Overview of antifreeze additives in concrete - description and properties. Additives that give concrete special properties Concrete mortar at sub-zero temperatures

In most of the territories of our country, cold or cool temperatures persist for more than half of the year. Considering that at concrete work ah "winter" begins with a temperature drop to +5 o C, then the "window" for work with concrete is very small. However, it can be extended, and significantly, through the use of various means. These are the so-called technologies of winter pouring of concrete.

During the normal course of the concrete curing process, moisture serves as a "gluing" element for cement particles. Upon her transition to solid state all processes are stopped.

But this is not the only problem. It is known that when freezing, the volume of water increases by about 9%. As a result, inside the mass of concrete is formed high blood pressure. If the grains of cement up to this point have not yet gained a certain level of strength, they are destroyed under pressure. After freezing, they will no longer fully acquire their properties and the concrete will not be strong enough.

There is another unfavorable moment in the winter pouring of reinforced foundations. Steel is an excellent conductor of heat, and it facilitates the removal of heat from the thickness of the concrete. Possessing good heat-conducting properties, the rods quickly cool down. Around them, the water freezes first. Ice pushes concrete particles aside, and in their place comes water that has not yet frozen from the still warm layers. It also freezes, pushing the concrete further back. As a result, the array is no longer a monolith: the framework is not connected to concrete stone. The strength of such a base after thawing and final hardening will be several times lower.

Of all these processes it follows that than less water in an incoherent state will be at the time of freezing, the less will be the loss of strength. Through various experiments and calculations, the boundary strength values were determined at which concrete can be frozen. They are called the point of critical strength. Depending on the class of concrete and the purpose of the building, the type of use of the structure, it is required to wait for the maturation of some compositions by 20%, for others, all 100% is required.

For reinforced concrete with non-tensile reinforcement (the type used in private housing construction), it is 50%, for foundations that will be subjected to alternate defrosting / freezing (baths and country houses without heating) - 70%. After reaching this point, the foundation can be frozen. After thawing, all processes in it will resume. The loss of strength in this case is no more than 6%.

Concreting methods in winter conditions

The speed of the hardening process depends on the temperature of the solution. With its increase, the activity of water increases significantly, the rate of curing increases. Therefore, when carrying out concrete work in winter or at temperatures below +5 o C, it is important to create and maintain the required level of heating. The optimum aging temperature of the solution is from +20 o C to +30 o C. There are several ways to do this:

make the solution warm;
insulate the formwork;
use additives and additives that accelerate hardening and/or lower the freezing point of water;
preheat the already poured concrete mass.

All of these methods work well. They are used singly or in combination.

First of all, it is necessary to choose the right cement for winter concreting foundation. It is known that during the hardening of concrete, reactions occur in which heat is released. For winter, it's a great feature. Wherein large quantity heat is emitted by fast-hardening Portland cements and compositions of high grades. Therefore, for kneading at low or sub-zero temperatures, it makes sense to buy them.

Only this will allow you to fill the foundation with a strip or slab foundation at positive temperatures during the day, and slight frosts at night. But at the same time, it will be necessary to make the batch warm (read below), and after pouring the foundation, the formwork will need to be thermally insulated: covered with mats, straw, etc. If you have already purchased a heat insulator, you can use it, you only need to monitor its condition, cover it with a film or other moisture-proof materials.

Temperature increase during kneading

During the winter pouring of the foundation, the temperature of the solution is adjusted to 35-40 o C. To do this, heat the water and backfill. In no case should the cement be heated: it will “brew” and become practically useless.

It is good if it is possible to use an electrically heated concrete mixer: it is connected to the network and the drum is heated. In another case, it is advisable to preheat it by scrolling through the heated water.

When kneading, water is heated to 90 o C. Crushed stone and sand must be heated to 60 o C. This is done by blowing hot air, heating in special ovens. Furnaces are for a private builder from the realm of fantasy, but you can arrange hot air blowing. For example, from a stove or a fire, stretch several duct pipes into a pile of rubble or sand.

