The best additives in cement to increase concrete strength. Supplements for concrete - overview of substances and materials for creating a special solution (55 photos) Universal additive to concrete

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Sika (Switzerland) is one of the world's leading manufacturers of construction chemistry - produces various additives in concrete: plasticizers, modifiers, waterproofing materials, hardening accelerators and other materials. These substances improve concrete mixes in many indicators - strength, mobility, waterproofability, frost resistance, chemical resistance and others. Chemical additives for Sika concrete allow the construction of reinforced concrete and monolithic buildings and structures at temperatures to -25 ° C, which is very relevant for our country.

Main types of additives to Sika® concrete

• Waterproofing additives in concrete - Sika® 1 Plus. This material is widely used in cement floor screed and plaster solutions. Chemical water repellent additives for concrete contain hydropobizers that block capillaries in cement stone and at the same time retain its vapor permeability.
• Plasticizers for concrete - Sikament® BV 3M, Sika® Antifreeze N9, Sika® Latex. These materials are added to concrete and building solutions, adhesive formulations and plaster, cement-sand outdoor ties. Chemical plasticizing additives for concrete improve the workability and plasticity of mixtures and increase the strength and waterproof of concrete. Plasticizer for SIKA® Antifreeze N9 concrete and concrete is a complex additive that provides a rapid hardening of concrete.
• Hardware Accelerators - Sika® Antifreeze N9, Sika® Antifreeze FS-1, Sika®-4a. These chemical supplies for concrete provide rapid hardening of concrete and a solution at temperatures up to -25 ° C. A distinctive feature is the lack of chlorides and other substances causing corrosion of steel reinforcement. The chemical additive SIKA®-4A is used in tampon-made solutions intended for rapid sealing of active water leaks and fixing various parts.

Advantages of additives in concrete Sika®

In Sika, you can buy additives in concrete at a bargain price. Sika plasticizers have multiple competitive advantages. They are:

• reduce cement consumption;
• increase the mobility and convenientness of concrete and mortar;
• improve plastic, waterproofing and frost-resistant properties of concrete;
• can be used in solutions for thin-walled and hustarized structures.

Where to buy plasticizers for Sika concrete?

Today, there are 4 plants for the production of additives in Concrete and 5 branches of the Swiss Concern Sika, the products of which are implemented through the developed dealer network. To buy plasticizers for concrete, use the services of our regional offices.

Preparing for the fill of the foundation you need to get a maximum of information about the concrete - the basis of any monolithic design. Selecting the optimal ratio of the components of the initial mixture (water-cement-sand-crushed stone), do not forget about the additives that improve its properties.

The range of construction chemistry today has hundreds of items. Not knowing which supplements in concrete are, it is impossible to work in extreme weather conditions and rely on high quality.

In this article, we will consider the most common types of additives into concrete mixes, we study the mechanism of their action and estimate the effect of using.

Varieties of additives in concrete

The need to change the properties of concrete is due to the following factors:

• Climatic (low and high air temperatures).
• Technological (acceleration of work, improvement of convenientness, the need for transportation).
• Operational (increase in strength, water and heat resistance).
• Financial (cement saving).
• Chemical environmental aggression (sea salt, groundwater with elevated substances that destroy cement stone).

The use of additives for concrete allows builders to change its properties in a wide range, improving the quality of the erected structures.

The classifier of modifying compositions includes several groups:

• plasticizing additives;
• air ducts and gas-forming;
• accelerating (slowing) concrete;
• sealing;
• anthorts;
• waterproofing;
• painting (pigment).

Why do we need plasticizing additives?

A newcomer in construction may seem that the concrete mix does not need to increase plasticity. Water pour is more, and concrete without any additives will become liquid and convenient for laying. In fact, excess water is the enemy of concrete.

There is a rigid dependence between the amount of cement and water, in which the frozen mixture is gaining maximum strength. Builders call it a water-cement ratio. Simply put, if you want to make a high-quality concrete, then at 10 kg of cement is allowed to add no more than 7 liters of water. Pour more liquid, you dramatically reduce the strength of the design (the concrete porosity increases).

The more dense concrete, the better it resists the loads. Therefore, for example, no more than 4 liters of water are added to the production of paving slabs to 10 kg of cement. How to distribute such a tough mixture in the formwork evenly, without emptiness and shells? Plasticizing additives come to the rescue builders. They make concrete fluid without adding excess water.

Plasticizers for concrete are the most sought-after types of additives. By reducing the grip of particles of the initial mixture, they protect it from stratification. Using such additives, it is possible to fill the injection mold and thin-wing formwork from the foundation without a vibrator.

