Multi-Ion Erosion Experiment and Corrosion Mechanism Verification of Steel Fiber–Reinforced Concrete under Stray Current

Abstract

The durability of concrete structures that have been in service for a long time under the coupled action of stray current and salt-brine environment has become increasingly important. Because of the excellent mechanical properties of steel fiber–reinforced concrete (SFRC), erosion experiments of SFRC were carried out to study issues such as the erosion depth, strength loss, ion migration, and microscopic morphology changes of SFRC under the action of stray current in a salt-brine environment. The color test and compressive strength were used to characterize the penetration depth of chloride ions and the strength loss of concrete, respectively. The titration method was used to detect the chloride and sulfate ion content. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) were used to characterize the microscopic morphology and composition; the finite-element method and discrete-element method were used to explain further and verify the mechanism of SFRC corrosion. This research showed under the action of an electric field, chloride ions transport faster than sulfate ions. The strength loss of SFRC is caused mainly by the erosion and expansion of steel fibers. Products such as gypsum and ettringite are generated only in the cathode area, which also reduces the strength of SFRC to a certain extent.