What should be the foundation for a house? How to properly prepare the mixture for the foundation, proportions of concrete in buckets Composition of concrete mortar for the foundation proportions.

Concrete- an important component of any construction. The operational characteristics of the structure being built largely depend on the foundation. Therefore, it is very important to properly prepare the solution for pouring it. Concrete mortar for large-scale construction projects is prepared in a factory.

Private developers, when building a house with their own hands, usually prepare it themselves in order to at least slightly reduce construction costs. Having chosen to prepare it yourself, it is important to observe the proportions for the concrete for the foundation. After all, the strength of the foundation of the house often depends on this.

Choice

The foundation is the load-bearing part of any building. To make it resistant to various loads, you need to choose the right concrete composition for it. In this case, its resistance to compressive loads will be sufficient, which means it can withstand the pressure of the entire house. Various are produced, therefore there are several composition options. Which one to choose for pouring the foundation? This question must be answered taking into account two factors:

Features of the structure (number of floors, weight, size of the basement).
Features of the soil on the site.

The choice of composition taking into account the first factor is made as follows:

M 150 is used for pouring foundations for frame and panel buildings.
For light houses made of logs and timber, M 200 is selected.
M 300 for block and brick buildings.

The dependence on the characteristics of the site is as follows. The more complex the soil on the site, the higher the grade of concrete you need to choose. So, for rocky soil it is enough to prepare a solution of M 150. For loamy soil, the composition M 200 is suitable.

Components

Any concrete, regardless of its brand, consists of the following components:

Cement.
Sand.
Crushed stones or gravel.
Water.

All these components must have the necessary characteristics, taking into account which they must be selected. Cement is the main ingredient in a concrete mixture because it is a binder. It is produced by cement factories. Cement is divided by grade and by the number of various additives it contains. The most popular Portland cement, it contains many special additives to improve the properties of the material. When pouring the foundation of a house, experts recommend that private developers use cement M 400 or PC 400.

You need to keep in mind, like many building mixtures, the shelf life of cement is limited. After a year of storage in packaging, it significantly loses its activity, which determines the properties and brand of the material.

Sand is one of the fillers for concrete mixtures. To obtain a high-quality solution, you need to take its choice seriously. It is worth noting that at the moment the choice of sand on the construction market is huge. If you wish, you can even purchase sand from the seabed, but not every sand material is suitable for concrete.

Thus, experts do not recommend using sand with clay admixtures for this purpose. Because of this, concrete is less durable and frost-resistant. But with river sand you can prepare a solution that is ideal in condition. It is often of very high quality and consists of homogeneous fractions.

and gravel just like sand in the solution acts as fillers. Thanks to them, the solution “shrinks” less, which makes the concrete structure stronger and more durable. When choosing crushed stone, you should pay attention to its shape. Because the convenience of pouring concrete mortar depends on it.

Flat and angular crushed stone is usually not used for mixing concrete. Because it requires more consumption of other components, which affects the strength of the structure. The best option for pouring the foundation is the use of crushed gravel. It consists of particles ranging in size from 3 to 70 mm. In addition, it is affordable for private developers.

Water. This component can have any characteristics, the main thing is that the water is clean without any impurities. Having all the above components and knowing the proportions of concrete for the foundation, you can prepare a solution of any required brand.

Video

Video on how to make concrete, as well as proportions in buckets.

Component proportions

The correct ratio of components in a concrete solution is the key to obtaining high-quality material. The optimal composition of concrete for the foundation for the construction of a private house is considered to be one part cement powder to four parts crushed stone (1/4). And in the proportion of cement and sand, the ratio is 1/3, that is, for 1 part of cement (M 400) there are 3 parts of sand. In general, the weight of cement in the cement mortar should be 1/4 of the total mass.

But concrete still needs water to harden. An important characteristic of concrete is the proportion of water and cement (the so-called water-cement ratio). The strength of concrete depends on this ratio: the lower its value, the stronger the material. For a concrete mixture used for concreting foundations, the maximum water-cement value is 0.75.

For private developers, for a small amount of work, it is easier to mix the mortar on the construction site. One batch of foundation mortar is made in a concrete mixer in approximately the following proportion:

300 kg of cement powder.
600 kg of sand.
1300 kg of crushed stone.

