Heating concrete with a welding machine. Warming up concrete in winter. The practical implementation of this method is simple

Climatic conditions in most of the Russian Federation dictate their conditions for all types of construction and installation work that are carried out during the cold season.

In this regard, pouring concrete structures in conditions of negative ambient temperature is possible only if the construction site has the technical ability to warm up the poured structure, including using electricity.

On an industrial scale, concrete is heated using special transformers and heating cables. At home, with small volumes of concrete work, it is allowed heating concrete with a welding machine power from 150 to 200 Amperes.

What is needed to heat concrete with a welding machine?

Household welding machine with a power of 150-200 A. Important! Not a welding inverter, but a welding (transformer) machine;
Heating wire PNSV with a diameter of 1.5 mm;
Single aluminum wire AVVG 1x2.5 mm;
Cotton tape;
Clamps for non-contact determination of current strength.

Preparatory work

The PNSV wire is cut into segments (heating loops) of 17-18 m. The resulting segments are evenly tied to the reinforcement frame for pouring the concrete structure. At the same time, make sure that the loops are located above the middle of the slab being poured; if a column is being poured, the layer of concrete above the heating loops should be at least 4 cm.

The garter is carried out with an insulated aluminum wire. The ideal option is if the loops are arranged “snake-like”. The distance between the loops is taken depending on the air temperature - from 10 to 40 cm. The rule here is “the lower the temperature, the shorter the distance.”

The number of heating loops depends on the power of the specific welding machine. Since one loop consumes 17-25A, in our case (power 250 A) no more than 7-8 heating loops with a length of 17-18 m can be used.

Important! When laying loops, the ends are marked - one end is marked with electrical tape, the second is left free.

The loops are laid and tied. Now it is necessary to extend aluminum wires onto them, which will be connected to the welding machine. The length of the aluminum wire is determined by the location of the welding machine, but not more than 8 meters.

I insulate the twists of the heating loop and the extension wire with CB electrical tape, and place it in such a way that it remains in the thickness of the structure being poured. Otherwise, the twist will overheat and burn. The markings are applied with electrical tape to the ends of the aluminum wires.

Connection to the welding machine and heating features

After pouring the concrete, all aluminum ends (extended) of the loops are connected to the welding machine. In this case, the ends marked with electrical tape and without it are connected to different poles of the welding transformer. Turn on the welding machine at the minimum load of the power regulator.

They check each of the loops with pliers - the current consumption should be no more than 12-14 Amperes. After 1 hour, you can add half the power of the device, and after 2 hours you can turn on the device at full power.

Again we check the current strength in each loop. The current strength should be no more than 25 A. As practical experience says, a loop power of 20 A is enough to efficiently heat the concrete at an ambient temperature of minus 10 °C.

Features of heating concrete with a welding transformer

Warm-up time depends on the power of the structure and the ambient temperature. At air temperatures down to minus 10 °C, two days are enough for concrete to hydrate;
The surface of the concrete structure must be insulated with drinkers or mats;
You should not overheat the concrete - the structure under the insulation layer should be slightly warm and nothing more.

November 16, 2013

How to properly heat concrete using a welding machine? Additional electrodes must be evenly distributed over the entire area of concrete, in two parallel circuits, connecting them in series. An ordinary incandescent lamp must be connected between the chains so that the voltage can be constantly monitored. And the temperature can be measured using a regular thermometer.

A self-contained installation for cutting and welding is called a welding unit using electric arc welding. The unit consists of the main elements: an internal combustion engine and a welding generator. In addition to the main components, most units are equipped with a large number of additional elements. For example, these may include a heating unit for frozen soil and rivers, ice, devices for plasma-air cutting, a welding current control system, a unit for reducing no-load voltages, a current generator that is needed to power power tools, and an electrode drying unit. It is known that the hardening process of concrete takes about a month. The main characteristics of water resistance, strength and frost resistance appear in concrete on the 28th day, and accordingly, during the laying period, it should not be exposed to water and frost.

Welding machines meet all reliability and safety requirements. The possibility of heating concrete with a welding machine depends on the air temperature and the amount of concrete that needs to be heated. It is necessary to use additional electrodes during the procedure in order to properly warm up the concrete mass.

If you are interested in vintage style in the interior, visit the website koffkindom.ru. Only there you will find everything about this style and its main features and characteristics.

