Concrete from 16 20 decoding. Concrete class - new (C) and old (B) designations. Correlation between classes and grades of concrete
The first half of September is over, but we continue to look for the most interesting events in Moscow in 2018.
- From 16 to 20 September
FROM 16 TO 20 SEPTEMBER
40. Concert Odnono
Odnono's music is much closer to spiritual mantras than to any of the "earthly" musical styles, although the last of the band's 10 albums, Betalab, has outlined a significant tilt towards "live" electronics with parts of ethnic instruments from various cultural traditions of the planet. On September 19, the team will return to the 16 Tons stage to once again become a beacon for everyone who seeks to become aware of themselves in this world. Start - at 20:00.
Until September 20, the HERE on Taganka Gallery will host the exhibition “Here Will Be the City of Organism Varenye” by the Varenye Organism art group, which includes Onton Abstract, Mitya Urbi Sokolov, Konstantin Antonov.
“Here will be the city of Varenye of the body” - this is an attraction city, a simulator city, an interactive city and an adventure city. The exposition-manifesto of public art as a psychoactive urban landscape, contributing to the disclosure of hidden human potentials. "Here will be the city of Varenye of the organism" - a presentation of an archive of unrealized ideas, sketches and layouts of future projects of a group of artists.
The exhibition will feature printed computer graphics, art installations, video installations. These works, reminiscent of schemes, or complex synthetic multidimensional spaces, are virtual projects of "non-children's" playgrounds. They form a new landscape space in which the object acts as a simulator for a person. For authors, the idea of a useful experience that can be obtained from a work of art is important.
"Varenye organism" is a union of "artists-molecules", as the authors of the project call themselves. They transform everyday space into psychic space, turn cities into huge playgrounds. The Union of Artists even has a specific mission - to generate new synapses with the help of technological games and unusual behavior.
42. Exhibition "Finds of my street"
Until September 17 inclusive, the Museum of Moscow will host the exhibition “Finds of my street”. Its opening is timed to the Archaeologist's Day, which is celebrated on August 15.
Once again, in the halls of the museum, you can see unique historical objects discovered by archaeologists on the streets of Moscow recently, since the beginning of 2018. The exhibition of archaeological finds of the 2017 season "Secrets of Moscow Dungeons" at the July Moscow Urban Forum 2018 was named the best in the nomination "City Exhibitions".
“Finds of my street” is about 100 artifacts, evidence of various periods in the history of Moscow, which until recently were literally under our feet on Moscow streets. At the exhibition, guests will see objects of everyday life of Muscovites from the Middle Ages to the end of the 19th century. A significant part of the items was found on the territory of the districts of Moscow, which are well known not only by historians, but also by the general public - Zaryadye and Kadash.
The exposition will include tiles with unusual plots, examples of the art of medieval casters, ceramics, religious objects. You can also see weapons, for example, a squeaker, found practically on Red Square, or boots of phenomenal preservation, allowing you to see the smallest details of the work of a five-century-old tanner.
43. Show “Ural Pelmeni. Beach shizon»
Another humorous show "Ural dumplings" this time will raise the topic of vacations and the beach. A real rest in Russian is when you try to eat as much as possible on all inclusive; when you smear sour cream on a body burned in the sun; when you are not afraid to swim behind the buoys and carry home a suitcase of souvenirs no one needs. "Beach schison" is declared open.
44. Exhibition “Confabrics of the 17th century. Monuments of facial sewing»
As part of the project of displaying individual works from the museum's storerooms, the exhibition "Konfalons of the 17th century" will be held in the hall of one monument until September 21. It will feature two items that were once part of the temple set. Banners are church banners, without which not a single religious procession can do.
Compared with the numerous surviving embroidered covers and shrouds, Old Russian banners are a rarity; they are not often seen in museum halls. The exhibited banners are made of velvet, decorated with fringe along the edges and tassels along the lower blades. On both sides, images are embroidered with silk and metal, so-called "golden" threads, which are probably associated with the dedications of the thrones of the temple.
In this case, these are “Saint Alexy, the Man of God” and “The Tikhvin Icon of the Mother of God”, “The Conception of the Righteous Anna” and “The Calvary Cross”. Spectators will be able to admire the skill of ancient Russian embroiderers, see the various techniques used in facial sewing of the 17th century, and also discover some of the secrets associated with the existence of these wonderful works of art.
The shrimp commercial fishery has a thousand-year history. And until very recently, sellers (fishermen) and buyers had disagreements about the price of shrimp. How to define it? By weight? By the piece?
