The effect of simulated concrete pore solution composition and chlorides on the electronic properties of passive films on carbon steel rebar

Effects of simulated concrete pore solution composition, pH, and added chlorides on electronic properties of passive films on carbon steel rebar were investigated using Mott–Schottky (M–S) analysis. Passive films showed n-type semiconductive behavior with two discrete donor species and high donor densities. Deep donor densities increased with increasing passivation time. Less protective films resulted in lower space charge capacitances and lower flatband potentials. Sulfates had little influence on electronic properties. Chlorides caused a loss of linearity of M–S plots. This loss of linearity required higher chloride levels and longer exposure times to occur in higher pH solutions.