How to properly prepare a mixture for the foundation, the proportions of concrete in buckets. We calculate the proportions of the concrete components for pouring the foundation The proportions of the concrete mixture for the foundation

The calculation of the proportion of concrete for the foundation is carried out taking into account the technical parameters of the components. The technology for preparing a concrete mixture depends on its purpose, volume, quantity and physical condition of the components. It can be prepared manually or using specialized machinery and concrete mixing equipment.

Solution components

Cement is a powdered binder that can harden in water and in the open air. In combination with large and small aggregates, it ensures the strength and reliability of the structure being erected.

Cement is obtained by grinding a mixture of clinker, gypsum and special additives in specified proportions. In turn, clinker is a product from the burning of limestone with clay and other components on which the properties and name of cement depend. Depending on the feedstock, the following types of hydraulic binder are distinguished:

Portland cement:
slag Portland cement;
pozzolanic;
lime;
backfill;
sulfate resistant and others.

When forming a cement-sand mixture (CPS) in order to obtain concrete of a given strength, it is necessary to take into account the strength grade of Portland cement. The following table shows the strength characteristics of the material according to the old and new system:

In addition, when choosing a material for the preparation of concrete with the desired characteristics, other properties of cement are taken into account:

The fineness of grinding directly affects the strength characteristics of the concrete mixture, especially at the beginning of hardening.
Density is reflected in the value of the water-cement ratio, and hence the water consumption. To reduce it, while obtaining a good workability of the mixture, plasticizing additives are used.
Frost resistance is especially important when building in winter or in areas with year-round low outdoor temperatures.
Fracture resistance. This indicator is influenced by such a concept as the uniformity of volume expansion during hardening.

Depending on what components cement is made of, the above qualities vary over a fairly wide range.

The concrete mixture, which, in addition to cement, includes sand, as well as crushed stone or gravel, is formed depending on the purpose of the composition. What proportions of cement, sand and gravel should be contained in it are determined in accordance with the recommendations of GOST 27006 - 86 (1989) “Concrete. Rules for the selection of compositions "and GOST 7473 - 94" Concrete mixes. Specifications".

For the concrete mixture, sand with a grain size of 1.2-3.5 mm is used. When choosing this component, pay attention to the purity of the material. In order for the prepared cement-sand mixture to be of high quality, the presence of silt and clay particles in the sand should not exceed 5%.

You can check the suitability of the sand for use with water. To do this, pour a small amount of the investigated component into the container, add water and shake the composition. If the liquid is cloudy and contains suspended clay particles, then the sand is not suitable for concrete preparation.

The composition of the concrete mixture used when pouring the foundation includes crushed stone or gravel of medium fraction. The use of coarse grains will lead to a loss of strength of the foundation for the construction of the building.

Production of high quality concrete is possible when using warm and clean water, without secondary impurities (oils, paints).

When preparing a cement-sand mixture, it must be borne in mind that there are no absolutely pure components. In practice, it can be difficult to accurately calculate the proportion of sand, cement for the foundation, especially when pouring the foundation for individual construction.

Additionally, it is necessary to take into account the factor that over time, cement for the foundation loses some of its properties. For six months of storage, the material reduces the binding qualities by a third. Accordingly, the grade characterizing the ultimate compressive strength decreases.

Concrete classification

Based on the purpose of the structural material and its specific gravity, the following types of concrete are distinguished:

especially heavy;
heavy;
easy;
especially light.

The composition with the highest density index is used in the construction of nuclear and power plants, with a specific gravity in the range of 500-1800 kg / m³ - for the manufacture of panels, wall blocks. Particularly light (less than 500 kg/m³) is intended for thermal insulation of house facades.

Heavy concrete (1800-2500 kg / m³) is used for the manufacture of prefabricated, monolithic reinforced concrete structures and foundations. Special impurities, which are added to improve its technical characteristics, increase strength, resistance to overheating, temperature extremes, reinforcement corrosion, and moisture.

The main strength indicator reflects the brand or class of concrete.

Preparing the mixture

Concrete is used in almost all areas of construction, when performing repair and construction or restoration work.

You can prepare a mixture for the foundation with your own hands by combining the constituent components in a concrete mixer, bathtub, box. In the manufacture of artificial material, it is important to observe the technology and proportions of concrete on the foundation.

