Corrosion behavior of HRB400 steel in concrete: Micro-mechanisms of competitive ion effects under alkaline and neutral conditions

Abstract

The corrosion kinetics mechanism of HRB400 steel in alkaline and neutral environments was elucidated through advanced characterization and computational methods. Results reveal that corrosion products formed in 2% Na₂SO₄ impede ionic transport, thereby retarding the corrosion process. At 4% concentration, corrosion products rupture the surface protective film, accelerating corrosion. In simulated sulfate corrosion solutions, the competitive adsorption of OH⁻ ions induces a 0.24 eV increase in surface potential, indicating that hydroxide participation effectively mitigates erosion by highly corrosive ions. The molecular dynamics (MD) simulations were conducted in the NVT ensemble (constant number of particles, volume and temperature) at a temperature of 298.0 K and constant volume. The density functional theory (DFT) calculations were performed using the generalized gradient approximation (GGA) with the Perdew-Wang (PW91) functional with a plane-wave basis set. The charge transfer rate of SO₄²⁻ was found to be 1.24 times that of Cl⁻ in neutral solution and 1.55 times greater in alkaline conditions.

Keywords

steel corrosion / electrochemical properties / structural evolution / density functional theory

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Central South University