How to warm concrete in winter during construction?

How does construction work in the winter?

Winter is a period of low temperatures, how does the construction of complexes of concrete structures occur at this time? It is known that concrete is a mixture of gravel, sand, cement and water in a certain proportion. And the time for which the solution collects design strength is 28 days. Also we know that water, freezing, takes up a larger volume, and is capable of breaking monolithic structures.

There are several ways to bypass the temperature limit, but they all boil down to one, keeping the solution temperature above zero. If this rule is not met, the erected structure will not be strong enough and will collapse very quickly. Below we will provide several popular methods of warming concrete on a construction site in the winter.

Shelter and heat guns

The technology is quite simple - a tent is being built above the desired site and heat is injected by heat guns. A fairly common grandfather's method of warming up the foundation with hot air. Used in small construction areas, a laborious process associated with the construction of a heat-retaining dome.

If you want to heat the concrete with a heat gun, please note that this will be a costly option. The only advantage of this technique is the possibility of heating a concrete screed without electricity. There are autonomous heat guns, most often diesel. If there is no 220-volt network access, this warm-up option will be the most beneficial.

You can visually see this way of heating on video:

Thermometers

Special electric heaters in the form of mats overlay the area filled with a prepared solution. Add substances to the solution to accelerate the setting process and prevent the crystallization of water. This method is good for heating large flat horizontal surfaces in the winter.

Complex designs, columns they will not heat. For more information on how to preheat the concrete structure with a mat, you can on the video below:

Forms with heating elements and electrodes

To warm up the walls and concrete columns of the company, developers use formwork with heating. The formwork is thermally insulated and heaters are installed on the side of the concrete solution. The design of the heater does not require additional sophisticated equipment, the elements are easily replaceable.

Electrode formwork consists of rods or strips of metal attached to the formwork at regular intervals. Electrodes are connected to a special transformer, and due to water in the cement solution, it heats up. As if the lack of warming shutters are standard sizes, and if the customer has a non-standard project, other ways of warming concrete in winter are used.

Electrodes

Most often used for heating columns and walls of concrete. After casting the frame elements in the formwork, insert the reinforcement into the solution, positioning and distributing them in groups, connecting to a transformer or welding machine, as shown in the diagram below:

It is also possible to place string electrodes along the frame in advance. The photo clearly shows the principle of installing electrodes in concrete:

The water in the solution plays the role of a conductor and gradually the current flows through the electrodes as the electrodes solidify. The wire rod after solidification of the mixture remains part of the structure. To the disadvantages of this method of heating can be attributed colossal energy costs and additional costs for electrode material.

CNSV wire

Universal and affordable way of warming concrete in winter with the help of high-resistance cable and step-down transformer. During the linkage of the frame from the reinforcement, the heating cable is laid, the dimensions and shape of the structure do not matter.

This heating method is applicable both on the building site and for the home builders. Let's talk a little more about how to warm the concrete mix with PNSV wire at home.

After reinforcing the frame structure or laying beacons under the filling floor, the wire is laid with a snake no closer than 20 centimeters from each other( the optimal step of laying).The length of one loop is from 28-36 meters. As a voltage source, you can use a welding machine. The connection scheme in this case will look like this:

Nuance of warming up, PNSV can not be connected with uncoated solution, t.without heat absorption due to the high temperature in the open air, it will burn out. To avoid burn-out, make the transition to the aluminum cable, leaving the output ends of the heating wire PNSV 10 cm from the solution. The manufacturer recommends a current in the cable of 11-17 amps, which can be controlled by current clamps. We talked about how to use clamp meters in a separate article.

For home construction, a PNSV with a diameter of 1.2 mm is sufficient. Its characteristics:

• resistance 0.15 Ohm / m;
• the working current of the solution immersed in a solution of 14-16 amperes;
• laying temperature from -25 to 50 ° C.

Wire consumption per cube of concrete 60 linear meters. The temperature to which concrete is heated is 80 ° C, its control is performed by any thermometer. The speed of dialing the temperature of the solution should not exceed 10 degrees per hour. To avoid senseless spending on electricity bills, the heated area is covered with any material that prevents the heating of the atmosphere, for example, they are covered with sawdust. To obtain an excellent result, the concrete mixture before pre-filling is also heated, the temperature of the mixture should not be below +5 ° C.Here, according to such an instruction, it is possible to warm concrete in the winter time with your own hands. The technology is laborious, but even an inexperienced person can do it. On how to lay the heating cable in the foundation, it is told in the video lesson:

By the way, instead of the PNSV cable, you can also use the BET cable to warm up the concrete. The video below briefly discusses the installation instructions for the heating conductor:

cable? In the article, not all methods of heating concrete in winter are indicated. There are induction, infrared and others, but they are not considered because of their low prevalence and complexity. We gave a general idea of ​​the technology of construction of concrete structures, and the possibility of using the home masters methods of heating screeds and walls. By the way, the use of the PNSV wire is possible not only during heating of the construction under construction, but already after that. It can be used as a ready warm floor or anti-ice on stairs or sidewalks. Short sections are connected through a step-down transformer from 400 to 1500 watts. To connect directly to the 220 volt network, the wire will be longer than 120 meters.

That's all I wanted to tell you about why you need to warm concrete in the winter and how to do it with heat guns, electrodes or wire PNSV.We hope that our instructions were clear to you. More information you can get by reviewing the video lessons in the article.

We also recommend reading:

• Heating the tracks with a heating cable
• How to save electricity at home
• How to choose a heat gun for the power