Industrial production differs from handicraft in large volumes, therefore, it involves the use of special technical equipment. Mechanical preparation of concrete mix for the foundation by specialized enterprises allows improving the properties and quality due to additives.

When forming the basis for building a house, you can use the services of a company that can prepare a concrete mixture using special equipment on the way to the customer.

To make a composition for the foundation with your own hands, you need to correctly determine the quantitative composition of the components. To obtain concrete grade 300 or 400, sand and cement are taken in proportions of 3: 1, i.e. for 10 kg of cement, you need to take 30 kg of sand, gravel (crushed stone) - 40-50 kg.

In this example, cement, sand, gravel weigh 80-90 kg, so 40-45 liters of water will be required to connect the components. You can knead the mixture using a mobile concrete mixer, a shovel or a construction mixer.

The preparation of concrete from a cement-gravel mixture requires compliance with the technology. If the solution turned out to be dense, then it must be diluted with water to such a consistency that it can be stirred with a shovel without much effort. The amount of water is affected by the moisture content of the aggregates, so do not add all at once. It is better to do this in portions with constant stirring.

For concreting it is better to choose a warm season. At low temperatures, to improve the quality of concrete, it is necessary to heat water, otherwise it may lose strength. And also use antifreeze additives.

Foundation types

The basis for the construction of buildings is formed taking into account the load, types of soil, construction. Depending on the type of foundation and its volume, the calculation of the need for materials is performed.

The tape base is a closed loop of reinforced concrete, arranged under the load-bearing and internal walls of the building. How to make a mortar for a tape type foundation? To calculate the need for materials, determine the volume of each section and add them up. The mixture must be poured continuously, with layer-by-layer compaction and observance of the protective layer of reinforcement.
The columnar type of base is used for light-type structures located on dense soils. In practice, a combination of both types of foundation is often used.
The slab type of foundation is practiced on weak, heaving soils. Made from reinforced concrete. Filling should be done in one go to prevent delamination of the finished structure. The concrete mixture is distributed evenly with obligatory compaction by vibrators or bayonet.
The foundations are pile-stuffed. The volume of concrete is calculated according to the geometric formula: the cross-sectional area of the well must be multiplied by the depth of the pile and by the number of rods.

The concrete mixture after pouring into any type of base requires moisture, otherwise the structure may crack due to the rapid drying of the top layer. The first week should be regularly watered and covered with a film or tarp.

Do-it-yourself concrete for the foundation

You can use the materials separately or ready-made sand and gravel mixture (proportions in buckets: 1 volume of cement per 5 volumes of the mixture).

Components per 1 m 3 of concrete must be mixed in the ratio:

cement - 300-350 kg;
crushed stone - 1200 kg;
sand - 600-700 kg;
water - 150-180 liters.

The calculation of the amount of cement and sand, crushed stone and water should take into account the properties of the materials, their qualitative composition, strength, the presence of impurities (clay particles may be in the sand).

To properly make a cement mortar for pouring the base, dry components are poured into the concrete mixer, mixed for 2-3 minutes. Then, without stopping to interfere, water is poured in portions. It is best to first dissolve the necessary additives in water. The mixing process should not be long, 5 minutes is enough.

Methods for calculating materials

The concrete recipe for the foundation includes the following components: cement, sand, gravel or crushed stone as aggregates,. Each component is responsible for quality. In order for the final result to meet regulatory requirements, you need to correctly perform the calculation and determine the required number of components, observing the proportions.

The calculation of the components and the preparation of concrete for the foundation in buckets is relevant for small volumes of construction work, where 1-4 m 3 of solution is required. The basis for this calculation is usually the volumetric value of the cement.

What should be the ratio of sand and cement for pouring the foundation

Each component of the concrete mix differs in volumetric weight, therefore, in practice, the following proportions are used: 5 buckets of sand and 9 buckets of crushed stone or gravel are taken for 2 buckets of cement.

A preliminary calculation of the ingredients can be carried out using an online calculator in liters or kilograms. The calculation of emergency situations is carried out taking into account the requirements for concrete and the characteristics of the main materials.

For example, to obtain 1 m³ in the presence of a 180 l concrete mixer, sand and gravel, you will need:

water - 215 l;
cement - 233 l;
crushed stone - 818 l;
sand - 389 l.