But the developer does not have the ability to weigh bulk materials when he is at the construction site. A completely reasonable question arises: how to make a foundation mortar correctly. To do this, you need to know the proportions of concrete for the foundation in buckets. Since all components have approximately the same bulk density, you can measure them and then the composition of the concrete for the foundation, the proportions in buckets will be something like this:

Cement 25 buckets.
Sand 43 buckets.
Crushed stone 90 buckets.

When determining the amount of water, they are guided by the measure of cement: for one bucket of cement powder you need to add an incomplete bucket of water. This volume may vary depending on the situation. For example, if it is reinforced, then the concrete is mixed with more plasticity so that it penetrates inside the frame more easily.

It is more practical to make it rigid, this will speed up the hardening. In both cases, you need to add enough water so that there are no puddles in the finished solution. To obtain one cube of concrete of different grades, the optimal ratio of components in volumetric terms is presented in the table.

concrete grade	cement M 400	sand	crushed stone
M 150	1 bucket	3 buckets	5 buckets
M 200	1 bucket	2.5 buckets	4 buckets
M 300	1 bucket	1.7 buckets	3 buckets

In these volumetric indicators, the bucket can be replaced by any volume measure, provided that the proportion is maintained.

When deciding how to prepare concrete for the foundation, you need to keep in mind that in addition to the proportions, you need to know in what sequence to lay the components. First, water is poured into the concrete mixer, slightly less than normal. Then half a portion of crushed stone is poured. And only then, cement with sand and again all components are thoroughly mixed.

At the very end, the remaining crushed stone is poured. After this, you need to give the concrete mixer a little time so that it thoroughly mixes all the components. And finally, having assessed the thickness of the solution, depending on the situation, add the rest of the water or leave it as is and mix everything thoroughly again.

Conclusion

After the foundation casting has reached the calculated hardness, to get rid of doubts about the correctness You can check the proportions and grade of concrete. To do this, place the chisel on the surface of the casting and hit it with a hammer. On ordinary concrete M 200 there should be a dent no more than 5 mm deep.

In contact with

When starting any construction, we want the constructed building to be strong and reliable, and for this it is necessary, first of all, to make a high-quality and durable foundation. It is pointless to build high and strong walls if, when laying the foundation, you do not provide the required quality and proportions of the concrete solution. And given the considerable weight of the building and the load, for the foundation they become a “golden key”, which opens up the opportunity to build up the walls of the building, regardless of weather factors, alterations and modifications, if the structure is installed on a powerful and durable foundation.

Types of foundations

Depending on the weight of the building being erected and the type of soil on which construction is being carried out, the type of foundation is selected:

Tape - performed along the perimeter of the building under the main load-bearing walls of the structure;
Slab - poured with a solid slab covering the entire area of the building, the most expensive option in terms of materials and labor intensity;
Columnar - used mainly for small structures, outbuildings, gazebos and other options that do not have much weight;
Ribbon-column– is a combination of elements of both a columnar and strip foundation; in terms of material costs it will be cheaper than a strip foundation.

Important! The concrete mixture often behaves in the most unpredictable ways when poured and hardened, so the best way to get a high-quality foundation structure is to pour the formwork in one go.

In this case, the shrinkage of the material will be more or less uniform, even if the proportions of ingredients spent on concrete for the foundation with your own hands were not maintained exactly.

Composition of concrete for foundation mixing proportions

It is not always worthwhile to strive to obtain a foundation of the highest strength and rigidity. In some cases, this approach is a waste of money, and sometimes such a decision directly contradicts the requirements for the foundation system of a particular building.

To make it easier to navigate the different proportions of preparing concrete mixtures, an index or grade is assigned to a specific concrete composition to characterize the strength and rigidity. M150 concrete is used for concreting minor objects, for example, you can make supports for a fence or the foundation of a light frame building. Brand M200-250 is widely used for the foundation of most private houses, one-story buildings with low load on the ground. M300 - suitable for two-story brick houses, M-400 is used in industrial construction.

Requirements for concrete for foundation

To prepare concrete of any grade, the same ingredients are used:

Cement is the main active element of a concrete mixture; it acts as a binder and holds together all other components into a single whole;
Sand is a filler that fills voids and acts as a cheaper cement substitute;
Gravel or crushed stone– it is better to use fractions with sizes from 1 to 5 cm, preferably a material with a rough surface, it helps to increase the strength of concrete;
Water – pure drinking water is used, not containing any impurities or additives.

