The erection of a building or structure in the winter is a time-consuming, but very real idea. However, it is important to take into account the peculiarities of construction in winter, when it is necessary to apply certain methods and methods to build a strong foundation. Of course, it is best to do construction in the period from April to October, however, emergencies can arise and the foundation is needed in winter.

This page provides information about the features of the arrangement of reinforced concrete foundations in the winter. We will consider the foundations suitable for construction in sub-zero temperatures, and the technological operations that accompany the process of their installation.

Only a professional approach and knowledge of laying technology will allow you to get a foundation that will not lose its qualities even in the most severe frosts and on frozen ground.

Features of building a foundation in winter

The installation of foundations in the winter is often resorted to not only because of forced necessity, but also in order to save on the cost of building materials and the services of workers, the price of which, out of season, is traditionally lower.

However, practice shows that it is extremely difficult to achieve savings here, the cost reduction is offset by the need to take additional measures to heat the foundation after concreting, the cost of which can reach up to 1 tr. rubles per day when using a heat gun.

Important: according to SNiP, the permissible minimum temperature for curing concrete mix is ​​+5 degrees, when lowered, the quality of the concrete structure deteriorates significantly after hardening.

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Difficulties in arranging the foundation in winter are associated with the following factors:

• Development of pits and trenches in frozen soil (feasible by attracting highly productive excavators);
• The need for heating the concreted structure (convection heating is used by means of a heat gun or electric heating of the reinforcement laid in the foundation).

The need for heating concrete after pouring the foundation is determined by the peculiarity of the flow of hydration, which occurs when the mixture gains strength. In the process of hydration, cement particles adhere to water and form compounds, the formation of which is impossible when the mixture is dehydrated due to the crystallization of the moisture contained in it.

When the mixture freezes, the hardening of concrete slows down significantly, and at strong sub-zero temperatures it stops completely. Freezing water crystallizes and increases its volume, due to the expansion of concrete, there is a decrease in the adhesion of the material with reinforcement, which is fraught with subsequent cracking and destruction of the foundation under heavy loads.

Important: foundation concreting in winter should be carried out using concrete with antifreeze additives that ensure the hydration process in sub-zero temperatures. However, even antifreeze compounds require heating of the structure after pouring.

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According to building codes, it is possible to allow concrete to cool to the temperature for which the additive is designed only after a certain intermediate strength has been gained:

• Antifreeze concrete M200 - 30% of the design;
• M300 - 25%;
• М500 - 20%.

Similar standards exist for concrete that does not contain antifreeze additives:

• M150 - 50%;
• M200 and M300 - 40%;
• M400 and M500 - 30%.

Important: if the structure after concreting will be subjected to cyclic freezing and thawing, it can be allowed to cool only after gaining 70% of the design strength, regardless of the class of the mixture.

Concrete, which has gained the required intermediate strength, after cooling, does not continue to harden, but goes into a preserved state. It will receive the final design strength only after 28-30 exposure at positive temperature. This means that if the work on raising the walls is also planned for the winter, it is necessary to heat the foundation for a month.

Foundations suitable for construction in winter

For construction in winter, an important step is the choice of the type of foundation, since not every variety is suitable for the condition of this time of year. Consider several options for construction and types of foundation.

Strip foundation in winter

The most popular with developers - strip foundation. However, there are a couple of nuances, given that this variety does not provide the desired result. So, for example, when laying the foundation in winter, it is necessary to perform a number of additional manipulations, and, accordingly, labor productivity increases, as a result, financial costs increase significantly. For laying a strip foundation, the so-called "wet operations" are characteristic, which is not always possible to perform, especially in cold weather. Therefore, if you use this type of foundation, then with the maximum number of finished structures made at the factory.

Important: only deep-laid strip foundations are allowed for arrangement in winter, the supporting sole of which falls below the freezing level of the soil. It is impossible to install a shallow-depth tape in winter, since such a structure is placed in a layer of frozen soil, which, when thawed, changes its volume, which leads to settlement and deformation of the foundation in spring.

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If, after pouring and heating the foundation, cracks have formed on the surface of the structure throughout the entire period of curing, they must be blown with compressed air and repaired using a home-made mixture of polymer glue and cement.

Foundation in winter based on concrete piles

The foundation based on concrete piles is another way of building in the winter. So, it is best to use bored piles, which are driven quite well into the wells with the help of a fender. However, before installation, a preparatory stage is necessary - drilling, and this is very difficult in frozen ground conditions.

The essence of the method is to develop wells in which reinforced concrete piles are installed. Modern drilling rigs, such as the BM-811, are capable of effectively drilling frozen ground. The cost of creating a well with a depth of 8-9 m in frozen soil, using this machine, is 10-15 minutes.

Important: driving reinforced concrete piles into frozen soil has low efficiency. To increase the efficiency of pile driving hammers in the process of arranging pile foundations in the winter period, the leader drilling technology is used.

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Screw piles in winter

The solution to the problem is the use of screw piles, which, thanks to their stability and unpretentiousness, are suitable even on soft ground.

A monolithic foundation is also suitable for winter construction, however, voids in the base and walls can cause serious freezing of the entire building and lead to the destruction of the surface.

The arrangement of a screw foundation in sub-zero temperatures differs from the summer installation of the foundation by the exceptionally greater laboriousness of screwing piles, for the implementation of which it is necessary to use mechanized equipment.