This type of additive is found under the names of super and hyperplasticizers. The difference between them is the strength of action. Hyperplastic additives reduce the amount of water without reducing concrete strength by 20%. Superplasticizers do not exceed 10% this indicator.

Another positive effect of the use of plasticizers is the economy of cement. By reducing the water content in concrete, it is possible to proportionally reduce the mass fraction of cement without breaking the "water-cement balance".

Why is concrete air?

The effect of airflowing additives is understandable from their name. For beginners, the need for their use is not always obvious. Air cavities in concrete reduce its strength. However, in small quantities they are useful because they increase the frost resistance of the monolithic structure.

The mechanism of action of air-boring substances is very simple. Water, frozen, tear concrete as paper. Creating air cavities in the material, we give water to expansion and reduce its destructive power. This task is performed by air-boring compositions. Their percentage must be minimal in order not to reduce the strength of the structure.

Gas-forming additives on the action are similar to air ducts. They also create in the concrete microinth, but their main task is different: reduce the weight of concrete and increase its heat insulating properties. Therefore, gas-forming substances are used in the production of wall materials (foam and gas blocks).

Accelerators and retarders of hardening

Considering the modifying additives, you need to say a few words about compositions that increase the hydration rate of cement stone. In cold weather, the concrete mixture is hardening very slowly, and in the cold this process stops. If you do not add to the water used for the knead, the accelerator of hardening, then it will be impossible to work with concrete at a minus temperature. Alternative option - the electro-heating mixture is quite complicated and cost.

The slowdown in the ripening rate of the concrete mix is \u200b\u200bnecessary when it is transported over long distances. In addition, the moderators are necessary in concreting of massive and extended structures (foundations and floors). In this case, the technology requires that the entire concrete is in a liquid state until the end of the fill. Without the use of modelers, the foundations, filled earlier, begin to fit, forming joints that weaken the design.

The more denser, the stronger!

There is direct dependence between the density of concrete and its strength characteristics. The additive-seal reduces the number of pores in concrete, filling the micro emptiness between its particles. Together with increasing strength, the water and frost resistance of the design occurs (a comprehensive effect of improving properties).

The consumption of the sealing additive is low (200-600 grams per 100 kg of cement), and the achieved effect significantly exceeds the purchase costs.

Get frost to us!

It is possible to fight with the destructive power of frost in two ways. We have already told about the first, considering hardening accelerators. The second method is anti-corrosive additives that give the water antifreeze properties. Freezing is not at 0С, and at a minus temperature (up to -25c), water has time to fully react with cement.

It should be noted that many types of hardening accelerators have a contamination effect on cement mortar (sodium nitrite, a mixture of sodium chloride with calcium chloride, urea in combination with nitrite and calcium nitrate). This fact should be considered when choosing.

Waterproofing additives

Concrete is very often used to fill the foundations. Therefore, the protection of basement and walls of the building from the penetration of water is a very important task. Without additives, concrete slowly, but still passes water through the micropores. Waterproofing additives give it hydrophobic properties (repulsion of water molecules). Using them, it is possible without rubberoid or bitumen coolants to overlap with soil waters access to the body of the structure.

The most popular concrete waterproofer in the past - liquid glass. "The experience of his work" at construction sites exceeds half a century. The only drawback of this additive is a large consumption (on 10 liters of concrete - 1 liter of liquid glass). Today, penetrating waterproofing has come to replace the liquid glass - and its analogues working on another principle. When contacting additives with cement, it crystallizes and clogs cracks and pores in concrete. In addition to the waterproof effect, Penetron has an anti-corrosion action, protecting the reinforcement frame from destruction.

Concrete Paintings

Considering the types of additives for concrete and their purpose, you should not forget about pigments. They are used for surface staining and painting in the mass of paving slabs, bulk floors, wall blocks and curly casting.

Posted by concrete The desired color is not a simple task. This material has a strong alkaline reaction and quickly discoloring ordinary dyes. Therefore, iron and chromium oxides are used for staining of concrete products, resistant to alkalis and solar ultraviolet.

Popular manufacturers and prices

The shelves of construction stores are broken from the abundance of means that modify the properties of concrete. However, with a detailed study of labels, you will make sure that the manufacturers of additives are not so much.

• Polyplast (trademarks of Linamix, airplastic, relaminix, cryoplastic)
• Superplast (line of additives in concrete Superplast, Edvance, Rigoform, Ferrocrit)
• "Biotech" (series of additions of biopan b)
• Alliance (Brand Armix)
• "Fort" (additives in concrete Fort and Fortis)

You can buy additives in bags, the main form of release is 25 kg, and the canes of 1, 5 and 10l.

