Concrete: how to keep the proportions for the foundation

Purchased solution or self-mixing

After analyzing the prices in the market, some decide to save money and mix the foundation solution with their own hands. Indeed, it is quite easy to acquire quality components. But one should take into account the fact that the foundation must be poured continuously throughout the entire volume in one pass. This means that a large amount of solution will be required.

For these purposes, you will have to rent a concrete mixer, because it is quite problematic to mix a solution in such an amount manually. As a result, you save on materials, but incur significant additional costs for the rental of special equipment and electricity.

To prepare the required amount of concrete, you will need to rent special construction equipment

The amount of concrete

In order to know how much mortar is required for purchase or self-mixing, it is necessary to calculate the amount of concrete required. This data can be found in the project documentation, but it is quite easy to calculate it yourself, or use an online calculator.

The design specification always prescribes the amount of concrete required for pouring.

Mortar for brickwork: composition and proportions

During the construction of a building, a variety of mortars are used for masonry, because everything here depends on the number of storeys of the building, the mobility of the soil and the type of structure that is being erected. Let's find out which mortar for brickwork is applicable in this or that case.

First, let's figure out the types of mortars for brickwork. There are only three of them: lime, cement-lime and cement. Mortar due to low strength, they are rarely used, although to improve the qualities of cement - yes.

Lime-cement mortar consists of slaked lime, which is diluted with water to the thickness of milk, cement and sand. To prepare such a solution, cement and sand are thoroughly mixed, after which strained lime is added. This simple technique allows you to increase the plasticity of the solution, so it is much easier to work with it. This mortar can be used for almost any type of brickwork.

Normal cement mortar also very often used in construction. It consists of sand and cement. The amount of sand in the cement slurry depends only on the quality of the cement purchased. Cement mortar is inferior to cement-lime in terms of mobility, therefore it is more difficult to work with it.

Now let's look at the brands of solutions. which are used in construction

The brand is very important to know, since the proportions of the mortar for laying bricks directly depend on it

M50 solution usually used to seal cracks and seams indoors during repairs. M75 used for partitions and walls indoors. For outdoor masonry, this solution is used only for the construction of temporary structures.

M100 brand solution used to fill the seams of panels, floor screed, masonry (from solid and large bricks). It is allowed to use mortar for laying the underground part of the brick foundation.

M150 brand solution used for filling seams of structures made of heavy concrete and screeds. This solution has a very high strength, therefore, in it, as well as in higher grades, it is unacceptable to use components that provide greater elasticity (lime, gypsum, clay).

For masonry work, they are almost never used solution M250... since it is used mainly for the manufacture of especially strong screeds and for the installation of monolithic unloaded floors.

Now let's deal with the proportions of the components for the solution... Usually, for the preparation of a solution, the following ratio is used: from 1: 3 to 1: 6 (cement-sand). The amount of sand depends on the quality of the cement. The higher the quality of the cement, the more sand will be required to prepare the mortar.

For preparing M100... as one of the most popular mortars for masonry, a simple ratio of 1: 4 (if cement grade M400) or 1: 5 (cement M500) is used. To make the solution more elastic, lime can be introduced into it, in this case the proportions for M100 will be as follows: 1: 3: 0.2 (cement M400, sand, lime) or 1: 4: 0.3 (cement M500, sand , lime).

When preparing a good solution, you should take optimal amount of water... For a conventional cement mortar, the optimal amount is considered to be 0.8 parts of water per 1 part of cement. To prepare the mixture, use only cold and clean water!

In many ways, the quality of the solution depends on the sand. It must be clean, without various stones. For masonry mortars use construction sand with a grain size of 2 to 2.5 mm... Before preparing the solution, sand must be sieved, because this way it mixes much better with cement.

Never do not prepare a lot of solution... after all, after only 30 minutes, it becomes unusable. Also keep in mind that the finished solution should be stirred from time to time. When heavy particles settle to the bottom, the solution becomes heterogeneous and stratifies. It is impossible to make masonry with such a solution.

Basic proportions

When preparing solutions, the working measure is the mass or volume fraction of the binder; the most common and convenient ratios include 1: 3: 5 (cement, sand, gravel, respectively). The regulated proportions, depending on the required concrete strength, are:

The strength of concrete is primarily influenced by the ratio of sand to cement, but in addition to strict control over the proportion of dry components, the amount of water introduced is monitored. When using Portland cement, the W / C proportions are:

When building a foundation on dry soils, it is allowed to introduce lime or clay into the cement mortar, these components increase its plasticity. The recommended proportions when using Portland cement M400 are:

In private construction, it is inconvenient to determine separately the mass of all the ingredients to be poured; a bucket is usually used as a measuring instrument. In this case, all fillers are pre-weighed dry. The W / C ratio largely depends on the moisture content of the sand, experienced developers introduce no more than 80% of the recommended proportion of water when mixing, and then, if necessary (insufficiently plastic consistency), fill it in portions. Fiber, PAD and other plasticizers are added to the concrete at the very end along with the liquid, their share usually does not exceed 75 g per 1 m3.