The problem is that both large and small shrimp can be caught in one catch of shrimp. It is clear that large shrimp are in high demand and should cost more. To make it more convenient for buyers and sellers, shrimp were sorted by size and then sold by weight. Thus were adopted trade standards for the size of shrimp, which are now used by fishermen, sellers and cooks around the world.
What do shrimp sizes mean?
When you buy shrimp by weight, look at the label. In addition to data on the manufacturer and the place of catch, it will necessarily contain numbers, for example - 13/15 or 27/34. What are these numbers?This is the number of shrimp per 1 English pound or 1 kilogram of weight. The packaging indicates which weight units are used.
Those. in 1 pound of shrimp there will be from 13 to 15. And in one kilogram from 27 to 34.
There are 2.2 pounds in one kilogram. The measurement system depends on the country of manufacture.
In Russia, you can find the size for 1 pound and 1 kilogram.
Sometimes shrimp packaging may be labeled U/15 or U/10. This is a designation for large shrimp and means "under 10" - "under" or "about" 10 pieces in one pound.
These shrimp sizes are also called caliber and are considered the international trade standard.
Some Argentine shrimp (red deep sea) are labeled C1, C2, C3, CR and L1, L2, L3 and LR.
- The letter C means that the shrimp is without a head, and L - with a head.
- The letter R means that the size of the shrimp can be anything from 30 to 150. Such shrimp are called not sized.
Shrimp sizes - Number of shrimp per 1 lb/kg of weight
For the convenience of buyers, we provide a table of the size of shrimp per pound and the equivalent per kilogram. Sizes are for raw, fresh-frozen headless shrimp. For boiled-frozen shrimp as well as shrimp with a head, the number of pieces is indicated per kilogram.| Pieces per pound (0.435kg) | Pieces per 1 kilogram | Example |
| 6/8 (U8) | 13-17 | |
| 8/10 (U10) | 17-22 | |
| 10/12 (U12) | 22-26 | |
| 8/12 | 17-26 | Shrimps 8/12 |
| 13/15 | 27-34 | Shrimps 13/15 |
| 16/20 | 35-44 | Shrimps 16/20 |
| 21/25 | 45-56 | Shrimps 21/25 |
| 26/30 | 57-66 | Shrimps 26/30 |
| 31/40 | 68-88 | Shrimps 31/40 |
| 41/50 | 90-110 | Shrimps 41/50 |
| 51/60 | 112-132 | |
| 61/70 | 133-155 | |
Sizes of shrimp - Number of shrimp per 1 kilogram
Here is a table of the most popular sizes per 1 kilogram in Russia:| Number of pieces per 1 kg. | Example |
| 40-60 | Shrimps 40-60 |
| 50-70 | Shrimps 50-70 |
| 70-90 | Shrimps 70-90 |
| 80-100 | Shrimps 80-100 |
| 90-120 | Shrimps 90-120 |
| 90-140 | Shrimps 90-140 |
| 90+ | Shrimp 90+ |
| 100-200 | Shrimps 100-200 |
| 120+ | Shrimps 120+ |
| 140-160 | Shrimp 140-160 |
| 200-300 | Shrimps 200-300 |
Sizes of shrimp - Number of Argentinean shrimp per 1 kilogram
Size table of Argentinean shrimp per kilogram:| Marking | Pieces per 1 kilogram | Example |
| C1 | 30-55 | Shrimps C1 |
| C2 | 56-100 |
Concrete is currently the most demanded building material without it it is impossible to build a single structure, because it is concrete that is considered the basic basis of building art. Before using this product for its intended purpose, it is necessary to understand what the product is, how ready-mixed concrete differs from ordinary concrete, and what markings are inherent in it.
What is concrete
First, let's look at the difference between a factory mix and a commercial mix. If the concrete mixture was kneaded at the factory, and then was sold at facilities under construction, then such a product has the name of ready-mixed concrete. The difference between the factory mixture and the usual one is the high quality of the first type. This is confirmed by the available certificates.
Taking into account the strength index, the concrete class is denoted by the letter B and the numbers: B5; B7.5, B10 and so on. The number present in the formula indicates the pressure, expressed in MPa, that the presented products are able to withstand. For example, B10 is concrete, which in 95% of cases is able to withstand a pressure of 10 MPa.
