Concrete is a building mixture that consists of four main components: sand, cement, water and crushed stone (gravel, screenings). Various plasticizers, fixers and other chemical additives are added to some types of concrete to improve the properties of the original product.

The ratio of materials by weight for preparing concrete is approximately the following: 1 part cement, 4 parts crushed stone, 2 parts sand and 0.5 parts water.

Brand selection

The choice of concrete grade depends on the future scope of its application, the loads to which it will be subjected, and the environment in which the concrete structure will be located.

The digital designation of concrete grades shows its compressive strength in kgf/cm². This parameter is determined by the cube strength test of concrete, in which cubic or cylindrical samples of a certain brand are tested under pressure after 28 days of hardening under normal conditions.

The main areas of application of M350 concrete are monolithic foundations, reinforced concrete structures of a certain type, floor slabs, columns, load-bearing beams, swimming pools, etc. This concrete is used in objects that are subject to special loads during operation.

Compound

Composition of concrete M350 determined by the quality of its ingredients, in particular the brand of cement. To prepare concrete of this brand, they usually take. But if concrete is prepared at a factory, then the technologists there take into account many more different nuances.

Concrete M350 contains standard components; it can be prepared using granite or gravel screenings. This brand is very popular in construction, which is due to its excellent characteristics and. When constructing the foundations of high-rise buildings, the use of this brand is prerequisite.

Density

An important factor is the density of M350 concrete. Combined with good frost resistance, water resistance and strength, this brand is the most popular in both mass and individual construction.

A common composition of M350 concrete, which is used mainly for home construction:

• 420 kg of cement,
• 750 kg of sand,
• 1050 kg crushed stone
• and 210 liters of water.
• some also add a plasticizer to this recipe.

The video in the article will also help you find out what the difference is between the brand and class of concrete.

Concrete grade M350 is considered the highest quality and most in demand. It is used on construction sites where large objects are being built.
After the concrete solution has completely hardened, it is quite resistant to physical stress. This brand of mixture is a leader in its characteristics. The strongest point is the value of its compressive strength.
Due to its high characteristics, concrete grade M350 has high speed hardening, so working with it is very convenient and comfortable.
The solution is manufactured in factories on a large scale and delivered directly to construction site. For small scale construction, the mortar is mixed in a concrete mixer on site immediately before use. After the work is completed, the structure must be covered to protect it from sunlight and external factors. After laying, the foundation must stand under specific conditions for a certain time.

Concrete M350 has the following characteristics:

The strength of this brand of concrete is classified as class B25, according to this permissible pressure by 1 square meter can reach 25 MPa.
Concrete of this brand is resistant to any temperature, including severe frost. It is widely used in the Far North, since the indicators specified by the manufacturer guarantee that the concrete solution will not crack from low temperatures.
M350 has very high water resistance. It is permissible to build structures made of this concrete near bodies of water and in areas with high humidity. The structure of the solution does not imply the formation of bubbles and the entry of air.

Concrete M350 has mobility P2, P3, P4. This indicator depends on the amount of plasticizer that may be included in the composition. concrete mixture.

Cement of this brand is used for the construction of powerful structures, structures, monolithic slabs, load-bearing walls V multi-storey buildings, columns that will serve as supports, floor slabs, reinforced concrete piles.
The composition of concrete includes cement (it makes up 17%), crushed stone (it makes up 33%), sand, and the manufacturer also uses special additives and plasticizers.
Sand can be used in various grain sizes, and crushed stone can be granite or gravel.

When producing M350 cement, the manufacturer uses thorough mixing of all components to obtain a homogeneous, uniform mass. The main requirement of the manufacturer is the homogeneity of the mixture.
If the mixture is poorly mixed, this will lead to a decrease in the coefficient to the maximum permissible load, which will entail a decrease in the technical and operational properties of the building. In addition, it is very important to maintain the exact proportions of all components and meet all technology requirements.

In order to produce one cubic meter of M350 concrete, it is necessary to mix cement (400 kg), sand (752 kg in pure form), crushed stone (1000 kg) with 175 liters of water.
The cost of concrete of this brand is set by the manufacturer independently; it depends on many factors that accompany production. The price is set based on current costs. The bulk of the amount goes to the components. The cost is calculated in a standard way.
Of course, in order to make a profit, the manufacturer is forced to make a certain markup on the product. For this reason, each manufacturer has its own price and it can vary dramatically. Construction organizations purchase materials on their own, so they have the right to choose which manufacturer to cooperate with. The cost of the material will be significantly higher if the mixture includes additional additives (anti-frost, etc.).