Important! Please note that cement, like food, has its own expiration date. After just a year of storage in packaged form, the strength of cement in finished concrete decreases by 20-25%. Moreover, the decrease in characteristics occurs unevenly, in different packages in different ways, even within the same batch.

Typically, cement grades M400 and M500 are used in construction work.

The sand for preparing concrete must be clean; you can use river or quarry sand; you must check that it does not contain clay impurities, as this will negatively affect the strength of the foundation.

To check the purity of the sand you are going to use, pour some sand into a clear bottle, add water and shake. Then evaluate the clarity of the water in the bottle. If the water is clear or slightly cloudy, this sand can be used to prepare a concrete solution for pouring foundation structures. If the water in the bottle is cloudy or colored, the sand will have to be rinsed or replaced.

In addition, the sand used to build the foundation must be sifted before mixing the concrete mixture. No plant debris, twigs, leftover leaves, or pieces of soil should get into the concrete foundation solution. All these plant inclusions negatively affect the quality of the poured foundation.

Crushed stone or gravel used in concrete for the foundation must also be clean, without soil or organic matter. Before mixing the mixture, you can rinse the gravel with clean water to ensure its cleanliness.

To mix the concrete solution, use only clean water. To avoid problems with the strength of the foundation system later, water from ponds and lakes, especially sea water, should not be added to concrete. The water should not contain salt impurities or any organic residues.

What proportions to use

If you need to prepare concrete yourself, use the proportions given in the table. A construction site is not a store, and no one will weigh the ingredients, and the proportions must be maintained as accurately as possible. To maintain proportions, it is enough to use information about the volumetric ratio from the second column.

Two words about the cost of concrete for the foundation

The work of preparing concrete mortar for pouring the foundation has always been very difficult and quite monotonous. Even with a 100-liter electric mixer, pouring, for example, the foundation of a 6x6 house, 120 cm deep, will require at least 15 cubic meters of concrete. In this case, it is necessary to deliver almost a hundred 50-kilogram bags of cement to the construction site, maintain the proportions and mix the mixture.

If we take the price of the ingredients cement - 150 rubles per package, sand - 500 rubles and crushed stone -700 rubles per ton, in this case the cost of a cubic meter of concrete for the foundation according to the proportions of cement, sand and crushed stone 1-3-5 will be just over a thousand rubles. Purchasing concrete from a construction organization will cost at least 2 thousand rubles. The difference is 15 thousand for hard work and a guarantee of exact compliance with the proportions of concrete, and therefore the quality of the foundation.

For large volumes of foundation pouring, it is still better to buy a ready-made solution. The question of the quality and proportions of concrete remains open. It is possible to study the quality of a sample only in a laboratory; moreover, the design strength of the foundation casting occurs only after 28 days, so the issue of compliance with proportions can be objectively assessed at the level of indirect signs.

For example, you can determine the nature of the plasticity of a concrete solution using the method given below. To do this, you will need a small container, the dimensions of which are shown in the figure. It is enough to fill the form with concrete and turn it over onto a flat metal sheet. The quality of the material can be judged by the degree of spreading.

The second option is to check compliance with the proportions and grade of concrete after the foundation casting has reached the design strength and hardness. If you try to prick the surface of the sample by hitting a chisel with a hammer, a mark no more than 5 mm deep will remain on ordinary M200 concrete, subject to the proportions and quality of the cement.

The grade of concrete and proportions for a private house largely determine the durability and reliability of the entire structure.

To select the correct mixture, it is important to take into account all influencing factors, incl. loads and geological features.

It is especially important to ensure optimal ratios of ingredients when preparing the mixture yourself.

In general, concrete is an aqueous solution of a mixture of binder and aggregate with the addition of ingredients to improve properties. The preparation technology is quite simple - the components are mixed in a certain sequence, the required amount of water is added and everything is thoroughly mixed.

The properties of a material are primarily determined by its composition. The concrete mixture includes the following components.

Cement

The basis of concrete is binder - cement, which holds all components together as they harden. In private construction, Portland cement grades M300-M500 are used for foundations (the number in the marking determines the strength of the cement).

