GRIMES, WILLIAM DARWIN.

Investigation of concrete-rebar interface conditions was
conducted for the purpose of identifying governing parameters
of the concrete cracking process in seawater. Experiments
included an examination of chloride ion penetration,
concrete pH as a function of metallic chloride concentration,
and pH distribution within reinforced, impressed current
specimens. Metal-concrete systems investigated included
iron, molybdenum, cadmium, zinc, aluminum, copper, and
nickel. Simplified models of the rebar corrosion process
are presented in conjunction with electrochemical analysis
of the projected interface chemistry. Results indicated
that chlorinities greater than seawater concentration may
occur as a result of potential gradients in reinforced concrete.
Laboratory simulations of interface chemistry indicated
that metallic and chloride ions may produce an acid
pH in concrete solutions when present in sufficiently high
concentrations. Heasurements of pH on the fracture face of
impressed current corrosion specimens indicated localized
acidic conditions can develop.