Methods of winter concreting (winter concrete): methods of heating structures, additives pmd

Construction projects face special difficulties during the winter, particularly when working with concrete. Concrete may have trouble curing properly in colder temperatures, which could compromise its strength and durability. To address this, a number of techniques have been developed to guarantee that concrete sets and functions properly even in cold weather.

Using heating methods to keep concrete curing temperatures at ideal levels is one practical strategy. In order to do this, heated forms, heated enclosures, and insulated blankets may be used to keep the concrete warm while it sets. By maintaining the chemical reactions required for proper concrete hardening, these techniques help to guard against frost damage and maintain structural integrity.

Adding winter admixtures—a class of additives—to the concrete mixture is another important tactic. These chemical substances work to lower the freezing point of the mixture and quicken the curing process, which helps the concrete solidify more quickly and withstand cold weather. Air-entraining agents, calcium chloride, and non-chloride accelerators are common winter additions that have particular advantages for concrete during cold weather.

Construction projects can proceed without interruption during the winter months by combining these two strategies: appropriate heating techniques and the application of winter additives. Builders can guarantee that their concrete structures are robust and long-lasting, no matter the season, by comprehending and implementing these techniques. As with any other time of year, winter concreting can be as dependable and efficient with proper planning and execution.

Features of winter concreting

The concrete mortar that is poured during the winter is complicated by the following factors:

1. At low temperatures, the hydration of cement begins to slow down, so the period of concrete strength gain increases.
2. The pressure in concrete begins to increase due to frozen expanding water, which eventually causes it to weaken.

The solution’s interconnected components are disrupted by the resulting ice crusts. The precise age of the concrete and the amount of water that has frozen determine how much its strength has decreased. The time when the freshly poured mixture is setting is the riskiest since strength develops as a result of its freezing. Cement hydration resumes as the temperature rises. Nevertheless, unfrozen mortar has a substantially higher strength than concrete.

Superior winter concrete that has reached a certain strength can survive the structure being destroyed. The finished mixture must be laid continuously to avoid the formation of cold joints, which is crucial.

The preservation of concrete from freezing during the setting process and the attainment of critical strength—50% of the reinforced grade—have made this the most widely used concrete construction technique in Moscow. Nearly 70% of the design strength of concrete is protected from freezing during construction in more significant structures.

• introduction of developed anti-freeze additives or chemicals into the composition;
• careful covering of the mixture with insulation;
• various types of heating of the concrete surface.

Use of anti-freeze additives

The most practical method available today for protecting concrete during the winter is to use specially designed anti-freeze additives. In comparison to concreting, which necessitates careful insulation of the structure, including heating with electricity or infrared rays, the method is thought to be less expensive. These unique additives can be used on their own or in conjunction with other heating techniques.

1. Additives for accelerating or slowing down the setting of the mixture. For example, these are electrolytes, non-electrolytes and urea, as well as polyhydric alcohols.
2. Modifiers created from calcium chloride and significantly accelerating the setting time of concrete.
3. Substances with antifreeze properties that accelerate the setting of the solution with increased heat release after pouring. These are trivalent sulfates created from aluminum and added iron.

The question of whether concrete can be salted in the winter is one that interests a lot of builders. Technical salt is the most widely available and reasonably priced antifreeze additive that keeps concrete work going in cold weather because it doesn’t erode cement.

Measures increasing the efficiency of using antifreeze additives pmd

Concrete must set and harden more quickly with developed antifreeze additives. Additionally, a number of the following crucial actions are taken in order to achieve a normal outcome:

1. Creation of areas of heat inside the concrete solution by heating its main components.
2. Insulation of the concrete surface for the necessary heat conservation generated during the isothermal reaction of cement with added water.
3. Use of high-grade hardening cements.
4. Making a mixture from preheated components requires a different order of the loading process in contrast to summer conditions and simultaneous loading of materials into the mixer drum. For example, in winter, hot water must be poured into the drum, then the selected filler is added, the cement mixture and sand are introduced.
5. The mixture is transported in a special insulated vehicle with a double bottom. The loading and unloading point is protected from the wind. Concrete must be poured using devices that must be insulated.
6. Snow and ice must be cleared from the formwork, the reinforcement must also be cleaned.
7. Winter concreting is carried out at a fast pace.

Advice: Avoid using any frozen fillers when concreting during the winter.

