Proportions in the manufacture of concrete at home. The process of making concrete. We select crushed stone for the purpose of concrete

It is quite difficult to exaggerate the importance of concrete in modern construction. It is used at various stages of building construction, starting with the creation of the foundation, ending with the final decorative work on the design of the landscape of the green zone near the house.

According to its physical properties, concrete is an artificial stone made from a certain set of components.

What is concrete made of?

All components are divided into four groups in accordance with the principle of operation of the component:

astringent base
mixing liquid
aggregate
additional substances.

Important! The materials of the last category are used mainly when laying concrete in difficult conditions or at the request of the manufacturer.

What are the main ingredients of the solution?

To create a concrete mix, prepare:

Cement
Rubble.

Important! A wide range of dry concrete mixes is presented on the building materials market, which are enough to be diluted with water exactly according to the instructions. But, making concrete with your own hands, with the right components, is also not difficult.

In the process of choosing a finished building mixture, be attentive to the presence of specific additives. Some of them affect frost resistance, hardening rate, degree of plasticity of concrete.

Criteria for the selection of concrete components

Water

In production processes, for the preparation of concrete mix, water is used, the composition indicators of which comply with GOST standards. When making your own, prepare drinking water.

Important! Check the quality of the water, it should be free of alkalis, sugar, oils, acids and other impurities.

Cement

The general name of the binder, which is based on marl, calcareous, clay rocks. Most often today, Portland cement is used in construction, with a high percentage of calcium silicates in the composition.

Cement classification:

Without additives, that is, their content in the composition does not exceed 5%. Marking "TO" or "CEM I".
With additives, the percentage of which varies within 35. Marking D + Indicator of the content of additives in percent, for example, "D15" or "CEM II".

When buying, pay attention to the following nuances:

admissible period of use of the mixture
storage conditions
make sure that the moisture level is correct, that is, that the cement is not damp
check the flowability of the substance (it should not be stale, compressed)
make sure each bag is labeled accordingly
the grade of cement should exceed the grade of the planned concrete (see below) by 2-3 times.

Important! Do not buy cement too early, enough for 1-2 weeks. If the terms and conditions of storage are not observed, it loses its quality, which will affect the strength characteristics of concrete.

The choice of sand has its own conditions and requires the right approach.

Pay attention to the following points:

Granule size. There are several types, the size range of which varies from 1.2 to 3.5 mm. Give preference to coarse sand.
Important! Please note that the smaller the granules, the greater the consumption of sand in the manufacture of the concrete mixture and the lower the strength of the finished hardened composition.
The purity of the substance. Use the cleanest material without impurities and dirt (plant particles, silt, clay, glass, soil, dust). Check for their presence by sifting or washing the sand.
Important! This criterion affects setting degree, consumption of cement for the preparation of concrete and water.
Flowability. The sand should be well dried, not wet, since the recipes indicate the amount of dry matter.

Important! In any state of sand, there is a certain percentage of absorbed moisture in it, which is usually taken into account when compiling the proportions of substances. In dry - this figure does not exceed 1%.

rubble

Pay attention to the following criteria:

Important! Please note that most often it is the quality of crushed stone that affects the strength of concrete.

Expanded clay

This material does not belong to the main components of concrete, but to create a lightweight solution (to reduce the load on the floors and frame of the structure), expanded clay is often used instead of crushed stone.

When choosing this material, pay attention to:

fraction size — from 3 to 5 mm
flowability of a substance
purity and uniformity.

Concrete marking

The classification of concrete is carried out according to:

class (B)
brand (M).

The brand of concrete indicates the compressive strength and load capacity. The indicators vary from 50 to 1000 kgf / cm2. That is, for example, M300 concrete can withstand up to 300 kg / cm2.
The mortar class indicates guaranteed strength in 95 cases out of 100. The range of indicators is from 3.5 to 80.

Plan the specific type of mixture based on the purpose.

The table below shows the acceptable grades and classes of concrete with strength indicators.

How to prepare a concrete solution?

You can prepare the mixture yourself in two ways:

manual
mechanical (using a concrete mixer).

