Over the years in construction practice, people have never found a more durable, practical, durable material than concrete. Consists of a mixture of cement, sand, water, crushed stone.

Also, modern builders add special strengthening additives to the solution, which make the material practically eternal, indestructible, and as durable as possible. However, in the manufacture of concrete mix, the proportions of all components must be very strictly observed. Otherwise, the foundation, the reinforced concrete wall of a multi-storey building, the basement, which is underground, will not be strong. The material will crack, it will be out of service ahead of time, and emergency situations will be created. So what mistakes in concrete production negatively affect the quality of finished products?

The most important mistakes

It should be noted right away that concrete mixes can be made in different ways. Everything will depend on what building structures need to be made from the resulting mixture. The biggest mistake is the incorrect use of the cement dosage. Excess or underestimation of this component totally affects the finished structure. You also need to clearly see which brand of cement to use before putting it in the future mortar.

Note! For the construction of reinforced concrete structures that will be used under water, the strongest, most expensive brand of cement is used. For simple structures used in the open air, it is permissible to add a low grade of inexpensive cement to the solution.

Another very important mistake can be attributed to the lack of high-quality mixing of the solution in the manufacture of large quantities of cement.

• Good mixing is one of the most important components in the manufacture of concrete on an industrial scale;
• In no case should you use dirty fillers, not sifted sand interspersed with pieces of clay. All this leads to a poor-quality solution, which will be very poor in finished products;
• Also you can't use dirty water... The liquid must be cleaned before mixing takes place. Water is cleared of mud, lumps of clay, all kinds of biological pollutants;
• Under no circumstances should you use cement powder after long-term storage.

And you need to be very careful to ensure that there is no overdose of various kinds of strengthening additives that are added to the reinforced concrete solution.

• Date: 20-11-2014
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• Rating: 24

Concrete is a unique and versatile material. It is successfully used at almost all stages of construction; it is used for making decoration Materials and paving slabs... The strength and durability of any structure depends on its quality. How to make strong concrete that can last for many decades?

The technological process for preparing durable concrete seems straightforward, but at the same time, the number of complaints about cracking, for example, of the foundation, is growing.

What do you need to know and consider in order for concrete to meet expectations for any purpose?

Basic concepts

Classically, concrete means a mixture of the following components:

1. Cement - connecting linkthat turns the components into a monolith.
2. Sand is the basis of strength and a filler for small voids.
3. Aggregate can be gravel, crushed stone and some other materials. It is the stone component that provides the unique strength of the material.
4. Special additives - all kinds of plasticizers, etc. With these chemical compositions the concrete is given the desired consistency and its quality is improved.
5. Water.

The main indicator of the quality of concrete is compressive strength. This characteristic reflects the ability of the solution to withstand mechanical stress, which is inevitable. This indicator is measured in MPa (megapascals) and reflects the level of load that concrete can withstand without deformation and changes in properties. The strength of concrete depends on the quality and type of cement used for preparation, the fraction of sand and aggregate, compliance technological process... Concrete is marked depending on its strength from B 3.5 to B 80, where the figure is an indicator of the pressure that this composition can withstand in 95% of cases.

The simplest concrete, often used for laying the foundation, is a simple mixture of cement and coarse sand. Depending on the use of auxiliary components, the strength of the composition increases, and hence the durability and reliability of the structure.

But before choosing a recipe that will make concrete strong, it is important to understand all the components. The effectiveness of the work will depend on their quality.

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Cement is the backbone

Cement is the main and most important ingredient in a composition called concrete. It provides binding of additional components.

Portland cement is ideal for making durable concrete. Due to its high content of calcium silicates, it ensures perfect adhesion (adhesion) of materials. An additional advantage of this material is the permissibility of work at lower temperatures, but this advantage cannot be overused. Mixing and pouring at temperatures below + 16ْ ° C will negatively affect the quality. If it becomes necessary to carry out work in a cold climate, it is imperative to use special plasticizers. To work in a warm summer period slag portland cement is suitable.

