Warming of concrete with wire PNSV: laying scheme and technique

The preheating of concrete with a PNSV wire, the layout of which will be described below, is used for outdoor work in winter. Such manipulations are necessary for the reason that when the temperature is lowered, the solution slowly begins to gain strength, in which water simply begins to turn into ice. Longer hardening of concrete causes the work to be delayed for weeks and months, in addition, there is a possibility that the structure will not achieve the required strength, it will crumble during operation.

Principle of operation of the wire

The technology of warming concrete with wire PNSV is that before the start of filling is taken the cable of the desired section and voltage, stacked, and then poured. Then the cable is connected to the network. Do not be afraid that the quality of the concrete will change under the influence of high temperatures, bubbles will not appear, as will the cracks after hardening, but the hardening process will not be stopped by low temperatures, which will give a firm and reliable construction.

Technical features of wire for concrete

Wire for warming concrete PNSV, as a rule, has some features. This is usually a conductive core that has an insulating coating. Protection can be made of polyester or polyvinyl chloride. The diameter is 1.2 mm, but the average resistance is equivalent to 0.15 Ω / m. It can be used in the temperature range -60- + 50 ° C. At operation the current can be equal to 14-16 Amps.

Stacking can be performed at -25- + 50 ° С. Before purchasing, you need to determine how much wire to use, so for 1 m ^{3 of the} solution you need about 55 m.

Winter heating of concrete with PNSV wire is completely safe, as during production the product receives high-quality insulation that prevents ignition. There is almost no danger that the vein will be broken, because it is strong enough. Do not operate the wire until it is immersed in the solution. Otherwise, there will be a burnout due to the increased current. However, such phenomena are not dangerous for conclusions, since they have in the structure of a wire of more impressive cross section, representing the so-called cold ends. They are produced from the APV-4, the maximum length of which is 1 m.

Scope of use

The method of warming concrete with wire PNSV assumes the possibility of using it not only in domestic, but also industrial scale. Sometimes installation in

Foundations and fences.

Carrying out the cable installation

Working with the cable involves responsible manipulation. Before you begin the laying process, you need to free the surface of debris and foreign objects, as well as those elements that can damage the wire. During this, it is important to ensure that the cable does not bend. To do this, it is recommended to lay in a semicircle, but there should not be any empty zones. The snake is the simplest method of laying.

After switching it is necessary to be careful. So, there should not be voltage drops, to achieve this, you need to use a stabilizer, otherwise the wire will simply burn out, and it will not be possible to remove it.

The scheme for warming concrete with wire PNSV is in the article. After you implement it in practice, you can make a fill and connect, which involves bringing the cable to a power source. It is recommended to use a transformer when connecting. As a rule, experts recommend the use of stations for heating brands SPB-40, SPB-80.

Connection can be made by two electrical circuits, the first of which is called a "star", while the second one is a "triangle". In the latter case, the wires in the wire are divided into 3 equal parts and the wires of each are mated in parallel. Formed sets must be connected to 3 nodes and connected to the 3rd terminal of the station.

Features of the warm-up

Before you start, you need to know the time of warming the concrete wire with PNSV.

During the first period the solution will be heated, while it is unacceptable to increase the temperature by more than 10 ⁰ C in two hours. The second period should be accompanied by a temperature increase of no more than 80 ^° C. At the final stage, cooling takes place. In this case, too, one should not rush, and the decrease should not be more than 5 ⁰ C for an hour.

Warming of concrete with a PNSV wire, the layout of which is described here, does not differ much from the installation technology of the "warm floor" system. In addition, this cable can be used to achieve these goals. However, in this case, the system will have to be slightly modified by constructing the TET from the wire strands, whereas on the top the system should be protected by insulation.

Cost of heating cable

Before buying, you need to familiarize yourself with the price of the cable. In different areas it can cost differently, but the average price remains unchanged, it is equal to 2 rubles / m. Do not buy the product without checking if it meets the established GOST standards, so the cable is manufactured according to the standards 12.1.013-78.

Processing of concrete after warming up

Many builders are wondering whether it is possible to manipulate the cutting or drilling of concrete after it has obtained strength. This issue is due to the fact that at the time of the heating shut-down, the structure does not yet acquire brand strength. Answer this question positively, but with some caveat. Cutting though it is possible, but it is unacceptable to produce shock loads. As the most suitable solution in this case is the use of a diamond tool. So, if you use diamond drilling in your work at this stage , then the holes in the concrete get even edges, and cracks will not appear. Moreover, if you drill a concrete body through a diamond bit , then you do not have to change the tool at the time of overcoming the reinforcement, which is true for reinforced concrete.

Recommendations of a specialist

Warming of concrete with a wire PNSV, the layout of which is in the article, can be produced by the method of its initial winding on a steel frame, and it is necessary to ensure that there is no tension. You can simply lay it between the elements of the metal frame. It should be remembered that the wire should not touch the surface of the casing, it should not protrude from the concrete body after pouring.

The heating wire can only be mounted after the reinforcing frame has been laid, it is not necessary to start the work before the elements are in the space of the enclosing structure. Welding works must also be completed by this time. Warming of concrete with a PNSV wire, the layout of which is shown in the figure, should not continue after the strength of the solution is set within 50%.

The heat that comes from the core should be able to heat up the solution to 40-800 ^° C. The period until the mixture completely gains strength will depend on the features of the object and, as a rule, takes up to three days. The heating station should operate on a re-short-term or long-term basis. The pitch between the wires should not be more than 15 mm.

Calculation of the heating of concrete by wire PNSV is presented in the article, but its compliance does not yet give complete success. After all, it is important to take into account the installation technology, which involves the elimination of the contact of the wire or its intersection. In order to be able to control the temperature regime in solution poured by solution, it is necessary to make special wells. Do not start the warm-up process until the solution has been completely laid, as this is contrary to safety considerations, and it can also damage the wire. It is more preferable to entrust this kind of work to specialists, since the installation of the cable is accompanied by certain difficulties and requires the master to have the skills to perform such manipulations.

Calculation of wire for warming concrete

In view of the above, we can draw the following conclusion: for 1 m ^{3 of} concrete it will be necessary to spend approximately 55 m of cable. In order to calculate the wire, you first need to know how much solution will be poured into the formwork. So, on 20 m ^{3 of the} mixture it is necessary to purchase 1100 m.

In general, construction works are preferred in the warm season, which is especially true for private developers. As a rule, the management of pouring concrete in the cold period is associated with the need to surrender the object to a certain time. Such work in the home construction involves additional costs for the purchase of antifreeze additives, heating cables and other. And labor costs in winter when pouring concrete are much more, because kneading is more difficult, as well as the subsequent distribution of the mixture on the formwork.