The first will, of course, be more laborious, but, with a small amount of work, it is quite acceptable and economical.

Use a concrete mixer for large volumes or increased requirements for the strength characteristics of the concrete mix.

Preparatory work

Preliminary work is necessary regardless of the further method of preparing the solution. They consist in the preparation of materials.
Sequencing:

Sift the sand.
Wash gravel.
Dry both substances.

Norms for the preparation of concrete

In order to get concrete of a certain brand and strength, follow the recipe.
Choose the most convenient principle for calculating the consumption of components:

kilograms
liters
percentage
number of parts.

Carefully consider the tables below, which indicate the various possible proportions for the preparation of concrete.

Important! Please note that in each individual case, deviations from the norm are permissible, which are regulated by the quality of the materials.

Cooking conditions

When preparing concrete on your own, be sure to observe not only the technical aspects of the process, but also the conditions under which the solution is produced:

air temperature 15-20
humidity level within 90%.

Important! If pouring is carried out in conditions of severe aridity or low temperatures, use special additives that regulate the solidification process, thermal insulation materials and additional irrigation.

Manual method for making mortar

The procedure for preparing concrete:

Mechanical concrete preparation

Types of concrete mixers

There are two types of concrete mixers:

gravitational
coercive action.

In the first case, mixing occurs due to the rotation of the drum with fixed blades installed inside it. In the second, mixing is performed by blades rotating in a certain mode with a stationary bucket.

Each type has its own advantages:

compactness, light weight, low cost are inherent in gravitational devices
get a better mixing quality when using a forced-type concrete mixer.

Important! For self-preparation of concrete at home, a gravitational apparatus is quite enough. Please also note that with a very large amount of work, you will most likely need not one, but 2-3 concrete mixers.

How to prepare high-quality concrete?

In the process of preparing concrete in a concrete mixer, an important factor is the sequence of loading the components. The quality of the prepared mixture directly depends on how correctly the technology is chosen.

There are many opinions on this matter. Below is a technology for a more rational approach to doing this work.

Cooking technology

Place the concrete mixer on a level surface.
If necessary, create additional underlays to increase the stability of the machine.
Lubricate the blades and walls of the concrete mixer with a mixture of water, cement and fine aggregate.
Important! This action will prevent the solution from sticking.
Turn on the machine.
Pour in half of the prepared water.
Pour crushed stone into the drum - half of the total volume.
Wait 2-3 minutes for mixing.
Add cement.
Important! When supplying cement after crushed stone, larger aggregate fractions prevent cement from sticking to the walls and blades. Plus crushed stone helps to split the formed lumps.
Wait for some mixing time (about 3-5 minutes).
Add sand.
Leave to stir for 2-3 minutes.
Add the remaining gravel.
In the process of mixing, pour in the rest of the water, bringing the solution to the desired consistency.
Important! After adding all the components, rotation for more than 2-3 minutes is not recommended. This can lead to loss of plasticity, delamination and water evaporation.
Switch off the unit.
Important! Observe the following safety precautions during all work:
- do not stick your hands and shovel inside when rotating
- wear protective gloves
- do not lean close to the drum.
Pour a small portion of the prepared mixture into a wheelbarrow.
Check the quality of the concrete.
Important! One way to check the quality of the mortar is to make a few ribs with a shovel. If the concrete is of the right consistency, they will retain their shape. But, at the same time, the mixture should be fluid.
Unload into a container if the desired plasticity is achieved.
Pour the mixture back and mix again if the concrete is not ready, then unload into a container.
Wash the concrete mixer.

Important! Consider the allowable mixing volume of the particular apparatus you have chosen. The main criterion is a large aggregate, which, if excessive, interferes with making a full-fledged batch of the proper level. For example, for a concrete mixer with a capacity of 132 liters, the maximum amount of crushed stone in one preparation is 4 buckets.

Video of concrete mix preparation

Conclusion

Ready-mix concrete can be used for a limited period, so calculate your actions and time to avoid long-term storage of the mass and premature drying of the solution. This will lead to a decrease in the initial quality, and, accordingly, will affect the strength during operation.