When purchasing cement, the main reference point is the brand. It is indicated on the bag, and the cost will depend on it. Usually it looks like this: M 500-D 10 (numbers may vary). The first indicator is the same strength, the optimal grade is M 500, M 400 can also be used, but this will affect the quality, the concrete will be less durable. The second indicator is the content of impurities, the D 10 value indicates that the cement contains 10% of foreign elements. In order for the concrete to be light enough and strong enough, you should choose a material with an indicator up to D 20.

In addition to a thorough approach to choosing a cement grade, a visual assessment is also required. Quality material must be dry, uniform and free-flowing. Even slight dampness will negatively affect the strength of the structure.

It is necessary to assess the need for concrete immediately before starting work, the maximum period is 2 weeks. In this case, it is better to purchase the missing bag than to leave the surplus; during storage, they will absorb moisture from the environment and become low-quality ballast. When buying, you need to carefully check the integrity of the packaging and the presence of the appropriate marking.

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You can't do without sand

It is possible to do without this concrete component in extremely rare cases. In the rest, it is sand that will provide sufficient density and high-quality filling of voids. What should be the sand to?

1. Clean. This is one of the most important characteristics. Foreign impurities, especially of plant origin, will decompose in the concrete, reducing its strength. If the sand was purchased clogged, it must be sieved. Let it take time, but it will significantly increase the strength of the future structure.
2. Uniform. Sand with a fraction of 1.5 to 5 mm is suitable for construction. But at the same time, you need to try so that the takeoff run is no more than 1.5-2 mm. The more homogeneous the sand, the stronger the structure.

It is preferable to use river sand, as it is often already clean. The ravine, however, often contains loamy impurities and silty inclusions. In some cases, it is possible to perform thorough washing and subsequent settling of the sand, but this is laborious, especially at home.

In some regions, far from large rivers, you can find the so-called stone or rock sand. It is a rock crushed to the required fraction. When using such a material, it must be borne in mind that it is much heavier than ordinary sand, which means that its use will not allow obtaining lightweight concrete, which is especially important when installing interfloor floors.

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What should be a quality filler

Almost any stone can act as a concrete filler suitable size... But here, too, there are several requirements that will help improve the quality of concrete.

1. The filler must be clean. As with sand, you need to make sure in advance that there are no impurities. If necessary, resort to sieving.
2. Regardless of the type of filler, all elements must have a rough surface, it is this that provides high adhesion. For this reason, it is worth refusing to use pebbles.
3. The optimal fraction is from 8 to 35 mm, the uniformity rule remains. But in the case of self-pouring, it is better to use gravel of different grades, for example, fine and medium. In this case, it will provide a better compaction even without the use of professional rammers.
4. In order to obtain a light but very durable filling material after hardening, it is recommended to use expanded clay.

Aggregates are usually quite heavy and must be stored in the immediate vicinity of where the concrete is mixed. In addition, it must be taken into account that gravel can become contaminated during storage, which means that it is better to organize the embankment on a solid base or on a tarpaulin canvas. When storing material on the ground, the bottom layer becomes scrap or requires washing and drying.

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But what about water and other components?

For concrete to be strong and last for many years, you need to use tap water, which is at least conditionally drinkable. It is strictly not recommended to use water from natural reservoirs, it contains acidic and alkaline impurities that will not allow making durable and lightweight concrete.

In addition, various components are often added to the solution, changing the properties towards improvement.

1. Plasticizers. it special formulationsallowing you to change the properties of concrete. With their help, you can reduce the need for water, adjust the fluidity and plasticity.
2. Lime. It is usually added to simplify the work with concrete, which is especially important for delicate manipulations. This is an optional component and use is at the discretion of the wizard.
3. Corrective components. With their help, concrete can be made resistant to low temperatures and other aggressive conditions. Moreover, if work is carried out outside the permissible temperature range, the use of such funds becomes mandatory.
4. Reinforcing additives. As a rule, PVC cloth is used, it is soft and not too strong, but when it is laid between the layers of the screed, it successfully protects the concrete from tearing and cracking. With its help, you can make a fairly strong, but at the same time light layer.

