A natural stone in all years it was considered the most durable and durable building material. The cost of stone and structures made from it is too high due to the high costs of its extraction, processing, and laying. Therefore, analogues were created natural stone- concrete. The most effective is concrete M350 B25 based on Portland cement. Thanks to high performance the material is considered ideal for the construction of structurally complex buildings and structures.

Composition and proportions of the mixture

Concrete grade M350 belongs to the elite categories of building mixtures. It is intended for the design of buildings with high physical, atmospheric and mechanical loads. Compressive strength characteristics are especially high. In many ways, such high properties are ensured by the correctly selected composition of the mixture.

F100 concrete contains cement, water, crushed stone, sand, anti-frost and plasticizing additives. Each ingredient differs in strength, grain size and other important parameters:

1. It is allowed to use sand with any grain size: coarse, fine and medium.
2. It is possible to use crushed stone or gravel of granite or lime origin.

The property of rapid hardening is ensured by the high content of Portland cement in the composition of the B25 solution. Ready-mix concrete M350 is produced from Portland cement not lower than M400. For 10 kg of mixture, the aggregate consumption will be: 15 kg of sand plus 31 kg of crushed stone. If the M500 grade of cement is available, then for 10 kg of dry mixture there will be 19 kg of sand and 36 kg of crushed stone.

Converting mass units to volume units:

• per 10000 cm3 B20 concrete from M400 cement should take 14 liters of sand and 28 liters of crushed stone;
• for 10000 cm3 f100 concrete from the M500 cement grade requires consumption of 19 liters of sand and 36 liters of crushed stone.

When calculating the proportions for a volume of 1m3 in mass terms you will need:

• 400 kg of 500th cement;
• 752 kg of purified sand;
• 1000 kg of crushed stone or gravel;
• 175 liters of water.

What kind of B25 mixture you will get can be judged by the proportion. The rigor to which it is observed, how thoroughly the ingredients are mixed, determines the homogeneity of the mass. If the conditions are not met, there will be undesirable losses in the strength of the finished concrete mass, which will reduce the technical and operational performance of the structure being built.

Advantages

The advantages of this brand are numerous:

1. High strength qualities within 327 kgf per square cm. allow the material to withstand maximum loads.
2. The high mobility of P2-P4 is regulated by plasticizers, so this value can reach even higher values. The most widely used category is P3.
3. Adjustable frost resistance in a wide range from F50 to F200. Thanks to this parameter, it is possible to achieve the structural integrity of the structure being built for the entire period of operation in harsh conditions caused by sharp fluctuations temperatures
4. Building materials of water resistance class W2-W8 significantly expand the possibilities of using the material. This property provides a high degree of protection against water absorption. With maximum moisture resistance, the materials obtain a structure without cavities or air bubbles.
5. Increased compression resistance allows 1 cm sq. material can withstand pressure up to 8 kg.
6. The m350 product is characterized by its abrasion resistance and resistance to aggressive environments.
7. High density 1800-2500 kg/m3 guarantees the reliability of structures. Categories with a volumetric weight of about 2200-2400 kg/m3 are more often used.
8. Environmental friendliness and durability.

Flaws

Despite its elitism and versatility, the M350 c25 B27 brand has technical disadvantages:

1. High fluidity due to the use of plasticizers, which increase mobility to P3, which narrows the scope of application of this brand.
2. Because of large quantity cement, ready-mixed concrete B25 quickly thickens and hardens, so quick delivery to the construction site is required.
3. The cost of 1 m3 of concrete in this category is high, which, together with delivery costs, increases the cost of the finished structure.

Areas of use

High-strength concrete m350 c20 with strength B27 and maximum moisture resistance, frost resistance F200 is intended for the construction of hollow-core floor slabs, airfield slabs and other buildings that can withstand enormous loads.

The use of additives varies the class of concrete over a wide range. Therefore, concrete can always be selected depending on the requirements for a particular stage of the construction process. For example, concrete grades C20 and C25 are used to pour slab foundations under multi-story houses, equip beams, columns and floors in monolithic construction. The material of this brand is used for the construction of most residential, public and commercial buildings.

