It is recognized that reinforced concrete structures are
often susceptible to stray current corrosion damage. Experiments
have been performed upon a reinforced concrete bridge
model in sea water, and these indicate that 0.01 percent of
stray direct current in this electrolyte may enter the structure.
Alternating current may also contribute to corrosion
of reinforcing steel, though experimental results reveal detection
to be more difficult than for direct current. Two
other sources of current in reinforcing steel are from cathodic
protection systems of utility attachments and from galvanic
coupling of the covered steel and bare steel. Mechanisms
by which the above types of current contribute to deterioration
of reinforced concrete structures are discussed.