Once again, we pay attention: do not heat the cement. It can be entered into warm room so that it takes room temperature, but it can not be heated.

During the winter mixing of the solution, the order of laying the components changes: water is poured, crushed stone and sand are poured into it. After several revolutions cement is added.

In addition, it is necessary to increase the kneading time. It should be longer by 20-50%: due to better mixing, reactions are activated and the temperature rises during hardening.

Warming and heating solution

To extend the cooling time of concrete, it is required to retain heat to the maximum. Because using everything possible means and available materials, carry out the insulation of the walls of the formwork. You can use tarpaulins, mats, some old warm clothes, fill the gap between the walls of the formwork and the soil, straw. Anything, as long as the heat doesn't leak into the air.

One of the tasks is to keep the heat of the solution

During construction in industrial scale electrical heating is also used different kind electrodes. They can be located on the surface, fixed on the formwork or introduced into the concrete solution. The method is effective, but rarely implemented in private construction. This pleasure is very expensive: the consumption of electricity for heating a cubic meter of concrete is 60-80 kW / h. At the same time, it is necessary to strictly control the temperature: measure it every two hours (or more often) and turn it off when it reaches +30 o C. Then turn it on again after a while. Control must be around the clock.

When pouring the foundation with your own hands in winter, it is realistic to use only heating cables. They are attached with inside to the formwork, and after its removal, they are dismantled. There is a second option - to "drown" the wire in concrete. Both methods work well, but only if the walls are insulated from the cold.

There are also on sale special heating mats for heating concrete. They are laid out on the surface, included in the network. Its cost is 2.5 thousand rubles / m2.

To maintain the temperature, there are greenhouses above the object. These are structures very much reminiscent of greenhouses. And their task is similar: to keep warm. The frame is erected, it is covered with a film or other similar materials. Inside they put a stove, a heat gun, etc., with their help they maintain a positive temperature. But at the same time, it is also necessary not to forget about moistening so that the moisture from the solution does not evaporate.

Another method of concrete heating is using infrared emitters. This method is good because, under the influence of waves, the solution itself is heated directly. The emitters are covered with aluminum casings, creating a directed flow. However, for effective heating, you need a large number of lamps.

Additives and Additives

Another way to pour concrete negative temperatures- usage chemical substances. Some of them accelerate curing by initial stage process. The mass fraction of all additives is not more than 2% by weight of cement. Large quantities can adversely affect the quality of concrete, so stick to the recipes.

One of the methods of winter concreting is the addition of special antifreeze additives to the batch.

The most common additive that increases the “frost resistance” of concrete and accelerates its hardening is calcium chloride. Potash and sodium nitrate are also used. If you add them during normal mixing, the freezing point will drop to -3 o C.

One "BUT". Chlorides cannot be used for reinforced concrete - they provoke the rapid destruction of steel. So the most common concrete hardening accelerator - calcium chloride - is not suitable for pouring the foundation.

Pouring concrete at sub-zero temperature possible if the solution is heated with the same additives. In this case, you can work at -15 o C. But for the normal quality of the foundation, you will need to insulate the fill and follow simple but mandatory rules.

Rules for winter pouring concrete

The solution is poured into the prepared formwork. Preparation consists in removing ice and snow, heating the reinforcement and the bottom of the foundation. This is the most difficult stage. Scraping off ice is half the trouble, but warming up the reinforcement and the entire perimeter of the foundation is a problem. The temperature should not be high, but it is necessary to achieve its positive values.

As an option, you can consider the device of portable braziers, which are lowered into the pit and kindled there. It is possible to use heat guns powered by gas cylinders. The use of other means is difficult due to their high cost.

For this reason, concrete in winter slab foundations problematic: such areas cannot be heated. For this type of bases, "winter" will be limited to light frosts at night and positive daytime temperatures. Filling can be started after the reinforcement and the bottom have a positive temperature.

