This paper addresses the issue of safe cathodic protection limits for pre-stressing steel in concrete given the concern of hydrogen embrittlement (HE). The local environment at the steel/concrete interface was found to vary as a funct ion of vertical position within a laboratory scale marine bridge piling. Embedded pH electrodes indicated that the pH within a steel crevice embedded within a concrete piling decreased from 12.5 to 7.7 in the atmospheric zone 30.5 cm above the waterline. Hydrogen permeation was detected using embedded sensors at applied potentials (Eapp) as positive as -694 mVsce which also confirmed a local pH drop to below 8. In light of this information, a reversible electrode potential (REP) -based safe limit would require knowledge of pH and Eapp as a function of vertical position, as well as an understanding of their influence on HE. To address the latter issue, notched pre-stressing steel tensile specimens were CERT tested at various cathodic polarization levels in (i) saturated Ca(OH)2, (ii) ASTM artificial oceanwater, (iii) under a mortar cover in ASTM artificial oceanwater, and (iv) a pH 4 environment simulating ferrous ion hydrolysis on corroding pre-stressing steel. CERT results were combined with permeation measurements to determine the relationship between mobile hydrogen concentration...
Keywords: Hydrogen Embrittlement, Cathodic Protection, Pre-stressed Concrete, Local Environment, permeation