So, all kinds of additives make it possible to improve concrete and make it more resistant to external factors.

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Correct mixing ratio

So, the quality components of the future durable concrete have been selected and purchased, but that's not all. Their ratio is equally important, in addition, the proportions differ depending on the type of work.

For pouring, crushed stone of a large fraction is required and enough liquid concrete good fluidity. This will fill in any voids. But before pouring, it is recommended to mount a substrate of low grade cement, the material for it should resemble wet soil in consistency.

The most common proportion: 1: 3: 6, respectively, cement, sand, aggregate and up to 1 part of water, depending on the need and type of construction. But this ratio is not universal, since the density of materials can change under the influence of many factors. The most reasonable would be to calculate the indicators, armed with technical reference books. If the weight is chosen as the main one for the measurement, it is necessary to dry the sand and aggregate so that the liquid does not interfere with the calculation.

This rule holds true for any ratio definition. It is necessary to use the same dishes and, if necessary, make adjustments. Otherwise, the error will certainly make itself felt, but at a time when it will be impossible to fix it.

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Mixing components

The mixing process is no less important. Inhomogeneous concrete is not only difficulties in pouring, but also a change in the ratio of components due to their adhesion to the tool.

The ideal option is to use a concrete mixer, this device is designed to make perfect concrete. The unit can be purchased or rented; today many construction companies offer this service. It is necessary to install a concrete mixer at a minimum distance so that during transportation the concrete does not have time to harden - this contradicts the technological process.

You can make high-quality concrete in the old fashioned way, mixing in an old trough. But in this case, you will have to make a lot of effort to make the mixture homogeneous.

There are two methods for preparing the solution:

1. Dry. When using it, all dry components are pre-mixed, and only after that water and plasticizers are added. The danger of this method is that it is extremely difficult to qualitatively and quickly enough to provide liquid access to the lower layers, and this can violate the proportion. With long mixing, the cement will begin to set, which will affect the strength of the concrete.
2. Wet. All dry components are gradually added to the measured water. This method is not without its drawbacks, but it is still preferable, especially when preparing a small volume of solution.

Concrete grade

Concrete class

Water tightness of concrete

Frost resistance of concrete

Concrete mobility

Choosing concrete for the foundation

Concrete has been holding the leading position among building materials for many years in a row. It owes such popularity to its unique performance, incl. high strength, frost resistance and moisture resistance. Moreover, varying the ratio of the constituent components of concrete makes it possible to obtain a material with slightly different properties, which makes it possible to use it in almost any conditions. The question of choosing a suitable concrete remains the most important and difficult, because further properties of the structure depend on this.

It is equally difficult to choose a suitable concrete manufacturer. The growing demand for this construction material led to the emergence of a huge number of proposals, which is quite difficult to navigate. In order for a potential buyer of concrete to be able to quickly find the best offer for himself, the concrete tender system "M350" was developed. It is presented on the page http://m350.ru/price/m350/ and allows the user to quickly familiarize himself with all offers for the sale of concrete M350 and other brands in the Moscow region and choose the most suitable one for himself, based on the price, location of the plant or operating mode manufacturer. The system allows save time and money.

To be able to choose the right concrete mix for specific purposes, you need to know what indicators to pay attention to. Among the most important are the brand and class of concrete, the characteristics of moisture and frost resistance, as well as the mobility of concrete.

Concrete grade

The most important characteristic of concrete is its ability to withstand compressive loads... This parameter is denoted by the letter M, and the index behind it indicates how much load each square centimeter of concrete can withstand. The exact value is determined in vitro by testing concrete hardened for 28 days, and the rounded value is recorded in the marking. For example, concrete that can withstand 98 kgf / m2 is denoted as M100, and concrete that can withstand 196 kgf / cm2 is M200. Simply put, the digital index indicates the amount of kilogram that can press on 1 cm2 of concrete without destroying it.