Under the given conditions, the calculator will calculate the need for materials for 1 batch and the number of loads.

When it is necessary to adjust the consumption of raw materials, taking into account the operating conditions of the structure being erected, the type of mixture, the use of a plasticizer, the value of the coefficient of expansion of concrete particles, it is necessary to use a correction table.

Composition: water, cement, sand and gravel/rubble. Proportions: if you count 10 kilograms, then cement - 10 kg, sand - 30 kg, gravel or crushed stone - 40-50 kg. To make concrete grade M300 or M400, you need half the water than the weight of the remaining components. Example: in this case, 80-90 kg of a dry mixture is obtained (cement (M500 / M600) + sand + gravel / crushed stone), which means 40-45 liters of water are needed. If the solution is too thick, dilute with water. It's best to stick to a consistency that you can stir the concrete with a shovel, but still apply some effort (and so that the mortar doesn't run off the shovel too quickly and easily).

Wet sand also contains moisture. Either dry it or take away a few liters of water. Also check the sand for cleanliness. The purer it is, the better the setting in the solution.

Crushed stone or gravel, use a fine fraction (1-2 cm, no more).

Do not buy cement long before construction. It quickly absorbs moisture and deteriorates. Better 1-2 weeks before the preparation of the concrete mixture.

It is desirable to fill any foundation in the warm season. In cold weather, you have to heat the water and the solution so that it does not begin to set earlier. Otherwise, it will lose a lot of strength, because it will not be firmly connected to the reinforcement and will not be compacted.

How to prepare concrete for a strip foundation

It is better to count each line (tape) of the foundation separately, and then add everything up. The length of the tape is multiplied by the height, then by the width. Let's say one foundation tape has the following values: length - 10 m, height - 1 m, width - 0.5 m. It turns out 5 m 3 of concrete per tape.

If you count each tape along its full length (from corner to corner), it turns out that the volume of each corner is counted twice. This is correct, since it is better to make more concrete than required. The foundation pit is not jewelry smooth.

It is desirable to pour concrete into the formwork in layers. For example, if the height of the foundation is 1 m, then it can be concreted in 4 layers of 25 cm each. During the pouring of each layer, it is advisable to compact it with a vibrator or at least by tapping with a hammer / shovel. After pouring each layer, air must be released from it, sticking reinforcement every 1-3 m (not very quickly). Also, each layer of concrete must be leveled with a board. For clarity, in the formwork, you can mark the height of each layer.

In the same way, the calculation, preparation and pouring of concrete into the grillage is performed.

How to prepare concrete for a slab foundation

Dimensions: length and width of 10 meters, height 25 centimeters. 10 times 10 times 0.25. Total: 25 cubic meters of concrete for a slab monolithic foundation.
The slab foundation must be rammed on every square meter of area. Since this type of foundation is a solid area, all the concrete must be poured at once. After pouring, it is better to do alignment, starting from the smaller side of the perimeter, and move to the opposite side with a snake. For leveling, you need a wide board with a handle for convenience. Be sure to release air in many places.

How to prepare concrete for a columnar foundation

Concrete for a columnar foundation is calculated according to the volume formula, it is poured all at once and rammed, followed by piercing the mixture to release air.

Preparation of concrete for a pile-rammed foundation

Compared to columnar foundations, only the calculation formula for cylindrical columns of stuffed piles changes. You need to multiply the height by the radius squared and by the number "Pi" (3.14). Calculation example: multiply the height of 1 m by 0.0625 (radius 0.25 m 2) and multiply by 3.14. It turns out 0.19, rounded up to 0.2 cubic meters. This calculation is for one pile column.

After pouring any foundation, you need to cover it with a protective film from precipitation. On the day of pouring, pour plenty of water over the foundation at night, otherwise it may give small cracks in the morning, because the top layer dries quickly. Moisten the foundation every few hours for the first week. From the second week you can once a day.

It would hardly be possible to imagine our surroundings - a district, a city, a country and the world as a whole - without modern architecture, the main material for which is still concrete, whose analogues appeared even before the beginning of our era: well-known mixtures of sand and soft limestone rocks with bottom of the Nile. Let's learn more about this amazing substance, thanks to which houses and buildings in all countries and cities of the Earth hold together.

Take a look around: the vast majority of all structures are built on a concrete base, but this is not even the most remarkable.