The strip foundation can also be poured during frosts: it is realistic to heat such a base and reinforcement in a limited volume. Not easy, but possible.

Everything can be done step by step. Break the whole tape into small areas, start heating at the same time or with a certain time interval on several of them (two or three, depending on the time required for kneading and heating the pit). Start pouring one area by moving the braziers further. While the first heated area is being poured, the next one will reach the required temperature. The flooded area is immediately covered with heat-insulating materials and proceed to the next, and moving along the entire perimeter.

It is imperative to knock down the ice and heat the reinforcement - this is the only way the foundation will be strong

The mechanism is clear. So it is possible to pour the foundation with concrete at -15 o C (but with appropriate additives, "hot" mixing and measures to preserve heat).

Another important condition- work must be carried out continuously. In winter, it is impossible to fill the foundation in parts. This is 100% correct. The gap between fillings should be such that a film does not have time to form on the surface of the previous part, and even more so that moisture does not freeze. Work must be carried out continuously until the end of the pour. The flooded parts must immediately be covered with heat-insulating mats. As you can see, several people are needed for this work. One cannot cope with all tasks.

note that Maximum temperature solution should be 35-40 o C. Its excess leads to a slowdown in the curing process. The situation will, of course, be better than when freezing, but not by much.

Results

Pouring the foundation in winter is not an easy task, but it is possible even with your own hands. Need helpers and careful preparation, but you can make a normal base at sub-zero temperatures. At what temperature can concrete be poured? It depends on its composition, but for private traders it is realistic, albeit at high cost, to achieve normal quality at temperatures not lower than -10-5 o C. Filling at positive temperatures during the day and frost at night will turn out to be less expensive.

The minimum temperature for pouring concrete is approximately 5°C. That is, this indicator is considered critical - up to this figure, any work with concrete can be carried out as usual. However, it must be remembered that optimum temperature for pouring concrete - 17-25 ° C, since such conditions make it possible to obtain the maximum strength of the solution. If the temperature approaches 5°C, the grout will likely be less solid and less durable and will not reach the brand specifications. Even when carrying out work, it should be remembered that the hardening time can increase significantly.

However, sometimes it becomes necessary to carry out construction work in winter at low temperatures. There may be several reasons:

limited building time summer period due to unfavorable climatic conditions;
the need to pour concrete on loose soils;
seasonal decline in prices for materials, including cement;
reduction in the cost of work by specialized firms due to low demand for their services.

There are two main technologies with which you can carry out concreting in the cold season.

The first is that concrete is poured at low temperatures on heated fittings, which can be ordinary electrodes. A standard 12-volt cable is connected to the armature, through which current flows. This is quite enough to metal rods heated up and heated the solution, preventing it from freezing. The disadvantages of this method are obvious - in addition to the use of special materials, you will have to spend a hefty amount on electricity.

In addition, pouring concrete at low temperatures can be carried out using warm formwork. The essence of this technology is to insulate the solution with special heat-insulating materials, such as foam or mineral wool. But there are also disadvantages here - it is necessary to cover concrete from all sides, which leads to high consumption. auxiliary materials and increase the time of work.

Pouring concrete at low temperatures: general recommendations

Thus, we can conclude that pouring concrete at low temperatures should be carried out only if it is not possible to postpone this stage. construction works until more favorable conditions arrive.

At temperatures below zero, the hardening of the concrete solution becomes problematic. This is often encountered when building foundations in autumn and winter. Experts assure that pouring concrete at sub-zero temperatures is possible without heating, but certain requirements are met for this to ensure proper hardening. concrete mix.

Concrete is a mixture of aggregates - sand and gravel, fastened together by a hardened cement milk. When it reacts with water, it hydrates, then it hardens with the simultaneous evaporation of water. Critical strength at normal temperature It is collected within one or one and a half days, depending on the humidity of the surrounding air.