Today, concretes are produced from M50 to M1000but concretes of the M100-M500 brands are in the greatest demand... The different level of concrete strength is explained differences in composition: the proportions of the components used and their quality are affected. Concrete contains sand, cement, crushed stone or gravel. Sand together with rubble (the so-called skeleton) are responsible for the bearing capacity of the future structure, and cement, combining with water, is responsible for the strength of molecular bonds. The higher the proportion of cement in concrete, the higher the strength of the concrete itself.

The quality of the components also plays a role. Sand can be both river and quarry - it is important that it is large and with a minimum amount of clay impurities. Optimal size crushed stone - 20-25 mm, it must be made of hard rocks. The cement grade also affects the strength of the concrete.As a rule, cement M400 and M500 is used, the latter for the preparation of concrete of a given strength will need less.

The least durable concrete grades are used in the construction of the lightest and less critical structures. Foundations of private and multi-storey buildings, industrial buildings are created using more durable compounds (M200 and higher). With the growth of strength, the price of the composition also increases, therefore, there is no need to use excessively strong compositions, as well as to save.

Concrete class

The class of concrete also indicates the strength of the material, it is modern derivative of the concrete grade... If, when determining the grade, the average value of the strength of the material is used, then the strength class assumes the determination of strength with guaranteed security. This is a more accurate value and is expressed with a coefficient of variation of 13%. Despite the fact that the class more accurately defines the characteristics of concrete, today most experts use the concept of a brand.

Classes define letterB and a number from 3.5 to 60: the higher it is, the more durable the composition is in front of you. There is a direct relationship between the classes and brands: for example, the M100 brand corresponds to the B7.5 class, the M200 brand - B15, etc.

The ratio between the class and the grades of concrete in terms of strength

Water tightness of concrete

The waterproofing of concrete is understood as its ability to keep water out. Previously, this characteristic was denoted by the Russian letter B, now useW, and the numeric designation next to it may begin from 2 to 20, equal to the pressure of the water column in kgf / cm2, at which a cylindrical concrete sample of standard height does not pass water.

If a foundation is built from concrete under conditions elevated groundwater level, then it makes sense to choose a composition with a high water resistance value, to which special hydrophobic additives are added. By the way, the use of such material will reduce the cost of full waterproofing of the foundation.

The highest indicators of waterproofness and water resistance are possessed by hydraulic concrete. For its production, use hydrophobic or plasticized Portland cement, sand and crushed stone of a higher quality than for conventional concrete. High levels of water resistance are also achieved through installation with maximum sealing.

Frost resistance of concrete

Frost resistance of concrete is indicated by the letter F with a numeric value from 25 to 1000: the higher it is, the more cycles of freezing and defrosting concrete can withstand without losing its strength properties. The choice will depend on the conditions in which the finished structure will be used, on the climate, the number of freezing and thawing periods during the cold season.

For the construction of hydraulic structures, airfield pavements and bridge supports, it is better to choose the most frost-resistant compounds. In private construction, concrete of class F100 or F200 is suitable for the construction of the foundation. You can also focus on density: the higher its value, the more frost-resistant the composition will be.

Concrete mobility

Concrete mobility (P) indicates the degree of its fluidity, which directly depends on the convenience of working with the composition. The numerical coefficient is expressed in the range from 1 to 5: the higher it is, the more liquid the composition will be. In private construction, concrete is used when arranging the foundation P2 and P3... More fluid formulations are used only in cases where it is necessary to pour a tightly reinforced base, or when concrete is supplied using concrete pumps.

It is, of course, more convenient to work with a more fluid composition, but water cannot be added to ready-made concrete to increase the mobility of the composition. In this case, the grade of the mortar immediately decreases, reducing the final strength.