American Red Oak (Du Roi) Family: Beech Other names: northern red oak (Canada and USA); southern red oak, Spanish oak (USA); red swamp oak, cherry oak (USA); Shumard red oak (USA). Distribution: Eastern Canada and USA American Red Oak - wood description The biscuit pink heartwood is reminiscent of other oaks. The grain is straight, coarse. Southern oak grows...

Niato (Palaquium maingayi) Family: Sapotaceae Other names: njatu (Indonesia); Padang (United Kingdom) Distribution: Asia Minor and Southeast Asia Description of Niato Wood The color of the heartwood varies depending on the species, but is generally pale pink to reddish brown, sometimes with darker stripes. The grain is straight or wavy and the texture is moderately fine. Weight is variable, but on average 620-720 kg/m3; specific…

In a hotel company, great attention is paid to safety issues. Guests must be confident in the safety of their belongings in order to use the services of the establishment without fear. Mechanical systems, which are easy to hack, have been replaced by electronic hotel locks. They are technologically advanced locking devices that not only provide a high level of security, but also perform auxiliary functions. Enterprise equipment...

We all know what swing doors are. This is not at all surprising, since they have long been used in many residential premises, offices, shops, etc. High sound insulation and reliable design make such doors very popular on the market. Thus, the swing door system is perhaps the most common due to its obvious and numerous advantages. On the website raumplus.ua you will find…

Warming up concrete with a heating wire;
Heating concrete using a cable;
Heating concrete using a welding machine.

For this operation, a heating wire of the PNSV brand is required. The operating principle of this method is based on heating the concrete with a very hot wire. The wire is heated using a step-down transformer, which has a voltage regulation circuit using a slider that regulates the number of turns on the winding. This method is convenient because with constant changes in weather conditions, you can regulate the amount of heat released into the concrete.

Technological map for heating concrete with wire

The heating wire is laid in an already prepared structure with formwork and reinforcing mesh, so that the wire does not touch the walls of the formwork, does not cross each other and does not go beyond the concrete pouring level.
After laying the wire, the ends should be brought out, but before this, the cold ends must be soldered (the soldering points should be insulated with metal foil to preserve the heat given off by the wire).
In order to calculate the amount of wire required, you need to use regulatory and technical documentation (drawings, flow charts, PPR, and so on)
You should check the resistance of the cores and insulation with a megger (it is necessary to find out the uniformity of the load).
According to the mounted circuit, voltage is supplied from the step-down transformer.

A new technological map is developed each time for different structures and grades of concrete.

The method of heating concrete with a cable is more economical than the method of heating with a wire since it does not require additional energy costs and additional equipment.

Technological map for heating concrete with cable

Draw up a cable installation diagram.
The heating cable is installed at the base of the structure before pouring concrete.
The heating cable is fixed with fasteners (clamps, wire).
After installing the cable, it is necessary to check its integrity and correct installation before filling.
Test the cable.
Connect the cable to the low voltage network.

The method is based on heating steel elements using a welding transformer.

Evenly place steel elements, for example, the remains of reinforcement of the same section along the bottom of the structure. (do not use reinforced structures as steel elements).
Connect the steel elements parallel to the electrical circuit with wires and bring them outside the structure; to monitor voltage changes, an incandescent signal lamp is mounted to the terminals (when the voltage changes, the lamp will shine either brightly or dimly).
Connect the welding machine to the terminals of this design.

Concrete hardening time is more than 1 month.

Attention!!! The welding machine should be connected to a separate group so as not to overload other low-voltage networks.

During frosts, the water contained in concrete hardens, which leads to a stop or inhibition of the chemical processes that contribute to the hardening of concrete. There are a couple of commonly used methods:

Adding antifreeze agents to concrete.

Pouring concrete into insulated formwork.

Antifreeze additives tolerate good frosts and retain their physical and chemical properties at temperatures of -30 C. The additives contain antifreeze, a liquid substance that prevents water from freezing. Additives containing Sodium nitrite and Sodium format are suitable for reinforced concrete structures. The main ability is the preservation of physicochemical and anti-corrosion properties when the temperature drops below 0 C.

Potash is a chemical substance, a good antifreeze additive. It dissolves well even with a small amount of water and does not cause destruction. The material is economically beneficial in construction when concrete is heated.

When using, you should read the instructions for use and safety precautions.

In general terms, the scheme for heating concrete with a welding machine remains exactly the same as with a step-down transformer - the difference is that in this case the power of the unit will be less. This method is acceptable for small objects and is almost ideal at home, given that you do not have to look for additional power. For example, we use a 250A device when pouring a small 4x5m slab, and as additional material we will show you a video in this article on this topic.