Each owner of a private house should know how to prepare concrete - this will help in arranging a house or a summer cottage. Often it makes no sense to order just a couple of cubes of factory concrete, it's just not profitable. To save money, the solution can be mixed by hand and in significant quantities if the right ingredients are available.

Tools

At home, a concrete solution is usually prepared manually for utility buildings, but when building housing, this procedure must be approached very responsibly.

The main rule for preparing the mortar: the brand of cement should be 2 times the brand of concrete that is needed for pouring. Those. if concrete M150 is needed, then cement must be at least M300.

For pillows under the foundation and preparation of work in dry soils, a solution of B7.5 (M100) of a hard consistency is used. As a filler, crushed stone 5-20 mm is used. From the same concrete, but more plastic, stairs, steps are made, fences, paths, etc. are poured. For the same purposes, in wet soils, it is recommended to prepare hard concrete B10 - B12.5 (M150). From a mixture of hard consistency of this brand, both the subfloor and the paths are made.

For laying the strip foundation, unloaded parts of the building, a hard mortar B15 (M200) or B20 (M250) is suitable. He, only a little more plastic, is suitable for cesspools, sedimentation tanks, septic tanks. For the foundation of a good residential building, you need to make concrete M300 (B22.5): this will be the best option and it is better to take crushed stone with fractions of 20–40 mm.

Concrete of the M350 (B25) and M500 (B40) grades is used for high-rise structures, heavy-duty structures, storage facilities, laying runways and in home construction - there is no need, and it is difficult to work with such a solution.

To mix the solution you will need:

trough or concrete mixer;
shovels;
hammer (for crushing hardened cement);
buckets;
sieve for sifting sand;
containers for washing the filler.

Components

Before you prepare concrete, you need to control the quality of the components well.

Water

Water should be as clean as possible, without impurities, dirt, clay, soil. It is impossible to take sewage from swamps, stagnant sources, chemically contaminated. The solution just won't set well. On average, half of the mass of cement is needed for water.

Never add water to an already prepared solution.

Filler

There is a fine filler - sand, and a large one - gravel, crushed stone. For light mixtures - expanded clay filler, slag, brick or limestone crushed stone. There is a rule: the strength of a large filler is two to three times the design strength of the finished solution. Crushed stone creates a kind of power skeleton for the mixture.

The aggregate should be as clean as possible, without earth, branches, soil, and especially clay. It is sometimes washed, sieved at the construction site. Permissible amount of impurities: 35% for crushed stone, 5% for sand. Organic impurities destroy the solution from the inside. It is recommended to sift, rinse and dry the filler before use.

Sand

It is desirable to take coarse sand, it is more versatile. There are 5 groups of sand: from 3.5 mm - with large grains; up to 1.2 mm - fine-grained. The last builders recommend only for lightweight concrete.

Checking the contamination of sand: 200 ml of it is poured into a bottle, water is poured, shaken, poured. Water carries away impurities, volume loss of more than 5% - poor quality. When kneading, it is taken into account that dry sand contains 1% moisture, after rain - 10%.

Fractions are used small (up to 12 mm, up to 40 mm). Granite screenings or crumbs are taken for floor screed, bulky work.

Rubble happens:

granite - the best;
gravel - standard for private construction;
limestone - not recommended for buildings, as limestone becomes limp from moisture.

The most popular fractions: 5–20, 5–10, 10–20, 20–40 mm. The size of the material should not exceed a third of the width of the product in the narrowest part and 2/4 of the distance between the reinforcement. Do not recommend crushed stone more than 150 mm.

It is advisable to use two fractions - fine (at least a third of the coarse aggregate) and large - so the concrete will be denser. Pebbles are categorically undesirable: they are smooth and do not bind the solution well. Expanded clay (3-5 cm in size) is suitable for light screeds in houses with wooden floors.

