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

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CHAPTER 9. RESEARCH STUDY #2 FINDINGS

There are several findings from the second research study, which include the following:

• An accelerated corrosion test was developed for weathering steel corresponding to a range of exposure conditions that demonstrated sensitivity to chloride environments.

• The protective oxide layer (patina) of weathering steel was degraded above 0.5 wt percent chloride. Above 1 wt percent chloride, the protective oxide was severely degraded.

• Sensors were able to indicate the corrosion rate of coupon material exposed to the same environment.

• Sensors allowed direct and immediate observation of the impact that environmental changes had on corrosion rate.

• XRD showed that the corrosion products produced in cycle test chambers were similar to those observed under field conditions.

• Bridge cable sensors were developed which were capable of monitoring corrosive conditions within suspension bridge cables and other occluded geometries.