The average prices of hyper and superplasticizers, accelerators and sedents of the hardening of concrete is in the range from 50 to 90 rubles / kg. The estimated cost of antiorrosal additives - 35-50 rubles / kg.

Mixtures of complex plasticizing and anti-corrosion action can be purchased at a price of from 70 to 110 rubles per 1 kilogram. For air ducting additives, sellers are asking from 200 to 300 rubles per liter.

Hydropobicators can be bought at a price of 150 to 300 rubles / kg. The cost of pigment additives (depending on the color) is from 150 to 250 rubles per 1 kg.

To improve the qualities of the concrete mixture, the manufacturers use the introduction of all sorts of additives into its composition. Additions to concrete improves many characteristics of the mixture used. Due to the change in the composition, resistance to low temperatures and corrosion increases, the time of frozen is reduced, the strength is reduced, etc.

Varieties of impurities

Each additive is responsible for certain properties of the resulting mixture. By qualitative parameters, the classification is carried out as follows:

• plasticizing (water-soluble preparations, bard from sugar patterns);
• air ducts (sulfonol, wood resin);
• hardening accelerators (sodium and calcium salts, polyamic resin);
• classroom retarders (etilsiconate sodium, polyhydroxyloxane, molasses);
• sealing (iron salts, calcium nitrate, aluminum sulfate, ethylene glycol resins);
• corrosion inhibitors (potassium and sodium bichromate, sodium nitrate);
• gas-forming (aluminum powder, polyhydroxyloxyan);
• antiorious (calcium and sodium chloride, calcium and sodium nitrate, urea) additives in concrete.

Listed species can be used as a single component or applied in a complex with each other. Combinations of added substances a large amount. Consider the properties of each impurity from the listed classification.

Plasticizing

The smaller the water-cement ratio in the concrete mix, the stronger the design of this material is obtained. But with the smallest value of the amount of fluid in the composition, the concrete mixture turns into a thick conglomerate.

The inclusion of additional components provides the plasticity of the mixture without adding extra liquid. Also plasticizers in the composition of concrete increase the strength and stability of structures to frost.

Plasticizers are divided into four groups in terms of reducing water use:

• weak (less than 5%);
• medium (5%);
• strong (10%);
• superxile (more than 20%).

Air Ducts

The addition of such impurities allows to obtain a porous mixture structure. Due to this, frost resistance of reinforced concrete structures increases.

Pores inside the material give free space for water expanding during freezing. The percentage of air ducting additives must be minimal, because a large amount of impurities reduces the strength of the mixture.

These additives are used to accelerate the process of soloing concrete. Low ambient temperature slows down the process of concrete hydration. The accelerator significantly reduces the hardening time, which allows the use of multilayer fill.

The technological cycle can also be slowed down by adding other impurities that brake solidification. In this case, the accelerator compensates for the loss of time.

Migration retarders

They apply in cases where it is necessary to increase the time interval of preservation of the mixture. In the first case, use justifies itself when the finished mixture must be delivered to the construction site, which is in great remoteness from the place of production. Also when the technological process provides for the phased use of a concrete solution. The moderator in this case allows you to maintain the liquid state of the solution for a long time.

Seals

The increase in the density of the mixture contributes to its durability. The seal fills the space between the grains of concrete, which leads to an increase in strength. Also, these components contribute to the reduction of pores, which significantly increases the impermeability of the structure.

Corrosion inhibitors

The principle of their action lies in the formation of an oxide film on the anode. Additives in small quantities in concrete will provide corrosion reinforcement protection. Inhibitors cannot be used in combination with chlorides, because they contribute to the destruction of the oxide film.

Gas-forming

Additives are used to produce aerated concrete. They provide an increase in waterproof and reducing the bundle of the mixture. In the process of obtaining the mixture, gas is based on 1.5-3%. This structure of concrete improves frost resistance, but reduces the strength properties of the material.

Anthorosny

They allow concreting work at temperatures to -25 ° C.

The main task of these impurities is to accelerate the solution of fluid output from the solution. Antiorrosal additives for concrete make it possible to carry out work at minus temperatures without additional heating.

Select the component added

Additives that are entered into concrete must be chosen in accordance with the requirements for technology. The selection of certain components must solve the following tasks:

• improve the technological properties of concrete;
• increase strength and waterproofability;
• increase resistance to frost and corrosion;
• reduce the amount of time for thermal processing;
• reduce consumption of expensive cement and aggregate;
• adjust the mobility of the mixture.

