Instructions for constructing foundations in winter. Strip foundation in winter Formwork in winter

13.03.2024

Pouring a foundation in winter is a labor-intensive and technically complex type of work that requires careful preparation and strict adherence to building regulations. Until recently, building the foundation of a house at subzero air temperatures was not feasible due to the lack of conditions necessary for the natural hardening of concrete. With the advent of new technologies, pouring the foundations of buildings in winter has become easier and more affordable.

The nuances of concreting in winter

The basis for hardening of a concrete mixture is hydration, which is accompanied by the transition of the material from a liquid state to a solid monolith. With a favorable level of humidity and an average daily temperature above 0 °C, a gradual increase in the strength of the foundation of the house occurs. In winter, instead of hydration, water crystallizes, which prevents the formation of strong molecular bonds and increases the porosity of the concrete mixture by 10%.

As a result, the strength of the foundation is significantly reduced and does not reach the planned level. Is it possible to pour the foundation in winter? Yes, if you use one of the developed methods for constructing a foundation at low temperatures. The choice of a particular option depends on the following factors:

climate nuances during low temperatures;
house dimensions;
the ability to increase the temperature of water and aggregate.

The brand of cement used, the fineness of its grinding, the chemical composition and proportions of the components of the solution are also important, which help to slightly increase the temperature of the mixture during the process of natural hydration.

It is allowed to heat only water and aggregates, since a similar action with cement worsens its binding properties.

Why do you need to build a foundation in winter? In private construction, such a need may be caused by the following reasons:

Construction of a house on areas with soil prone to crumbling. In winter, the soil freezes, holds its shape well and allows you to make a foundation pit without much effort.
Construction of buildings in areas with harsh climatic conditions. In this case, the warm period is short-term and is not always suitable for installing a foundation for subjective reasons.

In some cases, the construction of the foundation of a building during frost is justified by low prices for materials and the availability of free time for developers or owners of future real estate. Among the disadvantages of pouring the foundation of a house in winter are the need for special equipment for digging trenches, low productivity of work and additional costs for heating and purchasing additives.

Foundation construction technology in winter

When constructing the foundation of a private house in conditions of low temperatures, it is advisable to use a concrete mixture with modifying additives, and upon completion of the work, cover the structure with thermal insulation. Other methods are labor-intensive and require special skills.

To build a foundation in winter, you need the following:

concrete solution;
modifying additives;
crushed stone;
rods or mesh for reinforcement;
building level;
materials and tools for making formwork;
shovel;
thermal insulation;
concrete mixer.

First, formwork is made around the perimeter of the dug trench and a reinforcing frame is installed. Then the concrete solution is mixed, adding special components to it, the foundation of the house is poured and left for 3 days. During this period, the mixture hardens, after which it should be insulated.

At temperatures below -20 °C and humidity 60% or more, foundation construction work is not carried out.

Simple ways to fill a foundation in winter

There are three directions for creating conditions for foundation hardening: heating the mortar and formwork, as well as adding modifying additives to the concrete mixture. Each of them has its own characteristics and specific application.

Heating the solution

If you need to fill the foundation in winter with positive daytime temperatures and slight frost at night, then it is advisable to use the separate heating method. Using a heat gun or gas burner, the aggregate, water or concrete mixture is heated, fulfilling certain conditions.

Among them are:

the maximum permissible water heating temperature should not exceed +80 °C;
the preparation of the solution begins with mixing the aggregate with water, followed by the gradual introduction of cement grades M400 and M500;
introduction of additives that reduce the curing time of concrete.

To obtain a mixture with a homogeneous structure and high density, vibration equipment can be used. It reduces the air content and reduces the porosity of the material. After pouring is completed, the foundation of the house is covered with insulating mats, bags or tarpaulins and the temperature is maintained until the foundation becomes strong. Then the formwork is removed, observing the rules for carrying out concrete work during low temperatures.