Most often the developer uses mobile concrete mixer for preparing a small amount of concrete (up to 3 cubic meters) for the construction of blind areas, lintels, foundations of greenhouses, utility blocks, concreting paths and fences. But it also happens that, in order to save money, the developer prepares his own concrete for the foundation of his country house. In general, it is not recommended to do this, since the process of concreting the foundation should be continuous, but in fact this is what happens in the practice of individual self-construction. So what interests the developer most when preparing concrete himself?

What brand of concrete should I prepare?

Most often, for use in various designs of single-family private houses, it is enough to prepare concrete grade "M 350"(according to another classification it goes like concrete class "B 25".) When sold at concrete factories, it may be designated in price lists as BSG concrete with mobility p2-p4. We can say that concrete grade M 350 is the most popular concrete in modern construction is a universal concrete. Class "B 25" concrete has found its application in the manufacture of monolithic and pile-grillage foundations, the manufacture of monolithic floor slabs, columns, beams, walls, pool bowls, crossbars and others monolithic structures. What can we say if one of the areas of application of M 350 concrete is the production of PAG airfield road slabs, intended for use under extreme loads. If you decide to prepare concrete yourself and thereby save your money, then prepare it with a margin of safety, as they say, “you never know...”.

How to prepare concrete grade M 350 (class B 25)?

Let's make a table of proportions and ingredients for preparing concrete grade M 350.

Table No. 1. Proportions and ingredients for preparing M-350 concrete

*Important: If you decide to replace M-500 cement with another brand of cement and maintain all proportions, then you will receive concrete of a different brand and class. For example, using cement grade M-400, maintaining all proportions, you will get concrete grade M-250.

Before determining how much material we need to put into the drum of a household concrete mixer, we will determine the weight indicators for cement, crushed stone and dry sand. Since when filling a concrete mixer, the measure of part of the component is a ten-liter bucket, we will try to calculate its weight indicator for various materials.

Table No. 2. Weight of concrete mixture components in a bucket (1 bucket - 10 l.)

Cement brand M-500, kg.	Sand, kg	Gravel (crushed stone), kg
13.0	14.0	14.0

Now let's make a table to fill in the ingredients in the most popular household concrete mixers with a loading volume of 130 liters. and ready-made mixture with a volume of 100 liters.

Table No. 3. Preparing the mixture in a concrete mixer with a volume ready mixture 100 l.

Now, before we answer the question of how many materials for concrete we need to purchase, we will answer one more question.

How much reinforcement should be laid per 1 cubic meter? m. concrete?

First, let's decide for what work we need fittings. Again, we will proceed from ordinary logic. How to carry out certain concrete works is written in many GOSTs and SNiPs for construction. You can find information on carrying out the projects that interest you in any database of construction GOSTs and SNiPs. concrete works. There you will also find information about the quantity and technology of reinforcement reinforced concrete structure. For you, as a private developer, we offer a table with the characteristics of the fittings most used in low-rise construction. This table will help you calculate the required volume of steel reinforcement purchased for monolithic work ( reinforcing steel). Today, most often in low-rise construction, the so-called Class A3 fittings. Class A3 fittings are fittings with a periodic profile. As general information Class A1 reinforcement is smooth reinforcement. But as we have already said, we are interested in class A3 fittings, and in this class the most popular in low-rise buildings are reinforcement with a diameter of 8 mm, 10 mm, 12 mm, 14 mm.
Let's make a table with the characteristics of reinforcement of these sizes.

Table No. 4. Weight and dimensional characteristics of class A3 fittings

Name	Diameter fittings. mm.	Length produced products. m.	Weight linear meters. kg.	Meters in 1 ton products. m
A3 fittings	8	6,0; 9,0; 11,7; 12,0	0,395	2531,65
A3 fittings	10	6,0; 9,0; 11,7; 12,0	0,617	1620,75
A3 fittings	12	6,0; 9,0; 11,7; 12,0	0,888	1126,13
A3 fittings	14	6,0; 9,0; 11,7; 12,0	1,210	826,45

*Note: Maximum size fittings class A3 - d40 (diameter 40 mm.)

Now that we have data on the basic building materials needed for the preparation of reinforced concrete, we can specific example answer the next and most important question of any developer.

How much material do I need to purchase for monolithic work?

Let's make a small clarification before answering this question in detail. When carrying out any monolithic work, in addition to sand, cement, crushed stone (gravel), reinforcement, it is also necessary to purchase tying wire, material for arranging formwork and waterproofing, etc. But our goal is to calculate the volume of the main components included in 1 cubic meter. reinforced concrete.