The optimal temperature for the reaction is about 20⁰С, the solution gains its design strength within 28 days. So that in the early days the water does not evaporate too quickly, the concrete is covered with waterproofing.

At 5⁰С, the solidification of the composition slows down by 2 times, and at zero temperature, hydration stops. If before that the critical strength of concrete is gained, nothing will happen to it, it will gain strength after warming. If, before freezing, a set of critical strength did not occur, the material will not gain the required indicators, and will crumble after defrosting. In this case, it is impossible to pour any brand of concrete at sub-zero temperatures.

Methods of concreting in winter conditions

The main condition correct filling concrete at low temperatures is the preservation of heat sufficient to ensure curing. Popular ways of laying mortars in winter:

Pre-heating of the produced mixture;
The device of reliable thermal insulation and care of the solution;
Electric heating of concrete poured into the formwork;
The addition of special additives that reduce the freezing point of water and accelerate hardening.

Thus, it is possible to concrete on the street in winter without loss of strength indicators, but for this you need to adhere to the selected methods. In terms of costs, the use of heat guns is the most unprofitable option, the cheapest method is the addition of additives. Electric heating and thermal insulation device are intermediate options.

Temperature increase during kneading

To pour concrete in sub-zero temperatures, the components are heated. Fillers are heated to 55-60⁰С, and water is fed into the solution at 90⁰С. The cement is heated to room temperature otherwise it loses its binding properties. Before laying, the temperature of the solution should not be lower than 35⁰С.

When mixing, it is required to use a concrete mixer, into which heated water is first supplied, then fillers, and only then cement. When pouring such a mixture, the thermal energy of the monolith is enough to gain critical strength, taking into account the fact that additional heat is released during cement hydration.

Heating and insulation of the solution

At very low temperatures heated mixture requires additional insulation or heating. It is more economically feasible to insulate with the help of inexpensive heat-insulating materials that do not require additional sources energy. Hay or straw is lined on a concrete surface, old rags, peat, film or heat-insulating blankets are used. Sometimes the so-called "greenhouses" are arranged, similar to greenhouses.

If concreting at temperatures below -5⁰С, additional heating will be required. For this, the following technologies are used:

Heating with heat guns or stoves under greenhouses. This is a costly method that requires constant additional moisture. Suitable for sites that do not have electricity.
The use of thermomats powered by electricity. They are laid out on the surface of poured concrete and connected to a power source. Requires a large amount of electricity.
Infra-red radiators are installed above the flooded surface or around the formwork, the intensity and direction of heating is regulated by reflectors. Suitable for vertical and inaccessible structures.
Used to heat concreted area special cables or electrodes through which they pass electricity. The technique is convenient to use, but requires large volumes electricity. Installation of the electrode system requires more costs, because when drying, the resistance of the solution, which itself is a conductor, increases.

Introduction of additives

Improving the characteristics of the solution with special additives is the most convenient and economical method of pouring the solution in winter. Using it in conjunction with heating, you can speed up the work and improve the quality of concrete. There are two main types of additives for pouring concrete mortar in winter:

Compounds that reduce the freezing point of water. The solution hardens for quite a long time, but the water does not crystallize, so the quality of the concrete does not suffer. To speed up the reaction, thermal insulation is required. In this capacity, calcium or sodium salts and potash are used, which prevent the crystallization of water.
Additives that increase the rate of hardening of the solution. They reduce the time required for concrete to gain critical strength, so the water in the heated mixture does not have time to crystallize. Calcium nitrite-nitrate, the same potash, calcium salts mixed with urea are used.

The amount of additives depends on the temperature range in which the concrete structure will be poured. From -5 to -10⁰С add up to 5-8% by weight of cement. With a decrease in temperature to -15⁰С, the concentration is increased to 10% by weight of the added cement, and up to -25⁰С, at least 15% of additives must be added.