Construction of formwork

At slight negative temperatures, the thermos method without heating with electric heat sources, which involves installing thermal insulation around the formwork, will be effective. To do this, insulation is laid on all sides of the base, having previously secured a vapor barrier material. It performs two functions: it allows evaporating moisture to pass from the surface of the concrete and protects it from the penetration of precipitation.

Use of additives

The introduction of modifying components into the solution helps to increase the thermal energy generated by concrete during hydration. Also, special additives reduce the level of water crystallization, as a result of which the hardening of the foundation of the house occurs at a lower temperature. To form frost resistance, calcium chloride, sodium nitrate, and potash are introduced into the solution.

To properly harden the base of a building, you can combine concrete with modifying components and artificial heating.

Technically complex methods

In addition to natural heating of the concrete mixture when pouring the foundation, you can also use artificial methods using electrical appliances. These include:

Concreting using the thermos method. An insulating sheathing is made around the formwork, which is a metal casing with a water, steam or electric circuit for heating the concrete. This design prevents heat loss and reduces the cooling rate of the base.
Concreting with electric heating. It is performed using a current that is passed through wires laid when pouring the solution. The cable can also be used to entangle reinforcement or formwork. This option of concreting in winter is characterized by ease of execution and low cost.
Infrared and induction heating. In this case, the heat source is heating elements, special emitters or a cable, which helps create magnetic fields in steel formwork or reinforcement. This option of maintaining the required solution temperature requires special devices and complex preliminary calculations.
Pouring solution with steam heating. This method is highly labor-intensive and is carried out using powerful equipment and a large volume of water. Pipes are installed into the formwork structure, combining them into a single system for supplying steam and heating the foundation.
Construction of a greenhouse. A device of this design is a costly heating method. First, you need to erect a tent made of tarpaulin or polyethylene around the foundation of the house, and then maintain the desired temperature inside using heat guns, electrical appliances, or portable stoves.

The use of technically complex heating methods requires significant financial investments, so the effectiveness and necessity of winter pouring of the base should be assessed.

Requirements for construction work

To ensure the strength and reliability of the foundation of a house when pouring it in winter, it is necessary to follow some rules. Firstly, work cannot be carried out in parts with long periods of time between each pour. The concrete solution is laid in small segments, quickly covering them with the next layer. This avoids heat loss and keeps temperature changes to a minimum.

Watch the video to see what points need to be taken into account when pouring the foundation in winter.

In addition, it is also necessary:

Thoroughly clear the prepared trench of snow and remove any ice that has formed from the reinforcement and the bottom of the ditch;
cover the pit with insulating material;
pre-heat the bottom between the formwork walls;
provide passage to the formwork.

It is forbidden to pour concrete on top of frozen soil, since when it thaws it will settle and can cause the foundation to sag.

In the summer, building both the foundation and the structure itself is faster, easier and cheaper. But this is not always possible. This is due either to personal employment or to the short duration of the warm period. Thanks to the use of modern materials and the implementation of new technological solutions in practice, the question of whether it is possible to pour a foundation in winter has practically lost its relevance. These works are successfully carried out at sub-zero temperatures. Today, the effectiveness of concreting in frosts is being discussed from the point of view of economic and labor costs.

Features of foundation construction in winter

Making a foundation at low temperatures is not an easy process. Workers will have to work in the cold. Winter is generally considered not the best time to create a monolithic structure of slab or strip type, or to build piled and bored types of foundations. The main reason for this is that water, which is one of the main components of the working solution, crystallizes at temperatures below zero.

The formation of ice interferes with the normal process of formation of reliable bonds between concrete molecules - its hydration. Also, the expansion of water when freezing leads to a significant reduction in the strength of the foundation. This occurs due to the formation of pores in the concrete by ice crystals.

The hydration process itself occurs with heat release. Moreover, the larger the size of the concrete structure, the higher the heat transfer, and the cooling of the pour occurs more slowly.

In general, in winter, construction is carried out in the following cases:

when the summer period is short, which is typical for cold northern regions;
if it is necessary to erect the building as quickly as possible to the planned date;
The reason for this may also be the properties of the soil at the construction site.