Also, not only the qualitative indicators of the mixture should be taken into account, but also the conditions for their operation. To achieve the required conditions, various classifications of additives and their combinations are selected.

Introduction to the composition of plasticizing and air-penetrating impurities or their combination provides a slowdown in the hardening process if the excerpt is made in vivo. In this case, hardening accelerators are necessarily added.

This condition is especially relevant if the ambient temperature is less than 10 ° C. Supplements to concrete that accelerate solidification reduce the total time to 2-3 hours.

Heat treatment

If the designs are subjected to temperature influence, the addition of plasticizing and air-receiving components without increasing the collation rate is carried out only in one case. This happens when the technological cycle is 13-14 hours for portland cements. The exposure time before the start of thermal treatment should be at least 2 hours, and the temperature in the cycle process must be raised by no more than 15 ° C in one hour.

Cement savings

To reduce the amount of cement, plasticizers, water-repellent impurities and hardening accelerators are added to the concrete. The total value of cement saving for weak plasticizing components is from 5 to 8% of the total volume.

If efficient plasticizing additives are used for concrete, savings increase to 12%.

Designs of increased strength

Concrete solution from which they are manufactured is a multicomponent composition. It includes effective plasticizers, air-dye impurities and hardening accelerators. The question of the economy of cement in the manufacture of responsible structures is not raised. It remains the main component providing strength parameters. Also, special technologies are used to obtain high strength concrete, which provide the necessary quality design.

Calculation of the amount of additive

Provide the necessary material quality allows only the correct dosage of impurities. Experimental by the amount of additive that is added to the concrete can be determined by the following formula:

RD \u003d RC * x / γ * s,
where RD is the consumption of cement, kg; X -% dosing of impurities from the mass of cement; γ is the density of the additive solution; C - additive concentration,%.

RC \u003d P (1 - A / 100),

where A is the value of the reduction of the consumption of the binder,%.

Example

Calculate the amount of additive for the M300 brand. Cement consumption is 350 kg. It is necessary to introduce a plasticizing component - technical lignosulfonate. Reduce cement consumption by 5%, the density for this indicator is 1.021 g / cm³. Perform calculation:

• determine the consumption of cement, taking into account additives: RC \u003d 350 (1-5 / 100) \u003d 332.5 kg;
• it is necessary to determine the standard indicators, the dosage of the additive intended for concrete, from the mass of cement is 0.1-0.5%, we select the average x - 0.3% value;
• calculate the amount of additive: RC \u003d 332.5 * 0.3 / 5 * 1.021 \u003d 19.5 liters.

The composition with the inclusion of additive to the concrete solution will change in this ratio: cement - 332.5 kg, technical lignosulfonate - 19.5 liters.

Although it is said that the best - the enemy is good, but the technology of our company does not consider that. Almost no modern enterprise carrying out the production of concrete, cement or concrete mixtures without the use of special additives for concrete, significantly improving the quality and characteristics of the mixture and regulating the cement grasp processes and hardening it.

It would seem that these additives for concrete if the concrete mix is \u200b\u200bmade on modern equipment, and during its production, all norms and requirements for the time and thoroughness of kneading, the composition of the mixture is observed, the composition of the mixture, high-quality fillers are used: cement, sand, crushed stone, water ? A good concrete mix - in itself is good, but if it is possible to make it better: increase strength, make it more mobile, increase its moisture resistance, frost resistance, crack resistance, protection from salts, petroleum products, and so on the like, then why not do it ?

Modern concrete production, concrete and cement on both modern, which takes into account all the possibilities and nuances, allowing to make products "faster, above, stronger." Here, special additions for concrete, acting on the behavior of cement at various stages of setting and hardening, and affecting the qualitative characteristics of the manufactured concrete and hardening, and affecting the qualitative characteristics of the manufactured concrete, or, monolithic reinforced concrete design, are coming to the help.

Let's consider the main types of chemical additives that are used on modern concrete and concrete production. They can be divided into groups:

• supplements to concrete governing the basic properties of the mixture, such as mobility, plasticity, waterborne, pore formation, etc.
• types of additives that regulate the continuability and responsible for the velocity of concrete, the cement setting velocity, mainly affecting the hydration process in the initial stage of setting, hardening and set of concrete strength.
• supplement for giving concrete or reinforced concrete properties: polymer, biocidal, etc.
• anti-corrosion additives for concrete, allowing concreting at minus temperatures.
• additive to concrete that increases its strength, frost resistance, corrosion resistance.
• corrosion inhibitors steel, for steel reinforcement, which is part of any probe or monolithic reinforced concrete, is subject to the destructive effects of aggressive media in which many reinforced concrete structures have to work.
• expanding additives in cement that reduce the shrinkage, which increase the crack resistance, creating a self-printing of concrete and monolithic reinforced concrete structures.
• painting additives - Pigments for concrete.
• supplements to concrete for waterproofing to which various collections of additives can be attributed, hydropobizats and other means of lowering the permeability of the concrete structure.
• various reinforcing types of additives for light concrete: gas-forming, aircraft, foaming, etc.