Component requirements

To prepare a cement mortar for pouring a foundation, the following are used:

• Fresh Portland cement, ideally the date of issue does not exceed 2 months before the start of concreting. The recommended brand is M400 or M500.
• River sand with particle sizes in the range of 1.2-3.5 mm with silt or clay admixtures not exceeding 5%. It is advised to check its purity (fill with water and track the change in color and sediment), sift, rinse and dry if necessary.
• Pure crushed stone or gravel with a size of fractions from 1 to 8 cm, with a flakiness within 20%. When preparing concrete for the foundation, screenings of hard rocks are used; limestone is not suitable due to its low strength.
• Water: tap water, free of impurities and foreign particles.
• Additives: anti-freeze, plasticizing, reinforcing fiber.The introduction of such impurities is carried out with strict adherence to proportions.

The recommended proportions of cement and sand for masonry mortars are 1: 3 or 1: 2. The first ratio is considered universal, the second is chosen when building foundations on unstable soils. In practice, this means that for one bucket of cement with a grade of at least M400 (M500 at increased loads), 2 or 3 sifted quartz sand and no more than 0.8 parts of water are taken. A properly prepared mixture resembles toothpaste in consistency; to increase workability per 1 m3, 75-100 g of plasticizers (liquid soap or other PAD) are introduced.

How to make a foundation grout?

The process begins with the preparation of components and a concrete mixer, the presence of the latter is mandatory when mixing concrete for underground structures. The amount of building materials is calculated in advance according to the volume of the foundation and is purchased with a small margin

It is extremely important to fill it in one day; when preparing the solution on your own, all components are washed and dried in advance. Then they are poured into buckets into a concrete mixer in the following sequence: part of water → sand and cement → dry additives and fiber (if necessary) → coarse filler → remaining liquid in small portions

After filling in a new ingredient, the drum turns on for 2-3 minutes, no more than 15 minutes later, the finished solution is unloaded.

There is a time-tested method for selecting the correct proportions, chosen in the absence of data on the size of crushed stone. In this case, the bucket is filled with coarse filler, shaken several times and completely covered with water. The resulting volume of water corresponds to the required proportion of sand in the solution. After that, sand is poured into the bucket, again filled with water to determine the proportion of cement. But this approach is considered by some to be complicated and outdated, the more correct is the standard method of recalculating the mass fraction to the volume fraction and pouring the components into a concrete mixer.

Preparation of concrete for the foundation

• sand, gravel (crushed stone);
• cement;
• container for mixing concrete mixture.

Table of concrete grades and their corresponding grades used for strip foundations.

Cement cannot be stored for a long time and has the ability to react with moisture in the air. After a month, it can lose its original strength up to 10%, after a quarter, i.e. three months - up to 20%, and after half a year - up to 30%. Therefore, over time, its brand decreases, for example, from M200 to M180, which means that it is best to use this ingredient right away.

When mixing the mortar, in a concrete mixer, iron bath or wooden box, make sure that no impurities get into it. First, sand, gravel (crushed stone) and cement should be poured into a clean container. Then mix them thoroughly to get a homogeneous mass. After that, while mixing the concrete mixture, it is necessary to add water so that it completely and evenly moistens it. When using a concrete mixer, you first need to add water to it, and only then bulk materials. The concrete should be homogeneous in composition. The resulting solution should be used within two hours.

In what proportions to make concrete?

In most situations, for frame-type buildings, a columnar version of the foundation is used, which does not require a concrete mixture with increased strength indicators. For this type, M 200 concrete is suitable, which is made from M 500 cement, sand, crushed stone and water.

For one cubic meter of the mixture, you must:

• 300-350 kg of cement;
• 1100-1200 kg of crushed stone;
• 600-700 kg of sand;
• 150-180 liters of water.

This ratio of materials is formed by their qualities, for example, granite crushed stone has a high level of strength, in comparison with dolomite crushed stone or limestone, so it can be used in smaller quantities.

To create a mixture of concrete of the required consistency, it is best to use washed crushed stone, and only cleaned river sand, in which there are no various impurities of clay.