Tying screw supports with a grillage made of timber or rolled metal is not accompanied by a complication of the technology, it can be implemented within 2-3 working days.

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Related materials:

Advantages and disadvantages of building a foundation in winter

Before starting construction in the winter, it is worth finding out and comparing all the pros and cons of a future construction site, because the future of a building or structure depends on it. As for the advantages of building a foundation in winter:

• Substantial discounts on building materials;
• Regarding summer work, winter work is much cheaper;
• There is no threat of collapse of pits and washout due to rains;
• Equipment on the way to the site does not get stuck in liquid soil.

Foundation disadvantages in winter

• Special equipment is needed for digging a pit in frozen ground;
• Low productivity and a large number of additional work;
• The need for special strapping to protect against freezing;
• High risks of work stoppage due to severe weather conditions.

It might also be interesting:

Mandatory measures applied during construction in winter

In addition to choosing the type of foundation, it is necessary to comply with the construction technology. So, the whole process takes place with an artificial increase in the temperature of the mail, for digging a trench, excavation and drilling wells. For this, a special tent with a heating installation is installed.

Foundation pouring

Filling the foundation in this case does not differ from the standard procedure in the summer. However, there is one caveat:

• Before pouring the foundation, a reinforced frame with a heating element is inserted into it.
• Upon completion of the installation, a canopy with a heat gun is constructed above the foundation to regulate the temperature regime.
• After a few days, the canopy and cannon are dismantled, and the top layer of soil is sprinkled with a heat insulator to maintain the temperature of the heated base of the foundation.
• As a result, we get a full-fledged basis for the construction of a building in the winter.

When concreting the foundation in winter, the technology for preparing concrete changes. It is necessary to raise the initial temperature of the composition to 30-40 degrees by heating the constituent components. Water is heated in boilers to a temperature of 90 degrees. In industrial conditions, aggregate (crushed stone) is heated in steam drums to 40 degrees. Cement cannot be heated.

The mixing time of the mixture in the concrete mixer is increased by one and a half times.

When assembling the reinforcement cage, the reinforcement stored on the street must be heated to a positive temperature. Concreting itself is carried out at an accelerated pace, which does not allow setting and freezing of the laid layer of concrete before pouring the next batch.

Important: foundation heating can be implemented in two ways: by the "thermos" method and by contact electric heating.

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The "thermos" method provides for installation above the perimeter of the base of the tent and the use of a heat gun that heats the air inside the tent to the required temperature (minimum +5 degrees).

When using a heat gun with a power of 10 kW in a tent with an area of ​​100 square meters, the temperature increases by 8-10 degrees, in comparison with the street temperature. When working in frost over 15 degrees, guns with a capacity of 25-30 kW are used.

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The use of autonomous guns running on gas or diesel fuel entails significant financial costs. A device with a power of 30 kW consumes up to 70 liters. gas per day, which at current prices is equal to 1 thousand rubles per day. The cost of maintaining power generators connected to the home electrical network is significantly less.

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The method of contact electric heating consists in installing electrodes on the armoframe (placement step - 40 cm) or special cables, to which a welding generator is connected, supplying a voltage of 50-127 V (power is determined by thermal calculation). The average energy consumption for such heating is 70 kW per cubic meter of concrete. This method is used for heating massive slab foundations.

Order of foundation works

Perform any work at any time of the year at a high level. The staff of specialists and the fleet of special equipment allow us to cope with absolutely any job.

Our company "Installation of Piles" supplies and drives piles in the Moscow region -

In this article, we will discuss the topical issue of whether it is possible to pour concrete in frost and how to do it with the least damage to the quality of the final result. It is no secret that the use of cement-containing mortars in winter is practiced in industrial construction, since the construction of individual low-rise buildings can be mothballed until the warm season.

However, there are exceptions to this rule, and you have to pour concrete into the formwork at sub-zero temperatures. Let's consider how this can turn out and how to avoid such consequences.

In the photo - laying the foundation at sub-zero temperatures

Low temperatures are a negative factor in concreting

The instruction for the winter use of cement-containing mortars is significantly complicated by two features that negatively affect the setting and hardening rates of the material:

• slowing down the hydration of cement particles and, as a result, an increase in the length of time required for strength development;
• freezing of water in the composition of concrete, as a result of which the process of curing is stopped.

Let's try to figure out how many days after pouring concrete is afraid of frost and how the above factors affect the rate of curing.

Low temperatures in the range from 0 to +10 degrees inhibit the hydration of cement. That is, the cement particles are more slowly impregnated with water and the chemical reactions that are responsible for the intensity of strength development proceed more slowly. As a result, the material not only dries slowly, but even after complete drying, it has insufficient strength characteristics.

For example, under normal temperature conditions (+20°C), concrete gains at least 70% of the optimal strength indicators within a week. Similar strength indicators, at which it is possible to cut reinforced concrete with diamond wheels, at a temperature of +5 ° C, the material acquires within 4 weeks.

In the photo - the use of concrete with antifreeze additives

Temperature parameters are the catalyst for most different chemical processes and cement hydration is no exception. Therefore, in the process of manufacturing reinforced concrete products, various technologies for heating cement-containing mixtures are widely used.