What determines the brand of concrete? The brand of concrete implies the presence of letters and symbols: M50, M100, M150, M200 and so on. The number present in the formula indicates the compressive strength. It is obtained by the method of determining the average value from the results of testing samples. The compressive strength is obtained as the arithmetic mean of the 2 highest values in a series of 3 subjects. After the presented measures, a certain value is obtained, expressed in kgf / cm2, which shows the characteristics of the product brand in terms of compressive strength.
Table 1 - The use of concrete, taking into account the frost resistance group
| Frost resistance group | Designation | Scope of use |
| Low | less than F50 | Not very popular |
| Moderate | F50 - F150 | Frost resistance and water resistance of the material of this group has optimal performance. The presented products are widely used. |
| Increased | F150 - F300 | Due to the high level of frost resistance, such concrete can be used when laying the foundation in harsh climates. |
| high | F300 - F500 | This product can be used when laying the foundation with variable humidity. |
| Particularly high | over F500 | This high frost resistance is achieved through the injection of special additives. Involved in the construction of solid structures. |
Table 2 - The ratio between classes of concrete grades
| Strength grade of concrete | Concrete strength class (B) according to SNiP | Concrete strength class (C) according to SNB |
| M 50 | At 3.5 | – |
| M 75 | AT 5 | – |
| M 100 | At 7.5 | – |
| M 150 | AT 10 O'CLOCK | From 8/10 |
| M 150 | At 12.5 | From 10/12.5 |
| M 200 | At 15 | From 12/15 |
| M 250 | IN 20 | From 16/20 |
| M 300 | At 22.5 | From 18/22.5 |
| M 350 | At 25 | From 20/25 |
| M 350 | At 27.5 | From 22/27.5 |
| M 400 | At 30 | From 25/30 |
| M 450 | At 35 | From 28/35 |
| M 500 | – | From 30/37 |
| M 550 | At 40 | From 32/40 |
| M 600 | At 45 | From 35/45 |
| M 700 | At 50 | C 40/50 |
| M 700 | At 55 | C 45/55 |
| M 800 | At 60 | C 50/60 |
| M 900 | At 65 | – |
| M 900 | At 70 | C60/70 |
| M 1000 | At 75 | C 60/75 |
The video talks about how to check concrete for quality and brand compliance:
Which water repellent is better to use for concrete is described
Concrete is a popular building material that is actively used today in the construction of various structures. When choosing this product, you must focus on the formula that is indicated on the package. Only its correct decoding will allow you to accurately determine the technical characteristics of the selected product.
Construction is one of the most developing areas in the modern world, and every year specialists create new types of building materials that have a better set of characteristics than the previous ones. And if we talk about what is still used more often, then this, of course, is concrete products, a guarantee of strength and reliability for any structure.
Properties of concrete B 20
As we have already said, it is difficult to imagine modern construction without the participation of concrete of different grades. The most popular both in civil and industrial buildings is concrete grade B 20. Preference is given to this artificially created material because of the ideal combination of its cost and quality. This is especially true for private construction, since the entire work process is carried out by hand.
Concrete B 20, which corresponds to grade 250 (according to new building codes, it is marked as concrete C16 20) is made at concrete plants and delivered to construction sites in special mixers. During transportation, the solution is continuously mixed and fed to the construction site without losing its properties.
Consider the main technical characteristics of concrete in 20:
- Set of compressive strength (20 MPa) after 28 days. A certain one is achieved by using components of a given quality.
Note!
Only full observance of the proportional ratio of ingredients in the composition of the mixture can give the maximum result.
Any slightest deviation leads to a loss of properties, experienced builders and designers are aware of this, so the stage of creating a mixture is clearly controlled.
- Frost resistance (designation F) of products and structures made of material of this class varies in the range F100, F150, F200. The number after the letter indicates the number of cycles of alternate freezing and thawing of the sample tested under laboratory conditions. To increase the frost resistance index, special additives are introduced into the concrete composition.
- The specific gravity of M250 concrete is about 2.3 tons per cubic meter. This figure characterizes the density of the product, and depends on the percentage of air inclusions and hardened mass, after evaporation of the water that is part of the mixture.
- Concrete grade C16 20 may have a water resistance in the range from W2 to W. The water permeability of the specimens is tested by exposing the test specimen to a water column under high pressure until the infiltration begins.
- Another indicator is the modulus of elasticity. To determine this characteristic, the mixture is subjected to heat treatment in autoclaves to reduce the curing time.
