Title:
Cathodic Protection and Hydrogen Generation
Author(s):
Brian B. Hope and John S. Poland
Publication:
Materials Journal
Volume:
87
Issue:
5
Appears on pages(s):
469-472
Keywords:
cathodic protection; embedment; gas chromatography; hydrogen; polarization; prestressed concrete; prestressing steels; tests; Materials Research
DOI:
10.14359/1853
Date:
9/1/1990
Abstract:
The potential at which hydrogen evolution occurs on the surface of steel embedded in concrete must be determined accurately if cathodic protection is to be safely applied to prestressed concrete structures. Concrete specimens containing embedded steel were polarized using both rectified unfiltered AC current and true DC current from a potentiostat. Commercial cathodic protection rectifiers have characteristics between these two extremes. The specimens were enclosed in bell jars and samples of the air above the specimens were periodically collected and the presence and quantity of hydrogen was determined using gas chromatography. With the unfiltered current, hydrogen was first generated when the instant-off half cell potential was 0.94 volts CSE. At this potential, the peak was 1.37 volts CSE. With true DC current, hydrogen was first generated when the applied potential was between 1.1 and 1.2 volts. At applied DC potentials of 1.3 and 1.4 volts, 32 and 79 percent, respectively, of the applied energy was being used to generate hydrogen.