This study examines the influence of the steel potential E on the chloride threshold CT for carbon steel reinforcement embedded in concrete. Building upon the authors’ previous findings in alkaline solutions, this study uses realistic concrete conditions, providing a quantitative model for concrete systems. Concrete specimens with embedded rebars were exposed to a cyclic wetting–drying regime using NaCl solution while being subjected to varying levels of cathodic polarization until corrosion initiation occurred. The results suggest that CT remains largely independent of potential above a threshold potential ET0 but increases progressively at more cathodic potentials. The relationship can be expressed as <InlineEquation ID="IEq1"> <EquationSource Format="TEX">$C_{{\text{T}}} = 1.30{ }\% /{\text{cem wt}}.{\text{for }}E \ge - {16}0 \ {\text{m}}V_{{{\text{SCE}}}}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>C</mi> <mtext>T</mtext> </msub> <mo>=</mo> <mn>1.30</mn> <mrow /> <mo>%</mo> <mo stretchy="false">/</mo> <mrow> <mtext>cem wt</mtext> </mrow> <mo>.</mo> <mrow> <mtext>for</mtext> <mspace width="0.333333em" /> </mrow> <mi>E</mi> <mo>≥</mo> <mo>-</mo> <mn>160</mn> <mspace width="4pt" /> <mtext>m</mtext> <msub> <mi>V</mi> <mtext>SCE</mtext> </msub> </mrow> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq2"> <EquationSource Format="TEX">$C_{{\text{T}}} = 1.30 \cdot 10^{{\frac{ - 160 - E}{{520}}}} \% /{\text{cem wt}}.{\text{for }}E < - {16}0 \ {\text{m}}V_{{{\text{SCE}}}},$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>C</mi> <mtext>T</mtext> </msub> <mo>=</mo> <mn>1.30</mn> <mo>·</mo> <msup> <mn>10</mn> <mfrac> <mrow> <mo>-</mo> <mn>160</mn> <mo>-</mo> <mi>E</mi> </mrow> <mn>520</mn> </mfrac> </msup> <mo>%</mo> <mo stretchy="false">/</mo> <mrow> <mtext>cem wt</mtext> </mrow> <mo>.</mo> <mrow> <mtext>for</mtext> <mspace width="0.333333em" /> </mrow> <mi>E</mi> <mo><</mo> <mo>-</mo> <mn>160</mn> <mspace width="4pt" /> <mtext>m</mtext> <msub> <mi>V</mi> <mtext>SCE</mtext> </msub> <mo>,</mo> </mrow> </math></EquationSource> </InlineEquation> corresponding to a cathodic potential shift of 520 mV/dec required for a tenfold increase in CT. The increase in CT is likely attributed to both intrinsic and extrinsic mechanisms: intrinsic effects involve beneficial modifications of the passive layer composition induced by cathodic polarization, while extrinsic effects arise from chloride migration and hydroxide generation near the steel surface. The results emphasize the role of polarization-induced spatial variability in corrosion initiation. Incorporating this behavior into predictive corrosion models could significantly enhance service life assessment of reinforced concrete structures.

On the impact of cathodic polarization on the chloride threshold for carbon steel in concrete

期刊论文
出版模式：

开放获取
发表日期：

2026年3月10日

查看全文

Konstantin Fache,
Sylvia Keßler,
Jörg Harnisch

摘要

This study examines the influence of the steel potential E on the chloride threshold C_T for carbon steel reinforcement embedded in concrete. Building upon the authors’ previous findings in alkaline solutions, this study uses realistic concrete conditions, providing a quantitative model for concrete systems. Concrete specimens with embedded rebars were exposed to a cyclic wetting–drying regime using NaCl solution while being subjected to varying levels of cathodic polarization until corrosion initiation occurred. The results suggest that C_T remains largely independent of potential above a threshold potential E_T0 but increases progressively at more cathodic potentials. The relationship can be expressed as $C_{{\text{T}}} = 1.30{ }\% /{\text{cem wt}}.{\text{for }}E \ge - {16}0 \ {\text{m}}V_{{{\text{SCE}}}}$ $C_{T} = 1.30 % / cem wt . for E \geq - 160 m V_{SCE}$ and $C_{{\text{T}}} = 1.30 \cdot 10^{{\frac{ - 160 - E}{{520}}}} \% /{\text{cem wt}}.{\text{for }}E < - {16}0 \ {\text{m}}V_{{{\text{SCE}}}},$ $C_{T} = 1.30 \cdot 10^{\frac{- 160 - E}{520}} % / cem wt . for E < - 160 m V_{SCE},$ corresponding to a cathodic potential shift of 520 mV/dec required for a tenfold increase in C_T. The increase in C_T is likely attributed to both intrinsic and extrinsic mechanisms: intrinsic effects involve beneficial modifications of the passive layer composition induced by cathodic polarization, while extrinsic effects arise from chloride migration and hydroxide generation near the steel surface. The results emphasize the role of polarization-induced spatial variability in corrosion initiation. Incorporating this behavior into predictive corrosion models could significantly enhance service life assessment of reinforced concrete structures.