Fillers

They provide the bulk of the concrete. Any composition contains the following fillers (fillers):

Sand— for the preparation of the mixture, only purified from impurities with a particle size of 1-4 mm are used; in one batch it is not recommended to use sand with a spread of their size of more than 1-1.5 mm. Can be used river, sea or quarry sand that has undergone thorough cleaning and separation of excessively large fractions.
Crushed stone and gravel- strength characteristics are provided by the second important filler - gravel or crushed stone. To prepare concrete, raw materials with fraction sizes in the range of 7-40 mm are used. The roughness of individual elements improves their adhesion in the final product.
Water. Without it, it is impossible to prepare a solution. It provides the desired consistency. It is best to use regular tap or well (well) water. If you take it from open reservoirs (river, lake), then the composition will contain silt and various impurities that negatively affect the quality of the solution.

Additional ingredients (modifiers)

They are not considered essential components of concrete for the foundation, but their introduction makes it possible to obtain specific properties that are sometimes simply necessary during construction or operation. The following ingredients are used:

accelerators or retarders of solution hardening;
plasticizers;
superplasticizers;
antifreeze ingredients.

When adding modifiers, it is important to strictly observe the proportions, because their excessive content can disrupt the solidity of concrete.

The composition of concrete determines all its main characteristics - strength, specific gravity, plasticity, hardening time, frost resistance, water permeability. By varying the brand of cement and the ratio of ingredients, you can change the properties of the mixture depending on specific requirements.

How is the strength grade of concrete determined?

The most important characteristic of the foundation of a house is compressive and bending strength. These parameters largely depend on the strength parameters of concrete. Its strength marking is made up of the letter “M” and numbers indicating the compressive strength in kg/sq.m.

Modern strength classification provides for division into classes, designated by the letter “B” and a number (compressive strength in MPa). However, until now, manufacturers more often use the first marking.

Depending on the composition concrete can have a grade from M50 to M800. For the construction of small buildings on solid soils, it is quite enough to use the M200-M250 material. Most often, for private houses, the recommended strength is M400, and for the construction of large structures and heavy facades - M500.

When considering strength characteristics, it is important to consider that the declared value is achieved after a certain time. A gradual increase in strength as the structure is formed is a specific property of concrete.

For standard mixtures this period is 28 days. By introducing special additives it can be significantly shifted in one direction or another. In this case, the actual period for achieving the standardized strength is indicated in the marking (if there are no instructions, then it is assumed to be 28 days).

Influence of wall structure and soil composition

The choice of concrete grade for the foundation should take into account the design of the walls of the house and the geological parameters of the soil.

The wall material forms the load on the base, i.e. the impact on it from above, and the state of the soil is the degree of external impact from below.

When choosing, you can focus on the following recommendations:

wooden walls and masonry made of porous blocks - concrete M200-M250 is suitable;
single-story brickwork - M250-M300;
two-story houses with a brick wall - M300-M350;
weighted, load-bearing facade - M400-M500.

The composition of the soil and its condition plays an important role in the selection of material for the foundation. Of particular importance is the depth of groundwater and the level of winter freezing. First of all, to increase frost resistance and water resistance, it is necessary to correctly select the grade of cement in the concrete formulation.

For complex soils, the grade of cement should be 1.7-2 times higher than the grade of concrete (for example, for M250 concrete, Portland cement will be required at least grade M400). For hard (rocky) soils, the grades are approximately equal.

If the soil is assessed as clayey or swampy, then the strength grade of concrete increases by at least 50 units. So, for ordinary brickwork with a design grade of M250, you will have to prepare concrete of a grade not lower than M300 (preferably M400).

Choosing concrete for different foundations

Different types of foundations handle loads differently. So a columnar foundation works only in compression, and also in compression and bending. This specificity also determines the emergence of different requirements for concrete for these types of house foundations.

In addition to the specified selection criteria, there are several other important parameters that must be taken into account:

Frost resistance. In the marking it is marked with the letter F indicating the permissible sub-zero temperature. For example, concrete grade F50 can be used in almost any climate zone, because... able to withstand temperatures down to minus 50 degrees. For temperate latitudes, a material of at least F35 is recommended.
Mobility (P). It characterizes the fluidity or plasticity of the mortar during construction. When pouring manually, you can use P2-P3 solutions. If a concrete pump is used, then a material of at least P4 will be required.
Moisture resistance (W). This characteristic depends on the presence of special additives that provide moisture resistance. Under normal conditions, W4-W5 concrete is used. With a high rise in groundwater, the class of the material increases to W10.