Areas of use for different grades of concrete

Concrete has become ubiquitous, used to create foundations and many other structures. Depending on the purpose of use, concrete of a particular brand is selected. Here are the main uses for the most common concrete grades:

Choosing concrete for the foundation

Since concrete is used in the organization absolute majority foundations, the question of its choice precisely for these purposes requires more detailed consideration. To select the required brand, you need to know the weight that will be assigned to the structure, the conditions of its operation, take into account the type of soil, the level of groundwater, etc. All this should be mentioned in the design documentation, and for those who are building on their own, we will provide information on the use of different grades of concrete.

The less the load from the building being erected, the less durable concrete will be needed. If it will be built frame house, then you can get by with concrete M200, for a wooden house, it is better to arrange the foundation of concrete M250. For two-story wooden houses, houses from gas silicate and expanded clay concrete blocks, it is better to choose concrete M300... If reinforced concrete wall panels or construction plans will be used brick house, then concrete M350, M400 and higher are used for the foundation.

Influences the choice of concrete grade and soil type... The more heaving the soil, the greater the load drops on the foundation. So, for clay soils, it is better not to use concrete below M350, and for sandy and rocky soils, M200 is also suitable. If the groundwater level at the place where the house is built is high, then it is better to choose concrete with increased water resistance: even if M250 is suitable for the loads, it is better to use M350, for which W is almost twice as high.

Whatever brand of concrete is used, the characteristics of the finished structure are largely influenced by the correct dilution of the mixture with water, as well as the process of filling the mold with concrete and the uniformity of distribution of concrete.

01. We get high-strength concrete in ANYONE region

02. We are nothing NOT we sell

03. You NOT have to buy equipment

04. Concrete only from yours LOCAL components

05. Someone will do better? We will pay you ourselves!

Why we are the best
for high-strength concrete?

candidate of technical sciences
Vladimir Volodin

receives concrete
brand М2500 (B180)

Volodin Vladimir Mikhailovich (Technical Director)

01. Brought the brand of concrete to incredible М2500
(obtained the most durable production concrete in Europe)

02. Participated in exposing concrete in the skyscrapers "Moscow City"

03. Developed high-strength concrete for the Vostochny cosmodrome

04. Wrote a thesis on high strength concrete

05. Candidate of Technical Sciences ()

06. Winner of international competitions in concrete science ()

08. Inventor (patentee)

Dmitry Abramov (director)

01. Introduced technology at more than ten large factories in the CIS

02. Found a site with a raw material base for the production of the cheapest high-strength concrete (in Europe)

03. Inventor

Where is high-strength concrete used in Russia?

In Russia absolutely
do not know how to make
high-strength concrete
(in tangible volumes)

According to the latest research ...


Less than 0.3% profit concrete plants spend on R&D

"High-strength concrete" in Russia is:

High-rise buildings (above 40 floors) - strength about M1150 (B90)

Fiberglass concrete - M900 (at the same time, it is super-expensive, super-cement intensive)

Floor hardeners - maximum strength М800 (B60)

Architectural products (facades, etc.) - less than M800 (B60)

Paving slabs - less than M700 (B55)

Interchanges (for roads of the 1st category) - occasionally M600 (B45-B50)

Reinforced concrete special products - M600 (B45-B50)

Why is high-strength concrete sold 2-3 times more expensive than the cost price?

The lack of standards for the selection of recipes for high-strength concrete generates a lot of intermediaries and sellers of additives.

Nobody guarantees the receipt of high-strength concrete (except us).

Plants spend 0.3% of expenses on research (concrete science).

Prices for concrete for high-rise buildings "Moscow City"

Price list of CJSC "Ingeokomprom" of the supplier of concrete for high-rise buildings "Moscow City" for concrete mixes dated June 01, 2014
Information source: http://eprom.su/prajjs-list/ (screenshot from 03.07.2015)

How do we get the most durable concrete in the Russian Federation?

We "spied" on the Germans

We have worked for many years

over high-strength concrete

As a result, they surpassed their Western counterparts

In which cities did we receive high-strength concrete?