Grade C16 20 with a draft of a mixture cone up to 4 cm and a filler of a maximum fraction of 40 mm has an elastic modulus of 394 kgf / sq. cm and, accordingly:
- Fractions 80 mm - 424 kgf / sq. cm.
- Fractions 120 mm - 445 kgf / sq. cm), etc.
Application area
High physical and technical characteristics and advantages of B 20 concrete ensure its wide application in various areas of construction production and for various products:
- Construction of buildings of various scales, including large-sized ones. In the construction of high-rise buildings, the strength of structures that have to withstand serious loads is of great importance.
Important!
The use of one or another brand of concrete is strictly regulated by SNiP and GOST "Building materials", "Reinforced concrete structures".
Replacing the brand contrary to the recommendation of these documents is permissible only after agreement with the design organization and approval by the architectural control bodies.
- Manufactured under factory conditions designed for medium load.
Note!
The construction of buildings and structures from prefabricated reinforced concrete significantly reduces construction time, but requires the use of specialized equipment.
- Arrangement of platforms, paths, blind area. Concrete B20 copes well with the aggressive effects of environmental conditions and withstands the loads from traffic.
Production of concrete mix
To create high-quality concrete of the appropriate brand, the process technology and the percentage of the ingredients of the mixture should be strictly observed.
Composition of concrete M 250
The instruction for the preparation of concrete mix B20 gives the following calculation of the production composition per 1 m3 (1000 l):
- The main binder is cement - 360 kg.
- Fillers:
- Sand (humidity 5-6%) - 536 kg.
- Crushed stone (moisture content 1%) - 1141 kg.
- Water - 133l.
- Additives affecting frost resistance, plasticity, water resistance:
- Plasticizing C 3 - 3.085 kg (35% concentration).
- Plasticizing LST - 3.6 kg (20% concentration).
- Air-entraining START -0.72 kg (1% concentration).
building material cost
The price of concrete grade B20 directly depends on the additives introduced into the mixture and the quality of the coarse aggregate. Concrete on granite rubble will be more expensive than on gravel. The reputation of the manufacturer is also important. The latest equipment works at large concrete units and GOST standards are strictly observed.
On average, the cost of 1 m3 of concrete mix with indicators F150-200, W2-4 of well-known manufacturers (LLC Obrey, Garant Beton, BSU No. 5) will be 3400-3500 rubles.
Conclusion
We hope that the above information was useful to you, and we decide to recall a few important points. Firstly, in order to obtain high-quality products with proper strength, grades of at least 200 (for residential buildings) should be used.
Secondly, it is better to mix the mortar with a concrete mixer, this allows you to reduce the construction time and make the whole process easier for you (workers). In the videos presented in this article, you will find additional information on this topic.
The designer cannot do without understanding what concrete is, what its classes are. The main provisions on concrete are regulated in DBN V.2.6-98:2009 "Concrete and reinforced concrete structures", which in Ukraine has been put into effect since 2011. In fact, this regulatory document is a translation of a similar European standard.
For some designers, the new designation of the concrete class came as a surprise. Even construction organizations that are well versed in grades start making mistakes. In order to clarify the designation of the class of concrete, this material is written.
Correlation between classes and grades of concrete
It should be noted that almost no one uses the brand of concrete. However, to understand some of the old typical designs and other engineering solutions, you should remember where you can find a table of ratios for compressive strength.
If earlier the concrete class was designated as B20, now the same concrete class is designated as C15 / 20. The fact is that in some European countries, such as the UK, a cylinder is used to test the compressive strength of concrete. Its height is twice its diameter. In other countries, a concrete cube is used to test the strength. Therefore, for these samples, the indicators will be different.
Example. Concrete class С12/15 means:
- minimum compressive strength of the cylinder 12 MPa;
- the minimum compressive strength of the cube is 15 MPa.