For example, the previously mentioned 70% of the grade strength, at which it is possible to carry out diamond drilling of holes in concrete, the material gains within 12 hours at a temperature of 70 ° C and humidity over 80%.

While the temperature below 10 degrees Celsius slows down the curing process, the negative temperature completely stops these processes. Since the water in the composition of the solution partially or completely freezes out, the occurrence of chemical reactions becomes impossible.

In accordance with the technology of concreting, cement particles must be in contact with water during the entire period of curing. The average time required for this process to take place under normal climatic conditions is 28 days. But as already mentioned, a lack of heat can adversely affect the course of the process, and therefore a special approach will be required for construction in winter.

Features of working with cement mortars at low temperatures

Since we are considering winter concreting, we will agree that it takes place at sub-zero temperatures. Therefore, our main task is to prevent freezing of the water that is part of the solution.

Currently, there are several popular and effective ways to save water in cement mortars from crystallization.

Among these methods, we note:

• the use of antifreeze additives (PMD);
• application of electrical heating
• sealing the solution with polyethylene films and heaters;
• the use of temporary prefabricated shelters around the formwork with IR heaters or heat guns.

Let's talk about each of these methods in more detail.

Antifreeze additives (PMD) and their application

In the photo - antifreeze additives (PMD)

This method of ensuring optimal parameters for the hardening of the solution has become widespread. Almost all domestic specialized enterprises have mastered the production of winter concrete with PMD additives.

At the moment, several variants of winter-type solutions have been developed, differing from each other in the percentage of additives in relation to the volume of material used.

Among the advantages of the method, we note the following:

• Ease of use in the production of concrete with your own hands, since the additives are poured into the mixer simultaneously with other components;
• Complete safety, in comparison with the same electric heating;
• Affordable price of PMD, which has a positive effect on the cost of the finished object.

Important: The use of additives in individual construction has one significant drawback. To ensure optimal strength performance, PMD must be applied in strict accordance with laboratory studies, which most contractors prefer to turn a blind eye to.

Application of electrical heating

On large construction sites, before concrete is poured in frost, special electrical heating systems are equipped. For these purposes, powerful transformer equipment with a power of over 30 kW and a system of thermal cables are used.

The method has the following advantages:

• the possibility of effective heating throughout the entire thickness of the layer and, as a result, ensuring uniform setting of the mixture;
• the possibility of accelerated recruitment over large areas at temperatures up to -20 ° C;
• suitability of the method for combination with thermally insulated formwork.

Among the disadvantages, we note the high energy consumption and the high cost of concreting.

Sealing the solution with polyethylene films and insulation

Sealing and insulating the mixture with materials with low thermal conductivity today seems to be the most rational method of working with concrete at negative temperatures down to -3°C.

The process of hardening and drying of cement mortars is isothermal. In other words, when cement particles interact with water, a chemical reaction occurs and a certain amount of heat is released into the external environment. Thus, by covering the formwork and its contents with cellophane or peat-insulating material, this heat can be saved and used to ensure strength gain.

Of course, this method is not the best solution for severe frosts. But if necessary, the solution can be preheated, and after that it can be covered and then it can be built at a temperature of up to -10 ° C.

The use of heat guns and IR heaters

If the air temperature drops below -15°C, it is advisable to use more efficient heating methods instead of the previously listed methods. For example, during the construction of small facilities around structures made of monolithic concrete, temporary collapsible shelters are built, inside which heat guns are used.

In some cases, the formwork can be wrapped with thermomats with infrared heating function. This technique is quite effective, but expensive to implement.

Conclusion

So, we examined the features of concreting in winter and found out that sub-zero air temperature is not yet a reason to abandon construction. But if there is such an opportunity, it would be better to postpone the planned work for warmer days.

If you still have any questions that require exhaustive explanations, you will find the answers of interest by watching the video in this article.

The strength and durability of any building depends on the foundation that serves as its support. Currently, the most demanded in construction is a concrete base that can withstand the weight of a heavy building. Since after the construction of the house the supporting structure will be difficult to repair, it is very important to properly fill the foundation in order to prevent it from sinking into the ground, as well as the formation of cracks and other defects on it.

At what temperature can the foundation be poured

When planning the construction of a supporting structure, it is necessary to take into account weather conditions, the brand and quality of cement. An important role in ensuring the strength of concrete is played by special additives that make it possible to reduce the crystallization temperature of water, as well as to maintain an optimal operating mode during the period of foundation hardening. After pouring, the base sets within a day and then gains strength in 28 days. The temperature range from + 3 to + 25 ° C is considered standard for creating a base. It is known that the warmer it is outside, the faster the mortar dries, but the heat can be dangerous for fresh concrete.

If at a temperature of + 5 to 15 ° C the composition seizes naturally, giving off heat to the environment, then this does not happen in too hot weather. Under such conditions, the concrete frame may begin to form when the volume of material is further increased. Cooling down, the surface begins to settle, and the already formed crystalline structure prevents this process. As a result, due to internal stress, the foundation may become covered with shrinkage cracks 4–12 hours after pouring. So that the base does not crumble at temperatures above + 25 ° C, it is worth using quick-hardening Portland cement, which after 5–6 hours of pouring must be poured with water and shaded with old rags, cardboard or sawdust. To slow down hydration, it is permissible to introduce modifying additives and plasticizers. If cracks appear, re-tamping is required.

