Event Detail

Event Type: 
Applied Mathematics and Computation Seminar
Friday, May 16, 2014 - 05:00
GLK 115

Speaker Info

OSU Civil & Construction Engineering

The variability and uncertainty associated with chloride thresholds for
carbon steel corrosion in concrete can be explained partly by the surface
conditions of steel reinforcement, in particular, by the presence of
crevices on the steel surface. It has been suggested in the literature that
pore solution in the crevices on the steel surface may be different from
that of the bulk pore solution, and this difference may create the necessary
conditions for the breakdown of the passive film. To test this hypothesis, a
numerical investigation was carried out using a non-linear transient finite
element algorithm, which involved the solution of coupled extended
Nernst-Planck and Poisson's equations in a domain that represented typical
surface crevices on carbon steel rebar. The numerical simulations showed
that the chemistry of the pore solution, in particular pH and Cl-/OH-,
within crevices provided more favorable conditions for depassivation than
the bulk concrete pore solution. Local acidification and increase in Cl-/OH-
within the crevice were observed in all simulations, albeit to different
degrees. Simulations supported the hypothesis that the chemical composition
of the pore solution within the crevices differs from that of the bulk
solution through a process similar to the suggested mechanism of typical
crevice corrosion.