Cement. Rigidity

We will consider the characteristics of cement separately in close connection with the determination of its amount in the mixture. Proper preparation of concrete is based on a harmonious ratio of components. Concrete must be used all at once - it is never left "for later", so the amount of the mixture must be well calculated.

Rigidity

Rigidity is determined by slipping: if the mixture flows down from a horizontal plane, it is too liquid, plastic; when sliding when tilted - medium plastic; if it sticks without slipping, it is low-plastic; does not settle, remaining a lump - tough. Liquid concrete is easier to lay, but hard concrete is better in quality and strength.

The most popular brands of cement for private construction are M400, M500.

Table - The composition of the concrete mixture per 1 m3 of concrete:

So, the amount of material M400 for 1 cubic meter of the mixture:

for concrete B7.5 - 180 kg;
B10 - 200 kg;
B15 - 260 kg.

The main amount of cement sold on the market is Portland cement M500. If it is taken, then the above norms must be multiplied by 0.88. This and the following formula is useful for buying the right amount of cement. The length, width, depth of the foundation is multiplied - the volume (cubic capacity) is obtained, based on the above proportions, you can find out exactly how much cement is needed.

Nuances

Cement at home is often taken stale, from the remains of other construction. It should be borne in mind that such a material does not have the necessary properties. To prepare the mortar, you need a dry, not expired material without lumps - so the concrete will not crack. The shelf life of cement in its original packaging is 90 days, in open packaging - no more than a week for dry conditions and no more than a day for wet ones. Stale material must be carefully crushed with a hammer.

For the preparation of the solution by hand, concrete grades M100 - M350 are popular. All calculations are by weight and based on the mass of cement. The ratio of ingredients is calculated as their weight ratio to it.

The grade strength of the solution is determined by the ratio of water and cement (VC). Less water - a higher brand. But with its lack, the opposite effect can occur, so the rule "more cement - better (stronger) concrete" is erroneous. As mentioned above, the brand of cement should be 2–3 times higher than the design grade of mortar. Knowing the water-cement ratio, you can increase or decrease the grade of the mixture.

Handmade Recipe

Consider the option of how to prepare a concrete mix for home construction manually, based on the proportions with the tables. Here are two tables, using which you can determine the proportions and the number of components for 1 cubic meter of solution.

Table of water-cement ratio (aggregate indicators averaged):

Table - The ratio of water and cement

Concrete, brand	V/C
Concrete, brand	Cement M400	Cement M500
100	1.04	-
150	0.86	-
200	0.70	0.80
250	0.58	0.66
300	0.54	0.62

Calculation of water for filler per cube. m and the percentage of sand in it.

Table - The ratio of sand, gravel and water

You also need to know the approximate density of fillers, mass in kg / m2:

for gravel filler - 1600;
for crushed granite - 1500;
for quartz sand - 1500;
for expanded clay - 600–800;
for cement - 3000–3200 (bulk -1300 ÷ 1800).

Preparation of concrete M300 (1 cubic meter). Ingredients:

crushed stone with a fraction of 25 mm;
medium-grained sand;
Portland cement M400.

The first table defines V / C - 0.54; the second is the amount of water, with such a filler, 196 liters are needed. Cement: 196/0.54=363 l. Filler volume and percentage: 1- ((363/3000)+0.196)=0.680 m3. We look at the percentage of sand according to the second table - 45%, it turns out 680 × 0.45 = 306 liters of sand. Crushed stone: 680–306=374 l.

The volumes were determined in liters, so you can work with a 10 liter bucket. If the supplier measures fillers in tons, then it is not difficult to convert them into liters according to the above weight-volume density values in kg / m2 (for cement, you need to take bulk density).

Other popular recipes and proportions

The following proportions are generally accepted for the preparation of concrete at home: 1 (C) / 4 (Sch) / 2 (P) / 0.5 (V). In terms of weight, it looks like this: 300/1250/600 kg, water - 180 liters.

If you take cement M400 - you get concrete M250, if cement M500, then mortar M350. For solutions of low grades, it is necessary to reduce the cement content. For solution B20 (M250) there is another recipe: 1 (C - M500) / 2.6 (P) / 4.5 (Sch) / 0.5 (V) or in kg: 315/850/1050, water - 125 liters per cubic meter m.