Walls,
Scenery,
load-bearing beams and the like are composed of concrete or some of its inclusions.

Given this fact, of course, we can say that this mixture is used in almost all areas, not only in construction, but also in repair, laying railways, strengthening hazardous facilities, etc.

Since this material has varieties, the choice of which directly depends on the purpose of the object for which it is used, and the area of \u200b\u200bthe bookmark, that is, for the foundation, walls or just decoration, we will talk about the areas of its application with respect to general information, and delve into subsequent paragraphs.

The main areas of use of the cement mixture are:

Construction and repair industries;
Industry;
Railway works;
military industry;
Design;
Mining production;
Energy and oil industries.

Note that in the military, mining and construction fields, as a rule, reinforced materials are used, since it is necessary to give the structure not only strength, but also hardness: a mixture penetrated with steel pins gives much less chips and cracks when it is strongly impacted.

The composition of concrete for the foundation

All the physical properties of the concrete composition are completely dependent on what was added to it during production (that is, in the finished mixture), or with self-mixing. Let's analyze each component separately.

Cement

Its quality is controlled by TP-166-04, GOST 31108-2003 and SNiP 2.03.11-85. Very serious criteria are imposed on really high-quality cement, by which one can judge both the integrity of the manufacturer and the characteristics of the concrete mixture as a whole. So, good cement has a grinding, with a fineness of 350-380 m2 / kg, although it may differ slightly from this parameter, but not more than 10%. It should begin to set, if we take the average value for the construction area, in 2-3 hours, and finish in 4-5 hours. It is also desirable that the density of the cement paste does not exceed the value of 25-27% of water from the total mass of the mixture. Alkali in it should be no more than 0.6% of the total mass.

PGS and other aggregates

Its role can be played by both sand or gravel (crushed stone), and their combinations, which are also determined by GOSTs and SNiPs. The aggregate is required for the following purposes: giving greater strength to the composition and reducing the cost of its use due to the fact that not the entire volume is occupied by cement (sand and gravel with crushed stone are cheaper than it).

Construction sand is a fine aggregate, which differs from ordinary river sand in that its grains of sand have a slightly more regular rounded shape, and a little clay is included in the sand mixture itself to give the final mixture plasticity and softness.

The aggregate of the composition, which is large in fraction, is crushed stone, gravel or either granite chips. Their choice is based on what strength is required to obtain: for the most durable concrete grades (for example, M500), only granite chips are used, for weaker grades (from M350 to M100, they are used, as a rule, for the composition of concrete for the foundation) - gravel and rubble.

Water

It is the second most important component in the composition after cement. To knead the mixture, ordinary water is used, but resorting to rather sophisticated calculations, which take into account the water absorption of aggregates, cement itself, and additives with various inclusions, which makes it possible to achieve the required consistency of the construction test.

Additives and plasticizers

These include any impurities that help to give the composition any properties or speed up the processes occurring inside it. For example, plasticizers increase the strength and fluidity of a material, making it less susceptible to tensile failure. There are additives that can give frost-resistant, refractory and moisture-proof properties to concrete in the right proportion, as well as speed up the process of its hardening or increase strength. The choice of additives depends only on the need for their use in a particular case.

Grades and marking of concrete

In order to choose the most suitable concrete for any purpose of construction or production, its manufacturers were obliged by GOSTs to indicate the most important characteristics of the mixture. Here it is also necessary to note the difference between the finished mixture and dry:

the first is already hardened blocks,
the second is the composition whose proportions of concrete in buckets for a concrete mixer must be calculated directly on the construction site.

The most important indicators of the quality of the composition include:

Brand - M;
Frost resistance - F;
Mobility - P;
Water permeability - W;
Class - B.

As a rule, buyers look only at the brand and class of the composition, forgetting about other indicators, which often becomes a critical mistake.

After all, even durable material with high-quality granite filler may not withstand strong temperature changes or high humidity in the area, so it will begin to crack and crumble, which will lead to an accident rate of the entire building.

Let's figure out what each indicator of a certain brand of concrete means, the proportions in the buckets of which will be discussed a little lower.

