Durability study of CRTS III slab ballastless track under the combined effects of fatigue damage and carbonation

Abstract

To investigate the durability issues of CRTS III slab ballastless track concrete under the combined effects of fatigue damage and carbonation, this study develops a carbonation model for concrete and a reinforcement corrosion rate model, based on porous media theory and material transport principles, combined with experimental analyses. Numerical simulations were performed, and the results were compared with experimental data to validate the models' accuracy. The study also explores the influence of various parameters on CO₂ transport and internal reinforcement corrosion within the CRTS III slab ballastless track. The results indicate that, under fixed damage levels and carbonation durations, the carbonation depth of the self-compacting concrete layer is positively correlated with CO₂ concentration and temperature but negatively correlated with relative humidity. The average corrosion rate of the reinforcing steel anode is approximately proportional to the anode-to-cathode surface area ratio. As saturation varies, significant changes are observed in the corrosion potential at the cathode surface, whereas the anode surface shows relatively smaller changes. Additionally, the corrosion of the outermost longitudinal reinforcing steel in the self-compacting layer intensifies with increasing temperature. This model elucidates the mechanisms of CO₂ diffusion and reinforcing steel corrosion in ballastless track concrete under the combined effects of fatigue and carbonation. It provides a theoretical basis for durability analysis and assessment of CRTS III slab ballastless track systems.