In addition, concretes differ in specific gravity. When constructing the foundations of private houses, a lightweight composition is used. Such concrete can have a density in the range of 600-1600 kg/cub.m.

Proportions of concrete for the foundation

The ratio of ingredients in the solution determines the grade of concrete and its plasticity during installation. Each brand has a specific recipe, but the consistency of the solution is determined by the amount of water added. Proportions can be determined by weight or volume.

The most common method is volumetric mixing (in fractions), for which it is enough to have a measuring bucket. When using “dilute by weight” you will have to use scales.

If the material is prepared with your own hands, and therefore the exact brand is not always important, then the most common proportion (by volume) is used: cement (1 share), sand (3 shares), crushed stone (5 shares), water (1/2 share).

If you want to get a specific brand of concrete, you can use the following ratios of cement, sand and crushed stone:

M100 – by volume – 1:4.1:6.1; by weight - 1:4.7:7;
M200 – by volume – 1:2.5:4.3; by weight - 1:2.8:4.7;
M300 – by volume – 1:1.8:3.2; by weight - 1:2:3.7;
M300 – by volume – 1:1.2:2.3; by weight - 1:1.2:2.6.

When translating volumetric and weight ratios, you can use practical advice:

A bucket with a capacity of 10 liters holds 15 kg of cement, 20 kg of sand, and 18 kg of crushed stone.

How to cook it yourself?

Self-production of concrete mortar is carried out in the following order:

Preparing Ingredients– sifting, removing impurities.
Weighing the mixture components. Typically a measuring bucket is used.
Mixing with water. There are 2 methods - the dry method, when the components are first mixed together, and then water is gradually added, and the wet method, when half of the total volume of water is poured in, cement, sand and gravel are poured into it alternately, and then the remaining volume of water. For mixing, it is better to use a construction mixer or a hammer drill with a special attachment.

For work you will need a shovel, a construction mixer, a sieve, a wheelbarrow or stretcher for delivering components, a scoop, a measuring bucket, scales (steelyard).

When building the foundation of a private house (see:) it is very important to choose the right brand of concrete in terms of strength and basic characteristics. If you prepare the solution yourself, you must strictly adhere to the recipe. The quality of preparation and composition of concrete determines the durability of the entire structure.

Concrete is one of the modern materials that are used to create strong and durable structures. It consists of sand, some fillers and a binder. When concrete mortar hardens completely, it becomes stone. It is impossible to imagine a single construction project in which concrete would not be used.

However, the material must meet certain requirements. Only in this case can it be used to build a durable structure that will last for decades. To make the material as durable as possible, it should be manufactured using special technology. The proportions of concrete for the foundation of various structures are selected in accordance with the strength requirements for the structure.

Cement

Cement is always used as a binding agent when creating a concrete mixture. It is manufactured in different variations. The choice of a specific brand of cement depends on the final purpose of the concrete product and the conditions of its use. Bonding quality is one of the main characteristics of cement.

When choosing cement, it is important to consider its technical data. They affect the maximum load that the finished product can experience. This indicator is measured in Megapascals. When designating a brand of a domestic product, the letter D (impurities) is added. For example, if M400-D20 is written on the bag, then a concrete product made from such cement will withstand a load of up to 400 MPa, and the percentage of impurities in the powder is 20%.

For domestic purposes, Portland cement grade 400 is often used. It has good strength and is suitable for low-rise construction. For industrial purposes, choose cement grade 500 or higher. When constructing structures that will experience severe loads, you should choose cement powder of a higher grade.

Cement powder has such a characteristic as shelf life. After a certain time, the material begins to lose its beneficial properties. If the cement is fresh, it is friable and does not have compactions or lumps. When various compactions are present in the powder, cement should not be used in the work. Such a powder has already absorbed a certain amount of moisture, which affected its binding properties.

