Search

Monolithic construction has now become widespread in our country and around the world. In countries with a cold climate, monolithic construction has a serious drawback – it is the need to ensure the hardening of freshly laid concrete at low and negative temperatures. In Russia, there is a practice of using heating wires to solve this problem. This method of heat treatment has a number of serious drawbacks, which requires the search for new and more efficient organizational and technological solutions for the implementation of heat treatment of elements of a monolithic structure. First of all, this applies to monolithic floors with large dimensions, which makes it difficult to carry out such processing. As preliminary experimental studies have shown, a very promising solution to this problem is the use of electric heating of concrete by induction method with currents of increased frequency of 10-20 kHz. Methods of solving the problem are considered. The article presents a variant of the application of this method of electrothermal treatment of concrete mix after laying in the formwork. The basic relations describing the electrothermal effect of the variable electromagnetic field of the inductor on the concrete mixture are obtained. A map of technological operations has been developed to describe the organization of the technological process of manufacturing a monolithic floor with the use of electric thermal treatment by induction method. It is shown that, in contrast to the case of using electric thermal treatment with heating wires, the use of the induction method allows you to start electric thermal treatment as soon as the next part of the concrete mixture is delivered, unloaded and laid, without waiting for the concrete mixture to be laid within the entire gripper. The resulting graph of changes in the time of electric power consumption indicates a more uniform load of power supply networks and a decrease in the maximum power consumption. The results presented in the article give grounds to conclude that the electrothermal treatment of a concrete mixture of monolithic floors by induction method has undoubted organizational and technological advantages compared with the use of heating wires. [ABSTRACT FROM AUTHOR]