(M)- this designation shows the strength of the solidified mixture, which is calculated (in kgf / cm 3) by compressing a small cube from a given composition, which is previously kept at room temperature for at least a month in order to eliminate possible errors as a result of the influence of temperature features. The brand also reflects the cement content in the total mass of the composition, that is, the larger the value, the higher the cement content. For example, concrete grade M50 or M100 refers to low-strength compositions with a small amount of cement, and M500 or M600 - to the strongest blocks, where the content of cement and granite filler is maximum. But the difference in price between the M50 and M600 will be two to three thousand rubles.
(F)- this number is indicated by the number of cycles for which the concrete block completely freezes and thaws. This value is directly related to how large the volume of pores in the frozen composition is, since water enters these pores, expands and destroys the structure from the inside. The higher the frost resistance value (F), the smaller the number and volume of these pores. In brands of durable concrete - M500, M600 - F, as a rule, it starts from 200 cycles, and for less strong ones - from 50.
(IN)- the value of the strength class of the solidified composition. There is a correlation with the brand of material: the higher it is, the higher the class. For example, the M100 brand corresponds to class B7.5, and the M600 brand to B45. On average, the step of changing this value is 50 - 5, that is, M350 - B25, M400 - B30, M450 - B35, etc.

(P)- this is an indicator of the mobility of the still uncured mixture. It is determined by how easily it takes the desired shape without further upsetting. The most rigid mixtures are marked P1 and P2, and their draft is 1-5 cm and 5-10 cm, respectively. They are difficult and impractical to use when pouring complex shapes, which makes it necessary to use a special construction vibrator. More plastic compositions - from P3 (this is most often M300 concrete, the proportions of water, cement and filler may vary slightly) to P5 - it is easier to pump, deliver to the construction site and pour into complex formwork, but if you remove it before the mixture hardens, then she will be very strong. The value of concrete mobility increases with the help of plasticizers, and not additional water - this is important to consider.
(W)- this is one of the most important characteristics of concrete, which determines how quickly it will begin to pass water under pressure. Water permeability (W) can have a value from 1 to 20, but starting from 15-17 this material can be considered hydraulic, that is, intended for structures with constant water contact and very high humidity.

Proportions of concrete in buckets for a concrete mixer

To prepare concrete with your own hands, the proportions in buckets (parts) of which depend on the required characteristics, you need to purchase

cement mixture,
filler and additives,
concrete mixer(if the volumes are large enough), since it is difficult and long to knead the composition in decent volumes using a construction mixer, but for a small amount of the mixture, you can get by with them.

Cooking begins with the fact that you need to calculate the amount of ingredients:

cement,
sand,
stone filler,
water.

As a rule, the value of the required part of the water is half of the required value of the cement, and the amount of the remaining ingredients is determined by the ratios.

The composition of concrete for the foundation and the proportions in buckets for it can be calculated based on the ratios for grades M300 and M350 (they are most often used for the foundation of ordinary residential buildings).

So, this value will be approximately equal to 1×1.9×3.7, Where

the first value is the amount of cement,
the second is sand,
and the third - stone filler.

Thus, the proportions of concrete for the foundation in buckets will be (with 10 kg of cement):

10kg x 19kg x 37kg, and water, respectively, will need 5 liters.

In general, the proportions of concrete in buckets are determined by the following ratios:

М100 - 1×4.6×7.0
М200 - 1×2.8×4.8
М300 - 1×1.9×3.7
М400 - 1×1.2×2.7
М450 - 1×1.1×2.5

Also, the proportions for concrete in buckets and kilograms can be found in the table below.

The procedure for mixing concrete

Concrete is mixed either manually or with a concrete mixer. With the manual method, the procedure is as follows:

In one container, mix sand, cement and additives (plasticizers) to the extent that this mixture becomes completely homogeneous;
Now you need to add water in small portions to this container and stir;
Already here you can add a filler (crushed stone or gravel with granite), each particle of which must be covered with the composition.

When using a construction mixer, you must:

In the mixer tank, combine water with cement;
Add sand and filler there, stir for several minutes;
Pour in a few more liters of water to achieve the desired consistency.

How to pour concrete

The composition of concrete in proportions in buckets determines how easy it will be to pour. For the foundation and load-bearing elements of the structure, as a rule, a “hard” composition is used, that is, one that requires the use of building vibrators to evenly distribute and compact the composition.

