Insights into multiple coupling mechanisms of SO₄^2 −/Cl⁻ and Cr/RE elements on the corrosion resistance of rebar in simulated carbonated concrete pore solution

This study proposes a novel multiple coupling mechanisms of SO₄²⁻/Cl⁻ and Cr/rare earth (RE) elements on rebar corrosion resistance in simulated carbonated concrete pore solution. Increasing sulfate concentration increases the corrosion current density but decreases the average depth of the corrosion pits, ascribed to the competitive SO₄²⁻- Cl⁻ adsorption, leading to a transition from localized to uniform corrosion. There is coupling between RE and sulfate, Cr. Specifically, RE and sulfate form an insoluble salt to block the corrosive medium; RE confers a nucleation advantage to Cr oxides amidst the competitive dynamics between nucleation and growth within the rust layer.