An Experimental Approach for Evaluating Marine Exposed Reinforced Concrete Substructures

Simulated reinforced concrete substructure element (piling) specimens were fabricated, cured for twelve months and exposed partially submerged in natural sea water. The specimens were made of mortar with 20% Fly Ash and a low water to cement ratio, simulating a FDOT Type V concrete. Exposure involved, first, intermittent spraying of the above waterline zone to simulate splash and spray and, second, electrically connecting the embedded reinforcement to submerged bare steel bars to affect a potential gradient from relatively negative in the submerged zone to positive in the atmospheric as occurs in actual members. Three different polarization levels were achieved by inserting resistors. On-potentials and 24 hrs depolarization tests at various elevations were used to better understand the influence of these polarizations on potential vs. elevation and how it affects time to activation. Chloride analysis and visual inspection was performed on selected terminated specimens. The proposed specimen geometry coupled to a submerged rebar provides a good alternative to investigate chloride threshold on partially immersed substructures.