It is also taken into account that some building materials can be purchased cheaper in winter than in summer (during the work season). For builders, cold weather is a period often characterized by small volumes of orders or their absence. Mostly employed are those who specialize in interior decoration. Due to the increased supply of services, prices for them fall. They also pay attention to this when starting construction in winter. But there are no significant savings, because the work is carried out using more complex technologies.

The disadvantages of pouring concrete in winter are:

complexity of the work;
the need to attract heavy equipment;
difficulties with organizing the heating of the foundation being built;
increased costs for purchasing additives that increase the frost resistance of the solution.

Due to the release of heat by concrete during hardening, when working in frosty periods, preference is given to strip or slab (monolithic) types of foundations rather than columnar ones. When erecting them, if the ambient temperature is slightly below zero, then you can even do without special additives and heating, using thermal insulating formwork and a special covering (made of mats).

When starting construction, you should take into account that it will not be possible to carry out excavation work on frozen ground yourself, manually. This will require the use of technology.

Concreting technologies

It is possible to make a foundation in winter using various technologies. The choice of option for creating and maintaining the conditions necessary for the concrete hydration process to proceed normally depends on the following factors:

from the chemical substances included in the working concrete solution, their proportional relationships;
dimensions of the structure being created;
climate characteristics of the area;
availability of power supply network;
brand of cement used;
Possibility of organizing heating of water and liquid additives.

The more crushed the cement particles are, the faster it enters into a chemical reaction, releasing heat.

Normal work is facilitated by heating the aggregate and water to 32 degrees immediately before mixing. The temperature of the working solution in this case will be approximately 21º C. It must be taken into account that the cement cannot be heated, because it will lose its binding properties.

The solution must be mixed thoroughly. It is also recommended to increase the mixing time by approximately 25% compared to summer.

Application of concrete additives

The main method that allows pouring a foundation during cold weather is the introduction of antifreeze additives into its composition. Their introduction causes an increase in the amount of heat independently generated by concrete. Supplemented with increasing heat transfer, modifiers lower the crystallization temperature of the liquid. Thanks to this, the hydration process of poured concrete at lower temperatures proceeds in the usual way.

Calcium chloride is often used as an additive that increases frost-resistant properties. It is introduced into the working solution in an amount not exceeding 2% of the total mass. If this proportion is exceeded, the compressive strength of the created base is significantly reduced.

At a stable temperature level around -15 degrees, the following substances are used to add to concrete:

table salt (sodium chloride);
sodium nitrate;
potash.

The use of concrete modifiers is often combined with the organization of artificial additional heating of the base.

If anti-frost fillers are used, the formwork is dismantled when M400 concrete reaches 20% strength. For M and M300 this figure should already be 30%, and for M200 – 40%.

It is not recommended to independently experiment with adding available components to filling compositions. It is better to use ready-made building materials.

Warming up the poured base

In practice, different methods of heating a poured base are used. The simplest option is to preheat the water and filler, or the entire solution. Suitable for these purposes:

fryer;
heat gun;
burners of various types;
an ordinary fire.

Modifiers are added to concrete to speed up the hardening process. After pouring it, the entire structure is covered using the following materials:

bags;
tarpaulin;
straw;
thermal insulation mats.

You can also cover with rags or unnecessary blankets. Braziers or other heat-producing devices are installed around the base. They are used until the concrete reaches the required strength.

You can make a kind of tent around the structure, which will contribute to more efficient energy consumption. But in this case, it is necessary to monitor the humidity level so as not to dry out the poured concrete. You will also need to draw up a separate project for the structure and dismantle it after the work.

After the monolith reaches the required strength (according to SNIP III-15-76 it is 70% and does not depend on the brand), the formwork and insulation are dismantled. If the concrete has not completely hardened, it can be allowed to freeze. After defrosting, all processes will continue in the right direction, and the strength will be lost by approximately 5% of that calculated according to the project.

Alternative heating methods and their implementation are presented in the table below.