As an example, we give a calculation of the amount of material required for constructing the foundation of a greenhouse, which is presented in the article DIY greenhouse construction, especially since this material is very popular among visitors to the Internet portal on low-rise construction http://www.site.
Let's create a table again.
Initial data:
1. Foundation: reinforced concrete, strip, monolithic shallow: width 300 mm, height 400 mm.
2. Concrete mixer for preparing concrete: volume to be filled = 130 l., prepared concrete = 100 l.
3. The amount of prepared concrete for the greenhouse foundation= 2.2 m 3

Table No. 5. Consumption of materials for the foundation.

Qty batches.	Quantity of materials per 1 m 3 of concrete grade M 350					Total consumption materials for the foundation
	cement, kg.	crushed stone, m 3	sand, m 3	water, l	Reinforcement A3 (d8), kg.	cement, kg.	crushed stone, m 3	sand, m 3	water, l	Reinforcement A3 (d8), kg.
22	220	0,75	0,35	90	60*	484	1,65	0,77	198	132

*Note: For the construction of monolithic reinforced concrete foundations, it is recommended to lay 100 kg of concrete per 1 m 3 of concrete. fittings, but for such light buildings the limit is 60 kg. reinforcement per 1 m 3 of concrete.

And then everything is very simple. You make a small estimate for the material for building a foundation for a greenhouse. Since the volume of purchased material is small, it is best to contact a nearby store or building materials market, find out the prices, and make a sign something like this.

Table No. 6. Estimate for material for the foundation of the greenhouse.

Material	Unit change	Price, rub.	Qty	Price, rub.
Cement	kg.	4	484	1936
Sand	m 3	450	0,77	346
Gravel (crushed stone)	m 3	750	1,65	1237
Armature, A3, d8	kg.	23	132	3036
Total cost, rub.				6555

Using this specific example, we calculated the consumption of basic materials for the construction of a reinforced concrete greenhouse foundation. As we have already noted, of course, to build a foundation, it is also necessary to purchase formwork material, tying wire, insulating material, etc. But the purpose of this article was not to accurately calculate the costs of constructing a greenhouse foundation. The main thing is to show how to apply it in practice the data that a private developer needs when calculating the required amount of basic materials when preparing concrete on his own and, based on the data obtained, calculate the cost necessary materials. It seems to us that we have given very detailed answers to all the questions raised in this article.

Characteristics and proportions of concrete M350

In the construction industry, concrete mixtures with increased strength are used for the manufacture of loaded structures. In terms of durability and strength characteristics, they confidently compete with natural stone, the use of which increases the cost. One of these building materials is M350 concrete. This is a material for structural purposes that is capable of withstanding significant loads and also has increased resistance to external influences. In terms of sales volume, it is the leader among other brands of concrete.

Concrete M350 - technical characteristics

The material, popular in the construction industry, is marked with the M 350 index. Concrete has a set of properties that allow it to be used to solve a wide range of problems. Let us dwell in detail on the characteristics of common building materials.

The main indicators of the M350 solution:

• increased strength. The frozen monolith is capable of withstanding a compressive load of up to 25 MPa without the appearance of cracks, which corresponds to class B25. An increased safety margin is achieved through the use of increased volumes of Portland cement when mixing;
• plastic. The mobility indicator of the concrete mixture is located in the range P2-P4. The proven recipe allows the introduction of special additives called plasticizers. They allow, if necessary, to increase the degree of mobility of the concrete solution;

The most effective is concrete M350 B25 based on Portland cement

• water resistance. In terms of water resistance, the M350 mixture corresponds to the W8 indicator. After hardening, the concrete mass has a dense structure in which there are no air pores or cavities. This provides a high degree of protection of the array from moisture absorption;
• frost resistance. Construction material in terms of frost resistance it corresponds to the F200 value, which allows the solution to be used in harsh climates. The monolith does not lose its structural integrity after 200 freezing and thawing cycles;
• density. The increased density of the concrete mass makes it possible to maintain the integrity of the monolith under the influence of surface wear, as well as extreme loads. Depending on the aggregate used and its size, 1 cubic meter the solution weighs 2.2–2.4 tons.

Thanks to increased operational characteristics And unique properties the material is increasingly popular and in demand by specialized organizations and private developers.

Composition of concrete grade 350

To produce concrete mortar, marked with the M350 index, a cement-sand mixture, water, and also solid filler are used. Fine granite chips, crushed stone or gravel can be used to fill the volume. The composition, regulated by the provisions of the current standard, allows the introduction of special additives. They expand the scope of use of this mixture.

