In the event that the work on pouring the foundation is carried out in the cold season, it is necessary to do an electric heating of concrete. This will prevent it from freezing, which means it will make the structure strong and reliable.
What is the concrete electric heating for
Video – Electric heating of concrete in winter
As you know, concrete has various brands – the higher it is, the better the quality of the composition. Actually, the concrete brand is a value denoting its strength when solidified in ideal conditions, that is, at a temperature of at least 15 ° C for 28 days. The composition of any concrete mixture necessarily includes water, which at a temperature below 0 ° C turns into ice, thereby increasing in volume. This leads to the fact that concrete begins to expand and deform, making the structure of the unreliable.
In the event that a temperature is not lower than -5 ° C, you can do with less radical measures, introducing anti -control additives into concrete, heating water for kneading or covering the flooded structure with insulation or tarpaulin. At lower temperatures heating concrete, you must do it. In this case, the most optimal way is considered to warm up using electric wires laid in concrete. The cable attached to the power source is heated to a temperature of 80 ° C and gives the heat of the concrete mixture, the thermal conductivity of which is very large.
How is the electric heating of concrete in winter is carried out
By and large, the technology of concrete heating is similar to that used in warm floors. Before pouring concrete, the electric wire of the PNSV brand with a vein thickness of at least 1.2 mm is mounted on reinforcing structures. The optimal cable thickness is from 1.8 to 3 mm. In order to avoid sagging wires, they must be wrapped with steel wire to reinforcement. The number of wire depends on which volume of concrete needs to be heated – on average, its flow rate is about 60 p/m per 1 m3. It is better to entrust this calculation to a specialist.
After the number of wires is designed, you can start winding it for reinforcement. For this, whole cable bobbins are used, for each of the two endings of which the “cold end” of aluminum wire is mounted. The tips of both wires are cleaned at a length of 4 cm and twisted together. The resulting connection is protected using a small segment of a plastic pipe. When laying the cable, you need to ensure that the PNSV and its twist are necessarily in concrete, otherwise the wire will simply burn out. All “cold ends” are displayed on the edge of the structure on one of its sides. After a certain distance, it is necessary to draw the outputs of the wires outside. The number of such conclusions and the distance between them should be determined by experienced builders who have already dealt with such constructions.
To control the temperature of concrete in his body, a “penalty” is installed from a plastic pipe, avoiding contact with wires. The purified machine oil is poured into it to about half, and the temperature sensor connected to the thermometer is installed at the end. Heated areas of concrete are covered with 5-centimeter mineral wool.
The duration of warming up concrete depends on how quickly it freezes. For this, a special journal is being conducted, in which the results of the measurements of the composition temperature are entered, as well as the current strength in the wires. Employees of special laboratories should carry out such procedures.
Another way to warm up concrete using electricity is the installation of metal rods in a just flooded frame. To do this, it is first covered with a layer of mineral wool, then drives metal rods with a length of one meter through it and 6 mm in diameter. After that, the rods are interconnected by wires, which are brought to transformer stations.
Electric heating of concrete: safety precautions
Concrete heating should be carried out only with the help of specialized stations, for example, transformers of the Tmob-63/038 or KTPTO-80 brand. The current strength during the heating procedure should be large enough, and the voltage should be insignificant. The number of such substations depends on the daily rate of concrete pouring and calculated in advance. Connect substations must be clarified in accordance with the technological scheme.
All work with electrical equipment should carry out professional electricians with a level of tolerance at least the fourth.
Cable contact with thermal insulation, formwork and other wooden structures cannot be made. Before connecting the wires with transformer stations, you should check their resistance using a device such as a megommeter. During the operation of electrogening stations, you need to ensure that an inexperienced person does not approach the concrete structure. Therefore, “posts” of heating must be protected if possible.
It should be noted that conducting work such as pouring and heating concrete in the winter requires high qualifications, so it should be entrusted to professionals.