Pouring concrete at low temperatures: useful recommendations

The minimum temperature for pouring concrete is approximately 5 ° C. That is, this figure is considered critical - up to this figure you can conduct any work with concrete in the usual mode. However, it must be remembered that the optimum temperature for pouring concrete is 17-25 ° C, since such conditions make it possible to obtain the maximum strength of the solution. If the temperature of pouring concrete approaches 5 ° C, the solution is likely to be less solid and strong and will not reach the declared values for the brand. Even during work at critical temperatures, it should be remembered that the time of solidification can increase at times.

However, sometimes it becomes necessary to carry out construction work in the winter at negative temperatures. There may be several reasons:

• Limited construction time in summer due to unfavorable climatic conditions;
• The need for concrete pouring on loose soils;
• Seasonal decrease in prices for materials, including cement;
• The reduction in the cost of work by specialized firms due to the low demand for their services.

There are two main technologies with which you can conduct concreting in the cold season.

The first is that concrete pouring at negative temperatures is performed on a heated reinforcement, in the role of which ordinary electrodes can act. A standard 12-volt cable is connected to the valve, through which current flows. This is enough to make the metal rods heated and warm up the solution, not allowing it to freeze. Disadvantages of this method are obvious - in addition to the use of special materials, you will have to spend a fair amount on electricity.

In addition, concrete pouring at negative temperatures can be carried out with the help of warm formwork. The essence of this technology is to insulate the solution with special heat-insulating materials, for example, foam or mineral wool. But there are also disadvantages here - it is necessary to cover concrete from all sides, which leads to a large consumption of auxiliary materials and an increase in the time for carrying out the work.

Pouring concrete at low temperatures: general recommendations

1. All materials (sand, gravel) that will be used to produce the mortar must not contain ice and snow. It is best to warm them up.
2. All work should be carried out in the shortest possible time, so that the solution does not have time to freeze.
3. At negative temperatures, concrete pouring must be done at a time. It is not recommended to fill parts with the parts, as there may be cracks between the layers, which will make the concrete less durable.
4. Increase the speed of adhesion and solidification of concrete will help different additives, for example, potash, sodium nitrite, lignosulfonate, calcium chloride, sodium formate and others. However, it should be noted that each such additive has side effects. For example, calcium chloride can cause corrosion of the reinforcement.

Thus, it can be concluded that concrete pouring at negative temperatures should be carried out only if it is not possible to postpone this stage of construction work until more favorable conditions occur.