Freezing of water

The freezing time of the water is an important consideration when laying concrete mortar because it affects the structure’s strength. For this reason, when concrete freezes too soon, it will become brittle. Furthermore, the solution’s setting time is thought to be the most important.

The technology used for winter concrete indicates that the strength of the frost will have an impact on the concrete’s strength when it freezes nearly instantly after being placed in the formwork. Hydration will persist as the air temperature rises. However, compared to a comparable structure whose mixture did not freeze during laying, the structure will be weaker. However, if the concrete was strong enough to solidify before freezing, it will be able to freeze again without losing its structure or developing flaws. Continuous application of the mixture can help prevent cold joints.

The "thermos" method

The "thermos" method’s technology involves filling a formwork that is well-insulated with a mixture of normal temperature. Heat is released during the cement hydration reaction, which gives concrete its strength. Using high-grade cements releases a lot of heat during operation.

When antifreeze additives and other substances are added, the effectiveness of the "thermos" increases.

The process of using a "hot thermos" for wintertime concrete involves heating the mixture to between 60 and 80 °C. Special electrodes are used on the construction site to gradually heat the concrete mixture. Here, it’s a resistance in the circuit that’s using alternating current. Electric heating is done with dedicated buckets.

Methods of artificial heating and heating of concrete

The prepared mixture must be kept at a high temperature for normal concrete strength. When the "thermos" method is not sufficient, this method is employed.

1. Electrode heating of concrete, leading to current exchange and effective heating of the structure.
2. Contact heating using a conductor.
3. Infrared heating using emitters.
4. Induction heating using a special inductor coil.

Heating and heating concrete using electricity and infrared radiation

This method’s main idea is to heat the concrete and keep it there until the structure reaches the maximum strength that is needed. Electric current is typically used to heat concrete, which causes resistance in the electrical circuit. Its slow heating achieves the desired result.

• string;
• rod;
• strip;
• plate.

Plate electrodes made of premium roofing iron are the best choice. The portion of the formwork in contact with the concrete has them sewn onto it. The electrical network is then linked to the electrodes. When there is a potential difference between them, current flows through the concrete structure and heats up the area. Because of the characteristics of such work in the winter, the price of the item rises after the structure has warmed up. The expenses incurred are entirely justified since they stop the concrete’s weakness from showing and ultimately causing the structure to collapse.

The water resistance of concrete brands reveals how stable the material is against the effects of moisture. Furthermore, improved stability is indicated by a high coefficient.

Methodo info

When required, a unique infrared heating technique is applied. Its foundation is the conversion of infrared radiation into the required thermal energy.

Metal tubular emitters and quartz emitters are the types of special emitters needed to produce infrared waves. This technique is essentially used to effectively protect the mixture from heat damage while also warming up frozen concrete structures. The mixture is placed inside the formwork.

A coil is used in the induction process to produce heat in the metal components that are working in the affected area. This technique can be used to drill holes in strong concrete at any temperature and is used to preheat completed structures.

Although winter concreting is a difficult task, it is completely manageable with the correct techniques. Construction can continue without interruption even in cold weather if efficient heating techniques are understood and put into practice. Concrete is properly cured and given the required strength through the use of heating techniques such as steam heating, electric heating, and heated enclosures.

Winter concreting requires the use of additives in addition to heating methods. Concrete’s characteristics are altered by additives like air-entraining agents, accelerators, and antifreeze to improve its resistance to low temperatures. These substances aid in accelerating the curing process and preventing freezing of the concrete.

By combining these two techniques—heating buildings and applying specialty additives—construction projects are able to stay on schedule and preserve their structural integrity throughout the winter. Regardless of the weather, high-quality concrete work can be accomplished with careful planning and application of these techniques.

In the end, winter concreting necessitates thoughtful analysis and modification of conventional procedures. Construction workers can successfully handle the difficulties presented by cold weather by being informed and organized, guaranteeing sturdy and dependable concrete structures all year long.

In order to guarantee that concrete sets correctly in spite of the cold, winter concreting calls for specific methods. This includes applying techniques like heating the construction site or the concrete mix and adding curing-accelerating chemical additives. These methods guarantee the strength and longevity of the structure by keeping the water in the concrete from freezing. Even in the winter, construction projects can proceed effectively and safely by modifying these techniques.

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