Moscow - from М1450 (to М2500)

Ulyanovsk - M1200

Alma-Ata (Kazakhstan) - M1200

Samara Region - M1300

Vladivostok - M1200

Yakutia - M1000

Republic of Bashkortostan - M1200

Chelyabinsk - М1300-М1400

Krasnoyarsk - М1300-М1400

Yekaterinburg - М1200

Penza - М1400

Vladimir - savings from 85 to 850 rubles. per cube

Naberezhnye Chelny - M1300

Kaluga - M1200

St. Petersburg - М1400

other

At least 100,000 rubles. per day
we save for our clients

How much does our high-strength concrete production facility cost?

The price depends on the degree of our involvement.

The minimum price for the introduction of high-strength concrete:
The amount of your savings
for 500 m 3 of high-strength concrete

Unclear? Call us we will explain

THREE WEEKS is the average time from the start of working with us to the release of the first batch of high-strength concrete in your production.

If we start working with youYou will receive unlimited annual technical support for concrete science (phone, mail, additional alterations of the trains, if necessary, a business trip).

What if it doesn't work? If something does not work out, we will refund all the money.

Need more information?

Come to visit my place!
We are in a HUGE concrete plant
Address: Russia, togliatti, Nikonova 52
International Airport: KUF (Kurumoch) (40 min drive to us)
Railway station: "Zhigulevskoe sea" (6 minutes drive to us)

How to make strong concrete (concrete mortar) with your own hands.

Mortars and concretes are artificial stone materials that are obtained by mixing a binder (usually lime and Portland cement) and certain aggregates. The binder, when mixed with water, forms a stone-like body, which is explained by the processes of setting and rapid hardening. The strength of the stone-like body is provided by filler (gravel, crushed stone, sand). Next, I will tell you about all the stages of the question of how to make concrete with your own hands.

Components for making mortar

1. Placeholder

For mortar, most often, fine sand or other fine aggregate is taken. For concrete mortar you can take not only fine sand, but also coarse gravel or crushed stone. To make building plaster or masonry mortar, it is best to use fine sand, the grains of which do not exceed 2 millimeters in diameter. If the plaster has a special texture, it is possible to add sand with a grain of up to 4 millimeters. In our market, buyers are offered two types of sand: river and ravine. River sand is considered to be medium-grained, it is quite expensive, but its purity contributes to its use as a component for concrete mix. Gully sand can be fine-grained (from 0.5 to 1.5 millimeters), with a large amount of clay particles and other impurities. It is not suitable for good and strong concrete, but for mortars it can be used without fear.

For lean (light) cementitious concrete with strength class B7.5, only sand can be used as aggregate. In concretes of greater strength, in addition to sand, you can also use crushed stone or gravel with a diameter of up to 31.5 millimeters. It is considered correct to use a crushed stone mixture of different fractions, so that the finished concrete contains a minimum amount of voids between the stones.

Attention! The aggregate of concrete and mortar should be free of contaminants such as soil, glass, pieces of wood, peat, plants, silty or silty soil. If contaminants are present, remove them by sieving gravel or sand through a sieve.

2. Cement

Cement is a general name for binding powdery substances based on marly, lime and clay rocks and all kinds of additives. The most commonly used type of cement is Portland cement, named after the British Peninsula of Portland. Such cement contains a large amount of calcium silicates. Work in progress country house two types of Portland cement can be used.

Type I - does not contain additives, or their content does not exceed 5 percent. The European classification for such cement indicates the name CEM I.

In Russian practice, the presence of cement additives is indicated by the letter D and a number in the marking code that follows the brand. For example, if you see the marking PC 500-D20, then it means the presence of 20 percent of additives in Portland cement of the 500th grade. As we have already found out, this characterizes the type II cement. As for the designation DO, it characterizes type I cement, that is, a material without additives.

To prepare plaster and masonry mortar, you need to take cement of classes M400 (32.5) and M500 (42.5). Portland cement is ideal for preparing concrete mixtures that will be used in low temperatures (the average daily rate is below 10 degrees Celsius). If the temperature is high, for example in hot weather, it is better to use blast furnace cement or type III cement (the European classification indicates the name CEM III). It is well suited for the manufacture of masonry and plastering mortars used for fences and floors.

