Effect of chloride concentration on the pitting and repassivation potentials of reinforcing steel in alkaline solutions
- Univ. of South Florida, Tampa, FL (United States)
Reinforcing steel bars ({approximately}12mm diameter and 150mm long) were used in cyclic polarization tests in saturated Ca(OH){sub 2} solution and simulated concrete pore solution (SPS) with various levels of sodium chloride addition. Below a limiting chloride level ({approximately}O.004M [Cl{sup {minus}}] in Ca(OH){sub 2} solution and {approximately}0.4M [Cl{sup {minus}}] in SPS solution), steel was not found to undergo pitting corrosion even if it was polarized to the oxygen evolution potential ({approximately}O.6V/SCE). At higher NaCl addition, pitting corrosion could often be initiated but the pitting potential was non-deterministic to a great extent. In Ca(OH){sub 2} solution the average pitting potential was found to be strongly dependent on chloride concentration when [Cl{sup {minus}}]{ge}0.008M. In SPS solution, the average pitting potential was almost independent of the chloride concentration when [Cl{sup {minus}}]{ge}0.8M. The repassivation potential was found to be a strong function of the severity of corrosion attack that has occurred on the steel surface before repassivation, rather than a function of the chloride content of the bulk solution. The pitting tendency in chloride-containing SPS and Ca(OH){sub 2} solutions was interpreted on a statistical basis. The threshold thus determined good agreement with other values reported in the literature.
- OSTI ID:
- 697085
- Report Number(s):
- CONF-990401--
- Country of Publication:
- United States
- Language:
- English
Similar Records
The effect of chromate concentration on the repassivation of corroding aluminum
Initial steps of corrosion in the steel/Ca(OH)[sub 2] + Cl[sup [minus]] system: The role of heterogeneities on the steel surface and oxygen supply