If concrete from ASG (proportions do not play a special role here) is poured onto a sandy layer, then the sand must first be well compacted and then about 10 centimeters of crushed stone should be poured on top. It is already necessary to pour the mixture onto this sand cushion, but so that its layers do not separate, for which the pump nozzle must be constantly moved within the boundaries of the flooded zone. To prevent cracks in the case of a diseased area of \u200b\u200bthe slab to be poured, recesses are made in the composition, constituting 1/4 of the total height of the layer. When the mixture dries, these recesses close up.

Drying takes place at room temperature. If it is lower, then heaters are installed next to the hardening composition. The mixture completely hardens in 28 days.

As many years ago, no building can be imagined without a concrete foundation. This applies even to small buildings made of wood, such as a bathhouse. For your own house or the same bath, you can make the foundation yourself. But in order for it to be strong, strong and stand for many years, first of all, you need to know the proportions when preparing concrete for the foundation.

Main nuances

If you are going to do the preparation of concrete yourself, then initially you need to carefully understand such issues as:

Brand. Each brand of concrete mix is designed for certain loads. They vary in strength and quality.
Depending on the brand, the requirements for the components included in each brand are different. They also need to be known.
Decide on the goal and choose the optimal proportions for preparing, for example, a foundation for the foundation of any building.

This information is useful to anyone. If you yourself are not going to prepare the building mixture, knowledge about specific brands and their components will definitely come in handy. This will help make the choice easier and make it right.

But it should be noted that preparing the concrete mix yourself is much more profitable than ordering it at the factory, and if you need a foundation for a small fence or a bath, then preparing the mix yourself will be much cheaper. In some cases, you can even do without a concrete mixer and prepare the mortar manually.

The most important thing is to correctly determine the necessary proportions in the preparation of concrete. If you need a small amount of the mixture, then you can knead it with an ordinary shovel. But, if we are talking about pouring a foundation for a house or a bath or a tape-type foundation for a fence, then it is better to buy a concrete mixer. Currently, the stores offer a large selection of this technique, which differs in capacity. Therefore, it is not difficult to choose the best option, moreover, such a technique will always come in handy.

Component Selection

So, the concrete mixture includes four components: sand, water, crushed stone and cement. Water is a binder, thanks to which the mixture becomes homogeneous and acquires the necessary density.

Separately, crushed stone should be highlighted. Sometimes it is permissible to use gravel instead, but the requirements for it are different. Gravel should consist of various fractions. If the composition of the gravel mixture includes flat and wide stones, then their total amount should not exceed 10% of the total volume of the material. The gravel should not contain any foreign additives or impurities. All this will subsequently negatively affect the strength of the concrete foundation itself.

Not only for gravel, but for each component, there are a number of requirements. For example, the most ideal sand for preparing a solution is river sand. It is desirable that its particles are large. The use of sand mixed with clay is excluded. The last component leads to a complete loss of strength. Clay, which is part of the sand, and then the mixture, makes the solution greasy. Its property to swell strongly under the influence of water, and then, on the contrary, quickly shrink, leads to the fact that cracks often appear on the surface of the foundation even before it completely hardens. A large amount of clay may even contribute to the fact that the finished monolithic structure will fall apart into pieces.

As for crushed stone, the size of the fraction should be 1-2 cm, this is the most optimal option. In addition, the material must also be clean and contain foreign impurities.

And, perhaps, the most important component is cement. People who have never experienced construction often make a common mistake, believing that if more cement is added to the mortar, it will only become stronger from this. Actually it is not. That is why the proportions established by GOST should be observed when preparing concrete. Excess cement can cause the monolithic structure to simply fall apart into pieces.

The amount of cement depends primarily on what you are going to do with concrete. If we are talking about the foundation, then the cement grade M 500 is most often used.

And the last component of the solution, of course, is water. She must be clean. It is unacceptable to use water containing various impurities or particles of paint, oil, gasoline. This will lead to the delamination of concrete and the deterioration of its strength properties.

concrete preparation

Not only the quality of the materials determines the result of the strength and the quality of the concrete itself. You also need to know how to mix concrete, and what procedure should be followed.

If you will use a concrete mixer, then you must first start it and gradually add the components of the mixture.