To achieve maximum strength, you need to know at what temperature to pour concrete, and the best methods for ensuring curing. In addition, it is required proper preparation formwork. Before pouring the solution, it is necessary to thoroughly clean it from frost. The soil and fittings need to be warmed up, for which braziers are used, heat guns, infrared emitters and other devices. That is why it is not recommended to make slab foundations in a low temperature range, since it is difficult to completely heat all the elements over a large area.

Working with a strip foundation in such weather is quite possible. To do this, you need to warm up the trench gradually, pouring concrete into it. After pouring, a mandatory step is high-quality thermal insulation. The process continues until the perimeter is closed. With the use of additives in concrete mortar and high-quality insulation strip foundation can be poured at temperatures up to -15⁰С.

When working on laying concrete, regardless of the type of structure, continuity of work is needed until the monolith is completely poured. For the successful completion of work, it is necessary to calculate to ensure the supply the right amount solution and the optimal number of workers.

Filling in parts can lead to uneven properties of the structure and reduce its quality.

Before pouring the solution into the formwork, you need to make sure that its temperature is optimal - in the region of 38 ° C. If it exceeds 40 degrees, then the hardening rate will decrease due to a decrease in the quality of the cement. As a result, it will take too long to reach critical strength, the liquid in the solution risks freezing, and the concrete will lose its properties.

Answering the question whether it is possible to pour concrete in winter, one can say - definitely yes. With the right technological approach, these works can be carried out at the lowest temperatures. Laying without additional heating can be carried out in slight frosts, this will require good thermal insulation and pre-heating of the concrete solution.

At low temperatures, additional It is carried out various methods, which you need to choose directly at the construction site. The cost of heating and thermal insulation pays off, since substandard concrete will reduce the quality of the entire structure.

Industrial construction does not stop during the cold season, but hardening of concrete at low temperatures is problematic. Crystallization of water leads to a decrease in strength, which negatively affects the quality of structures. The use of antifreeze additives in concrete will help to solve the problem, wide selection offered by the industry today.

The use of antifreeze additives allows pouring mortars at temperatures up to -50ºС. They are liquid or powder formulations that are added to the mixture. It is important to know that concrete additives added during frost provide only 30% hardening. The final hardening occurs after the defrosting of the monolith.

There are several types of antifreeze additives that differ in the principle of action:

Compositions that lower the freezing point of the liquid, as a result, the process of cement hydration continues, setting proceeds according to the standard mechanism;
Additives based on sulfates accelerate the compaction of concrete, while generating excess heat, which increases the rate of hydration of the cement;
Complex additives increase the solubility and activity of cement laitance, while the compounds that appear as a result of reaction with water reduce its crystallization temperature.

Varieties

There are various antifreeze additives, each of which has its own mechanism of action. A popular additive is sodium carbonate, otherwise called potash. This is a powdery crystalline composition that accelerates the hardening of the concrete mixture. The use of this type of additive reduces specifications material, including strength. To reduce this effect, sodium tetraborate is added to potash.

Attention! Potash belongs to dangerous substances, therefore, when working with it, safety requirements are observed.

Sodium tetraborate is a complex substance consisting of sodium and calcium salts, with the addition of ammonium. It is an additional antifreeze additive used with sodium carbonate. Without it, the structure can lose up to 30% of its strength after thawing and complete curing.

Sodium nitrite is an effective antifreeze additive that reduces the crystallization temperature of water, accelerates the hardening of the composition, and has an anticorrosive effect. Its use is dangerous, since sodium nitrite powder is a flammable, explosive, toxic substance. It is used in frosts down to -25ºС. It cannot be miscible with lignosulfonic acids, as it releases toxic gas when interacting with them. Calcium nitrite-nitrate has similar properties.

Sodium formate is an antifreeze additive for concrete that reduces the crystallization temperature of water and accelerates the hydration of cement. It is added in a proportion of not more than 6% of the total mass of concrete. To improve plasticization, naphthalene lignosulfonate is added to the additive.

