This research carried out the durability assessment of manufactured sand concrete under the combined effects of stray current and chloride ions. Experiments demonstrated that manufactured sand concrete resists chloride ion penetration 15%–25% more than natural sand concrete does, with the best performance registered at 6.4% stone powder content. Stray current causes the electromigration effect which causes chloride ion migration to be more rapid. The depth of chloride penetration is about 30% greater when 10 V is supplied compared to 40 V. COMSOL Multiphysics-based numerical simulations (a finite element analysis software) showed that the irregular morphology of manufactured sand particles increases the transport paths of chloride ions, creating a “tortuosity effect” with a value of 1.35. This value is higher than that of natural sand, which is 1.22, and the circular aggregate models, which is 1.15. At the same time, the stone powder filling effect reduces the porosity of concrete. The simulation results accurately matched the experimental data by more than 90% for the early stage of corrosion. This research offers theoretical evidence for the feasibility of manufactured sand concrete applications in coastal metro engineering and shows its best performance under severe conditions of stray current and chloride exposure. The use of manufactured sand provides significant sustainability benefits by reducing natural sand depletion and environmental impact while maintaining superior durability performance.