№	Method of heating poured concrete	Practical implementation
1	creation of a "thermos"	To do this, a heat-generating casing is installed around the perimeter of the formwork, consisting of a metal casing with a steam or electric or water circuit located inside it
2	heating the fill with steam	This method is implemented by laying the required number of pipes in the formwork, through which steam is supplied from a specially created pipeline
3	use of electricity	To implement this option, a steel wire is used to heat the poured solution, fixed in a certain way in the reinforcement frame or on the formwork, or simply laid directly in the concrete, through which an electric current is passed
4	use of induction heaters	such devices located along the perimeter of the foundation warm it up by heating reinforcement or metal formwork with an electromagnetic field

Infrared heaters are also used in practice. Steam heating is an expensive and labor-intensive method that is used quite rarely.

The point of all methods is to speed up the setting of the solution.

Of all the methods considered, the most accessible are simple insulation of the base with various materials (followed by heating it) and installation of an electric heating circuit. Carrying out heating work requires the performer to have a certain level of qualifications in this field of activity, so specialists should be involved.

Pouring a foundation in winter requires strict adherence to a number of nuances. The rules for carrying out the work are as follows:

It is not allowed to fill the base in parts: the formwork mounted under it should be completely filled with mortar;
in order to avoid heat losses when laying concrete, the layers must be made of small height and length, immediately overlapping them with the following ones;
when a helium shell forms on the surface of the fill, it must be chipped off;
during the preparation of trenches for the foundation or foundation pit, they should be thoroughly cleared of snow and any existing ice should be knocked off the reinforcement;
immediately after digging and laying the sand cushion, you need to lay straw on the bottom: such a cover will prevent it from icing;
It is impossible to pour concrete on frozen soil; it must be pre-warmed;
it is imperative to ensure free access to the formwork from all sides;
if, after digging, water appears at the bottom of a trench or pit, then it must be removed;
it is better to use formwork with increased thermal insulation properties;
Until the concrete reaches a sufficient level of strength, it is necessary to heat the entire poured structure, maintaining a positive temperature.

If you lay concrete directly on frozen soil, then under the influence of heat generated as a result of hydration of the solution mass, the soil will begin to thaw and sag. In this case, the settlement may be uneven and the foundation may be deformed.

There are few rules for the correct, effective implementation of concrete pouring work. But they require strict compliance. It is easier and more economically feasible to perform them during preparation and during pouring than to redo everything afterwards.

Methods for pouring a foundation in winter are shown in the videos below.

It is possible to build a concrete foundation in winter. A high-quality result is achieved by using anti-frost modifiers or creating a heating system, or combining these two methods. In this case, it is recommended to use ready-made additives sold in construction stores from well-known manufacturers and finely ground cement. An important point is careful adherence to the technology of work and the nuances of the process.

Building a foundation in winter is a troublesome and time-consuming undertaking, but it is quite possible. For this time of year, there are special methods and technologies that allow you to build, which will be no worse than a foundation built in the warm season. Of course, the season, starting from April and ending in November, is the most favorable for building a foundation, but there are times when at this time of year it is not possible to build a foundation, and only winter remains for construction. With the right approach, you can build a strong, reliable foundation even in severe frost and on frozen ground, but you must carefully follow all the rules and take into account specific features.

Working with the foundation in winter is a rather difficult process, because people will have to work in severe frost. You can purchase special construction uniforms for them. It holds heat well and prevents the worker from freezing.

Developers often ask the question: is it possible in severe frosts? Yes, it is possible, experts will answer, but in compliance with mandatory rules and requirements.

