DEVELOPMENT OF IDEAS ABOUT ELECTRICAL CORROSION OF RAILWAY TRACK STRUCTURES AND IMPROVEMENT OF THEIR PROTECTION METHODS USING ELECTRICALLY CONDUCTIVE COMPOSITIONS

Abstract

Research is devoted to the  development of ideas about the mechanism of the flow of corrosion currents through the structures of railway tracks and buildings and the justification of methods of their protection against electrical corrosion. As a result of theoretical studies and field tests, the electric circuits of the leakage currents from the pulsating unidirectional electric potential of the POEP, which arise during the passage of the electric rolling stock along the electrified direct current railway tracks, have been clarified. Current carriers are installed in the elements and  structures of the track and buildings. In concrete, soil, which are conductors of the second kind, these carriers are mainly cations Ca2+, Na+, anions OH-. It was found that in reinforced concrete sleepers, supports of passenger platforms due to the influence of POEP, zones of neutralization and leaching of concrete, cathode and anode zones of steel reinforcement are formed. Corresponding chemical and electrochemical reactions of leaching and carbonization of lime, oxidation of iron, etc. occur in these zones. It is proposed to prevent corrosion processes in these zones by diverting currents with grounded screens-coatings made of electrically conductive compositions based on mineral binders -Portland cement with a complex chemical additive or sodium silicate and a filler - dispersed graphite. The proposed indicator of the  effectiveness of these screens-coatings, which is the degree of reduction of the current strength through the structure. As a result of experimental studies, it was  established that it depends on the share of the contact area of the steel grounding device with the screen from the area of the screen itself, and the corresponding dependencies were obtained. New methods of protecting track structures and structures from electrical corrosion are substantiated, and appropriate structural and  technological solutions are developed.