The following components are used to manufacture the material:

• Portland cement of high grades. The use of cement grade 400 and higher as a binder makes it possible to obtain ready-mixed concrete with high performance. As the grade of cement used increases, the strength of the concrete mixture increases;
• sifted sand. The crumbly material must be thoroughly cleaned of impurities. It is allowed to use sand extracted from quarries, as well as river sand of any grain size. The properties of the mixture do not depend on the size of the sand used;
• crushed stone This is a fairly common filler in the construction field, used for the manufacture of concrete. In the absence of crushed stone, valid regulations allow the use of fine limestone or mid-fraction granite;
• water. It is gradually introduced into the concrete mortar. The first portion is added at the mixing stage. Then small volumes of liquid are introduced until a homogeneous concrete solution of the required consistency is obtained;
• special additives. The introduction of antifreeze additives makes it possible to increase the frost resistance of the mixture to perform work in negative temperatures. The introduction of plasticizers increases mobility concrete composition when pouring.

An important condition for ensuring the required qualities of concrete is high uniformity of mixing, as well as compliance with technological recommendations and recipes.

Compressive strength characteristics are especially high. In many ways, such high properties are ensured by the correctly selected mixture composition

Concrete recipe M350

To obtain a high-quality solution with increased strength characteristics, it is necessary to maintain proportions. Concrete M350 can be made independently or ordered from a specialized construction organization. The amount of ingredients added varies depending on the brand of Portland cement used.

When dosing the components of the mixture by weight, the following ratios should be observed:

• per ton of M400 cement it is necessary to use 3.1 tons of crushed stone and 1.5 tons of sand;
• when using 1 ton of M500 cement, 1.9 tons of sand and 3.6 tons of crushed stone will be required.

Using a measuring container, in some cases, volumetric dosing is convenient. The following recommendations should be followed:

• Portland cement grade M400 in a volume of 100 l should be mixed with crushed stone - 280 l and sand - 140 l;
• For 100 liters of M500 cement, 190 liters of sand and 360 liters of crushed stone should be added when mixing.

The quality of the monolith is influenced by the uniformity of mixing of the components, as well as strict adherence to the recipe. To ensure the technical and operational properties of the structure being built or the product being manufactured, the amount of input ingredients must be correctly calculated.

By using additives, the class of concrete varies over a wide range

What are the advantages of grade 350 concrete?

This brand of concrete has numerous advantages:

• increased strength properties. The concrete mass does not collapse under the influence of significant compressive loads, as well as during active abrasion of the surface during operation;
• high degree of mobility. This makes it easier to carry out concrete work, and the use of special plasticizers can further increase the elasticity index;
• adjustable frost resistance. At the stage of preparing the solution, it is possible to ensure the required level of frost resistance to maintain the integrity of the monolith in difficult conditions;
• long service life. The composition of the M350 brand retains its original strength characteristics for a long time and is not destroyed under the influence of aggressive factors;
• increased density. Thanks to effective sealing liquid concrete, there are no cavities or air pores in the array. This significantly increases the degree of water resistance and expands the possibilities of application;
• environmental cleanliness. For production, environmentally friendly raw materials are used, which do not have a negative impact on people after completion of the hardening process.

Thanks to these advantages, concrete grade M350 has established itself as a universal building material for structural purposes.

Areas where 350 concrete is used

The M350 brand mixture is used to perform various tasks:

• fills monolithic foundations for critical objects. Thanks to the increased safety margin, the concrete monolith is able to maintain its integrity while withstanding increased loads;
• concreting supports using the pile-grillage method. The concrete solution is poured directly into the cavity drilled in the soil to form a future support;
• production of interfloor floor slabs. Hollow-core panels have high strength properties with low weight and can be manufactured without additional reinforcement with reinforcement;
• pouring slabs for airfields and highways. Concrete mortar poured into special molds with a pre-installed reinforcement cage. After hardening, the products have increased strength;
• formation of support columns that can take a significant load from the mass building structures. Along with compression, such elements are subject to bending moments and tensile forces.

Due to its high strength and durability, it has always been valued in construction. a natural stone. But its extraction, processing and laying are very labor-intensive processes, which affects the cost of the material and structures made from it. That is why, already in ancient times, artificial analogues of natural stone began to appear.

The most effective among them was concrete based on Portland cement. Concrete M350 is an excellent structural material that allows the production of critical structures for various purposes.

