Електрокорозія бетону і залізобетону: аналіз впливу та методів захисту

Abstract

UA: Стаття присвячена комплексному аналізу проблеми електрокорозії експлуатованих бетонних і залізобетонних конструкцій, зокрема, в умовах електрифікованих залізниць. Розглянуто основні джерела та механізми виникнення блукаючих струмів, їхній вплив на фізико-хімічні властивості бетону і корозію арматури. Особливу увагу приділено порівнянню впливу постійних і змінних блукаючих струмів, а також ролі хлорид-іонів у прискоренні руйнівних процесів. На основі аналізу останніх наукових публікацій і фундаментальних досліджень висвітлено основні аспекти руйнування конструкцій і запропоновано методи їх захисту. Автори статті також розглядають актуальні виклики залізничної інфраструктури України, підкреслюючи необхідність розроблення і впровадження ефективних стратегій для забезпечення її довговічності та безпеки.

EN: The Ukrainian railway infrastructure, as a key economic link, is strategically important but constantly faces significant loads and aggressive environments. This makes it vulnerable to structural damage. One of the most serious threats to the durability of its concrete and reinforced concrete structures is electrocorrosion. This phenomenon is caused by "stray currents" and high voltage, which arise from incomplete insulation between the rails and the ground. These currents intensify the migration of chloride ions and Ca2+ cations, accelerating rebar corrosion and concrete degradation. The article systematically analyzes and summarizes current understandings of electrocorrosion, identifying key destruction mechanisms, influencing factors, and protection methods. It also outlines critical research gaps and practical implications for enhancing railway infrastructure durability. Studying the durability of concrete and reinforced concrete is critically important because, while processes like carbonation and chloride penetration are well-researched, electrocorrosion is a distinct and complex problem. The alkaline environment of concrete usually provides a passive layer on steel rebar, but the penetration of carbon dioxide and chloride ions destroys this protective layer. Stray currents are divided into direct current (DC) and alternating current (AC). DC stray currents, typical for subways, cause significant corrosion of buried metal pipelines and accelerate pitting corrosion of steel, even surpassing the effects of fatigue. AC stray currents, common in ACelectrified railways, lead to a reduction in the service life of structures, although they cause less overall corrosion. The mechanisms of corrosion due to AC stray currents are more complex, including the rectification model, the alkalization mechanism, and the autocatalytic mechanism. Stray currents significantly alter the physicochemical properties of concrete: they accelerate the diffusion of calcium ions, increase porosity, and weaken the concrete's ability to bind chloride ions, creating an accelerated corrosion cycle. Experimental studies have shown that an AC voltage of 40 V, in combination with water flow, causes the maximum loss of concrete strength and intensive dissolution of cement paste minerals. The practical significance of these studies lies in improving the classification of concretes by permeability and developing protective solutions. These solutions include steel and liquid glass screens with deep grounding, as well as replacing traditional rail fastenings on sleepers and ballastless bridge deck slabs with resilient fastenings that have increased electrical resistance. The Ukrainian railway infrastructure faces additional challenges: aging structures, consequences of military actions (damage to railway tracks and electrical infrastructure, which disrupts grounding and insulation), insufficient quality control of materials, and the lack of comprehensive monitoring systems. Conclusions emphasize that electrocorrosion is a complex problem requiring a comprehensive approach to monitoring, diagnostics, and the implementation of modern protection methods. Prospects for further work include developing integrated real-time monitoring systems, in-depth study of the long-term effects of low AC voltages, creating new corrosion-resistant materials, optimizing existing protection systems, and adapting advanced computational methods for predicting degradation processes.