If we have so many groups, then how many additives will be? Immediately I say - a lot! List them all - hardly enough forces and time. We allocate only the basic, which can be useful to a wide range of builders. Probably not the Soviet, if I say that, but rather, his more advanced heir is - the most used additive for concrete used in the production of concrete mixes. In any case, Besto Plasticizer C-3 is almost always used. In general, chemical additives contributing to a decrease in water content in the composition of concrete mixes are most in demand. A lot of advantages from their use, namely: increases the flow of concrete mix without adding excess water, it becomes more plastic, cement saves, the density, waterproof, frost resistance, etc. increases.

Here and come to the rescue special additives for concrete - plasticizerswho began to use from the forties of the last century. Today, we are mainly dealing with their new version, so-called superplasticizers. They appeared in the USSR even at the beginning of the eighties. Unconditional leader here - c-3 plasticizer. One of the main manufacturers of Superplastic C-3 is Polyplast. What are so good plasticizers, let's see:

• Cement savings. To obtain equal concrete of the same mobility using a C-3 plasticizer and without plasticizer, a cement is consumed by 15% less consumable to one cube concrete mix. This magnificence is achieved by reducing the amount of water of the indion. But to preserve the necessary mobility of the mixture, manufacturers necessarily introduce superplasticizers or plasticizers in concrete. Thus, the waterproof ratio is also reduced at the same time and the mobility is not reduced.
• Without prejudice to the strength of future concrete and reinforced concrete structures, the mobility of the mixture increases. What is especially important for monolithic construction, where concrete pumps and concrete pumps are used in all the way, which require concrete P4-P5 for normal operation (cone precipitation from 16 cm).
• An increase in final strength characteristics up to 25%.
• Due to improved workability, the need to vibrate the fresh mixture is disappeared!
• Opportunity without any problems pour out hustarized designs: columns, narrow wall formworks and so on.
• Obtaining increased density compositions (high impermeability), which positively affects the waterproof of the concrete and reinforced concrete structures in general.
• Increased frost resistance up to F350 and crack resistance.
• Decreased shrinkage of hardening concrete or concrete.
• The ability to receive high-strength concrete and concrete, with indicators of compression strength above 100 mp! For example: M-350 (B25) concrete sample of the M-350 (B25) 28 of the daily age has a compressive strength of only 25 MPa. That is - four times less. Applying special modifiers can be obtained with a mixture with the varying strength of the brand used during cement shutdown.
• Plants producing the progress make their benefit from the use of plasticizers by reducing the time of steaming or reducing the temperature in the chambers. And this is a significant savings of energy resources, accelerating the turnover of foremosnasty and, as a result, an increase in production volumes.
• Increases the adhesiveness of reinforcement with concrete already 1.5 times (if certain chemist physics) increases)

It seems to me that the listed advantages are enough to understand that produce concrete mixes or concrete without plasticizers - is not the most profitable event. However, in our barrel honey there is a spoon of fiction. Little such, but there is. And this is a slight slowdown in the timing of setting and hardening the concrete structure. It can be considered a negative effect, maybe someone will seem positive, but the essence is one. To compensate for slowing the action of plasticizers, a special additive for concrete is sometimes introduced - the hardening accelerator. She compensates for everything that touched the plasticizer, namely the graph of normal hardening of the cast design.

To date, complex types of additives in concrete are increasingly and more often. As a rule, they are two-component. For example: at the heart of the C-3 plasticizer, and an accelerator of hardening, or an air ducting additive, or a microsill, etc. Thanks to such combinations, concrete plants receive high-strength mixtures with unique characteristics.

Other types of additives for concrete and solutions

Accelerators of hardening concrete To compensate for the action of the plasticizer, a slightly braking hardening process, sometimes special additives are introduced - hardening accelerators. Also, hardening accelerators can be used with non-standard fills when a quick grasp of the lower layer of the concrete array is required so that you can continue to clean further. The classic example is a monolithic bowl of the pool, when the bottomwork of the bottom and walls of the pool must be laid in the concrete mix so that when pouring into the wall it does not give up with its mass just a castible bottom. Typically, this process is stretched over time, but it can be significantly reduced if the accelerators of the hardening of concrete are used. Another area of \u200b\u200buse of accelerators is concreting in cold weather. After all, the lower the ambient temperature, the slower the cement hydration process, the beginning and end of the setting and the strength set occur in slow motion. Accelerators also help here.