More proportions (cement: sand: crushed stone; water - half of the cement):

1:3.5:5.7 - M150 (for floors, paths);
1:2.8:4.8 - M200 (fences, foundations of garages and baths);
1:1.9:3.7 - M300 (walls, strip foundations);
1:1.2:2.7 - M400 (very strong, professional, quickly sets and hardens).

simple secret

There is an easy way to determine proportions. Crushed stone is poured into an empty bucket and evenly distributed. Measured utensils (a jar of 1 liter) add water until its level is equal to the edge of the gravel. The volume of liquid is the required volume of sand.

Further, crushed stone is poured out, in its place sand is poured with the same can of the same amount as there was water. Then water is poured again until it covers the sand. This determines the required volume of cement. The last component is water, its amount is 50–60% of cement.

The method is based on the principle that sand fills the voids between the gravel pebbles, and cement fills between the grains of sand. In this case, the strength of the solution will be approximately the same as that of crushed stone. This method does not take into account the expansion of the filler grains, some other parameters, but it is simple and can be used for non-critical structures.

Mixing methods

The preparation of the concrete mixture is carried out in two ways:

manually;
using a compact concrete mixer (mechanical or automated).

Many are mistaken in believing that manual mixing requires a container - no, cooking is carried out by means of a shield made of boards, they also use metal, tin shields, troughs from various materials, the concrete mixture is kneaded even just on a flat hard surface. If the shield is built from boards, they need to be tightly fitted and, ideally, upholstered with roofing iron, although it can also be kneaded simply on a sheet of such iron with edges slightly turned inward.

First, sand is poured in a slide along the length of the shield, a furrow is made in the center, cement is poured there, the sand is wrapped little by little from top to inside, gradually stirring. Further, in two shovels, sand and cement are mixed 3-4 times, then everything is wetted with water from a watering can, mixed again. Then gravel is evenly thrown, the mixture is simultaneously mixed, water is gradually added until the required consistency is formed.

Another sequence: cement - water - sand - gravel (crushed stone).

There are two types of these devices: with a gravitational or with a forced mechanism. The simplest and most affordable first. This is a pear with blades inside, rotating in an inclined position. For kneading, you need about 2-3 minutes of rotation.

Preparation is carried out in stages - so the concrete mixture mixes well:

the mechanism always turns on empty;
water is poured;
pour half of the cement;
fall asleep all the large filler;
add the second half of the cement;
sand gradually falls asleep;
rotation - 2-3 minutes.

Everything is poured only into a horizontally standing (maximally inclined) bowl. The more horizontal the concrete mixer, the better. After unloading the concrete, the bowl must be washed with water so that there is no solidified solution on it. There are small mechanisms, they are convenient, but at a time they are able to mix no more than 4 buckets of gravel, if you load more, you won’t be able to tilt the bowl, the batch will be of poor quality.

In winter, the order changes: first hot water, then crushed stone, cement, sand. Potash (potassium carbonate), antifreeze additives are added to the solution, but you need to know the measure, they destroy the reinforcement.

For someone who has never dealt with cement, it is difficult to understand what a concrete mortar is and how to properly prepare it. But even experienced builders are not always aware of all the subtleties of working with it. In this article, we will describe not only the process of preparing a concrete solution, but also the correct choice of its components.

It is not difficult to independently prepare a concrete mix for pouring a foundation, small reinforced concrete structures, and paths. You can knead it in any old tub, trough, box or knocked down wooden shield. In the manufacture of a small amount of solution, the process can be mechanized using special nozzles. If you need a lot of concrete, you will have to use an ordinary shovel, small garden forks, a hoe, or other device suitable for the occasion. But, before you start mixing, you should choose high-quality cement, crushed stone and sand.

Concrete components

The quality of the main component - cement

The strength of our solution will be determined primarily by the quality of the cement, so its correct choice is especially important. There are a lot of factories producing such products in Russia and they sell them, as a rule, in neighboring regions. Therefore, it is worth focusing not so much on the manufacturer as on the appearance of cement.

