Reinforced concrete bridge substructures in Florida coastal waters have historically experienced
deterioration as a consequence of embedded steel corrosion followed by concrete cracking and
spalling. Galvanic anode cathodic protection (CP), as affected by thermally sprayed zinc for cast-inplace
components and zinc mesh jackets for precast ones, has been employed to control this corrosion
and extend useful service life. In either case, the CP systems include a submerged bulk zinc anode
(SBA) to reduce current drain from the lower portion of the thermal spray or jacket components. To
investigate the extent of any contribution of SBAs in protecting the above-waterline zone, two
substructures were instrumented with SBAs only and monitored. In addition, the substructures and
SBAs were modeled using Boundary Element Analysis, the results compared with the field
measurements, and the utility of cp using SBAs alone projected.