Welding transformer BRIMA TIG 250

Warming up the concrete

Note. According to SNiP 13.03.01-87 for load-bearing structures, if the average daily temperature outside drops below 5⁰ C, the concrete should be electrically heated. This is used to prevent an ice film from forming in the fresh mortar around the reinforcement.

At home, you can heat concrete with a welding transformer.

Using a heating loop

Schematic diagram - how to heat concrete with a welding machine

Note. In addition to loops, heating of fresh concrete structures can be carried out using the electrode method, in heating formwork, liquid installations, induction and infrared radiation.

If the solidification of the solution occurs with failures in the temperature regime (the mixture freezes), then the strength decreases sharply and the surface becomes crumbling - this is immediately visible when cutting reinforced concrete with diamond wheels or diamond drilling holes in concrete.

Heating of reinforced concrete structures with heating loops based on the principle of supplying a limiting current to the cable is needed mainly for platforms (slab foundations) of floors and less often for walls, when the room itself is not heated. Such circuits, as a rule, are powered through step-down transformers, which have voltage regulation - this allows you to maintain the required thermal power depending on changes in air temperature outside. This method is more economical than the electrode method (see also the article “Aerated concrete wall chaser: design features and application”).

What do we need

PNSV (Heating Wire, Steel Type, Vinyl Sheath)

So, as we have already said, we need a transformer, which means that at home for these purposes we will use the power of a welding machine - in our case up to 250A, although more is possible, but we will specifically consider the minimum in order to learn how to get the maximum benefit. In addition, as the instructions require, we will need PNSV wire - in this situation we will cut pieces of 18 m each.
We also need an aluminum single wire with a cross-section of 2.5-4 mm2 (APV is suitable), cotton insulating tape and pliers, and current clamps. And, of course, such work can be carried out only in those areas where there is a 220V power source - this can be a power line, but also (this happens at the beginning of construction) you can use a carburetor or diesel (more economical) generator.

PNSV resistance depending on cable thickness

Let's get started

This is what the setup will look like

We have a 250A welding machine, now we need PNSV, the quantity of which we will calculate based on the formula R=U/I, and if we know that U=220V, I=250A, then R=U/I=220/250 =0.88ohm.

What follows from this - if we have a maximum of 250A at the output, then in order not to overload the device we will make 8 loops of 25A each with our own hands - this will be quite enough. To do this, take a piece of PNSV 18 m long and 3.0 mm in diameter (0.05 cm/meter) - for a 4x5 m slab this will be enough.

You strip the ends of the PNSV by 40-50 mm and connect an aluminum wire to each of them (you can, of course, use copper, but the price of aluminum is much lower) - make sure that the twist is tight - the correct operation of our design will depend on this. The length of the aluminum wire will depend on the distance at which you can install the welding machine - it would be more advisable to bring it as close as possible. If these ends turn out to be short, don’t be upset - they can be extended at any time to the required length, just isolate the twist carefully (see also the article “Pigments for concrete: main characteristics, scope of application and methods of self-preparation”).

Laying hinges on a metal reinforcement frame. Photo

Now we need to lay the PNSV, distributing it evenly over the entire area so that the twists with aluminum are inside the slab being poured, but in no case touch the metal frame! It’s best if you can thread the PNSV between two sheathings - inside the frame - so the cable will end up inside right in the middle of the slab, like butter in a sandwich between two pieces of bread of the same thickness.

When pouring the solution, you can easily displace the wire, so it should be tied to the reinforcement with pieces of insulated aluminum, but be careful not to damage the insulation on the PNSV - this way heating the concrete with a welding machine will be effective and safe.

You can also cut the PNSV into pieces, one loop at a time, and remove the aluminum ends from each, so it will be much easier to thread the wire between the reinforcement bars in the frame, but here you need to be careful not to mix up the ends. It is best to mark them with an insulation marker (use the + and - signs).

To connect the welding machine, you can use cables - ground and the one that goes to the holder, or screw the aluminum wire directly to the terminals. Try to connect the circuit as quickly as possible after filling and turn the voltage regulator to minimum, turn on the breaker and check the voltage.

At first, a jump to 240-250A is possible, but as the mass warms up and hardens, it will drop, and you can gradually increase it as needed.

Conclusion

Since you need to heat concrete with a welding machine gradually, check the voltage every 2 hours, gradually increasing it (read also the article “Concrete footing: what is it and how is it done correctly”).

In about 8 hours you will reach the maximum and within 3 days the stove should dry out (but this is not the degree of use).