Spacing of heating wires for electric heating of concrete

The paper analyzes the formula for determining the spacing of heating wires available in regulatory, technical, and scientific literature. It is shown that this formula originates from the formula for calculating the spacing of heaters in thermoactive formwork. The study concludes that the studied formula is erroneous and proposes another formula which is mathematically rigorously substantiated. Based on E.V. Shubin’s method, the graphs of temperature distribution in concrete between heating wires are calculated and plotted, taking into account their mutual influence at different spacings of wires and their thermal power. The paper proposes a method for determining the dimensions of the near-electrode zone of heating wires and defines the dimensions depending on the spacing of wires. Temperature gradients in concrete are calculated, and the values are compared with the maximum permissible ones. As a result, the paper proves that the spacing range of heating wires recommended by the current regulatory and technical documentation leads to significant temperature stresses. It also gives recommendations for assigning the spacing of heating wires and their thermal power depending on the degree of reinforcement of reinforced concrete structures. Such a spacing of wires ensures the protection of structures from unacceptable temperature deformations.