The possible susceptibility of tendon strands for Hydrogen Embrittlement (HE) as a result of exposure under stress during the ungrouted period was examined. The work included placing stressed strands in tendon ducts within concrete piles exposed to field conditions for various periods, and subsequent evaluation of the electrochemical and mechanical behavior of the exposed strands for indications of HE as function of exposure regime. Chloride presence, even in small amounts, resulted in surface rust development after periods as short as one week. Mechanical performance per standardized tensile tests was not appreciably degraded, but hydrogen content measurements indicated significant hydrogen buildup. The effect of hydrogen on strand ductility was further investigated with cathodic hydrogen charging to identify regimes of vulnerability. Considerable embrittlement resulted in those experiments. Fracture morphology with a prominent shear component along the drawing direction was observed. However, even noting the above susceptibility, the propensity for brittle behavior of strands stressed while in the ducts was quite limited under the conditions examined.

Subject
Test methods, Hydrogen embrittlement, Water, Hydrogen content, Tendons, Wiring, Stress cracking, Hydrogen charging, Stress, Bending, Piles, Fracture, Hydrogen
Keywords:
Hydrogen Embrittlement, Shear Cracking, Hydrogen Content, Mechanical Testing
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2016
Association for Materials Protection and Performance (AMPP)
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