Urea - PMD, prolongs the liquid phase of water, practically does not affect the setting speed.

calcium and sodium chlorides, ammonia water reduce the freezing point, but have an increased corrosive effect. They strongly influence metal elements therefore not recommended for use in reinforced concrete products.

How to use

The choice of additive and the method of its application depends on the conditions and material where it will be introduced. Any concrete additives used at sub-zero temperatures are introduced into the solution with water, according to the manufacturer's instructions. After thorough mixing, it is recommended to wait a while for this component to diffuse in the composition.

According to SP 70.13330.2012, in order for the composition to achieve the desired strength, it is important that before the temperature of the composition reaches the mark for which the additive is designed, it gains no more than 20% of the planned strength.

Consumption of antifreeze additive per 1 cubic meter material depends on the average daily ambient temperature. Up to -5 degrees, it is recommended to add up to 2% of the additive by weight of the solution, up to -10 degrees, this figure increases to 3%, up to -15 degrees, no more than 4%. At severe frosts calculation is made individually for each type. The rate of hardening of the solution is reduced, and the maximum strength is achieved after the end of frost.

When adding plasticizers and PMD, it is necessary to observe certain rules work. The recommended range of the poured solution is from +15 to +25ºС. To dissolve the additives, a certain amount of water is required, which must be heated, this ensures complete dissolution of the substances. Sand and gravel used in the solution are also heated immediately before adding. Cement must not be heated, as it will lose its astringent properties. The poured solution must be covered, this is especially true during snowfall.

Advantages and disadvantages of additives

The main advantage of concrete with antifreeze additives is the ability to perform work all year round. Picked up in correct proportion, they improve the adhesion of the components, improving the quality of the solution. They also have other advantages:

increasing the service life due to the compaction of concrete;
increase the plasticity of mixtures, making it easier to work with them;
the frost resistance of ready-made concrete increases, which is important for elements of load-bearing structures;
application of PMD is the most cheap way pouring at negative temperatures;
the use of additives reduces shrinkage during solidification, while maintaining the integrity of the structure;
antifreeze additives fill the pores of concrete, thereby significantly increasing its water resistance;
some compositions significantly increase the corrosion resistance of the monolith, extending the service life of structures, buildings and structures at times.

The use of antifreeze additives has its drawbacks. If used incorrectly, the strength characteristics of concrete are reduced, therefore, when working, it is necessary to strictly adhere to the instructions. Some additives are flammable and toxic, which must be taken into account when working with them. Even with additives, the hardening rate will be relatively slow in frost. To achieve the desired strength when laying in winter, more cement is required, which increases the cost of construction.

Do-it-yourself anti-frost additives

In private construction, if it was not possible to carry out all the work in the warm season, it is necessary to continue in the winter. Therefore, it is allowed to prepare anti-frost additives for concrete with your own hands at home. To do this, you only need table salt or sodium chloride. Such an additive reduces the freezing point of water and reduces the time of critical solidification of the mixture.

To make a do-it-yourself antifreeze additive in concrete, salt is dissolved in water and added to the solution. The concentration up to -5 degrees is 2% by weight of the solution, up to -15 degrees, the mass fraction of chloride reaches 4%.

The disadvantage of this additive is its corrosive activity towards metal, so it is not suitable for reinforced concrete structures. It should be borne in mind that the rate of solidification of the solution at negative temperatures will be, on average, 3 times lower than under normal conditions.

Pouring concrete is an integral part of most construction work. As is known, ideal period for repair and construction work - this is a warm season and pouring concrete is no exception to this rule. However, what should those who decide to continue construction despite the frosty weather do?

Pouring concrete at sub-zero temperatures in most cases is contraindicated by SNiP standards, since extreme cold does not allow the compositions that contain liquid to fully polymerize. But in some cases, the circumstances are such that the concrete must be poured, no matter what. And the question is quite natural, is it possible to pour concrete at sub-zero temperatures?

