What does this research mean for the field?

In sulfide-containing cementitious environments, carbon steel does not passivate but remains immune to chloride-induced corrosion until all reduced sulfur species are completely oxidized, rendering conventional critical chloride threshold concepts inapplicable during this period. Novelty: ClaimNovelty.NOVEL_FINDING. Consensus alignment: ConsensusAlignment.CHALLENGES_CONSENSUS.

What question did this study set out to answer?

To determine how reduced sulfur species and chlorides influence the electrochemical passivation and corrosion initiation of carbon steel in simulated blast-furnace slag concrete pore solutions.

August 29, 2026Construction and Building MaterialsOpen Access

Chloride-induced corrosion initiation of carbon steel in sulfide-containing cementitious environments

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Authors

ANAli NikoonasabFederal Institute For Materials Research and Testing TMT. MüllerFederal Institute For Materials Research and Testing MRMichael RaupachRWTH Aachen University

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Implication

Laboratory study demonstrates that sulfides suppress carbon steel chloride corrosion in slag-based concrete solutions, indicating standard critical chloride thresholds are temporarily invalid.

Key Points

To determine how reduced sulfur species and chlorides influence the electrochemical passivation and corrosion initiation of carbon steel in simulated blast-furnace slag concrete pore solutions.
Conducted electrochemical tests using a three-electrode cell to measure open-circuit potential, polarisation resistance, and electrochemical impedance spectroscopy across anoxic, oxic, and fully oxidized states.
Assessed critical chloride thresholds by incrementally titrating sodium chloride up to 4 M into synthetic slag pore solutions containing varying concentrations of reduced sulfur species.
Carbon steel did not form a passive film in sulfide-containing solutions prior to complete sulfur oxidation, maintaining active open-circuit potentials between −550 and −700 mV Ag/AgCl and polarisation resistance of 3–50 kΩ·cm².
Corrosion initiation did not occur up to 4 M chloride in pore solutions containing ≥ 50 mM hydrosulfide ions, as sulfur species actively scavenged dissolved oxygen below detection limits even after days of air exposure.
Passivation occurred exclusively after full oxidation of reduced sulfur species to sulfate, raising polarisation resistance to 65–145 kΩ·cm² and rendering conventional chloride threshold concepts inapplicable during the unoxidized phase.

Cite This Study

Nikoonasab et al. (2026) studied this question.

synapsesocial.com/papers/6a9298d38e5d7d1fc0c10aab https://doi.org/10.1016/j.conbuildmat.2026.147963

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Implication

Laboratory study demonstrates that sulfides suppress carbon steel chloride corrosion in slag-based concrete solutions, indicating standard critical chloride thresholds are temporarily invalid.

Chloride-induced corrosion initiation of carbon steel in sulfide-containing cementitious environments

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Member takes

Implication

Key Points

Cite This Study

Chloride-induced corrosion initiation of carbon steel in sulfide-containing cementitious environments

Discussion

Member takes

Implication

Key Points

Cite This Study

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