Concrete heating in winter: the use of antifreeze additives.

In this article we will talk about how to heat concrete in the winter and why it is necessary. Considering the fact that construction work using this truly universal material is carried out all seasonally, the relevance of the topic of warming up cement-containing mortars is becoming increasingly important.

With the development of building technologies, fundamentally new possibilities of controlling the temperature of concrete in adverse climatic conditions appear. But, before we talk about the technologies used, let us consider in more detail how much concrete is heated in winter and what are the reasons for carrying out such works.

Why warm concrete

It is no secret that the use of cement-containing solutions is carried out both in summer and in winter. Moreover, the situation in the construction industry sometimes develops in such a way that it is impossible to cancel these works due to “bad” weather.

The way out of a difficult situation was the heating of concrete in winter. In order to understand the principle of preserving the operational properties of a material, consider the features of its preparation.

With significant temperature drops, as is the case in winter, water freezes. Consequently, this fundamentally important component cannot participate in chemical reactions that take place during the formation of the structure of concrete.

Moreover, the hydration of dry fillers is completely stopped, due to which it becomes impossible to harden the solution until the state when the cutting of reinforced concrete with diamond circles can be applied.

Another important reason to think about how to heat concrete in winter is the internal pressure that grows in the thickness of the material. Due to the increase in water volume (on average by 10%), concrete collapses, as the above-mentioned reasons cannot harden and become stronger.

Of course, as the ice is thawed, the hydration process is resumed, but the already destroyed structure of the mixture is not able to fully recover. As a result, the strength characteristics of concrete are greatly reduced, which adversely affects the durability of construction sites and structures.

So, we found out that the technology of heating concrete in the winter time is expedient and necessary, now consider the main ways to control the temperature of a building material.

Concrete heating technology

Since cement-containing mortars have been used for a long time, there is no shortage of concrete temperature control methods.

However, the following methods gained the most popularity:

• the use of antifreeze fillers, which are added to the composition at the stage of production of the mixture;
• use of the "thermos method";
• concrete heating by specialized heat sources.

Important: The choice of a method depends on the brand of concrete, the type of concrete products, the degree of energy equipment of the construction site and the ambient temperature.

Consider each of the above methods in more detail.

Antifreeze additives

The use of special antifreeze additives has been used for a long time. This method is effective, easy to implement and the price of the ingredients used is low. The main advantage of this method is that there is no need to heat the solution, since the material does not freeze, despite the negative temperatures in the thickness.

However, this method has its own temperature limitations. For example, the most demanded additive - sodium nitrate can be added to concrete at air temperature not lower than minus 15 °.

Thermos method

"Thermos method" is a more innovative technology, in accordance with which the ready-mixed concrete mortar is poured into insulated formwork. The temperature of the internal formwork volume can reach + 25 ° C. The formwork design is hermetic, as a result, the mortar acquires the required strength due to the stored heat and exothermic emissions emanating from the cement.

This concrete heating technology involves the use of fast-hardening cement grades. An effective solution is the addition to the composition of special additives that accelerate the course of hardening (sodium nitrate, calcium chloride, potassium carbonate, etc.).

A separate kind of this technology is the so-called “hot thermos”. In this case, the concrete is first heated to a temperature of + 70 ° C and poured into a thermally insulated formwork.

Concrete heating by specialized heat sources

The warm-up method using specialized heat sources can be implemented in several ways, including:

• electrode;
• transformer;
• infrared.

All these methods are quite effective and technological, so consider each of them separately.

• Electrode heating is characterized by the fact that heat is released directly in the concrete mixture by passing an electric current through it.. Work with construction materials on this principle found the most common in the casting of walls and other vertical structures with a large area.

If necessary, the electrode method can be applied to preheat the concrete before pouring it into thermally insulated formwork.

This method of controlling the temperature of the mixture is characterized by high efficiency. However, there is one major drawback, namely, the need to supply high electrical power - not less than 1000 kW per 3 m? mixes. Of course, not every construction site can boast of such power supply parameters.

In addition, as the concrete dries, the heating stops. Therefore, additional heating methods may be required to ensure the optimum temperature of the material, up to the concrete set of optimum strength parameters.

• Winter concreting with the use of heating wires or transformers, because of the ease of implementation and relatively low cost, is the most popular and sought after method. The technology involves laying a mixture of special transformers or heating wires.

A characteristic difference of this method from the previous one is less power consumption and the ability to work in small areas. This technology allows to warm concrete up to + 50 ° С, which is quite enough for construction in adverse climatic conditions.

• Infrared heating mixture is one of the most promising and innovative..

The advantages of the method include the possibility of heating the solution of any density in the most inaccessible places. This advantage could not be more important in the construction of complex architectural forms, which can be obtained in the usual way, using diamond drilling holes in concrete.

Important: Due to the lack of direct contact of the solution with conductive elements, this method is considered the safest.

Conclusion

As you can see, the instruction of industrial heating of building solutions, when using the correctly chosen method, is simple and effective (also learn how the concrete heating station is used on the building site).

Of course, most of the methods can be used in the construction of large objects and structures. On the other hand, nothing prevents the use of a self-insulated formwork for the construction of low-rise individual housing facilities.

Are there any questions that require comprehensive answers? In this case, watch the video in this article.