Cement is the basis of any capital construction. This popular material is used at all stages of the construction of buildings and structures-from laying the foundation to concreting pavements and paths. There are several types of cement, but the most popular is Portland cement, which is a powdered binder based on ground Portland cement clinker and gypsum stone. When interacting with water, Portland cement takes on the consistency of plastic dough, which subsequently hardens to form a solid artificial stone.

What does the cement brand mean?

The main characteristic of any cement is its brand-a symbol that is expressed in numbers and means the strength of the finished concrete product after aging for 28 days (the time during which the cement gains 95-98% of its maximum strength). The brand of cement is assigned in accordance with the GOST 31108-2003 standard, based on the results of compression and bending tests of samples. Grades of Portland cement are expressed in numbers from 100 to 900 (M100, M200, M300, etc.). The figure indicates the compressive strength of this material. So, M 400 grade cement is not less than 400 kg per square centimeter. Today, the most popular brands on the market are M400 and M500-they are optimally suited for all types of general construction work in terms of price and quality. High-grade cements and special construction mixes are intended for hydraulic engineering, military, tunnel and airfield construction. The marking of cement also reflects the presence / absence of special additives in the dry mix-modifiers that improve the characteristics of concrete (improve anti-corrosion characteristics, increase frost resistance and moisture resistance of the solution, increase the speed of solidification, etc.). The presence of additives and their amount is indicated by the “D”index. Its numerical value is indicated in the range from 0 to 20 (D0 – 0% of additives, D5-5% of additives, D15-15% , etc.). Then the letter “H” or” B ” follows in the marking (N – normal hardening, b – fast hardening). Here is an example of decoding Portland cement according to the state standard 10178-85:PC M400 D20 B — fast hardening Portland cement with additives, the amount of which does not exceed 20%. The number 400 indicates that the compressive strength of the finished product is at least 400 kg per square centimeter.

Decoding the modern marking of cement

If the Portland cement is certified according to the current GOST 31108-2003 standard, the marking type “M400 ” or” M500 ” on the package may not be. new label looks like this: CEM I 42.5 B, CEM II 32.5 B, etc. According to the new rules, it indicates one of two designations:

CEM I-Portland cement that does not contain any additives;
CEM II-modified Portland cement (with additives)

If according to the 1985 standard, the strength of Portland cement was indicated in kilograms per square centimeter, then according to the new rules, this key parameter is indicated in megapascals (MPa). For example, the M500 brand corresponds to the designation-42,5. then the marking should be followed by the index: H-normalnokverdet or b-bystrokverdet. Example of decoding Portland cement according to the modern standard of designations:CEM II 42,5 B-fast hardening Portland cement with additives, strength corresponds to the M500 grade. TSEM I 22,5-Portland cement without additives, strength corresponds to the M300 brand.

What brand of cement should I choose?

If cement is needed to prepare concrete that will be used for filling critical construction elements (foundations, lintels, floor slabs, etc.), it is recommended to use the M500 brand (CEM II 42.5). For masonry mortar in the construction of walls made of bricks and blocks, M400 cement (CEM I 32,5) is quite sufficient. In general, this brand is considered optimal for performing a wide range of general construction works in the “price-result” ratio. It meets all the requirements of private construction. When choosing from the M400 and M500 grades, many experts recommend Buying Portland cement of the highest grade — the cost of the material will differ slightly, but the cement consumption will be significantly lower. For example, when choosing M500 (CEM II 42.5) for the preparation of concrete and masonry mortar, approximately 15% less binder material is required than when choosing cement of a lower grade M400. To prepare one cubic meter of concrete of the common M200 brand, it is enough to purchase 400 kg (8 standard bags) of M500 cement or 10 bags of M400.

How do I check the quality of cement?

Unfortunately, not all products presented above the market meet GOST standards. To purchase high-quality cement of the declared brand, and not a dubious product with an admixture of ash and granite dust, you should carefully study the accompanying documentation and check whether the packaging contains information about the manufacturer, make sure that the packaging is authentic. Each batch of Portland cement is accompanied by a quality document containing the following information:

manufacturer’s name, production address;
marking (symbol for cement) that contains information about the strength of cement and the presence of additives;
batch number and date of shipment;
designation of the GOST 31108-2003 standard

The date of manufacture (packaging) of cement has the same priority as its brand. It should be remembered that over time, cement loses its declared strength — the longer a bag of cement is in a warehouse or in a store, the worse the quality of the product. When choosing cement, you should pay attention to the physical properties of the dry mix. The cement should have the form of a fine powder from light gray to dark gray in color. The presence of green shades indicates a sufficient iron content, which is a good sign. can check the quality of cement by performing a small analysis. To do this, you will need mineral water (such as Essentuki-17), rubber gloves, a container and a kneading spoon. About half a glass of cement is poured into the container and mixed with a small amount of mineral water to a thick dough. From the resulting mass, an oval cake is formed, thickened to the center and thin at the edges. A high-quality mixture starts false setting almost instantly, noticeably heats up in the thick part.