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/ft��. 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/ft�� exhibited similar behavior as the blocks polarized at 3 mA/ft��, 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. / Graduation date: 2001
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/32791 |
| Date | 08 June 2000 |
| Creators | Rehani, Manu |
| Contributors | Koretsky, Milo D. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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