heated rooms, and for open work in the summer.

The light shade of Portland slag cement allows it to be used for the preparation of decorative solutions, saving on the purchase of expensive alkali-resistant dyes.

An important advantage of cement based on blast-furnace slag is the low rate of loss of activity. Therefore, it can be stored longer than regular Portland cement.

The beginning of setting (hardening) for this cement occurs 3.5 hours after the preparation of the solution, and ends after 6 hours (air temperature +18 - + 22C). By this time, the solution loses its plasticity, and any mechanical impact on it leads to the irreversible destruction of the cement stone. For conventional Portland cement, the setting process ends after about 2 hours.

Special types of cements

Since cement is used in all sectors of the construction industry, there are many varieties of this binder.

The most famous of them are:

• Fast setting Portland cement, abbreviated BTC. It gains 60% of brand strength within 3 days and is used for high-speed construction;
• Sulfate-resistant cement (SSPC) it is used for massive foundations that experience the destructive effect of sulfate groundwater (dams, moorings, breakwaters);
• Cement using surface-active additives. If an additive is introduced into the composition that improves the plasticity and workability of the mortar, then the cement marking contains the letters PL. To reduce water permeability, a hydrorepellent substance is added, and the letters GF are added to the marking;
• Portland cement. It is used to isolate boreholes from groundwater penetration.
• Waterproof expanding cement. It is designated by the letters VRTs. He has very high density and is used for sealing cracks in reinforced concrete structures, waterproofing water pipes and mine structures;
• White (BTs) and colored cements. They are used for the preparation of decorative concretes and mortars used for laying facade and facing bricks.

The cost of this material depends on its brand and type. In addition, the final price of cement is influenced by the reputation of the manufacturer (brand).

The price of one bag of Portland cement grade 500 (weight 50 kg) that does not contain additives (PC M500-D0) is from 200 to 250 rubles.

Cement with additives is slightly cheaper. A 50-kilogram bag (M500, 20% additives) will cost you between 190 and 220 rubles.

A standard bag of M400 cement from different manufacturers costs from 160 to 190 rubles.

Prices for white cement M500 of domestic production start at 390 rubles. Turkish white cement M600 D0 (50 kg) is significantly more expensive. Its cost ranges from 540-570 rubles.

Consumption rates

When answering the question of how much cement is needed per cube of concrete, one must take into account its brand and the required structural strength. Great importance also has a release date, since this type of binder loses activity over time and is very sensitive to storage conditions.

Practice shows that it is more profitable to buy cement of a higher grade, since for the preparation of concrete or mortar of the same strength it can be taken 15-20% less than low-grade cement.

For example, the consumption of cement per 1 m3 of a solution of the "three hundredth" brand is: M500 - 500 kg, and M400 - 600 kg. To prepare one cubic meter of M200 concrete, you need to buy 400 kg of M500 cement or half a ton of M400 Portland cement.

To simplify the calculation of the composition of concrete or mortar, you can use the following formula: for structures that do not carry a large load (paths, floor screed, plaster), a ratio of cement M500 and sand 1:5 is sufficient.

For foundations, ceilings and other critical structures, the proportion should be 1:2. For tub solutions, a ratio of 1:4 is usually used.

Deciding for yourself which cement is better to choose, remember that the date of its release is no less important than the brand. Even if all storage conditions are observed, every 30 days it loses about 10% of its activity. This means that if 3 months have passed since the date of manufacture, then instead of the M500 you will buy the M350.

If the cement has been in the warehouse for six months, then its grade will not exceed 200 kg/cm2. Make a high-quality solution on such material, and even more so durable concrete unreal. Therefore, before buying, ask the seller for a document that clearly indicates the date of manufacture.