Deaders of hardening concrete By name it is clear - what makes such types of additives. Apply them to increase the time of the alternating concrete mix. It may mostly be necessary for transportation to long distances, if it is impossible to quickly fill and so on. That is, with the use of hardening retarders, we take a time out to have time to do something: eat donuts, drink beer, sleep while concrete will relax in Badier or trough. Moreover, this pleasure is stretched for a few hours. Something like this. A group of modeers can be attributed to waterways. They also have a slowing effect.

Air ducting additives As you already understood from the name, they "involve" air. When mixing the mixture, millions of smallest air micropulosion are created. What is it for. The main task is to create a microporous structure in concrete or concrete. Porous chocolate remember? That's the same, only microscopic pores. Due to the presence of these most pores, the frost resistance of a concrete structure or the progress increases. Why? Yes, because the water inserted the concrete design, when freezing, there is to expand. In those pores. Cheap and angry.

However, and here is not without conceiving. Cement stone they will be removed from the destruction, but there are no aggregates. Rubbanium also goes from frost and water, as without magic bubbles. But this is a completely different song. Of the minuses of such additives - reducing the strength of the concrete structure. Slightly, but there is. In any case, high-strength concrete with such additives will not make. And frost resistance can be enhanced by other methods, for example: to reduce the water-cement attitude, or to introduce as a mixture of hydrochloride, with the same amount of cement. Due to this, water resistance (W coefficient w in the labeling of mixtures) is significantly increasing. Water simply does not fall into the concrete structure.

Contamination additives for concrete The main purpose of antiorrosal additives (PMD) is to ensure the possibility of winter concreting at minus temperatures and the absence of additional warm-up warm-up design. Separate types of additives allow concreting at temperatures up to - 25 degrees. This is "tin" of course, but if there is such a need, then you do not have to choose. So there are anti-corrosive additives. Those who are familiar with the "subject" and so understandable, everyone will try to explain in several phrases.

The main essence of solidification of the solution or concrete mix is \u200b\u200bthe so-called cement hydration. Simply is the process of crystallization of minerals (silicates, aluminates) present in cement, when it interacts with water. The speed of this process significantly depends on the ambient temperature. At low positive temperatures, the cement setting process is stretched over time (several times), under negative temperatures, it stops at all, according to a banal reason for the freezing of the water itself. Here with two of these gados and fights, by virtue of their capabilities, an anti-corrosive additive for concrete.

The main tasks of modern antiorrosal additives are to reduce the time of setting cement and accelerate the time of the hardening of concrete (under conditions of low temperatures), reduce the temperature of the freezing of water. In Russian expressing - to make it so that water freezes not at 0 degrees, and at -10 or -20. Probably remember that salty water is a classic example of lowering the freezing temperature. There is another task in modern antiorrosal additives - not harm. Just like the Hippocratic: "... in accordance with my forces and my understanding, refraining from the causation of any harm ..." And they can harm. Not all, but can.

There are quite a few myths regarding the harmfulness and usefulness of certain anti-corrosion additives for concrete. They are attributed to all the scary sins: and you are corrosion of reinforcement, and reduce strength, and a decrease in frost resistance, and still the dog knows what to make up. Unfortunately, I am not a chemist and not a naturalist, but I will try to summarize once read, heard and the tried yourself.

The first myth: when using antiorrosal additives, in monolithic reinforced concrete or homemade concrete concrete reinforcement. This myth came to us from distant times - "When the trees were big." Take the most common sodium nitrite in Russia, so it is the opposite inhibitor. Many antiorrosal additives have a positive effect on the adhesiveness of reinforcement with concrete. I'm not talking about modern complex additives.

Myth second: reduce strength. With a normal% administration of additives in concrete, there is some lag at the rate of a set of strength, but at the achievement of classical adolescent age 28 days; the leading of a laboratory inclusive concrete sample (hardening at +20 degrees) is coming to no, and further often there is a greater increase in the valuable strength of concrete With contamination additives. Here is your grandmother and reduce strength.

