Hydrogen Permeation Through Cathodically Protected Iron Membranes in Simulated Concrete Environment

Hydrogen permeation through cathodically protected iron membranes in simulated cement pore solution (SPS) with 3.5% NaCl addition was measured using the electrochemical permeation technique. Hydrogen permeation through mortar-covered membranes was also measured in 3.5% NaCl solution using the same technique. The effects of applied cathodic current density, hydrogen charging time, and mortar cover thickness on the hydrogen permeation rate were investigated. Scanning electron microscopy and energy dispersive x-ray spectroscopy analysis were used to examine the membrane surface for solid deposit formation. The results showed that increasing the applied cathodic current density resulted in an increase in the hydrogen permeation current. The permeation current showed a descending trend with time as a result of the formation of calcium-rich deposits on the cathodic surface of the membrane. Surface coverage by the calcium deposits increased markedly after three weeks of hydrogen charging.