Theoretical Model for Critical Chloride Content at Rebar Depassivation Based on Corrosion Thermodynamics
LI Chenzhi
SONG Xiaobin
JIANG Chao
Abstract：Theoretical models for pitting potential(Epit)and self-corrosion potential(Ecorr)of rebar were established based on the pitting nucleation mechanism and steel polarization theory,respectively.Based on corrosion thermodynamics,the critical chloride content(Ccrit)on the surface of rebar was defined as the chloride content(c(Cl-)/c(OH-))at which Epit is equal to Ecorr,and a theoretical model for Ccrit at rebar depassivation was proposed.The results indicate that Epit exhibits a negative linear correlation with lg[c(Cl-)/c(OH-)].An increasing chloride content decreases Ecorr by causing a negative shift in the anodic polarization curve rebar.Ccrit varies exponentially with Epit,Ecorr,temperature and pH value of concrete pore solution,which partly accounts for its significant scatter.For a typical temperature of 298 K and a pH value of 13.5,the benchmark value of Ccrit is 1.41.
Keywords：pitting potentialself-corrosion potentialcorrosion thermodynamicscritical chloride content
Publication Date：2025-05-30
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：7( 404-410 )