For areas where there is no warm season or situations in which winter construction is vital, there are several technological solutions that can be used to form concrete structures without compromising quality. In this article, you will be given detailed instructions how to pour concrete at sub-zero temperatures.

Pouring concrete

At sub-zero temperatures, the liquid in cement mortar freezes and the ice crystals break crystal lattice concrete, thereby weakening the strength future design. After thawing, the bond structure is not restored, and the structure loses a significant part of the strength potential, up to complete destruction.

The direct effect of sub-zero temperatures on concrete structure admissible only after she acquires required amount strength, frost resistance, etc. In construction terminology, this value is called the critical strength threshold - after overcoming it, frost does not negative impact on the concrete structure.

The threshold of critical strength is determined depending on the brand of concrete solution. The standard cement mix of the M400 brand must gain at least 30% of its maximum strength, and the lower the concrete grade, the higher the percentage of gained should be.

Before pouring concrete in sub-zero temperatures, it is necessary to create conditions that will prevent it from freezing. There are several technologies that help create or maintain the temperature necessary to overcome the critical strength threshold.

Among them are the following:

Mixture heating. Before pouring concrete at sub-zero temperatures, the solution is heated to a certain state, which gives it the opportunity to overcome the critical strength limit as it cools;
Internal heating. Maintain positive temperature in reinforced reinforced concrete structures it is possible through internal electric heating, which is carried out at the expense of electricity and metal components;
External heating. It is possible to create the temperature necessary to achieve critical strength using external steam or;
thermal insulation. Pouring concrete at minus 5 degrees can be carried out using high-quality insulated formwork, which does not release heat from the inside and allows cold to penetrate inside;
The use of specialized additives that prevent water from freezing.

Each of these technologies has its own characteristics, which must be taken into account, giving them their preference. Consider the above options in more detail.

Mixture heating

concrete mortar kneaded on heated water, the temperature of which can be from 60 to 90 degrees. This technology can only be used if the temperature environment does not fall below -15 degrees. This circumstance should be taken into account if you are wondering, “At what sub-zero temperature can concrete be poured?”

Specialty Blends

AT cement mixture various antifreezes are added to prevent the formation of ice crystals. Most often, calcium chloride or sodium chloride (table salt) is used for this purpose, which can be no more than 2% of the total mass of the components. If the temperature does not fall below 15 degrees below zero, then modifying additives will save the structure from freezing.

Note!
Despite the fact that the price of modifying components is quite affordable, it is best to purchase factory mixtures that guarantee technical qualities product.
A homemade recipe mixed with your own hands can be a waste of resources.

thermal insulation

If you want to pour the foundation at sub-zero temperatures, then you can do without heating or third-party additives. It is enough to qualitatively insulate the formwork with sheet or loose insulation.

During the crystallization of the concrete solution, heat is released, which is quite enough to overcome the critical strength threshold if the formwork is assembled according to the thermos principle. However this technology undesirable to use at too low temperatures.

Note!
Heat-insulating formwork can be used in conjunction with the above technologies - in this way, you will increase their effectiveness.

Internal and external heating

Internal heating is carried out by connecting to the reinforcing frame alternating current from a special transformer - the metal is heated and heats the cement mixture. External heating consists of a specialized mobile formwork, which contains heating elements that are powered by steam or electricity.

The disadvantages of this technology are the high cost of construction - the enormous consumption of resources for heating affects. Also, this technology cannot be used independently, since without the presence necessary knowledge and equipment, it is impossible to achieve the desired effect.

Among the advantages, it should be noted that you may not think about the question, “Up to minus how much concrete can be poured?” - concrete heating allows pouring at temperatures up to -25 degrees.

Outcome

The correct approach to the question of how to pour concrete in sub-zero temperatures makes it possible to obtain a high-quality result even in the most adverse conditions. In the future, eliminate small errors and establish additional elements concrete cutting will help you diamond circles and diamond drilling holes in concrete. More detailed information on this topic you can get by watching the video in this article.

Categories

Popular