Be sure to pay attention to the date of manufacture - over time, its activity decreases sharply. Fresh cement, when squeezed in a fist, does not turn into a lump, but easily wakes up between the fingers. A high-quality product of fine grinding loses its properties especially quickly during storage.

When it is fake, dolomite dust, mineral powder, ash and other fillers are used. When they are mixed, of course, the concrete will not only set more slowly, but even after hardening it will not be strong enough:

the color of high-quality cement powder is darker;
the solution from it sticks well and sets quickly;
the color of the dried concrete outside is slightly lighter, but if you beat off the corner, its inner surface is dark;
after complete drying (after a month), it is very difficult to hammer a nail into the finished concrete.

NOTE: You can check the quality of purchased cement as follows. Mix a small portion of concrete in the required proportions, and after hardening, place a chisel on it and hit with a hammer. On high-quality concrete, only a light mark will remain after the impact. If the metal breaks off small pieces from it - cement grade 200. Has the chisel punched a half-centimeter hole in the concrete? The brand of cement is not higher than 100.

The strength of the solution depends on the brand of cement. When it is designated, the numbers after the letter M mean the ability to withstand a load of 1 cubic meter. cm. That is, M200 cement can withstand a load of 500 kg per cubic centimeter. Naturally, the higher the grade, the stronger the concrete will be. Special grades with a strength of 600-700 are rarely used, therefore, when working with complex or multi-tiered structures, it is better to use cement grade M500.

The letters following the numbers indicate the presence of additives in it. For example, a product of the M500 B brand is fast-hardening, VRTs is waterproof, BC is white, intended for finishing. The designation BC20 will mean that it contains 20% brightening impurities. The most important additive for us - PL - makes it frost-resistant, therefore it is desirable to use it for outdoor work, especially in Siberia and the North.

During long-term storage, the cement powder becomes caked, compacted and its specific gravity increases. Therefore, if you bought it in advance, be sure to store it in a dry, draft-free place. It is advisable to additionally wrap the paper bags with plastic wrap. Please note that after six months of storage, its quality will decrease by at least a third.

Which sand is best

The best sand is river sand. It is washed with water and, unlike quarry, does not contain impurities. When working in the winter, it is better to use the river, completely free from clay inclusions. At sub-zero temperatures, their lumps are poorly soluble in water, even with prolonged mixing, and the concrete surface will be uneven.

Choice of gravel

Dolomite, limestone crushed stone is most often used to create small lightweight structures, the quality of which is not subject to increased requirements. Gravel or granite material is more durable and able to withstand the coldest temperatures.

IMPORTANT: When buying, remember the most important rule. Dirty gravel or sand are the main enemies of good and high-quality concrete.

Let's prepare a solution

The proportions of the mixture directly depend on what brand of concrete (that is, what strength) we will need. The most common proportion when using the M500 brand is 1:2:3 (i.e., you will need a part of cement, two sand and three gravel). The higher the brand, the less cement leaves. Therefore, the proportions for the M350 will be different. In any case, the ratio of water and cement should be no more than 0.5.

Table - M500 cement concrete

Required brand of concrete	Proportions of cement, sand and gravel (TskhPkhShSh), kg	Output of concrete from 10 l of cement

For the manufacture of a garden path, concrete M200 and small fillers (pebbles or crushed stone) are sufficient. Good and durable asphalt will be obtained from grades 300 and higher. For the foundation, of course, you need a more durable structure. The ideal option would be the M500. On average, 6-7 bags of M500 cement will be needed per cubic meter of the mixture.

IMPORTANT ! Remember that the prepared mixture hardens very quickly, so you need to use it within half an hour. In no case should you try to dilute it with water when hardening.

To avoid the formation of unmixed lumps, water is added only after the cement has been mixed with sand. The mixture for plastering must be sifted through a sieve with a mesh size of 5 mm, for normal work larger meshes can be used.