Digging a trench. When digging it, you need to monitor the water filling the bottom of the pit. You can't let her freeze. If ice does form, the frozen water should be removed.
Concrete solution. Special substances are added to the concrete solution that will prevent it from hardening quickly, as a result of which the foundation built in winter will be strong. In addition, such substances contribute to better pouring of concrete into the formwork. When choosing components, you should pay attention to their properties. Some substances, on the contrary, reduce the hardening time. A large number of modifiers are produced in liquid form, and the required amount should be determined on a certain scale. Instructions can be found on the packaging. You should be aware that the use of active substances will reduce water consumption by up to 15%, and their use at temperatures below 20°C will be inappropriate. You should also know that if the humidity is more than 60%, it is better not to pour the mixture into the formwork. It is better to carry out all work in dry weather. When using modifiers for a concrete mixture, you should not neglect the heating and thermal insulation of the structure. They are required in any case.
Frost resistance. Concrete must be resistant to low temperatures, but this does not guarantee that the work will be carried out in accordance with the standards.
Heat preservation. Thermal insulation is important for the foundation and formwork. It will increase the temperature of the solution and prevent the water in the solution from freezing.
Heating the concrete solution. At very low temperatures, the concrete mixture should be well heated. If the thermometer temperature drops below 15°C, heating becomes especially important. The mixture is heated to 50°C. This speeds up the setting of concrete. After pouring, the entire structure should be heated and try to maintain the temperature above 0°C until the concrete is strong enough. Experts suggest purchasing special heated formwork systems or installing a heating system directly into the casting. Such a system consists of grids made of reinforcement. Electric current is connected to them through a transformer. The metal becomes hot and transfers heat to the concrete. But the disadvantage of such a system is the high cost of such heating. But even at an ambient temperature of -30°C, the concrete mixture will set perfectly, be strong and durable.

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Types of foundation suitable for construction in winter

The first option is a strip foundation. This option is most popular among developers. The disadvantage of pouring the base in winter is also low labor productivity. Workers must rest more often, and some operations require significantly more time than in the summer.
Experts recommend reducing the number of “wet” operations as much as possible. For example, the use of ready-made concrete blocks. They are delivered from the factory and placed directly into the finished pit. For the blocks you will need very little concrete mortar, which means a significant reduction in “wet” work.

Another option is a foundation built from prefabricated concrete piles. If the intended building is light, such as a cottage, garage or barn, you can use pile technology. This type of foundation is especially popular among wooden houses. By following all the rules of construction, you can build a strong and reliable pile foundation in winter, which will not be inferior to other types of foundations. Concrete piles are divided into two groups: bored and drilled.

Bored piles are made by pouring concrete into drilled holes, and bored piles are driven into the ground. The second group is much more convenient and faster, since the piles can be bought from the factory and do not require mortar. But the disadvantages of these piles are their high cost and very loud noise during driving the piles into the ground.

The solution to the problem may be to use . Currently, this technology is very common among developers and is in demand in the construction market. But for the winter season and on difficult ground, not all will be ideal for work. For example, for bored piles a huge amount of preparatory work must be done, and for bored elements it will be necessary to purchase special equipment.

For screw piles, nothing like this is required, which is why they are leaders in the construction market, occupying first places for the construction of foundations in the construction of low-rise buildings.

Screw piles were first used two hundred years ago in Great Britain. They then spread to Europe and America. The first piles were used in the construction of bridges on soft soil. Recently, foundations built on screw piles have become more and more popular in civil engineering.

Many companies have appeared in Russia that produce screw piles. They are ideal for any construction, as they are steel pipes with a diameter of 10 cm and a length of 2.5 m. Special blades are made at the end of the pipe, thanks to which the piles can be screwed into the ground. They can be screwed into any type of soil absolutely silently. No special technologies are required, since they are screwed in manually. Thanks to their design, the piles will remain stable in the soil. The foundation on screw piles is ideal for winter. In addition to frozen ground, it will sit perfectly on weak, shifting and very wet soil. A foundation made of screw piles is well suited for difficult soil: forested areas, a highly branched underground communications system and complex terrain of the site.

Another advantage is the preservation of the green area around the house. This includes trees, shrubs or lawns, which will pleasantly surprise nature lovers. For a pile screw foundation, careful site preparation can be avoided. It can be laid at any time of the year.

Since the piles are screwed in manually, you don’t have to involve outside workers and do everything yourself. This is another way to save money, since with a general budget, a strip foundation will be much more expensive than a pile-screw foundation. It is very simple to study the principle on screw piles. The process itself has now been carefully developed and studied in detail.