In hot weather, the foundation may crack

Is it possible to pour the foundation in winter

The most favorable time for the construction of the supporting structure is the period from April to November. However, the situation may turn out so that the filling will need to be carried out in the winter, because in some regions of Russia there is practically no summer. Modern building technologies make it possible to create solid foundations even in cold weather. The construction of the foundation in winter is especially important on shaky soils. After waiting for them to freeze, you can dig an excellent pit. In addition, you can save a certain amount on the purchase of building materials out of season. Most often, strip foundations are erected in winter using concrete blocks and concrete pile structures designed for lightweight wooden objects.

According to various estimates, over the past five years, the share of winter concreting in the total volume of construction ranges from 10 to 17%. This is a solid jackpot for manufacturers and suppliers of construction chemicals, and, in particular, those additives that must ensure the efficiency of the process at low temperatures. On the other hand, it was manufacturers who influenced the growth of winter construction. The interest here is mutual.

How cement mortar behaves in frost

When planning winter work, it is worth remembering that ordinary concrete is not suitable for them. In frost, it is permissible to use only cement with special additives and modifying additives. The latter reduce water consumption by about 10-15%. At air humidity of 60% and above, the use of modifiers is not recommended, besides, it is worth remembering that they can react with some metals. To ensure the strength of the structure, concrete must be heated in the first two days after pouring. The desired temperature regime of the mixture can be maintained using:

• thermal guns;
• special heating wire laid when pouring concrete;
• electrodes (reinforcing bars) to which voltage is applied.

There is also a method of heating the concrete mixture using a welding machine, but it essentially boils down to the use of electrodes and is applicable only for small volumes of pouring.

Only water and fillers are allowed to be heated, but not cement, otherwise it will lose its qualities.

For winter work, concrete with special additives is required.

Typically, in the regions of the Russian Federation, a solution with a temperature above 21 ºC is not used, taking into account the fact that 4.5–5 ºC will go into the atmosphere. Therefore, for the working composition, the liquid is heated to 32 ºC. Hotter water is first mixed with fillers, and then in portions with cement.

Is it possible to pour concrete in frost without heating

Whether it is possible to pour the foundation in cold weather without heating should be discussed separately. Even temperature fluctuations from +5 to 0 ° C for concrete mortar are considered winter. In the cold season, when concreting, it is important to ensure smooth hardening of the mortar by at least 60%. This guarantees the preservation of the structure of the base and its ripening when the thaw comes.

However, the foundation will gain strength only at a positive temperature of the solution, therefore, without artificial heating for construction work, you need to choose a fine winter day. Of no small importance is the composition of cement: the so-called cold concrete includes antifreeze additives that lower the freezing point of water. For these purposes, potassium and sodium chlorides are used in concentrations from 2 to 15%. Using anti-frost modifiers, it is possible to dismantle formwork with M200 mortar already at 40% strength, M400 - at 20% and M300 - at 30%.

Video: heating concrete foundation in winter

When can you pour the foundation in the spring

Those who decide to start building the foundation in early spring (until April) should be careful. First you need to wait for the thawing of the soil and heat, when at night the temperature does not drop below 0 ° C. It is also necessary to take into account the "drying" of roads, which lasts one to two months, during which heavy vehicles (concrete pumps, scows, toners and other vehicles) are restricted from moving on regional roads. Without the listed transport, it is impossible to build a monolithic foundation. Since April, the cost of consumables begins to rise.

In the spring, the roads are washed out, so heavy vehicles cannot pass through them.

Unexpected frosts can cause irreparable damage to the structure, so when the weather forecast is unstable and work is already planned, it is recommended to insure the purchase of antifreeze fillers. Even at an air temperature of +23 °C, concrete gains its normative strength only after three weeks. At lower temperatures, the terms increase markedly, as a result, it is impossible to hurry with laying the walls after pouring.

As practice shows, a house built on bare ground costs a few years. In the absence of a base, the lower blocks or wooden crowns collapse due to soil deformation.

Is it possible to pour the foundation in the rain

At present, rain is not a reason to stop concreting, as it was in the recent past. Using simple equipment and a suitable brand of cement, you can pour the foundation in wet weather. By itself, water does not have a negative effect on the solution, just before it hardens, erosion and imbalance can occur. Therefore, everything depends on the strength of the precipitation.

If the site is not flooded with rain, then a canopy will be enough to continue work. An ordinary polyethylene film will protect from light rain, which must be used with caution, because concrete hardens only in fresh air. Of course, in warm and sunny weather, the solution is better saturated with carbon dioxide and hardens faster, forming a solid base. But building foundations in the rain also has its advantages, since the concrete mixture becomes stronger at 80% humidity.

Polyethylene film cannot be kept on the surface for a long time, since the concrete does not harden without fresh air

How to work during the rain

The main requirements for the ongoing work on pouring the foundation in the rain:

1. The content in the solution of cements M400, M500 and M600, created for work in contact with moisture.
2. The right way to lay concrete. The unusual shape of the base or its deepening involves the use of special equipment that does not allow the formation of voids and displaces excess liquid.
3. The use of waterproofing, which can be removed no earlier than two to three days.

The modern market offers a wide range of building mixtures with various parameters. Fast-hardening and long-hardening compositions are produced, as well as concrete with antifreeze additives. But pouring a foundation in extreme weather is a risk that must always be considered. At low temperatures, cracks can form in the base, and erosion can occur during precipitation. All this can adversely affect the strength of structures.

