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I don’t want to build in the winter, but there is such a situation that it is simply necessary! To knock down a change house from a tree and insulate it, or to sheathe a metal frame to equip a barn - the task is quite simple. But what to do if it comes to capital construction or those structures where concrete and other mixtures simply participate? All of them can freeze and lose in their previous characteristics, and therefore you can’t just mix the mortar and fill the foundation in a frank winter minus. At a minimum, it is necessary to use special additives that will make the composition harden in the cold and at the same time make it waterproof, durable, plastic for convenient work.
reveals some interesting secrets of professional builders who share their experiences and talk about winter construction.
Winter concrete with additives only
If you decide to build in the country in the winter, in concrete and dry mixes from which the solution is prepared, it is necessary to add special components that regulate the plasticity of the mass, its performance, limit freezing of water in the solution, which means that they retain their characteristics and do not allow joints, screeds and foundations crack.
Hardening the concrete mixture in frost is simply not possible. It freezes, turns into a solid layer of spoiled material, which will no longer give the specified characteristics, even if it becomes sunny and warm in a few days. It will be just a mass with clots and cracks.
There is a solution to warm concrete during pouring, for example, if it is a screed of a few centimeters, which, in theory, should dry quickly. Frost does not allow the mixture to solidify, but heating returns a positive temperature, and the layer gradually returns to normal. But there are some “buts”!
For example, an artificial change in temperature affects the characteristics of all the components of the mixture, humidity and other indicators, and therefore such concrete will not have the quality that it could show when cured under normal conditions. In addition, it is very difficult to heat the screed in the same garage or shed, because the heating must be uniform and stable. So, you need a few heaters, which can also hit your pocket, because they can show considerable electricity bills.
It remains to use antifreeze additives that do not allow the mixture to freeze, and that little by little is gaining strength even in conditions of freezing temperature.
These substances work simply - they do not allow the water in the solution to freeze, which means that the general poured concrete block, screed or foundation will not “tear” with frost. Moreover, in the cold, all chemical reactions that occur in the concrete mixture during the solidification period are significantly slowed down. This is the reason that nothing good will come of ordinary concrete in winter.
What are anti-frost components? Often, these are certain combinations of the following substances - carbon dioxide, soda ash, sodium chloride, ammonium hydroxide, sodium nitrite, ammonium nitrate, sodium nitrate, calcium chloride and others.
There are additives with which you can work even at -35 ° C, and at the same time the concrete turns out to be of high quality. But be sure to remember that the whole mixture is kneaded strictly according to the instructions, because in no case should you deviate from its requirements.
Plasticizers for concrete
A very thick composition does not fit well into the formwork, it does not have the necessary plasticity and does not go into hard-to-reach places. Very often, the task of pouring is complicated by reinforcement, especially very thick, where the material does not fall at all, leaving voids that negatively affect strength.
It would be possible to add water to the concrete mixture to make it more liquid. But this cannot be done, because then the brand of the composition for water resistance and frost resistance is reduced, the solution itself loses in quality. Moreover, this can not be done in the winter, when frost can seriously ruin the concrete.
Therefore, today, as, in principle, and many years ago, plasticizers are used to increase the ductility of concrete.
On private construction sites in the Soviet Union, ordinary soap, laundry detergents, and also lime and clay were often used. But today there are special additives on the market that increase the ductility of concrete. They work on the principle of facilitating the sliding of particles of the concrete mixture, that is, they reduce the internal friction of the mass.
Plasticizers are often used both in summer cottage construction and in the winter, it is only necessary that the formulation of the preparation meet the requirements as much as possible.
Similar substances are also used for the preparation of winter concrete, so that in addition to plasticity, it also obtains the necessary strength, and sometimes with higher rates.
It should be understood that the introduction of certain additives into the concrete mixture, correcting its properties, can affect other properties and future characteristics. Therefore, often instead of one additive, several are added at once. Many parameters must be observed in order to prepare a high-quality composition in adverse conditions, including also the temperature of the mixture, the number of aggregates, the intensity of mixing, etc.
Reinforcing additives for concrete consist of different materials, but today the product based on silica fume is considered the most popular. For its preparation, special raw materials are processed at high temperatures, due to which the additive receives high chemical activity in water. Silica fume increases the strength of concrete and accelerates the setting process of the mixture.
We build a country house in winter
Improving the brand of concrete for water resistance and frost resistance
Concrete mixture is a popular construction material for many reasons. First of all, due to reliability and strength, durability and ease of use, the ability to create a wide variety of projects on the basis of the composition, as well as due to other qualities, among which there are high indicators of water resistance and frost resistance.
Improving these qualities, we increase the general characteristics of the material, making it absolutely hassle-free in subsequent maintenance and increasing the operating life.
It has long been known that a special finish or even waterproofing concrete does not always cope with the task, and it quickly deteriorates due to the effects of the same atmospheric phenomena. We definitely don’t need this in the country, because if we are building a house, a garage or even a small gazebo, we need the construction to last a very long time.
Therefore, it is advisable to use special additives that positively affect the quality and characteristics of concrete, especially when it comes to foundations and socles, where protection is most needed. They can also be attributed to the floors in the shower, on the site near the garage, where we often wash the car, in the pools, as well as in structures that are built on sites with a high level of groundwater.
To obtain the desired characteristics, bituminous substances, surfactants, as well as components with a maximum inclusion of sodium aluminate, are introduced into the composition. They work simply - fill the pores in the finished concrete.
We have already said that often not one but several additives are used at once, well, or several characteristics improve with a certain composition. So, to improve the quality of water resistance, you can use silicate glue, the same liquid glass, which increases the concrete grade in terms of frost resistance and water resistance, and also increases the setting speed of the mixture, future strength.
Often, such additives are very similar to frost-resistant, only the cooking formula differs, the percentage of additives in the composition.
Unreinforced concrete is improved by the addition of compositions based on calcium chloride, up to 2% by weight of cement. But there is one “but” - the corrosive effect of calcium chloride on the metal. Therefore, the additive is not used in reinforced concrete.
For reinforced structures, components are used whose main substances are sodium nitrite and potash. Most often used for the preparation of mixtures that go to monolithic joints and joints between precast concrete structures. These additives can provide setting and overall quality at fairly low temperatures: when using nitrite-sodium - up to -15 ° C, using potash - up to -25 ° C.
It is important to remember that potash-based additives lead to the fact that the concrete mix quickly loses in workability. Therefore, the use of additives should be immediately before work.
There are many other mixtures and additives that help builders in different periods of work. But today we paid attention to those who can help us with the construction of the cottage in bad weather.
You can always make the concrete composition harden in the cold, but not because the water just freezes in it, but correctly and consistently, so that the future design acquires the qualities necessary for construction. One has only to choose the right time for cottage undertakings, well, or use special materials and additional components that will ensure the convenience of work and the quality of the structure.