However, you should not forget about the abnormal% administration of additives in concrete. Here it is possible possible trouble. Here, the conversation can delay if you start remembering all kinds of early freezing techniques, etc. Therefore, going around two replicas. In case of insufficient administration of PMD, the mixture is frozen, the cement hydration process stops and is resumed only with the arrival of the temperature sufficient to extinguish the frozen liquid. In most cases, it passes painlessly. Unless of course, this is not a bridge and not carrying a brigade, which managed to load something heavy for winter.

In completely outflowing concrete, accidentally frozen with a sharp decrease in temperature, the situation is somewhat worse, but also quite tolerant, provided that the cast structures are not loaded. However, much depends on the size (volume) of the cast concrete. Again, it is important - when a concrete is a frozen: at what stage the cement was, whether critical strength was drawn; Whether water (rain, snow melting) was affected by a rapid concrete surface, etc. Here, perhaps, it is possible to loss of strength on average up to 20% and in some cases a decrease in the frost resistance of percent to 50 is also observed exfoliation of the upper layer, erosion, etc.

If we consider the results of laboratory and inventory tests, it can be concluded that the contamination additive for concrete (especially complex) has a positive effect on the resulting characteristics of a concrete structure, or reinforced concrete. The density (waterproofability) increases, promises a positive inhibitory effect on the reinforcement, the design strength in comparison with the incompatible concrete increases.

Again, all this is possible under one condition that the additive is not left. If there is no confidence, then the risk of akin "Russian roulette". There is a time-tested polyplast, but where is the guarantee that it is a polyplastic, and not a rashplastic spilled in the neighboring hangar in the construction market. Counterfeit is our universal trouble. One thing Cherkizovsky Guccture and Cardin, and quite another - when the Erzatz product concerns health and construction. If you think about the possible consequences, it becomes a little in itself.

Additives of course a lot. List them and describe - the task is not easy. I mentioned only the most used. As far as possible, I will try to supplement this page with the description of the compositions ignored today. In the meantime, what is - that is. With superplastic non-freezing greetings, Eduard Minaev.

Durable monolith is obtained after pouring the mixture of cement, water and various fillers (sand, lime, rubble, slags). Similar compositions are widely used in the construction of foundations, cast walls, pools, berths, airfields, roads. With the help of special additives for concrete, you can prepare the perfect solution for any object, increase the pace of construction and reduce the total costs of it. Additional components give the ready-made composite properties, allow you to maintain work regardless of the season.

Types of additives, review of characteristics and properties

The need to change the structure of concrete is determined by various factors:

• technological - accelerated concreting, raising plasticity for better laying, the need for a time stock for transportation;
• operational - increased strength, density, waterproofability, resistance to extreme temperatures, thermal insulation properties (in cellular concrete);
• climatic - frost resistance and rapid hardening of the composition in winter, and if the work is carried out in the heat - slow down grasp;
• economic - reducing cement volume in solution;
• aggressive environment is salted sea water, mineralized groundwater, fungal microorganisms.

Classification

Taking into account each factor, you can pick up suitable compositions. In classifiers, several groups of additives in concrete mixes are usually distinguished, each of which has its own purpose:

• plasticizers;
• gas and foaming;
• mobility regulators;
• anti-sore;
• accelerators (moderators) of hardening and grasp (more about);
• seals;
• increasing water resistance of concrete structures.

Brief description of the main varieties of additives

1. Plasticizers.

Builders observe a tough proportion called a water-cement ratio - it determines the purpose of the concrete structure. To obtain a durable wall in 10 kg of cement, no more than 7 liters of water, paving slabs are poured - not more than 4 liters (for resistance to high loads). Plasticizing additives allow you to make a solution to flow, without pouring water into it and thereby reducing the strength characteristics of the finished product. The adhesion between the particles of the mixture is reduced, but it does not reside, it does not occur in it.

The composition becomes more moving, concreting is facilitated. Without the help of the vibrator, the shape for the tile or thin-walled formwork for the manufacture of the foundation is filled. Having reducing the weight of cement by introducing an additive and does not disturb it in relation to water, it is possible to save considerable funds. They are divided into super- and hyperplasticizers, the first to reduce the amount of cement by 10%, and the second - by 20%.

2. Waterproofing.

Concrete is used to manufacture monolithic and block foundations. Gradually, through micropores, it absorbs the subsidiary or atmospheric moisture. Waterproofing design is provided with rolled materials, bituminous coating, and now for this purpose additives for waterproof are used. They give an artificial stone hydrophobic properties: its particles begin to repel the water molecule.

More recently, waterproofing was achieved due to the introduction of liquid glass (silicate adhesive). Its price is available, but also consumption is too large: 10 liters of concrete requires 1 l of material. Appointment is not only waterproofing, but also protection against corrosion reinforcing metal parts. The additives are usually produced on the basis of polymers whose properties are an increase in their volume in the solution and blocking the microcracks when the mass was experiencing.