Attention! Cement can only be purchased in bags with appropriate markings. Immediately before purchasing, you must check if the cement is damp or caked. If all the signs are present, it is recommended to refuse the purchase. Only a trusted reputable manufacturer who has been selling mortar for more than a year can guarantee the conformity of the cement brand declared on the package or on the bag. By the way, the main difference good manufacturer from the underground is not the cost of ready-mixed concrete, but the availability of a high-quality delivery service.

3. Lime

Lime is required for the manufacture of cement-lime mortars. In addition, it is used to improve the workability of the solution. To date, it is no longer required to extinguish lime to prepare solutions. Instead, you can buy slaked (hydrated) fluff lime at a low price, which is sold ready-made in bags. Alternatively, instead of dry mix, lime can be sold in buckets as a lime dough. It is added to cement-lime plaster and masonry mortars to increase their workability.

Attention! If you decide to use lime as part of the question of how to make concrete at home, use extreme caution, as lime has strong corrosive properties. It is recommended to carry out work with protective gloves, remembering to ensure that the material does not get into the eyes or on the skin. The same applies to the use of dyes, as well as the subsequent work on grinding and polishing the product.

4. Additives

The composition of a concrete mixture or mortar may contain certain additives that can either improve or simply change their certain properties.

Plasticizers or plasticizing additives can increase the fluidity of the mixture, as a result of which the builders receive a solution in a more liquid consistency. This solution is much easier to apply.
Thinning agents or superplasticizers can reduce the amount of water used for stirring.

In addition, their use makes it possible to improve the workability of the mixture, increase the strength, frost resistance and water resistance of mortar or concrete.

Individual additives can accelerate the hardening of the concrete mixture or mortar.

Also, there are additives with the help of which it becomes possible to carry out work in the temperature range from 10 degrees below zero to 35 degrees of heat.

Special additives are commercially available that slow down the hardening of the concrete mixture, which is useful when concreting in hot conditions.

Air-entraining or aerating additives increase frost resistance and reduce the water holding capacity of the solution in the hardened state.

Supplements are usually sold in plastic containers in liquid form. The packages must contain information on dosage, quantity and basic properties. Additives in mass ratio should not exceed 2 percent of the total mass of cement.

5. Water

The quality of water used for mortars and concretes is regulated by GOST standards. In particular, the water must comply with drinking standards and must not contain foreign impurities, including sugars, oils, alkalis and acids. It is forbidden to use poorly cleaned marsh and wastewater... It is best to follow the principle that any drinkable water can be used to stir the solution. If you prepare a concrete solution using water from a lake or from a river, you will have to check the suitability of such water in a special construction laboratory.

Composition and proportions

Before starting to consider the question of how to prepare concrete or reinforced concrete, I would like to draw your attention to the fact that the composition and proportions will directly depend on its main purpose. That is, it is correct to use strong concrete for the foundation. high density, while for filling the fence, you can stop at lighter brands. Once you've decided on the components, pick the right brand. In most cases, for imported concrete and do-it-yourself mortars, it is better to choose the M300 or M400 brands. As for the proportions, the cement / sand / crushed stone components should be used in proportions of 1/3/5. This means that per cube of concrete, one part of cement requires the addition of three parts of sand and five parts of crushed stone or gravel. If we talk about water, then its amount should be half the weight of other aggregates. For example, if you get 100 kilograms of dry mixture, then you need to take 50 liters of water.

If you get too thick (dense) mixture, you can add a little more water. The consistency should be such that you do not need to make great efforts to stir the solution with a shovel. For wet sand, there should be less water. If work is carried out in frost, water and concrete should be heated, which will protect the composition from premature setting and loss of strength. For work, it is better to use a purchased concrete mixer or devices / mixers and containers made by yourself. What material and what components they consist of (pumps, molds, vibrating screeds, etc.), you can read in another article.

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