If you use low quality sand, holes and potholes can form in the base.

When choosing a cement, initially pay attention to the manufacturer's company.As a rule, the more famous the organization, the less likely it is to purchase a low-quality product.

Water should also be used clean, so that it is free of impurities and salts. If the construction is carried out in the cold season, then the water, like other components of the concrete solution, should be heated up to + 60C in order to give the solution the necessary consistency and strength.

How to mix concrete correctly?

For the preparation of a small volume of solution, a bucket is used as a measure of the weight of the components. The proportions are calculated in accordance with the fact that the components have different bulk density. Based on this fact, when preparing a 1-m3 solution, a ratio of 9: 5: 2 (gravel or crushed stone, sand and cement) will be needed.

The production of concrete M 200 is carried out according to the rules in order to achieve a high quality mixture as a result.

Rules for mixing concrete for a foundation:

1. Initially, sand and crushed stone should be well mixed together so that there are no lumps afterwards when adding water. Furrows are made on the surface, into which cement is poured. The mixture should be mixed until a completely uniform color is obtained.
2. Give the mixture the shape of a cone and add water in small portions, mix everything thoroughly.

When deciding what is the best way to mix the solution, needs and financial capabilities should be correlated. The best option would be to use a concrete mixer, but buying it for a small building is unprofitable, so it is better to use manual production.

Preparation of concrete mix for strip foundations

For this type of foundation, you first need to calculate the amount of material required. The parameters of one tape (length, width and depth) should be multiplied by their number.

Example. Length 20 m, width 0.5 m, depth 1 m. We multiply these values ​​and get, on one side of the foundation it is necessary to prepare 10 cubic meters of concrete solution.

Having prepared the required amount of the mixture, it is poured into the formwork. It is performed in layers, for example, if the depth of the base is one meter, then there should be four layers, each 0.25 cm. After laying each of them, it is necessary to tamp. Then, to release excess air, reinforcement should be slowly pushed into the solution every meter or two.

Preparation of concrete for a columnar foundation

Calculations in this type of foundation correspond to the strip version. The difference is that the concrete solution is not poured in stages, but immediately, after which it is rammed.

Preparation of the solution

So, after all materials and tools are prepared, you can start making a solution with your own hands.

1. 1 layer of cement is poured into the container, then a layer of sand, after which all layers alternate. The number of such layers should be at least 6. Thus, all components can be diluted more efficiently. Sand and cement should be poured into a bed. The total height must be no more than 300 mm.
2. The components poured into the container must be mixed several times with shovels until a homogeneous mass is obtained. Do not forget that the quality of the finished mixture and further work will depend on the mixing process. After everything is mixed correctly, experts recommend sifting the composition through a sieve with 3x3 mm cells again. The homogeneous mass must be absolute.
3. After mixing the dry components, you cannot immediately add water or other components, for example, water glass. The addition of liquid should be done gradually and carefully. Water must be added very slowly, so you can control the process of acquiring the desired consistency density. If the supply of liquid is large, it is the gradual addition that will not allow the mass to become too liquid.

An equally important indicator for cooking is the temperature of the liquid: it should not be either low or high.Try to use water that is close to the ambient temperature. An important role is played by the ambient temperature: it is necessary to dilute ready-made cement mixtures at an air temperature of at least +5 degrees.

As for the consistency of the cement mortar, everything here will depend on the area in which it will be used. For example, a thick material is required for masonry, and liquid material for filling.

For screed

The rules for preparing the solution depend on the purpose for which it will be used. For example, it is easier to prepare a mixture for a screed than for organizing a foundation. Crushed stone is not required here, and the proportions of the remaining components will be as follows: cement of the M400 brand and sand in a ratio of 1 to 3.

To properly prepare the consistency, follow the steps in the following order:

• lay a sheet of metal on the floor;
• pour 1/3 of the sand and 1/3 of the cement onto the surface, mix until smooth, repeat this action until the ingredients run out;
• make a pile from the resulting dry mixture, and in it a notch;
• Pour some water into this "container" and mix everything well.

For the foundation

As for the preparation of the mixture for the foundation, the process is more complicated here, and the best solution would be to use a device such as a concrete mixer.

Begin the kneading process by adding water. Determine the required amount at a ratio of 1: 4. Experts recommend initially pouring less water, since you can add it at any time

During the preparation of the cement mixture for the foundation, it is very important to monitor the consistency. It is better that it is liquid, but water must be used carefully

If there is a need for density, this indicator can be achieved after the kneading process is completed.