Concrete is a material used in building construction, where it is used for foundations, walls and roofs. Concrete is also used to make small piece items, such as paving slabs, garden vases and urns, balusters, and sometimes even kitchen countertops.

Distinctive characteristics

Thanks to modern technologies that make it possible to make concrete of very high quality, this artificial material stands next to natural marble and granite in terms of its strength. Despite the fact that it is not as aesthetic as natural materials, unlike natural stones, it does not emit a radiation background, and a beautiful appearance can be given to it using the latest processing technologies.

During the construction process, you can either make concrete with your own hands or buy a ready-made composition at a hardware store. In the event that you have opted for self-preparation of the solution, you will need to figure out what components the concrete consists of, and in what proportions they need to be mixed.

Composition of concrete

Making concrete with your own hands involves connecting the following components in a special container or concrete mixer.

Cement is a key element and basis for the manufacture of both concrete and mortar. It consists of limestone, which, when mixed with water, crystallizes and solidifies.
Ballast - a mixture of sand and gravel, also known as "general mixture". In most cases, it is made in a 3: 1 ratio, that is, one part of fine river sand is taken for three parts of gravel chips.
Building sand - sea, eolian, lacustrine, alluvial or deluvial - arising in the course of the activity of reservoirs and watercourses, has a size of 0.1 to 5 mm. The shape of its grains of sand is round, and it is this fact that makes it easier to adjust bricks or concrete slabs to the desired level by driving them into the mortar. Such sand also contains clay, which, when soaked, makes the solution more viscous.
Crushed stone is crushed rock with a grain size of more than 5 mm.

When you make concrete with your own hands, to obtain a holistic monolithic structure, the elements listed above must be mixed with water. When calculating the required amount, it is necessary to take into account not only the ratio of water and cement, but also the initial moisture content of other materials, their ability to absorb moisture.

Mortar is the basis for concrete production. It finds its application in furnace and plaster work, and is also used in the construction of brickwork. The composition of the mortar includes binders (cement, clay, etc.), which are usually used no more than two, as well as aggregate, which can be sand, sawdust or fine slag.

DIY concrete: proportions

The most common ratio of the components that make up concrete is 1:3:6, that is, one part of cement accounts for three parts of sand and six parts of aggregate. Depending on how thick or thin your solution is, add 0.5 to 1 part water. However, if you want to get the highest possible quality mortar, make an accurate calculation of the proportions of the components, in which the density and binding characteristics of cement, aggregate and sand will play a significant role. You can find out these characteristics from the regulatory documents attached to building materials.

Basic additives for concrete preparation

In order to make concrete better and improve some of its characteristics, one or another special additives that are widespread in modern construction can be mixed into the solution. When making concrete with your own hands, depending on the quality of which indicator you want to improve, you can add the following components to it:

Plasticizers - are used to make concrete more plastic to increase the convenience of its laying.
Hydraulic seals - isolate the concrete from getting into its structure of excessive moisture.
Dedusters - increase the strength of the material and reduce the risk of abrasion.
Hardening accelerators and retarders - are used to control the setting time of the solution.
Antifreeze additives - allow you to work with concrete in the cold at temperatures below zero.

The use of additives significantly improves the quality of the solution when you make concrete with your own hands. When purchasing additives, pay attention to the fact that some of them can improve the quality of not one, but several characteristics of concrete, that is, produce a complex effect on it. At the same time, some of them may not be combined with others, so be sure to read the instructions carefully before purchasing a supplement.

Also, additives often change the amount of water required to make the solution down. If the new proportions are not indicated in the instructions for use, then add water very carefully, gradually and in small parts.

Making concrete for the foundation

Consider a few rules, following which you can make good concrete for the foundation with your own hands.

The consistency of the mortar, from which concrete for the foundation will be obtained in the future, should be as thick as possible. After the mixture is laid out in a pre-prepared formwork, it must be compacted. This is done with the help of a special vibrator, but if it is not available, you can also use an ordinary rebar rod.

Compaction should be carried out until the so-called cement milk appears on the concrete surface - a liquid mixture of cement and water that occurs when the solution reaches its maximum density. Compaction is necessary in order to remove air bubbles from concrete and thereby increase its strength.