Before laying the foundation, you should calculate how many piles will be needed for the job. The more piles, the more costs. The number of elements is calculated, taking into account the weight of the building itself, the soil, soil freezing and groundwater levels.

The work methods used by professional builders are being improved. New technological techniques reduce the duration of construction activities, increasing the quality of constructed structures regardless of climatic conditions. Until recently, developers, pondering whether it was possible to fill the foundation in winter, gave a negative answer. Now the approach has changed - technology allows concreting in winter, guaranteeing the quality of concrete.

Different approaches to the question of whether pouring concrete in winter is possible

Discussions periodically arise between builders about the possibility of carrying out concrete work at temperatures below zero degrees Celsius. There are two positions:

supporters of traditional methods are confident that cement hydration can only occur at positive temperatures. They deny the possibility of using special techniques and believe that in winter the strength of concrete is lower and it is preferable to pour concrete in the fall;
adherents of the latest technologies do not doubt the effectiveness of proven know-how. They believe that it is possible to concrete the foundation in winter, regardless of the level of temperature decrease, and at the same time ensure the strength characteristics of the foundation.

Each opinion is based on certain views and experiences. Let us dwell in detail on the features of performing concrete measures in cold climatic conditions. The main task is to prevent water crystallization. After all, frozen ice crystals increase the porosity of the mass and create an obstacle to the hydration of the concrete mixture.

Pouring the foundation in winter is quite feasible

Pouring the foundation in winter - how hydration proceeds

Provided that special methods are used, involving the introduction of additives or heating of the solution, the hydration process in winter and summer is no different.

It provides the following stages:

formation of a surface film based on sodium salts;
absorption of water by the binder in the outer layer of the massif;
contraction of the outer layer with a simultaneous increase in density;
stopping moisture absorption and further increasing hardness.

The concrete mass acquires operational hardness gradually:

The initial setting of the solution lasts no more than 24 hours. The liquid mixture hardens, but it is not strong enough to carry out further work;
the final set of hardness occurs within 28 days. Duration is affected by weather factors and recipe.

The construction of the foundation in winter has its own characteristics. As a result of crystallization, water freezes in concrete pores, which impairs the strength of the mass. The main requirement when pouring concrete in winter is to create a solution temperature favorable for hydration.

Pouring the foundation in winter - methods used

By maintaining an optimal temperature, builders ensure the required duration of concrete hardening.

Winter foundation installation is the only way to speed up the pace of construction of structures in a harsh climate zone

Various methods are used for this:

steam heating;
heating with electricity;
directional heating by an infrared source;
temperature increase by induction radiator;
protection of concrete with a thermal tent;
insulation of the massif with heat-insulating formwork;
introduction of additives that prevent water from freezing.

Let's look at the features of popular technologies.

Using steam heating

Hot steam can deeply heat concrete and create favorable hardening conditions. Heat treatment of concrete for 24–36 hours with steam heated to 75 ⁰C is equivalent to gradually settling the concrete for half a month at a positive temperature.

The duration of processing is determined by the following points:

the required hardness of the monolith;
the brand of Portland cement used;
heating intensity.

Heat treatment is carried out by creating a steam jacket. It is constructed near the surface of the formwork and allows steam to flow unhindered around the concrete.

This is a rather labor-intensive and costly method, as it involves heating the trench, pit or concrete to a higher temperature.

Application of electrical energy

With the help of electricity, it is possible to provide normal conditions for hardening. The following methods of increasing temperature are popular:

the use of a heated cable of the PNSV brand, which, after installation, is filled with concrete mixture;
the use of electric heating from a step-down transformer through electrodes inserted into the array.

The electrode heating method does not require significant costs and provides for the possibility of using various conductive elements:

stretched wire. A vertically positioned string is effective when concreting elongated structures in the form of support columns or load-bearing beams;
reinforcing bars. Depending on the size of the concrete products, the rods are immersed in the solution to the required depth and cannot be reused;
metal plates. Plate electrodes are placed on oppositely located formwork panels, ensuring direct contact with the solution.