Waterproof structures ensures penetrating waterproofing penetron and its analogues. Reacting with cement, they form crystals that fill air pores.

3. Additives to accelerate hardening and sealing sedels.

Increase the pace of hydration of cement stone falls in cold weather, especially if the work is carried out in winter. At low temperatures, the mixing and hardening of the mixture is inhibited, and these processes stop with frost. In winter, it is necessary to work normally, the compositions for quick grapplation are introduced.

How to produce concreting if transportation occurs for a long time? Special retarders helps to slow down the ripening. They are used when pouring large and massive objects, so that the concrete remains all this time in fluctuate.

4. Frost-resistant additives.

In winter, the hardening of concrete is a very low rate - as a result, the product is loose, and its frost resistance decreases. To avoid this, the solution is heated at the construction site, and in the absence of such an opportunity, special components are used. Their purpose is to ensure the fill at minus temperatures (below -5 ° C). In winter, antiorrosic compositions are needed, which reduce the temperature of the freezing of water in the mixture and stimulating the grasp in the range from -5 to -25 ° C.

The following chemical compounds are widely used as winter additives:

• potash or Potassium carbonate - with it, concrete is captured and harden even at -30 °;
• calcium nitrate - stimulates hardness in winter;
• sodium nitrate and nitrite, calcium nitrate - in combination with urea, at negative temperatures, not only contribute to the hardening, but also protect the reinforcement from corrosion (sodium nitrite poisonous and flammable);
• calcium chloride;
• sodium formate and other salts of organic acids are frost-resistant components that do not have harmful effects on health (there are no plasticizing properties).

When introduced into the solution of these compositions, a saline precipitate on structures does not appear, they become more durable even when the cement is used by low-grades. Supplements to enhance frost resistance are used if concreting monolithic, as well as pre-stressed structures - dam, dam, bridges.

Antiorrous mixtures are not recommended to be administered if it rains or air humidity exceeds 6 0%. Contraindication is also the presence of more than 50 mg / mol of reaction-capable silica - because of this, additional pores appear in the concrete. There is a side effect in calcium chloride: it corps fittings.

5. Sealing.

Their purpose is to reduce the percentage of the content of pores by filling the micropustotes between molecules. Simultaneously with the seal of the material, its strength, frost resistance, water absorption is reduced. Cost, taking into account low flow (approximately 0.5 kg per 100 kg of cement) low, and the economic effect is significant.

6. Air Ducts.

When the water freezing in the micropores, its expansion occurs, and the concrete is torn like a paper. It is possible to lift its strength and frost resistance by the normalized increase in porosity. For this purpose, concreting is carried out with a minimum amount of air ducting drugs.

Gaw-forming additives also produce the effect of pore formation, but the purpose of the technology is different - to reduce the volumetric weight of the solution, give it heat-insulating quality. Gas consonants are injected into the mixture in the manufacture of foam and aerated concrete.

7. Complex.

They combine the effect of two or several ingredients. The option is optimal to obtain a predicted result, if the characteristics of the concrete mix should be changed in several directions. Separately taken components may incorrectly react among themselves, so specialists advise to buy a complex cooked in the factory and balanced in composition. Complex additives simultaneously improve its pore structure and other characteristics - waterproof, frost resistance.

Combined action produce the following types:

• Modifiers are their purpose in obtaining a special concrete with improved technical characteristics. With the help of additives, waterproofing is provided (brand for water permeability from W12), corrosion resistance, durability, strength not lower than B125. Concrete is only prepared with additive modifiers if it should be expanding, straining, compensating for shrinkage, applied to vibropressing.
• Fiber additives. These are fibrous materials based on polymers, glass, steel. Concrete reinforcement (increase its stability and deformations), increase the heat resistance, reduce the shrinkage, increase the plasticity.

The cost of additives

It is worth paying attention not only to foreign brands, but also on the products of reliable domestic companies. In order to really increase the frost resistance, intensify, or slow down the seal, the proportions specified in the instructions should be clearly observed.

Name	Purpose	Packaging volume	Price, ruble
GoodHim Interplast R.	Plasticizer for masonry solutions	1 L.	120
Frieze	Increases frost resistance, accelerates grasp	10 L.	300
C-3.	Superplasticizer	1 kg	70
Sasi Tire M.	Modifier	5 L.	1700
NTF Acid	Slows down grappling	1 kg	130
Fiber FV polypropylene	Mounting tie.	0.6 kg	240