15 MPa - this is the usual class. B15, which we use.
| Strength class of concrete (C) according to DBN | Strength class of concrete (B) according to SNiP | Average strength of concrete of this class R | The nearest grade of concrete in terms of strength is M, kgf / cm 2 | Deviation of the nearest concrete grade from the average strength class R - M / R * 100% |
|
| MPa | kg/cm2 | ||||
| - | B0.35 | 0,49 | 5,01 | M5 | +0,2 |
| - | B0.75 | 1,06 | 10,85 | M10 | +7,8 |
| - | IN 1 | 1,42 | 14,47 | M15 | -0,2 |
| - | B1.5 | 2,05 | 20,85 | M25 | -1,9 |
| - | IN 2 | 2,84 | 28,94 | M25 | +13,6 |
| - | B2.5 | 3,21 | 32,74 | M35 | -6,9 |
| - | B3.5 | 4,50 | 45,84 | M50 | -9,1 |
| - | AT 5 | 6,42 | 65,48 | M75 | -14,5 |
| - | B7.5 | 9,64 | 98,23 | M100 | -1,8 |
| C8/10 | AT 10 O'CLOCK | 12,85 | 130,97 | M150 | -14,5 |
| С10/12.5 | B12.5 | 16,10 | 163,71 | M150 | +8,4 |
| C12/15 | B15 | 19,27 | 196,45 | M200 | -1,8 |
| C16/20 | IN 20 | 25,70 | 261,93 | M250 | +4,5 |
| С18/22.5 | B22.5 | 28,90 | 294,5 | M300 | +1,9 |
| C20/25 | B25 | 32,40 | 327,42 | M350 | -6,9 |
| C25/30 | B30 | 38,54 | 392,90 | M400 | -1,8 |
| C28/35 | B35 | 44,96 | 458,39 | M450 | +1,8 |
| С32/40 | B40 | 51,39 | 523,87 | M550 | -5,1 |
| С35/45 | B45 | 57,82 | 589,4 | M600 | +1,8 |
| С40/50 | B50 | 64,24 | 654,8 | M700 | +6,9 |
| С45/55 | B55 | 70,66 | 720,3 | M700 | -2,8 |
The average strength of concrete of each class is determined with a standard coefficient of variation equal to v=13.5% for structural concrete and v=18% for heat-insulating concrete according to the formula
where B is the value of the concrete class, MPa:
0.0980665 - conversion factor from MPa to kg / cm 2 >.
Concrete class and its application in construction
It should be understood that in addition to the class of concrete, its frost resistance (F), water resistance (W) and a number of other indicators should be taken into account. Often, developers search the Internet for information about the class of concrete that must be used for a particular design. There is no direct answer to this question. It is necessary to analyze each individual case, taking into account the existing loads on the structure. However, there are general recommendations for the use of a concrete class.
С8/10 (В10) used for the construction of concrete preparations for monolithic structures. He does this so that when laying concrete, the "milk" does not run into the ground. Also, concrete preparation allows you to more accurately control the required values of the protective layer. In some cases, this class of concrete is used for the construction of screeds and walkways.
C12/15 (B15) often used in private construction for all structures that perceive a purely vertical load. These can be foundations, walls, columns, fences, etc. Not recommended for concreting complex building elements.
С16/20 (В20) almost universally used for concreting monolithic structures, from foundations to retaining walls. It can be used for concreting floor slabs that do not bear a large load.
C20/25 (B25) used for the manufacture of pile foundations, grillages for large structures, crossbars and beams with a large span. Pools, vertical walls and ceilings are also built from concrete of this class.
C25/30 (B30) It is used for the construction of bridges and hydraulic structures where high strength of concrete is required. Also, this class of concrete can be assigned under difficult operating conditions of structures.
Table of possible applications of the concrete class
| Construction concreting | |
| Concrete class for armored belt | |
| Concrete class for garage floor | |
| Foundation concrete class | C12/15 (B15) or C16/20 (B20) |
| Concrete class for monolithic slab | Basically C20/25 (B25) |
| Concrete class for columns | C16/20 (B20) or C20/25 (B25) |
| Concrete class for grillage | Basically C20/25 (B25) |
| Retaining wall concrete class | C16/20 (B20) or C20/25 (B25) |
| Concrete class for blind area | С8/10 (В10) |
| Concrete class for strip foundation | C12/15 (B15) or C16/20 (B20) |
| Concrete class for bored piles | Basically C20/25 (B25) |
| Floor concrete class | C8/10 (B10) or C12/15 (B15) |
| Concrete class for monolithic walls | Basically C20/25 (B25) |
| Concrete class for paving slabs | C8/10 (B10) or C12/15 (B15) |
| Screed concrete class | C8/10 (B10) or C12/15 (B15) |
| Pool concrete class | C25/30 (B30) |
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1 Serzhik 23.12.2018 23:17
I quote Ilona:
And it does not bother anyone that B15 is interpreted as 15 MPa (according to the European standard) and is immediately equalized to 19.27 MPa as the corresponding class B15 (the existing standard).
Doesn't bother at all. I read and see all the letters. Where the minimum strength is written and where the average strength value is written - it is natural that there will be different numbers here.