Sand selection

Sand can have different characteristics. The strength of the final result will depend on how correctly it is selected. When preparing concrete mortar, different types of sand are used. One of the main conditions is the absence of dust or clay particles. If there are quite a lot of such inclusions, the mixture will be of low quality. This can be especially true for fine sand, which contains a high percentage of dust particles. It cannot be used to make concrete.

How not to make a mistake when choosing sand? After all, only by choosing a high-quality material can you make the most durable concrete possible. It is better to choose river or sea sand. He is the purest. Quarry sand should not be used to create a concrete mixture without preliminary cleaning. It usually contains a lot of tree roots, leaves and bark. Quarry sand must undergo washing and settling.

If any organic inclusions get into the concrete, it will lose a certain percentage of its strength. This is explained by the formation of voids in the finished solution when mixing concrete with dirty sand.

Another important factor is the moisture content of the sand. Even if the material is dry, it can contain up to 2% water, in wet sand up to 10%. If you use too wet sand for the mixture, the strength of the finished product will significantly decrease. The exact proportions for preparing concrete are chosen in accordance with the requirements for the final result. The differences between different grades of concrete are summarized in the table:

Gravel and crushed stone

The main fillers for concrete are often gravel and crushed stone. This material is a rock that has been crushed to a certain size. It can be classified depending on the size of the individual elements. Crushed stone can have a rough or smooth texture.

Crushed stone can be:

very small - individual components range in size from 3 to 10 mm;
small - stones have a diameter of 10-20 mm;
medium - such crushed stone has a size from 20 to 40 mm;
large crushed stone has a diameter of 40-70 mm.

To make concrete that will last for many years, it is necessary to choose crushed stone such that the size of its individual parts is no more than 1/3 of the thickness of the finished product.

In addition, it is important to take into account one more indicator - the voidness of the filler. It is determined by the amount of empty space between the stones. It is quite easy to determine. To do this, you will need to fill a 10-liter bucket with crushed stone and see how much water is needed to fill the remaining space. When using 3 liters of water, we can say that the voids of the filler are 30%.

This indicator affects the amount of sand and cement that will be used to create concrete. The less voidage, the less other components will have to be used to create the mixture.

To fill the voids as much as possible, crushed stone of different fractions is used. Stones of both small, large and medium sizes are taken. It should be taken into account that fine elements must be used in at least 1.3 of the total amount of crushed stone.

In addition to gravel and crushed granite, depending on the purpose of using the concrete product, expanded clay and blast furnace slag are used. Other fillers may also be used. If lightweight concrete is being prepared, wood shavings are chosen as a filler. When creating ultra-light types of concrete, gases are used as filler. However, when producing such concrete, certain requirements must be observed. Otherwise, the finished product will not meet standard standards. Table of general requirements for concrete:

Fillers for concrete mixtures can be dense or hollow. Natural materials have less background radiation than artificial ones. Granite rocks have the lowest indicator. However, finished products with any fillers will not be sources of radioactive contamination, so this indicator is often not taken into account.

Water

Water is one of the most important components of the solution, which must also meet certain requirements. If the water quality is poor, it will negatively affect the strength of the concrete product. The basic rule when making a mixture is this: if water can be used for cooking, it is also suitable for mixing concrete. It is not recommended to use water from the swamp.

Each element of the solution has a certain moisture content. The moisture present in building materials is excess water that can spoil the finished concrete mixture. To figure out how to prepare concrete, you will need to determine the necessary properties of the finished product.

The volume of water used affects such an indicator as the plasticity of concrete. The plasticity of a solution is usually determined by eye.

To determine this indicator, you should take the solution on a shovel. If it slides off a horizontally placed tool, it has high ductility. When concrete slides in the case of a slight tilt of the shovel, it can be considered medium-plastic. Concrete has low plasticity and will not slide even if the shovel is tilted strongly.

Strength gain

Concrete acquires a certain strength only after a certain time. After a week, the finished material gains a certain strength (up to 40%). However, only within 28 days from the day of pouring can concrete become as strong as possible. Special requirements for this indicator are imposed when creating concrete for the foundation.

The calculation of concrete composition must be carried out taking into account certain data. Among them are:

brand of cement powder;
characteristics of the granulometric composition of crushed stone and sand;
plasticity of concrete to be achieved;
required grade of ready-mixed concrete.

