Corrosion resistance of electrified railway tunnels made of steel fibre reinforced concrete

Steel fibre reinforced concrete (SFRC) has been widely used in the construction of buildings, roads and bridges where high compressive and/or tensile strength is preferred. From a structural perspective, SFRC is an ideal substitute for conventional steel reinforcement in railway tunnel construction. However, it is still not clear whether discontinuous steel fibres can pick up and transfer stray current, especially stray alternating current (AC), and lead to similar corrosive attacks as occur in conventional steel reinforcement. The development of suitable approaches for the assessment of the corrosion susceptibility of SFRC under stray AC conditions is a primary aim of this paper. The analytical model, validated by experimental data, indicates that SFRC has an inherent corrosion resistance to stray AC due to the electrical double layer developed on the steel surface. The presence of a small amount of chlorides (0.3 mol/L in the concrete pore solution or 2% by mass of cement) however reduces its corrosion resistance.