Mixture varieties m350 w6 b20 C25 belong to the heavy category. The materials are suitable for the construction of cottages, for the construction of critical stairs and flights, wells for sewers and septic tanks, and other objects that can withstand high tensile pressures.

Due to its high moisture resistance, which gives it the ability to withstand atmospheric phenomena and the effects of underground and melt water, W6 - W8 concrete is used for the construction of airfield slabs and concrete pavement for airfields.

M350 concrete is most often used for the device monolithic foundations: strip, pile-grillage, columnar and slab foundations, manufacturing concrete stairs, crossbars, beams, hollow-core floor slabs, columns. For private construction, ready-mixed concrete class B25 M350 is also used for constructing swimming pool bowls. Monolithic walls and monolithic slabs floors. Concrete M350 is very durable, has high frost resistance and is very resistant to abrasion. This concrete belongs to structural concrete, often used in reinforced concrete structures. For example, PAG airfield road slabs are produced from M350 concrete, which are used in extreme conditions. Due to stricter requirements for the safety of buildings and structures, M350 concrete is often used in commercial construction to reinsure and increase reliability building structures.

Base, cement

• crushed gravel;
• granite crushed stone;
• crushed limestone;
• cement M-400 and M-500.

Proportions and composition of concrete M350 B25

The GEOBETON production association delivers and supplies concrete to any district of St. Petersburg and the Leningrad region from 4 control units in the north, south and east of the city, in close proximity to the Ring Road. To buy concrete M350 with delivery, just send us an application or use the calculator.

Concrete grade M350 B25 produced by us has all the necessary certificates. Control of raw materials and finished products is carried out by the plant’s own certified laboratory. At the request of the customer or design parameters during the production process, it is possible to introduce additional plasticizer additives into the concrete mass to increase the water resistance and frost resistance of concrete.

The most famous and most in demand building material has been and remains concrete. Not a single small or large construction site can do without it. There are many varieties of this material, but heavy concrete M350 occupies a leading position in the unofficial rating. It is used in the construction of responsible monolithic structures, as well as for the production of prefabricated reinforced concrete products, including prestressed ones.

Specifications

All requirements for source materials and properties of the final product are set out in GOST 26633-2012 “Heavy and fine-grained concrete. Specifications" Therefore, when producing concrete grade 350, one should strive to achieve the following indicators:

• Compressive strength is determined by destructive or non-destructive testing. In the first case, standard cubes measuring 10*10*10 cm are made and kept under conditions at a given temperature and humidity conditions. Then the test is carried out on a special press. The pressure at which the cube begins to collapse is an indicator of its tensile strength. For class B25 concrete, this value corresponds to 25 MPa or 350 kg/m/cm2.

Non-destructive testing methods are usually applied to ready-made structures. For this, ultrasonic and radiometric instruments and laboratory hammers are used: old ones - Fizdel and Kashkarova or modern ones, for example, Schmidt OS-120.

• Mobility. This indicator is determined based on the results of testing heavy concrete M350 using a standard cone. If the cone draft is 0-10 mm, it is a rigid mixture, from 10 to 50 mm is a low-moving mixture, from 60 to 140 mm is mobile and over 150 mm is cast. Plasticizing additives help regulate mobility without changing the water-cement ratio.
• The frost resistance index for our concrete should be F200. This means that the tested samples will not change their properties, structure and integrity after 200 cycles of alternating freezing and thawing.

The list of technical characteristics of concrete M 350 is completed by its volumetric weight, which can vary from 1800 to 2500 kg/m 3. This variation depends mainly on the properties of the coarse aggregate and the raw materials from which it is made. The normal and most acceptable weight value for 1 m 3 of m350 concrete is considered to be 2200-2400 kg/m 3.

Preparation

To obtain the correct concrete mixture, an accurate selection of its components is necessary. The quality of the final product is affected by:

• production time, brand and condition of cement;
• strength of crushed stone (it is not advisable to use gravel for capital structures);
• purity and fractionation of sand; it does not contain clay and silty impurities.

Water should also only be used clean, normal temperature, not cold.

For orientation, we offer two options for M350 concrete recipes. One of them can be called traditional or standard, the other – folk, since for measurements many independent craftsmen use buckets rather than scales.