Building a foundation in winter is a rather laborious and troublesome business, but feasible. It is believed that the time from April to November is the most favorable period for the installation of the base of any structure. But there are situations when work falls on the winter. Thanks to modern building technologies, it is possible to build a reliable foundation that will not be inferior in its characteristics to the foundation laid in the warm season. From this article you can find out what foundation pouring is in winter, whether it is possible to fill it and how to make such a foundation.

When is winter pouring necessary?

With careful observance of all the rules of construction, the construction of a strong foundation is quite feasible even in severe frosts and, as a result, frozen soil. Pouring the foundation in winter is not always required, it all depends on the project. Most often, the decision to start construction in the cold period is associated with the characteristics of the soil. There are areas where the soil crumbles in summer, and only in winter, when the ground is well frozen, can a good foundation pit be dug. In this case, it is an excellent solution in the implementation of the task. In many regions of Russia, winter is the main season, and summer is practically non-existent. Therefore, for the construction of the foundation of another period simply does not happen. In addition, it is believed that the cost of material and labor in winter is much lower than in the summer months, although serious savings are unlikely to be expected. Sometimes pouring the foundation in winter is necessary when you need to complete the construction process as quickly as possible.

in winter time

For arranging the foundation of any structure in the winter, there are several types of foundations. Let's consider them in more detail:

1. The most common among developers is a strip foundation. In this case, experts advise to reduce the so-called "wet" operations, for example, use ready-to-lay them in the pit.

2. Foundation of concrete piles. This type of foundation is ideal for light structures, in particular wooden houses. By observing the construction technology and adhering to the basic rules, you can get a solid pile foundation that is not inferior in quality to other types. Further from the article you can learn everything about pouring the foundation in the winter.

How to fill the foundation with piles? First of all, you need to distinguish between their types. Concrete piles are bored and bored. Screw pile foundations are ideal for winter work. Suitable for any difficult soil.

Concrete preparation

When arranging the foundation, the question often arises: "Is it possible to pour the foundation in winter using ordinary concrete?" No you can not. For these purposes, the one that includes special modifiers is suitable. Thanks to additives, concrete has time to gain the necessary qualities, it does not set ahead of time. In addition, modifying additives make it much easier to pour concrete mortar into the formwork.

When choosing modifiers, attention should be paid to the frost resistance indicators and the rate of concrete hardening. The required amount of the substance is determined by the scale indicated on the package.

How to apply modifiers?

When using modified additives, it is necessary to focus on some key points:

The use of frost-resistant substances can reduce the amount of water consumed by 10-15% in the manufacture of concrete mortar.

The minimum temperature at which the use of modifiers is acceptable is 25 degrees below zero.

When air humidity reaches 60%, the use of additives is prohibited.

It is necessary to take into account such factors in which the individual components of the modifiers interact with certain metals.

The use of additives does not cancel some additional measures when arranging the foundation during the cold period. When the air temperature is low, additives alone that affect the frost resistance of concrete are not enough. It is necessary to warm up the concrete, equip additional thermal insulation to maintain a certain temperature of the finished structure.

The use of additional tools that make it possible to fill the foundation in winter

Another way in which the answer to the question of whether it is possible to fill the foundation in winter will be positive is to ensure that the base is warmed up. It is known that concrete gains its highest strength during the first two days. It is during this period that the foundation especially needs protection from low temperatures. To heat the base around the entire perimeter, special equipment is used - a thermal gun. With its help, the temperature necessary for the solidification of the concrete solution is provided and maintained. The larger the foundation, the higher the power of the device should be.

You can also heat the foundation with electronic current. This method allows you to maintain the temperature necessary for solidification by transferring heat (from hot to cool). Concrete is heated by reinforcement rods, to which an electric current (380 V) is connected.

Negative moments of pouring the foundation in winter

So, the answer to the question "is it possible to fill the foundation in winter" is obvious. However, despite the many positive arguments in favor of this process, there are some negative points:

Although the savings in the cost of building materials are evident, at the same time, the price of earthworks in frosty weather increases greatly. Also, you will incur additional expenses for heating the concrete solution, structures, so in general, saving construction in winter is very doubtful.

Work efficiency in winter is much lower than in summer, as it is much more difficult to work in cold weather.

The price of additives and modifying substances that affect the properties of concrete is low, but for the construction of even a small foundation area, a lot of them are required. And so the price of building material increases significantly.

Sometimes it is necessary to use special equipment, in particular for digging a pit.

Therefore, before thinking about whether it is possible to pour the foundation in winter, it is necessary to calculate all the costs and consider all the pros and cons of this undertaking.

List of basic materials and tools for creating a foundation

The following materials and tools are required for arranging and pouring the foundation:

• shovel;
• sawdust;
• building level;
• hacksaw;
• Master OK;
• cement and concrete solutions;
• modifying additives;
• thermal insulation;
• reinforcing mesh;
• rubble.

How to fill the foundation in winter?

Is it possible or worth it to do so? These questions often bother beginners in construction. After all, it is very difficult to carry out any work in the cold, snow and frost can interfere. The advice of experts will tell you how to properly fill the foundation in winter with your own hands. The work rules are:

First of all, a trench or pit is dug, while the ground moisture, which will be collected at the bottom, is controlled. Water freezes at sub-zero temperatures, ice forms, which must be removed, since nothing can be placed on such a base.