The composition of concrete can be calculated by the mass of its components or their volume. Cement is always taken as a unit. Other components of concrete are calculated as a certain part of the volume of cement. The proportions of concrete to choose for the foundation should be determined according to the required grade of the finished product.

Calculation by weight

The composition can be calculated according to certain standards. The main goal is to obtain a solution of medium plasticity.

At the beginning of work, it is necessary to determine what the water-cement ratio will be. For this purpose, the W/C indicator is determined. It represents the ratio of water and cement. This characteristic is determined experimentally or using a special table.

To measure the amount of materials that make up concrete, a 10-liter bucket is usually used. It is used as a measuring vessel. To simplify the calculations, it should be mentioned how much certain materials are contained in a 10-liter bucket:

about 13-15 kg of cement powder;
from 14 to 17 kg of sand - this figure depends on the percentage of moisture in the material;

It should be understood that the method of such calculation is somewhat inferior to the methods used by professional builders. However, this method is still good for household purposes. In addition to using proportions by mass, proportions of the mixture composition according to volume are also used. This method is less accurate.

Proper mixing of concrete

Concrete can also be mixed manually, but mixers or concrete mixers are more often used for this work. In the first case, the finished mixture is small in volume. To properly mix the solution, you will need a container of a certain volume. Usually a tin trough is chosen for this purpose.

The proportions for preparing concrete of medium plasticity grade M400 should be as follows:

cement - 1 part;
crushed stone - 2.7 parts;
sand - 1.2 parts.

With 10 liters of cement, 31 liters of water must be used. Manual mixing is the most popular method for creating concrete products in the homestead. The number of components used can be calculated using the table:

Preparing concrete by hand is quite simple. Sand is poured into the trough. Then a stripe is drawn in it in the middle. Cement is poured into the groove. Then these ingredients must be thoroughly mixed. After this, crushed stone is added. The resulting mixture is kneaded until each stone is covered with the solution. At the same time, add water a little at a time. Its quantity regulates the plasticity of concrete. When the mixture is homogeneous, the concrete can be poured.

When mixing by hand, it is important to pour the prepared solution as quickly as possible. If there is a short delay, the concrete will begin to delaminate. In this case, water begins to appear on top of the solution. It is better to mix the concrete in a concrete mixer.

Using a concrete mixer

When using a concrete mixer, cement powder is first poured into the device and water is added. Then you need to add sand. Then the solution should be kneaded, adding water along the way. When a homogeneous solution is obtained, filler is poured into it.

The advantage of this method is that the concrete will not delaminate. It can be in the mixer for about 1 hour without losing its properties. The device should not be placed far from the concrete pouring site. This condition must be observed so that the concrete does not lose its properties during delivery to the installation site. If you follow these simple rules, you can get a reliable and durable design.

When planning the construction of a house, garage and other objects on your site, you want them to last as long as possible. To do this, first of all you should take care of a reliable and solid foundation. Its quality characteristics are determined not only by the laying technology, but also by the composition and proportions of concrete for the foundation. When mixing a solution with your own hands, it is important to understand how changing the ratios between ingredients affects the final result.

The main ingredients of the solution are cement and water; it also includes aggregates: sand and crushed stone (gravel, granite screenings, expanded clay). To obtain certain properties, special-purpose additives are introduced.

Cement is a binder that combines solid particles of the mixture into a concrete mass. It is highly hygroscopic, so you need to buy it immediately before use. Depending on the composition and fineness of grinding, the following varieties are distinguished:

Ordinary Portland cement - the material normally withstands moisture and low temperatures. Used for pouring foundations operated under normal conditions.
Portland slag cement is a good choice for monolithic foundations constructed in mild climate zones with high humidity and infrequent frosts. Such concrete hardens more slowly than usual, but has high moisture resistance and strength.
Pozzolanic Portland cement - shows an average level of strength with maximum resistance to moisture. It is used for pouring underground and underwater foundations that do not experience heavy loads.
Fast-hardening – cements with special additives that accelerate the setting process and reduce the maturation period of concrete to 2 weeks. Can be used in any climatic conditions.

Based on compressive strength, cement is divided into several grades - from M100 to M500. The numbers indicate the degree of strength, which is expressed in kilograms per cm2.

