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• 1. [Article] Transport of chloride ions during accelerated cathodic protection of reinforced concrete structures

  Chloride ion migration was studied under accelerated cathodic protection conditions using 6" x 6" x 6" mortar blocks of varying initial chloride content and water to cement ratios. An iron mesh embedded ...

  Citation × Citation Citation Abstract Copy Title: Transport of chloride ions during accelerated cathodic protection of reinforced concrete structures Author: Rehani, Manu Chloride ion migration was studied under accelerated cathodic protection conditions using 6" x 6" x 6" mortar blocks of varying initial chloride content and water to cement ratios. An iron mesh embedded parallel to one face in the blocks acted as the cathode and zinc was thermally sprayed on the opposite face to form an anode. First, the potential response of two blocks was studied at a current density of 3 mA/ft². One block was outfitted with a heat sink and moisture barrier while the other block was periodically wetted. Second, eight blocks were polarized at various current densities for a period of one year. In both sets of experiments, the blocks were maintained in controlled humidity and temperature. The potential across the blocks was recorded at periodic intervals and mortar samples were drilled to measure the chloride content as a function of aging. Based on observations of the first study a theoretical model was constructed which indicates that zinc based electrochemical products form at the zinc-concrete interface. The effect of the electrochemical product on raising the resistance across a cathodic protection set-up may be of consequence and should be further studied. Blocks polarized at 6 mA/ft² exhibited similar behavior as the blocks polarized at 3 mA/ft², but the response was twice as fast. This result indicates that studying cathodic protection under accelerated conditions is valid. The chloride content of samples obtained from one set of blocks over the course of the experiment was normalized against the initial chloride profile. The normalized profiles were calculated as a function of aging and they supported the hypothesis that chloride ions would move away from the rebar and towards the sprayed zinc anode under cathodic protection. Title: Transport of chloride ions during accelerated cathodic protection of reinforced concrete structures Author: Rehani, Manu Chloride ion migration was studied under accelerated cathodic protection conditions using 6" x 6" x 6" mortar blocks of varying initial chloride content and water to cement ratios. An iron mesh embedded parallel to one face in the blocks acted as the cathode and zinc was thermally sprayed on the opposite face to form an anode. First, the potential response of two blocks was studied at a current density of 3 mA/ft². One block was outfitted with a heat sink and moisture barrier while the other block was periodically wetted. Second, eight blocks were polarized at various current densities for a period of one year. In both sets of experiments, the blocks were maintained in controlled humidity and temperature. The potential across the blocks was recorded at periodic intervals and mortar samples were drilled to measure the chloride content as a function of aging. Based on observations of the first study a theoretical model was constructed which indicates that zinc based electrochemical products form at the zinc-concrete interface. The effect of the electrochemical product on raising the resistance across a cathodic protection set-up may be of consequence and should be further studied. Blocks polarized at 6 mA/ft² exhibited similar behavior as the blocks polarized at 3 mA/ft², but the response was twice as fast. This result indicates that studying cathodic protection under accelerated conditions is valid. The chloride content of samples obtained from one set of blocks over the course of the experiment was normalized against the initial chloride profile. The normalized profiles were calculated as a function of aging and they supported the hypothesis that chloride ions would move away from the rebar and towards the sprayed zinc anode under cathodic protection. Close