The greatest effect is provided by the use of a heating cable. The technology allows you to regulate the heating intensity of the wire that transfers thermal energy to the concrete mass.

This method can be carried out at any temperature and weather conditions.

The following heating methods are less popular in the construction industry:

infrared;
induction.

They have serious disadvantages associated with increased energy intensity, complexity of implementation, and uneven heating of significant volumes of concrete.

Construction of a thermal “jacket”

Construction of an easily erectable tent with internal heating is an economically viable method. Main elements of the tent:

power structure made of durable metal profile;
covering made of polyethylene film or tarpaulin material.

Heating inside the structure is carried out using the following equipment:

heat guns with autonomous power supply;
portable stoves using various energy sources.

This method of construction is very well suited for all weather conditions, even the most severe frosts

Heating of formwork panels

Warming up the formwork panels is also used to maintain the temperature regime. It is based on the formation of thermal insulation cladding based on the elements of the formwork structure.

Various coolants are used:

water vapor;
Electric Energy;
hot water.

The heating circuit is formed from hermetically connected lines that transfer thermal energy to the solution. This method has weaknesses:

uneven evaporation of moisture from concrete;
the appearance of cracks in the heating zone.

At the same time, situations are possible when heating the formwork is the only possible method of maintaining the temperature.

Is it possible to pour the foundation of a cottage in winter?

The financial capabilities of private developers do not always allow the use of industrial heating methods. After all, it is problematic to purchase or rent special equipment, as well as maintain the required temperature throughout the day.

As you can see, pouring the foundation in winter has its advantages

That is why quite simple technologies are used when constructing private buildings:

heating the concrete mixture during the preparation stage;
introduction of frost-resistant modifiers into the solution.

Using these techniques, you can concrete the foundation of a private house in winter.

How can you increase the temperature of the mixture yourself?

It is easy to increase the temperature of the concrete solution on your own, observing the following rules:

Heat the water to 75–80 degrees Celsius.
Mix it with aggregate.
Add cement to the mixture.
Stir by adding hot water until the solution reaches the desired consistency.

After pouring, use a vibrator to eliminate air pockets.

The use of additives to increase frost resistance

Frost-resistant additives, which prevent water crystallization, make it possible to carry out winter concreting without the use of energy-intensive heating processes.

Today in the construction industry various types of additives are used to improve the quality of concrete and its hardening.

To ensure the desired effect you must:

study the manufacturer's instructions;
analyze the compatibility of components with the materials used.

Independent use of additives does not cause difficulties for private developers.

Preservation of the foundation for the winter

Private developers are interested in whether it is necessary to cover the foundation for the winter, and also when to close the vents in the foundation for the winter. Preventing a newly poured concrete foundation from overcooling helps increase its strength. In this case, sealing of the vents should be carried out before the onset of the first frosts.

Preserve the base in stages:

Waterproof the base. Waterproofing the foundation in winter is carried out 30 days after concreting and involves covering the surface with polyethylene or roofing felt. When aquifers are located close together, a drainage system is constructed.
Insulate the surface. Thermal insulation will allow you to maintain favorable temperature and humidity for a long time, eliminating the influence of temperature changes. Expanded clay, expanded polystyrene, sand, sawdust or straw are used as insulation.

It is important to reliably cover the heat insulator with polyethylene and secure the film with heavy objects.

Conclusion

Not all winter concreting options can be used by private developers. Study the technology thoroughly and perform an economic analysis. Only then choose the optimal method. In addition, there is another option - wait for warmer weather and save money.

During the construction and design of residential or non-residential buildings, it often becomes necessary to fill the foundation with concrete mortar in late autumn or already winter. When the air temperature drops below 0°C. According to the recommendations of specialists and the concrete manufacturer, the optimal temperature for pouring and hardening the mixture is +5°C. Hence, the next question arises - how to pour concrete in winter without warming up?