The next step is the installation of formwork and reinforcement frame. The formwork is poured with concrete mix. The necessary positive temperature must be maintained for a certain period of time (to accelerate the setting process) using heating equipment. Immediately after pouring, the foundation can be insulated with roofing material, plastic wrap. From above, you can sprinkle with a layer of sawdust (20-30 cm). As a result, we have a finished foundation in winter.

Is it possible to flood for the winter? The answer is yes. But it is still recommended to build walls on such foundations at positive temperatures, since the concrete mortar needs a certain time to acquire strength. Having prepared the foundation in winter (taking into account all the rules and nuances), you can get a strong and durable structure.

Traditionally, the construction of a house has always been considered a “summer” event, and among private developers, few even thought of starting active work in the winter. However, it so happened that Russian winters are quite long, and in some regions the cold season generally reaches 6 ÷ 8 months. And if you exclude them from the process of building a building, then building a house can take several years. To speed up this process, special technologies have been developed and special materials have been produced that allow concrete work to start or not stop even in the winter cold.

However, in order for the foundation of the structure to turn out to be reliable and monolithic, you need to very accurately imagine how it is right in winter. Knowing all the nuances of this rather complicated process and following all the technological recommendations, you can start working at low temperatures so as not to waste winter time in vain. Often, starting construction during this period, by the fall, the owners expect to move into a ready-made new house.

In addition to the need to speed up the construction of the house, the need to pour the foundation in winter can also be due to specific reasons. For example, such measures are also resorted to due to the fact that the soil in the area is characterized by increased flowability, so it will be much more convenient to work with it when it is in a frozen state.

When constructing the foundation, it must be remembered that it is not recommended to install a columnar structure in winter, since small volumes of concrete, when solidified, are incapable of any kind of heat retention, they quickly cool down with a violation of the processes of hardening and maturation of the solution. That is why, if the foundation is poured at sub-zero temperatures, you need to choose a monolithic or tape version.

Start off foundation work for building a house necessary from the preparatory work, which in winter is usually characterized by increased labor intensity.

Preparatory work

• The place where it is planned to build a building must be cleared not only of snow, but also of the surface layer of soil.
• Further, a general marking of the cleaned area is carried out - this is done by installing pegs on which a marking cord is pulled - it will visually indicate the external dimensions of the future foundation.

The next step is marking the width of the required trench - also with the installation of pegs and pulling the rope. To make it convenient to dig a foundation pit for the foundation, its inner boundary is outlined along a stretched rope, and an even strip is hollowed out in the ground using a perforator or a pneumatic jackhammer - it will mark the edge of the foundation.

• Next, a trench is dug, which should have a depth of at least 500 ÷ 750 mm. Depth is usually calculated depending on the type of soil.

If the soil does not lend itself to a shovel, then it should be gradually crushed with a perforator or pickaxe. In this case, the earth is removed from the pit in layers.

• When the trenches are completely dug, they are prepared for pouring concrete. To do this, sand is backfilled at the bottom - it must be dry, so you need to choose material that was stored indoors or at least under a roof. The sand cushion will be an excellent waterproofing layer for a strong foundation if it is well compacted. After compaction, the layer thickness should be 80 ÷ 100 mm.

A layer of crushed stone of the same thickness is poured onto the sand cushion and is also carefully compacted.

• Further, from the bottom of the trench and to the height of the future foundation, it is built from the boards. If even high-quality boards are used for it, which are tightly fitted to each other during assembly, then additional insulating materials, it seems, are not required.

Formwork for the "winter" foundation with a reinforcing belt

If gaps have formed between the boards, and there is a risk of mortar seeping through them, then it is best before installing the reinforcing structure waterproof formwork with polyethylene film, at least 200 microns thick.

Good advice is to use such an insulating layer in all cases. It will maintain the correct water balance in the concrete solution (water will not flow out or be absorbed into the formwork material), and the maturation of the concrete will proceed more evenly and efficiently.

Another option for waterproofing the formwork can be the use of a conventional inexpensive roofing material.

• It can be separately noted that for "winter" foundations, fixed formwork is often used, which will simultaneously be a heater for the poured mortar and will not allow it to quickly harden. The hardening process will take place gradually, which is very important for the strength of concrete.

Modern convenient solution - fixed formwork made of hollow polystyrene foam blocks

• Further, a structure of reinforcing bars is mounted in the prepared formwork, which are interconnected by welding or wire twisting. For this design, metal rods with a diameter of 8 to 15 mm are suitable - this parameter will depend on the width of the foundation and the planned design load on it.

After all the preparatory processes have been carried out, you can begin to calculate the consistency and component composition of the solution. These parameters are selected depending on the approximate temperature at which concrete work will be carried out.

Pouring concrete

When preparing, it is necessary to take into account such factors as the brand of the solution, the temperature outside, the quality of the material, special additives that can delay the crystallization of water at low temperatures. Without taking into account all these nuances, the solution after solidification will not be as strong and durable as planned, as it will quickly begin to crumble. In this case, the work will have to be completely redone, because such a foundation simply cannot withstand the load from the walls.

