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Publication Number: FHWA-HRT-09-044
Date: October 2009

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CHAPTER 5. RESEARCH STUDY #1 FINDINGS

There are several conclusions that can be drawn from the first research study. First, the exposure of U-bend specimens fabricated from 16-mm-diameter 2304 SS to simulated pore solution with chlorides at an ambient temperature of 165 oC failed to reveal any susceptibility to stress corrosion cracking. Second, the critical chloride concentration to initiate corrosion of 2304 SS specimens polarized to +100 mVSCE while exposed to simulated pore water to which chlorides were incrementally added ranged from 5.00-9.86 wt percent Cl^-. In addition, no definitive corrosion initiation occurred after 929 days for three concrete slab specimens with 2304 SS reinforcement that were ponded with a Cl- solution. Some momentary activity followed, but repassivation did occur for one specimen. Last, the Cl- threshold to initiate active corrosion of 2304 SS in concrete was greater than 12.5 kg/m³(4.51 wt percent cement).