Reinforced concrete--Corrosion.

The FDOT has been using supplementary cementitious materials while constructing steel reinforced concrete marine bridge structures for over 3 decades. Previous findings indicated that such additions in concrete mix makes the concrete more durable. To better understand corrosion propagation of rebar in high performance concrete: mature concrete samples that were made (2008/2009) with Portland cement, a binary mix, a ternary mix and recently prepared (April 2016 with 50% OPC + 50% slag and 80% OPC + 20% Fly ash) concrete samples were considered. None of these concretes had any admixed chloride to start with. An accelerated chloride transport process was used to drive chloride ions into the concrete so that chlorides reach and exceed thechloride threshold at the rebar surface and initiate corrosion. Electrochemical measurements were taken at regular intervals (during and after the electro-migration process) to observe the corrosion propagation in each sample.

Highway drainage pipes utilize concrete reinforced with steel wire to help mitigate water,
earth, and traffic loads. Drainage pipes reinforced with zinc electroplated steel fibers
offer a lower steel alternative to traditional steel wire cage reinforcements. The objective
of the thesis research was to determine the physical and electrochemical characteristics of
zinc electroplated steel fiber corrosion propagation. Experimental programs include:
Fracture analysis of zinc electroplated steel fibers embedded in dry-cast concrete pipes
exposed to varying chloride concentrations; Visual analysis of zinc electroplated steel
fibers embedded in concrete exposed to varying chloride concentrations; Electrochemical
analysis of zinc electroplated steel fibers embedded in concrete exposed to varying
chlorides; Chloride threshold determination for zinc electroplated steel fibers immersed
in simulated pore solution. Between the four experimental programs the most significant
conclusion is that oxygen, moisture, and chlorides past the chloride threshold must be
present for corrosion to propagate significantly on the zinc electroplated steel fibers.