• To mitigate the effect of low temperatures, after the formwork is installed, before concrete is poured into it, a temporary tent is erected over the structure. Its frame can be put together from boards and timber - the base must be rigidly installed and have a height higher than human height, since the builder will have to work under it. You can use for a temporary frame and metal parts - profiles and fittings.

Outside, the structure is tightened with reinforced polyethylene film, which has sufficient strength to withstand the wind load and the severity of the snow cover. The roof of the tent should have a steep enough slope so that precipitation does not linger on it, otherwise even the reinforced film can tear, and the presence of an awning simply loses its meaning.

Film sheetscovering the foundation must be securely fastened together, and even better - purchase or rent a ready-made specialized awning, which you just need to install over the structure.

Such a temporary tent will allow you to maintain the necessary temperature conditions for the gradual solidification of the solution without the risk of freezing, that is, the tent will become a kind of greenhouse that will retain heated air. In severe frosts, under such a shelter, you can turn on heating devices, for example, heat guns.

Temperature maintenance can be ensured by installing an electric or gas "heat gun"

For pouring, it is necessary to create a temperature in the tent of at least 5 ° WITH, for concreting without the use of antifreeze additives, it is critical. Lower temperatures will lead to crystallization and destructive processes.

But even at a critical temperature, the setting of concrete and its hardening will take much longer, therefore, if it is possible to transfer the pouring of the foundation to warmer days, then this is recommended. By the way, if we analyze the table with the maturation of concrete under different temperature conditions, we can see that the gain in time in some cases will turn out to be very insignificant.

• When pouring the foundation in winter, it is recommended to use cemenTTfine grinding, which releases more heat when reacting with water and additives than normal. For mixing, it is best to use water heated to 40 ÷ 80 degrees.

When kneading the solution in hot water, it is first mixed with additives, and then introduced into the cement in parts and mixed thoroughly. as an increase in the preparation time of the solution helps to maintain the desired temperature in the solution for a longer period. The homogeneous mass of the solution better fills the entire space of the formwork, as its fluidity increases.

In a thin, well-mixed concrete solution, medium or small crushed stone is often added, which will add rigidity to it, which is necessary for the foundation.

In addition to crushed stone and additives for frost resistance of concrete, plasticizers are often added to it, they contribute to the strength and moisture resistance of concrete, as well as its adhesion to reinforcing structures. Thanks to plasticizers, it is possible to reduce the consumption of cement mortar by 25%.

• Another way to keep the foundation warm is to run a 12 volt electrical cable to it. It will heat the reinforcement bars, which in turn will give heat to the solution, preventing it from freezing. Significant disadvantages of this method of heating are the complexity and cumbersome preparatory work, the need for special equipment, uneconomical use of electricity, and hence very significant cash costs.

• You can hear a lot of different opinions about the benefits of special anti-frost additives in concrete mortar, they say, they make it possible to pour the foundation in conditions of negative temperatures without any other measures for temporary insulation of the structure. Is this true, and what are antifreeze additives in concrete?

Will antifreeze additives solve the whole depth of the issue? Unfortunately no …

These are special chemical compositions that solve two main problems. Firstly, they increase the density of the aqueous base of the solution, which means that they sharply lower its freezing point. Secondly, they contribute to a kind of catalysis of the concrete maturation process by more actively involving air oxygen molecules in the reaction precisely at low or even negative temperatures.

In construction practice, sodium nitrite or formate, potash, calcium hydrochloride, lignosulfonate are usually used to prepare "winter" solutions. Such reagents can be purchased in specialized stores, but here you can prepare high-quality concrete yourself, without special equipment, without special methods of calculation and correct dosage - it is extremely difficult, if not more categorical. The wrong component ratio can completely spoil the concrete, which even in the most optimal solidification conditions will turn out brittle, crumbling, loose, etc. In addition, it must be borne in mind that the use of special additives can have a “detrimental” effect on the condition of the reinforcement - not every metal is suitable for these purposes.

Another consideration that does not speak in favor of antifreeze additives. Yes, they allow certain technological processes to be carried out at negative temperatures. However, this does not mean at all the acceleration of the construction work. Take a look at the table - it shows the approximate time for concrete to gain grade strength at low temperatures using antifreeze additives:

Type of antifreeze additive	average temperature during ripening	1 Week	2 weeks	4 weeks	3 months
sodium nitrite	-5°C	30%	50%	70%	90%
	-10°C	20%	35%	55%	70%
	-15°C	10%	25%	35%	50%
Potash	-5°C	50%	65%	85%	100%
	-10°C	30%	50%	70%	90%
	-15°C	25%	40%	60%	80%
	-20°C	23%	35%	55%	70%
	-25°C	20%	30%	50%	60%

Conclusion: even with a relatively slight frost - about -5 ° WITH, and with the use of anti-frost additives, it is possible to talk about the readiness of the foundation to continue any further construction work only after 3 months. So does it make sense in the conditions of private construction to rely on such technology, if there is practically no gain in time, and the quality of the solution can significantly decrease? What is profitable and justified in large-scale industrial construction with its laws of planning and logistics, in the conditions of a private small construction site, can turn into a completely unjustified, unnecessary waste of effort and money.