Many qualified specialists and construction companies use special heating systems for pouring the mixture in the autumn-winter period, which are represented by three methods:

Electric heating of the solution in special bunkers immediately before pouring to an optimal temperature of 50-70°C;
Electric heating of the mixture using heat guns, which are installed under the greenhouse (awning, film) and directed directly to the concrete surface;
Electric heating of a poured foundation using alternating electric current, which is passed through specially installed fittings or pre-laid heating wires.

However, if it is not possible to use the above methods, then in this article we will look in more detail at how you can pour concrete in winter without auxiliary heating.

Helpful information

Pouring mortar at sub-zero temperatures has a number of specific nuances. Winter conditions in the construction industry begin when the average air temperature is below +5°C, or when this indicator drops below 0°C during the day.

The main task in the process of concreting in winter is to ensure the hardening of the solution in a humid and warm environment during the entire period of its hardening. In other words, you need to provide optimal conditions for the concrete solution to gain a percentage of strength - at least 60%, which will guarantee the preservation of the structure of the entire foundation and its optimal hardening after the thaw.

The poured mortar must gain its strength in winter, which will be sufficient for full or partial loading of a monolithic structure, as well as for stripping.

Below we provide a table with optimal data on the curing time of the concrete mixture and strength gain.

Important! Concrete can gain strength only if the solution temperature is positive.

During the concreting process, you must first protect the solution from freezing so that the hydration process proceeds normally, and the solution does not gain sufficient strength to ensure optimal ice resistance, and maintain the ability to harden at above-zero temperatures without deteriorating the main properties of the monolithic structure. When high conditions for dynamic characteristics and frost resistance are imposed on the foundation, the concrete should be protected from freezing until it gains sufficient grade strength. The percentage of optimal strength gain for a mortar will depend on the brand of cement used, additives, mixture temperature and other conditions.

Special Additives

If you do not have the opportunity to fully heat the concrete, then you need to use special antifreeze additives, which have a number of advantages:

Accelerate the hardening process;
Increase the duration of hardening of the mixture;
Understand the freezing point of water;
Allow concrete to gain sufficient strength at subzero temperatures.

Anti-frost additives allow the concrete not to freeze until the entire process of hydration of the mixture has taken place. Otherwise, the water will begin to tear apart, freezing the set part of the foundation. Typically, water will rise to the top layers of concrete (which may cause peeling if it thaws and freezes).

Hydration will only occur when water is in a liquid state, and the reaction rate at subzero temperatures decreases rapidly. For this, a frost-resistant additive is used, which also accelerates the hardening and setting process.

Depending on the ambient temperature, the method of pouring the monolithic structure, the requirements for the solution and the method of caring for hardening concrete, the amount and type of additives introduced into the finished mixture will depend.

Concrete heating

The second important factor, if it is impossible to pour concrete in winter without heating, for full concreting is heating the solution. Depending on external factors, air temperature, massiveness of the structure, you can heat the water for the solution or fillers - gravel, crushed stone, sand, etc. The optimal temperature for the solution when leaving the mixer should not be more than 40°C, otherwise the concrete will thicken almost instantly. The minimum temperature of the solution when pouring massive foundations is considered to be at least 5°C, and for pouring thin structures at least 20°C.

When the filling of the structure with mortar is completed, it is necessary to cover the entire foundation with a thick film or special insulation materials (foam plastic, sawdust, mineral wool, etc.). You can also additionally insulate the entire perimeter of the formwork.

In order for concrete to gain sufficient strength without heating, the following methods can be used:

You can burn a fire on the leeward side for 3-4 hours (this method is especially effective at negative temperatures down to -5-6°C).
As stated above, insulate the foundation using heat-insulating materials.

Conclusion and video

After winter, we carefully inspect the entire monolithic structure, picking or tapping in doubtful places. If defects, peeling, or insufficient complaints about the concrete mixture begin to appear, then it is necessary to contact the plant supplier of the solution and make claims about the quality of the concrete. Good luck!

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