Description electrodes heating concrete technology and practical tips

To eliminate water crystallization, part of the solution of the concrete, it is necessary to maintain a certain temperature-drenched masses.The fact that a binder (cement) is reacted with the liquid, rather than ice.And as a final concrete hardening occurs for a long time (up to 4 - 5 weeks, depending on the nature of the manufacturing operations and the composition of the mixture), its heat treatment is carried out continuously until ready built by design.

understood that the heating is only needed during the cold season.This makes it possible to work in any season, regardless of the ambient temperature.There are many methods, but, perhaps, the most common is the warm concrete mix electrodes.Such conductors E / current different shape, size and location specifics.

But technology and the principle of their action remains unchanged - concrete heats e / field which is formed between the electrodes when applying a voltage to them.The solution becomes an element of the conductive circuit (with its internal resistance), in which electrical energy is transformed into heat.By adjusting the voltage nominal value, it is possible to achieve the desired heating temperature.Depending on the characteristics of "processed" design, the best option is selected data items.

Species electrodes

Rod

As such, most often used rebar although you can install and narrow strips of metal (composite rebar, of course, will not work, but for reinforcing - that's it).Its length should be slightly larger casting thickness (for inclusion in the chain), and the section is selected based on its structural characteristics and electrode placement plan (generally not more than 10 mm for private housebuilding).For easier fitting included in the solution, one end sharpened.

Rod electrodes make it possible to warm up "fill" with the configuration of any complexity and form, so the most frequently used, especially in the individual building.They feature perpendicular to the longitudinal axis of the structure.And so they do not come into contact with the reinforcing bars cage.

String

In fact, it's kind of the same core, but the location - along the axis of the casing.Apply at warming designs with a small cross section and great length (beams, columns, and several others).To simplify the connection of wires sticking out of the top of the casing edges are bent (the letter "G").

Strip

Represent pieces of iron bars (20 - 50 mm, thickness 3), which are stacked on top of the cast solution.Such heating is used to fill a small thickness (solid screed plate and the like), all elements are placed on one side of the structure.

Plate

are located on opposite sides of the fill, the inside of the casing.Their dimensions are chosen in accordance with its parameters.Naturally, they are installed in pairs, the number and arrangement of which are defined individually for each design.

Types

warm-Through (domestic, submersible)

is used for structures having a greater thickness or a complex shape.As the name suggests, the electrodes are placed inside the filled weight of the solution.General rule - the electrodes are installed at a distance of at least 3 cm from the formwork.

peripheral (surface, sewn)

Under the band established lining.In practice, this most often pieces of roofing material are taken, allowing the electrodes are easily removed and reused.

general rule

If the casing is installed a metal frame, then use voltage over 127 V PROHIBITED .For unreinforced structures, it can be no more than 380 W.

Important Factors for heating concrete

• As curing drenched mass changes its e / resistance, as there is moisture evaporation.Consequently, it is necessary to systematically adjust the force applied current, so the circuit must be switched control element (e.g., resistor, transformer with multiple outputs).
• surface structure to be warming, must be covered with materials that reduce heat loss.This can be sawdust, mats, P / E film, roofing felt, and the like.Otherwise, the process itself becomes meaningless warm.
• When the rod method, you need to follow the same distance between the electrodes in the same row and in the neighboring.This ensures uniformity of "lines" download and eliminate unbalance between phases.
• reduction of energy consumption can be achieved by introducing into the solution of special-plasticizer additives that accelerate the process of concrete hardening.
• Experts do not recommend the use of electrode heating for small designs.For this purpose, there are other methods.
• as "power" can not use a constant current source, as in this case to avoid the electrolysis liquid.
• When small amounts of fill in the welding transformer can be used as a voltage source.
• Uniform recommendations for the placement of electrodes in the (c) there is no filling solution.The scheme is determined individually and depends on external conditions, shuttering parameters of cement and other factors.
• at regular intervals (depending on the specifics of the work) is the temperature measurement.To do this, doing special "pits".
• PROHIBITED.When using the reinforcing cage bars as electrodes to operate with a voltage of over 60 V. In exceptional cases (more of the nominal value) - only if the additional measures and locally (in some segments of the construction).

For quality artificial stone of the solution heating is recommended integrated mass that combines several techniques, including, and "passive" ( "thermos").