Water enters into a chemical reaction with cement, resulting in a wet solution; regular water from the tap is quite suitable - clean and without excess salts. The sand must be free of clay and foreign inclusions (no more than 5%). The optimal grain size is 1.2-3 mm; too small fractions are unsuitable. Washed river sand is best suited for foundation construction. It is recommended to sift it before use. For self-preparation, choose crushed stone with a fraction of 10-20 mm. The ratio of large and small particles should be approximately the same. This reduces the number of voids in concrete and reduces cement consumption. Crushed stone is checked for cleanliness and the absence of clay impurities and debris.

For marking, alphanumeric designations are used, similar to cement. In the construction industry there is a wide range: from M75 to M1000. The numbers reflect the calculated compressive strength at the time of full curing (28 days after pouring). The indicator is measured in kg/cm2. The higher the grade of concrete, the greater its strength. For foundation construction in private construction, M200 or M300 is usually sufficient.

Proportions of concrete mixture solution

In order for the concrete to be of high quality, and the base to be reliable and durable, it is important to choose the correct ratio of components. In compositions that are produced in factories, cement, sand, crushed stone and water are mixed in a ratio of 1: 2: 4: 0.5. For private housing construction, the volumetric ratio of ingredients depends on their characteristics and planned strength.

To get the weakest grade M100, you need to prepare a mixture in the ratio 1:4:6:0.5. If weighed on scales, then the following composition is required to produce 1 m3:

cement – 206 kg;
sand – 780 kg;
crushed stone – 1200 kg;
water – 185 l.

At home, it is much easier and faster to carry out calculations in buckets. The basis is usually a galvanized container of 10 liters. In this case, the proportions of the concrete components look like this:

cement – 10 l = 1 bucket;
sand – 41 l = 4;
crushed stone – 61 l = 6-7.

To fill a strip foundation for a fence, garage, or various outbuildings, it is better to prepare M250 in the ratio 1:2:3.5:0.5.

The construction of low-rise buildings requires the creation of a more reliable foundation. If a pressure of at least 400 kg is expected for each centimeter of the foundation of the grillage, then you should choose a proportion of concrete for the foundation of 1:1:2.5:0.5. When the developer does not have accurate data on the load on the base, you can play it safe and make very strong concrete M450. The ratio 1:1:2:0.5 is suitable for it. A foundation of increased strength costs 4-4.5 times more than the M100 brand, so the strength must be justified not only from the design side, but also from the economic side.

Making concrete yourself

The easiest way to mix the solution is with a concrete mixer. But if the technology turns out to be unavailable, then it is quite possible to do it manually. Stock up on tools and equipment for pouring the foundation:

shovel 2 pcs;
bucket 2 pcs;
mixing container (metal or plastic trough, wooden box);
wheelbarrow;
tamping;
plumb line, level;
meter, tape measure.

Use one bucket and shovel only for cement. They must be dry and clean. The second pair of tools is intended for sand and crushed stone. Measure all components of the composition in buckets in the required proportions, lightly compact with a shovel and level on top.

Pour crushed stone and sand into the prepared container and mix thoroughly.
Use a shovel to form grooves on the surface, into which you then pour cement.
Mix the dry mixture until the color becomes uniform.
Shape into a cone, make a depression and pour in a small portion of water. Pour the mixture from the edges of the cone into the liquid until completely saturated. Then form a new cone and add water again. Repeat the manipulations until the concrete reaches normal saturation for pouring the foundation.
Unload into formwork no later than 2 hours after preparation.

Kneading nuances

Concrete that is too thick can be thinned with a small amount of water. The structure should be uniform, and mixing should be done without unnecessary effort. The other extreme – oversaturation with moisture – should also be avoided. Liquid concrete slides off the shovel quickly and easily. If the sand is wet or the foundation work is being done in wet weather, then the volume of water must be reduced in proportion.

Concrete sets within 10-12 hours, complete hardening occurs in 5-7 days. After 2 weeks, the foundation gains up to 80% strength. It becomes fully ready for use after 28-30 days (at a constant ambient temperature of about 20°C). If fast-hardening types of cement are used, the maturation period is halved.

Construction experts recommend building a foundation only in the warm season. At positive temperatures, a normal chemical reaction occurs and it hardens well. In cold weather you have to constantly heat up the water and concrete. If this is not done, then ice will form in the solution, which leads to weakening of the strength and destruction of the foundation from the inside.