The standard shrinkage of concrete is 2-3 centimeters. You can check it with a cone made of metal, having a base width of 20.3 cm and a height of 30.5 cm. The resulting solution must be poured into the cone and turned over, and then follow how the material spreads and settles.

In cases where you do not know what composition of the mixture will be optimal for the foundation, use m400 or m500. Use gravel, crushed stone or sand as its filler. Do not use broken brick and limestone for this: concrete will not be strong.

Concrete making tools

Do-it-yourself concrete preparation can be done using tools such as shuffle shovels, electric and manual concrete mixers, and hand-held electric mixers. Despite the fact that the quality of hand-kneaded material is higher than that of mechanized material, doing it with a shovel is a very long and tedious task that will drag out the construction site and require a lot of your strength.

In order to make concrete for the foundation with your own hands, it is recommended to use a concrete mixer. In addition to optimizing the manufacturing process, it also prevents possible poor agitation of the solution, which can reduce the density of the final product.

In case of unsuccessful pouring of concrete, small voids form inside it, which can be removed only with the help of a deep vibrator. If, taking into account all the shortcomings and errors, you get grade 100 concrete, it will be able to withstand a load of 100 kg / cm², which will be quite enough to build a small house. A foundation pillar made of such material, having a cross section of 200 × 200 mm, can withstand a load of 40 tons, and five such pillars - a load of 200 tons.
If you want to make a strip foundation, keep in mind that in this case the weight of the structure will be distributed over a greater density. Accordingly, even if you make small mistakes and deviations from the rules of construction when laying the foundation, it will still be able to withstand the weight of the structure. But do not forget that the official standard for the strip foundation is the concrete grade m200 and above.
Do not fill the strip foundation during cold weather: in this case, you will have to constantly heat the mixture. If the water freezes inside the concrete, its volume will increase, which will lead to the destruction of the product from the inside.
When pouring the foundation in the summer, moisten it for two to three days so that the concrete does not crack, and its setting occurs evenly over the entire surface.

Heat resistant concrete

Heat-resistant concrete is a product that is able to retain its physical and mechanical features and properties when exposed to very high temperatures (about 16,000 °C). Its use in construction usually occurs in the construction of chimneys and blast furnace foundations.

A feature of heat-resistant concrete is the use of liquid glass or Portland cement as one of the main elements in its manufacture. In order for concrete not to collapse when heated and cooled, chromite ore, magnesite brick, fireclay and andesite are also added to its composition.

The density of freshly laid concrete will depend on the choice of one of these materials: fireclay will give a density of 2200 kg / m 3, andesite - 2400 kg / m 3, magnesite - 2600 kg / m 3, and chromite - 3000 kg / m 3. As it hardens, its density usually decreases by 150-200 kg/m 3 . The filler in the case of the manufacture of heat-resistant concrete is sand or heat-resistant crushed stone from rocks.

If you plan to build a large structure, then you need to take crushed stone, the grain size of which will be at least 40 mm. For the construction of less massive structures, crushed stone with a grain size of about 20 mm is suitable. The choice of material must be made taking into account the operating conditions of the future building.

Production of heat-resistant concrete

Making heat-resistant concrete with your own hands is quite easy if you follow the established rules and strictly follow the proportions of mixing its components. There are two main ways to produce heat-resistant concrete: you can either make it from a ready-made mixture sold in hardware stores, or create it yourself by mixing the right ingredients in the prescribed proportions.

Naturally, the most preferable is the use of a ready-made mixture, as this guarantees exact observance of the proportions of the components and protects the mixture from contamination during its manufacture: it is enough to simply dilute it with water, and the concrete will be ready.

When purchasing a ready mix, make sure it is made by a certified manufacturer. It should be accompanied by instructions that indicate the method of preparation of the composition and the conditions for its operation. Prepare concrete as recommended. The finished mixture should be stored in a dark place.

Now that you have learned how to make concrete with your own hands, you can start building.