Table with the composition of concrete M350 per 1 m 3:

If we talk about the proportions in buckets, then the ratio of materials will be as follows: for 1 bucket of cement, take 1.7 buckets of sand and 3 buckets of crushed stone. Water is added in such quantity as to obtain a mixture of the desired workability.

To prepare concrete, it is necessary to prepare the estimated amount of materials (the basis is the consumption of cement per 1 cubic meter of mixture), as well as the following tools and devices:

• a mobile concrete mixer, or a suitable container for mixing the composition - a trough, a bunker;
• construction mixer, you can use a hammer drill with an appropriate attachment in the form of a stirrer;
• clean water not only as a component of concrete, but also for washing tools and equipment.

First of all, add the dry ingredients and mix them as thoroughly as possible. If we use plasticizers, antifreeze or any other additives, then we first dilute them in a certain amount of water intended for mixing the concrete mixture. Now add the resulting solution to the dry composition, without stopping stirring, and then gradually pour in such an amount of liquid to achieve the desired plasticity.

Important! To prevent delamination when working with the concrete mixture, you should not get carried away with the long operation of the concrete mixer. To obtain high-quality concrete, 5-7 minutes are enough.

In order to reduce the time it takes for concrete to reach its design strength, various technologies are used: heat treatment steam, electric heating, creation of optimal heat and humidity conditions during storage of finished products.

Where is it used?

Due to its good performance properties, high strength and density, this category of concrete is used quite widely, including for:

• Construction of foundations for powerful buildings or equipment. In this case, it is necessary to take into account the ability of the soil to bear high loads and use reliable materials for formwork, since a cube of M350 concrete weighs quite a lot - up to 2.5 tons.
• Production of critical prefabricated reinforced concrete products - beams, trusses, crossbars, columns, covering and floor slabs (ribbed and hollow-core).
• Construction of monolithic structures - reinforced concrete grillages for pile and columnar foundations, walls and partitions using the sliding formwork method.
• Creation of structures for arranging airfield and road surfaces.

The scope of use of heavy concrete B25, except for price, is not limited in any way. The main thing is that the material is of high quality.

When designing buildings, after calculating the strength of building structures, a grade (or class) of concrete and a reinforcement scheme are proposed. Strength for normal use is within the limits of B15...B20 (M200...M250). Concrete B25 and higher classes are usually recommended by designers for critical industrial, socio-cultural, shopping and entertainment, and other similar facilities and their structural load-bearing elements.

The cost of class B25 concrete is compensated by the fact that, while maintaining the load-bearing capacity, it allows one to reduce the geometric dimensions of the structure and, accordingly, the weight. This gives a tangible economic effect by reducing the load on foundations or installation work.

Let's consider what concrete class B25 or in the old classification M350 is, its characteristics. After the introduction of new standards, which changed the units of pressure from kg/cm² to MPa (megaPascals), SNiPs and GOSTs changed the methodology for determining strength. Instead of the destructive force applied to a cube-shaped sample, measured in kg/cm², determining the brand, new specifications, called concrete class. They correspond to pressure in MPa, which in 95 cases out of 100 can withstand a cube with an edge of 15 cm without destruction. For example, the new standard implies that strength class B25 corresponds to grade M350.

Main characteristics:

• Average compressive strength is 327 kg/cm²;
• Workability - within P2…P4;
• Frost resistance – F200;
• Water resistance – W6-W8;
• Density, since B25 is a heavy type, has an indicator of up to 2500 kg/m².

For example, the designation B25, W6, F200, P2...P4 indicates that this is heavy concrete (grade M350) class B25, mobility P2...P4, with frost resistance up to 200 freeze-thaw cycles and an increased water resistance coefficient W equal to 6 kg/cm² .

Composition and proportions

To correctly design concrete with strength class B25, it is necessary to calculate the number of components that will be required for preparation. These include:

• Portland cement;
• Sand;
• Crushed stone;
• Water;
• Additives used to increase the plasticity (workability) of a liquid concrete mixture, density, frost resistance, water resistance, and other properties.