Prices for various types of antifreeze additives in concrete

Antifreeze additive in concrete

Video: pouring a strip foundation in winter

So, let's go back a little, to the expediency of winter pouring the foundation. It is usually performed in the following situations:

• The construction must be completed within a strictly defined time frame, without the possibility of their transfer.
• The climatic conditions of the area where the construction is being carried out are unsuitable for this process in the usual summer period.
• Loose soil extremely complicates the construction of the foundation in the summer, and it can only be built in solid, frozen soil, which is able to maintain the desired shape of the trench for a long time.
• Cost savings, since in winter the prices for building materials are much lower.
• Construction companies reduce prices for their services in the winter, due to the lack of a large number of applications for work.

Before starting work, it’s worth weighing everything very well - wouldn’t it be more profitable to postpone the start of pouring to spring?

But, despite the above arguments for saving on materials, building a foundation in winter will always cost more than at positive temperatures, since large amounts of electricity will be needed for heating. Therefore, when planning these events, you first need to carefully calculate everything and choose the option that will not only help save personal money, but also allow you to create comfortable working conditions.

If, nevertheless, it is decided to pour the foundation in the winter, then you need to know some of the nuances of this process that will help to make a high-quality foundation for the future building:

• The materials used in the preparation of the solution must be of high quality. It is unacceptable that the components are frozen, with inclusions of snow or ice. Therefore, it is worth purchasing components for the solution, which were stored only in the right conditions and at positive temperatures.

And even better - do not mess with the independent preparation of "winter" concrete, acquiring a ready-made solution balanced for specific conditions of use from local manufacturers.

• The solution is poured at a time and, if possible, as quickly as possible so that negative temperatures do not have time to affect the ingredients of the solution.

This - more one argument to the fact that it is impossible to prepare and pour a large amount of solution on your own one time - it is better to use offers from firms that produce, deliver and pour concrete into the formwork. On your own, you will only need to quickly distribute the solution over it.

It is almost impossible to independently prepare a solution for the "winter" pouring of the foundation, since it is necessary to quickly and uniformly fill the entire volume of the formwork

• It is impossible to fill the solution in layers, since gaps can form between them, into which moisture will penetrate, and at low temperatures it will turn into ice that can destroy the hardened concrete.

Concrete curing processes

Concrete poured and distributed over the formwork goes through two stages until it is completely readiness - grasping and hardening.

• The first stage takes place within 20 ÷ 30 hours. At this time, the concrete becomes denser, but not strong enough for further work.
• The second stage is the hardening and the beginning of concrete hardening, since the latter lasts for quite a long time. The hardening period depends on temperature, humidity, quantity and quality of additives, as well as the brand of concrete solution.

The most favorable temperature for pouring and solidifying concrete is the range from + 15 to + 25 degrees, and the closer it is to the highest point in this “corridor”, the faster solidification and hardening will be. It is clear that creating such conditions in winter is simply unrealistic.

Predetermines its strength 27 ÷30 days after its pouring, if the work was carried out under optimal temperature and humidity conditions. The higher the brand of mortar, the faster the foundation will be ready.

The rate of solidification and maturation of the solution directly depends on the temperature at which these processes take place. If the temperature value changes, then processes slow down or accelerate along with it. Hardening of the finished foundation is faster if the temperature that is optimal for this process is maintained in the poured mass with the help of heating.

It should also be taken into account that if the temperature in concrete drops below + 4 ÷ 5 degrees, then the maturation processes slow down almost to a minimum, freeze, and can only continue again when external conditions normalize. However, such jumps have an extremely negative effect on the structure of the created concrete structures.

At negative temperatures, the hardening of concrete completely stops, since it is mixed with water, and it crystallizes. When positive temperatures return, the concrete thaws, and hardening may continue, but there will no longer be an optimal bundle of materials and the required strength of the foundation.

Only after the concrete has completely hardened in the foundation structure, it will not be afraid of any frost.

For greater clarity, there is another table that shows how temperature conditions affect the maturation of concrete structures. You can roughly estimate the timing of the work in order to draw a preliminary conclusion - does it make sense to start with the winter laying of the foundation.

hardening time of concrete, days	-3°C	0°C	+5° С	+10° С	+20° С	+30° С
1	3%	5%	9%	12%	23%	35%
2	6%	12%	19%	25%	40%	55%٭
3	8%	18%	27%	37%	50%٭	65%
5	12%	28%	38%	50%٭	65%	80%٭٭
7	15%	35%	48%٭	58%	75%٭٭	90%
14	20%	50%٭	62%	72%٭٭	90%	100%
28	25%	65%	77%٭٭	85%	100%	-

A few notes on the table:

• The percentages are calculated based on the considerations of the reference grade strength for concrete mortar M200 - M300 made from Portland cement M-400 or M-500 without the use of additives.
• Values ​​with one asterisk (٭) are the conditional terms for the possible stripping of the poured foundation without the risk of deformation of the structure.
• Values ​​with two asterisks (٭٭) are possible dates for resuming safe construction work on a poured foundation.

cement prices

Video: an example of pouring a foundation in winter

Having learned all the nuances of pouring concrete in the winter, we can come to the conclusion that the best option would still be to carry out this technological process at favorable temperatures. If this needs to be done at this particular time, then it is better to entrust this stage to professional builders who have experience of similar works and the corresponding special equipment. Self-activity in such a matter can be extremely destructive - a huge amount of amateurishly done work can be simply spoiled.