First, a small amount of water is fed into the device, to which cement is added and mixed until homogeneous.
When the solution has become a homogeneous consistency, sand is added to it. It is impossible to pour out all the sand at once, this must be done in small batches.
When the mixture with stirring has become homogeneous, crushed stone and the remaining water can be added. Each material must be added to the mixture in small batches and wait until the solution becomes homogeneous, you also need to add water.

A large amount of water contributes to the fact that the resulting slurry will have less strength. But too little water, in turn, will lead to greater density. Such concrete is difficult to pour into the formwork, to level. In addition, if it is poorly mixed, it can delaminate.

Of course, the question immediately arises, what proportions for concrete are the most optimal? The ratio should be as follows: cement: sand: crushed stone - 1:3:5. that is, for 1 kg of cement there are 3 kg of sand and 5 kg of crushed stone. These are the main proportions for the preparation of concrete, which are used in private individual construction when laying the foundation. If we talk about the ratio of cement and water, then it varies between 0.4-0.7.

Concrete grades

Calculations for different types of concrete will be somewhat different, depending on the receipt of the required grade. Grades of ready-made concrete M 150, 200 are much less in strength than M 450.

Consider the number of components for the preparation of different grades of concrete.

Concrete M 100 - 1: 5.8: 6.1 (cement: sand: crushed stone);
Concrete M 200 - 1: 3.5: 5.6 (cement: sand: crushed stone);
Concrete M 300 - 1: 2.4: 4.3 (cement: sand: crushed stone);
Concrete M 400 - 1: 1.6: 3.2 (cement: sand: crushed stone);
Concrete M 450 - 1: 1.4: 2.9 (cement: sand: crushed stone).

If you carefully look at the components, you can identify a certain trend in which, in order to obtain a high grade of concrete, the proportions of sand and gravel should be less in relation to the amount of cement.

To prepare the mortar for the foundation, it is best to use the grade of cement m 500. In addition to the ratio of quality components, it should also be taken into account that the prepared concrete mortar cannot be stored. It must be applied within two hours. If foundation pouring is carried out in winter or at lower temperatures than in summer, warm water must be used to prevent early hardening of the concrete.

Experts recommend using special additives when building a foundation in winter, which are added directly to the solution, this is done in order to preserve the properties of concrete as much as possible, which depend not only on the correct proportion of sand and concrete.

Professionals recommend pouring the foundation only in the warm season, which significantly reduces your own labor costs and saves time. For laying the foundation in winter, it is necessary not only to use warm water and special additives. The concrete itself, directly poured into the formwork, will also have to be heated. At negative temperatures, water freezes. It will also seize in a concrete solution, which will lead to the fact that, turning into ice, it will swell and become the cause of the destruction of the foundation.

In addition, experts recommend maintaining the proportions of concrete in buckets for convenience. For example, to prepare a solution, take 2 buckets of cement, 2 buckets of crushed stone and 6 buckets of sand. Concrete prepared in the correct ratio will have all the strength characteristics.

Concrete comes in various grades, which are classified according to its strength, such as M100, M150, M200, M300, etc. Both the composition and the proportions of its components largely depend on the brand of concrete.

To be honest, if you use purchased concrete, then you don’t have to worry about its composition and proportions. You only need to name the brand of concrete, the fraction of crushed stone used in it and the address where to deliver it, and the manufacturer, in turn, is obliged to take into account your wishes and prepare the concrete mix strictly following the technology.

What determines the composition of concrete for the foundation

It is not always possible to order ready-made concrete due to various difficulties. In this case, you will have to prepare concrete for the foundation yourself, and in order to prepare a high-quality mixture, you must strictly observe the proportions of all components.

So what should be the composition of concrete for the foundation in order to give it maximum strength and reliability throughout the entire life of the building?

It will not be possible to answer this question unambiguously, because a lot depends on the components used, the type of foundation, its area of application, soil moisture, and many other factors.

We have already talked about how to pour the foundation and save on this, and we will not repeat ourselves, today we will consider the components that make up concrete, as well as their exact proportions.

The main components that make up concrete

As a rule, the following components should be present in good quality concrete:

1. Cement
2. Sand (river or washed)
3. Crushed stone (gravel)
4. Water
5. Various additives

The main link in concrete is cement. He, with the help of water, connects the individual grains of sand into a single creamy mass - a solution. Cement can be of various types and brands, the most popular are M400 and M500, which will be discussed further. Also on sale are the M200 and M300 brands, but they are rarely used in private construction.