One of the main parameters when preparing concrete mortar is the water-cement ratio, that is, the proportion in parts by weight per unit volume of water and cement. An insufficient amount of liquid will lead to difficulties during mixing and poor workability. Excess - the structure will be loose, permeated with a network of air bubbles and shrinkage cracks, which will lead to a decrease in load-bearing capacity.

To prepare the B25 mixture, cement with higher strength is usually used, that is, its grade should be no lower than M400...M500.

Quartz sand, which can be river or quarry, is used as a fine aggregate. It is better to use clean river sand, since quarry sand may contain impurities that negatively affect the setting process.

Coarse aggregate – crushed stone. To prepare the solution, gravel or granite with a fraction of 30...50 mm is most often used. The use of granite crushed stone increases density and frost resistance.

The composition of class B25 concrete, proportions for preparing 1 cubic meter of mortar with mobility P3, without plasticizers and other additives are given in the table:

Scope of application

High-strength concrete, starting from B25, is used for prefabricated and monolithic elements frames, reinforced concrete structures buildings - floor slabs, columns, crossbars, trusses and crane beams. Concrete B25 (M350) and higher classes are used for the manufacture of monolithic foundations, pile-grillage reinforced concrete structures, bathtubs, and walls of swimming pool bowls. Heavy, super-strong compounds are used in road construction for the construction of bridges and tunnels. Concrete B25 (M350) is well suited for the construction of airfield runways, which must withstand long-term cyclic loads.

The use of such concrete is regulated by SNiPs and GOSTs related to work on the manufacture of reinforced concrete products. When concreting, vibration compaction must be used. To do this, when pouring prefabricated structures in a factory, stationary vibration stands or vibration platforms should be used, and when casting monolithic structures, vibrators with a flexible shaft should be used.

In addition to the widespread use of class B25 in industrial construction, it can be recommended for the construction of individual residential buildings.

It is necessary to prepare such a composition with careful adherence to the recipe. However, to prevent unforeseen and force majeure situations, it is better to order the mixture at mortar-concrete units, where incoming quality control of materials is required, as well as inspection of the resulting products. Upon delivery, the seller bears full responsibility for the quality of the solution and compliance with the characteristics.

OOO Atlant sells ready-mixed concrete M350 in any volume with delivery throughout Moscow and the Moscow region at a low price, because we are a manufacturing company. Shipment is carried out around the clock, 7 days a week.

Heavy concrete M350 differs from products of other brands in improved strength characteristics, good wear resistance and water resistance. Concrete structures of this brand can withstand large vertical and horizontal loads, and are resistant to precipitation and temperature changes.

The composition of concrete grade 350 includes traditional components - cement grade M500 d0, sand (fineness modulus - 2.4-2.6), as well as granite or crushed gravel (strength grade 1400 and 1000, respectively: fractions 5 to 20).

Scope of concrete application:

• construction of reinforced concrete structures, monolithic foundations, beams, slabs, swimming pools;
• construction of residential, administrative and industrial facilities;
• laying road surfaces, storage areas, pedestrian sidewalks. The use of concrete with a compressive strength of B25 is not always advisable in small-scale construction due to its high cost.

You can buy B25 M350 concrete mix without extra charges and overpayments directly from the manufacturer right now at Atlant LLC. Delivery of the order is made in Moscow and the Moscow region.

Prices for concrete grade 350

Main characteristics of B25 concrete and price per cubic meter

1. Compressive strength class - B25. Concrete of this grade can be used in large-scale capital construction.
2. Frost resistance index - F200. Concrete can withstand up to 200 complete freeze/thaw cycles.
3. The mobility of the concrete mixture is P2–P5. For more convenient installation of the solution, a polycarboxylate-based plasticizer is added to its composition.
4. The water resistance index of B25 concrete is W6–W10. The mixture contains virtually no air bubbles, which prevents the absorption of moisture by the concrete solution.

The cost of B25 concrete with granite crushed stone aggregate is 3,700 rubles per cubic meter, on the placeholder from crushed gravel- 3450 rubles per cubic meter. Prices are indicated without delivery and including VAT - 18%.

Order ready-mixed concrete of this and other brands directly from the manufacturing plant Atlant LLC. Shipment is carried out 7 days a week, around the clock.