For finishing

The cement mixture is also used for interior decoration. The need for it appears when it is required to carry out high-quality plastering of the surface.

The use of the components that are in the composition of the cement makes it possible to obtain the required consistency

Note that more solution is needed for this to work. If there is a need to sand a small area, you can use manual mixing, but in any case, the concrete mixer will make this process faster.

Concrete classification

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

• especially heavy;
• heavy;
• light;
• especially lightweight.

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. Especially lightweight (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 precast, monolithic reinforced concrete structures and foundations. Special impurities, which are added to improve its technical characteristics, increase its strength, resistance to overheating, temperature extremes, reinforcement corrosion, and moisture.

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

What is PGS

ASG is a sand and gravel mixture, the components of which are mined in open pits, from the river and seabed. If a simple concrete structure is made strictly from materials according to GOST, then concrete from such a material contains raw materials that roughly meet the requirements of the standard. Therefore, this composition is more often used in the construction of private houses as a filling component for the production of concrete mortar.

In the field of construction of buildings and structures, such a mixture is used:

• for the base under the roadway;
• for the device of the base for foundations;
• for filling garden paths;
• for arranging trenches, etc.

The main purpose of this material is auxiliary work during construction.Unlike concrete that meets GOST, made from a sand and gravel mixture does not withstand high mechanical loads. However, having enriched it with the main filler, you can prepare a heavy look, which is used for the construction of lightly loaded structures (playgrounds and low-rise houses), as well as for the blind area of ​​buildings.

Related article: DIY foundation for a country toilet

According to the location of the ASG for concrete, it is subdivided:

• on a career (mountain-ravine);
• on the river (lake);
• to the sea.

According to the degree of enrichment, the sand and gravel composition is divided into 5 types depending on the amount of gravel contained in it:

The most popular is considered to be group V, from which you can prepare a solution corresponding to the brand of heavy concrete M200. Other types with a gravel content of up to 15% are considered natural.

Types of concrete foundations

In construction, several types of concrete foundations are used. Most often, buildings are erected on tape or columnar bases. Both types, in turn, have several versions.

Strip foundation

It is located strictly under the load-bearing walls and is a support belt, repeating the outlines of the elements resting on it. The depth of the bookmark is determined depending on the level of freezing of the soil and, as a rule, is below this level by 20-30 cm. There are the following types of strip foundations:

• monolithic;
• made;
• rubble;
• rubble-concrete.

For the device of a monolithic foundation, concrete is usedreinforced with various types of reinforcing mesh. Work on the reinforcement and pouring of concrete mix is ​​carried out directly on the site, with or without formwork (automatic calculation).

The monolith is laid during the construction of a building from heavy materials, with a basement or basement floor.

The prefabricated foundation structure consists of reinforced concrete blocks. In this case, narrower elements are installed on wide - foundation cushions, which ensure the distribution of the load on the ground. The block base can be solid or discontinuous. Mounting such a base is less laborious than pouring a monolith, but it requires adjusting the blocks to the dimensions specified by the project and is inferior in strength. The prefabricated type is suitable for soils with shallow freezing, not prone to swelling.

When installing the foundation, the boot is used on soils with a high water level and deep freezing. The work on laying such a foundation is laborious and time-consuming. This is due to the fact that large rubble stones are placed on the cement mortar with adjustment in size and shape. The main advantages of such masonry are its durability and strength.

Concrete substitute and its benefits

The rubble-concrete foundation consists of approximately the same amount of fine stone and cement mortar. In terms of characteristics, it is similar to rubble, but the materials for it are more accessible, and the bookmark is easier, because in this case, careful adjustment is not needed.

Column type foundation

Designed for the construction of light structures. Usually, small country houses, sheds, baths are built on its basis. At the same time, support pillars are placed at the corners of the building and in places with the greatest load. For their formation, concrete or concrete blocks are suitable, as well as rubble and a metal pipe. It is undesirable to mount a columnar base on loose soils saturated with moisture.

For the construction of large objects on unstable, soft or heaving soils, columnar-strip foundations are suitable. They combine support pillars that go deep into the ground to reach its hard layers and a concrete tape, which is a connecting element and is located at a shallow depth.

Correct installation of the foundation structure for the building ensures its durability.For pouring the base, you can use ready-made mixtures that are supplied to the construction market by industrial enterprises. However, in private construction, it is preferable to make concrete for the foundation with your own hands, as this significantly saves the budget. Of course, it is impossible to obtain the M500 brand in this way, but this is not required for low-rise buildings.