The next component is sand. It, as already mentioned, is necessary to dilute the cement and obtain a solution. The sand used should not contain various impurities, vegetation and foreign objects. Therefore, it is desirable to use "washed" sand or river sand. The most common admixture in sand is clay or lime. If there are lumps or stones in the sand, it must be sieved.

Such an admixture in the sand as clay, for example, will not allow the laid concrete to shrink completely until it has initially hardened. Thus, already relatively hard concrete will continue to shrink, leading to cracks in it.

rubble, or as it is called, gravel is the main component that is part of the concrete for the foundation and is its basis. In other words, crushed stone is for concrete, it is like a brick for a brick wall. It can be of various fractions (the size of one stone) from 5 mm, depending on the purpose of the future concrete structure. The average size of the fraction used in concrete for the foundation is (5 - 10) mm or (10 - 20) mm.

Often, crushed stone in concrete is replaced by other components, such as expanded clay, slag, etc., but such concrete is not used for foundations, so we will not consider them.

Water- an indispensable component, not a single construction site takes place without it. Water is the element by which all other dry ingredients are mixed. Also, water is involved in the process of concrete hardening, so it must also be added, observing the proportions. Water must be stocked up in advance, because during pouring, there will simply not be enough time to carry it from outside the construction site.

Various additives are used in concrete to improve its performance, both during curing and eventually. In other words - if, for example, you need a strip deep foundation, then frost-resistant additives are added to the concrete, if it is necessary to obtain a plastic concrete mass, then various plasticizers are added. Also, additives can be used to accelerate hardening, to increase the final strength, and many others.

The proportions of the components in the composition of concrete

We have already figured out what is included in the composition of concrete, now let's talk about what proportions of the components to use, how to properly and how to mix it all.

Almost always, speaking of the proportions of concrete, we mean the ratio of one volume of cement to a certain amount of the same volumes of sand, crushed stone and water.
First of all, as I said, the proportions of the components directly depend on the brand of concrete required. The brand of cement itself also plays an important role.

To begin with, consider the proportions of the components for Portland cement grade M400, since it is the most popular:

In the process of preparing concrete for the foundation, there is no need to use high-precision scales and measuring cups, it is enough to measure volumes with ordinary metal buckets, for example, 10 liters.

Approximate volume of water per 1 bucket of cement (10l)

Concrete brand	M100	M150	M200	M250	M300	M400
Water volume, l	11	10	9	7,5	6,5	5

The amount of water added depends not only on the proportions of the remaining components and the brand of concrete, but also on how wet the sand and gravel are in your area. The table shows the approximate volume of water per 1 volume of cement. And it is possible to determine exactly how much water per volume of cement only experimentally.

As a rule, in practice, pouring concrete for a foundation in normal soil, such exact calculations are not used, but average proportions are taken - 1 bucket of cement, 3 buckets of sand, 4 - 4.5 buckets of crushed stone and about 1 bucket of water.

Since the foundation must be monolithic, it must be remembered that 2 people manually, using a concrete mixer, will be able to prepare and pour a maximum of 2-3 m 3 of concrete per day. It is advisable to foresee this, and find the required number of assistants in advance.
It is better to mix concrete with mechanical or electric mixers. Mix the concrete mixture well with a shovel in the bath - it will not work.
When using a concrete mixer, it is not always convenient to mix the dry mix first and then add water. This approach threatens to "stick" sand to the back wall of the mixer. It is best to first pour most of the necessary water, then cement, and then sand and gravel.
Naturally, M400 concrete will be much stronger than M100, but it will also be much more expensive for a foundation made of such concrete. Therefore, there is no need to immediately chase after the most durable; in most cases, the M200 with a good reinforcing cage can also come up.
If you are pouring concrete at sub-zero temperatures, then I advise you to read my article on this topic. Properly arrange the heating of concrete and its insulation.
Concrete that is too liquid for a foundation levels well and is more comfortable to work with in some cases, but too much water in the concrete composition will adversely affect its structure and ultimate strength. Too little water - there will be great difficulty in leveling and moving the concrete. Therefore, always stick to average viscosity values.
For the installation of a conventional strip buried foundation on good soil, concrete of a grade of about M200 can be used, but for a strip non-buried foundation, concrete of increased strength is used.