Purpose and features

Heavy concrete is the most popular type artificial stone. Due to its high density and strength, this material can last more than 150 years. If we consider the materials most in demand in various fields of construction, then it is concrete M350 or B25 that is most often used for the manufacture of load-bearing structures and various prefabricated elements.

To produce concrete M350, which features a composition with a high consumption of binder, it is necessary to accurately maintain the proportions of raw materials per 1 m3. In addition, it must be remembered that such material does not tolerate the use of sand or coarse aggregate of poor quality.

To ensure a given density, all types of strength, high frost resistance and low water resistance, the composite requires the use of sand with a particle size modulus of 1.8 - 2.5, as well as coarse aggregate made of dense rocks with a crushability grade of at least M800.

Areas of use

Artificial stone of this class has a high density and strength of 33 MPa, which allows it to be used in the manufacture of load-bearing columns, supports, crossbars, floor slabs, road and airfield slabs, as well as elements of elevator shafts and other structures that make up the skeleton of any building. Concrete of this class is often used for foundation construction in industrial or warehouse premises, because for movement special equipment High strength material is required.

Concrete M350 is in demand in monolithic and hydraulic engineering construction, in the manufacture of reinforced concrete products, as well as in the installation road pavements. A verified composite recipe and exact adherence to the composition per 1 m3, as well as ensuring high-quality mixing of raw materials are a prerequisite for obtaining high-quality B25 concrete.

Basic material parameters

Concrete M350 belongs to the materials of the middle segment. Its production requires more binder per 1 m3 than for ordinary classes, therefore specifications M350 concrete is much more diverse. For an artificial stone of this class and composition, the following main parameters are distinguished:

• compressive strength limit;
• tensile strength in bending;
• density;
• frost resistance;
• waterproof;
• water absorption (for road concrete and paving elements);
• grade for mobility of concrete mixture;
• air content (for bridge and road construction).

The strength of concrete determines its ability to withstand mechanical loads various types. Strength is the basic property used to design the composition of the material.

Frost resistance demonstrates the ability of a composite to withstand alternate freezing and thawing without destruction. There is water in the body of concrete, so when passing through 0 0C, ice can form in the pores, which can destroy the structure of the material. That is why frost resistance is one of the durability parameters. Water resistance characterizes the density of the composite body and its ability to resist external influences.

The basic characteristics of the material and their numerical values ​​are presented in the table.

Ratio of components during manufacturing

It is the composition of the material that determines all its properties. For concrete, the ratio of raw materials is most often written as a mass proportion per 1 m3 of the finished mixture.

Concrete is a complex composite, the base materials for which differ significantly in density and voidness. Products are shipped by volume, not by weight, therefore the composition of concrete per 1 m3 is designed so that the proportions of inert aggregates, binder and water ensure an absolutely dense body, and their dosing is carried out by weight.

Basic proportions

The approximate composition of M350 concrete per 1m3 can be presented as follows:

• cement = 360 – 390 kg/m3;
• sand = 650 – 750 kg/m3;
• coarse aggregate = 1000 – 1100 kg/m3;
• water = 170 – 190 kg/m3;
• plasticizer or complex modifier in optimal dosage.

Compliance with the prescribed proportions of all components ensures that the specified properties of the material are obtained. Do not forget that due to the complexity of the system, it requires thorough mixing for 2 - 3 minutes to ensure uniformity of the concrete mixture and concrete.

Features of composition selection

It must be remembered that concrete grade M350 must have a dense structure with a minimum number of defects. That is why the proportions of the components are selected in compliance with certain rules.

Amount of water

The less water is used to make artificial stone, the denser its structure, the higher its strength and durability. Therefore, it is better to set the water-cement ratio to no more than 0.5 - 0.55. With high requirements for waterproofness and frost resistance, the proportion of water to cement is often reduced to 0.4 - 0.45. In both cases, the use of special additives - plasticizers - is required, otherwise the mobility of the concrete mixture will be low, which creates problems during its transportation and placement.

Taking into account the purpose of the structure

The basic proportions of M350 concrete can vary depending on the purpose of the material. The composition of the composite for monolithic construction is characterized by a higher sand content and higher mobility.

Factory production requires accelerated strength development, therefore the amount of cement in the concrete composition increases, and the proportion of crushed stone to sand shifts towards increasing the former.

Obtaining highly stable compounds

When assigning high grades of frost resistance and water resistance, a change in the air content of the concrete mixture and concrete is required, so special additives are introduced into the material. To compensate for their negative impact on the strength of artificial stone, the consumption of binder increases. Such proportions of raw materials are most often used in the manufacture of concrete for hydraulic engineering and road construction.