Model
Digital Document
Publisher
Florida Atlantic University
Description
Effects of reinforcement and coarse aggregate on chloride ingression into
concrete and reinforcement corrosion initiation have been studied with experimental
and modeling (finite element method) analyses. Once specimens were fabricated
and exposed to a chloride solution, various experimental techniques were employed
to determine the effect of reinforcement and coarse aggregate on time-to-corrosion
and chloride ingress and concentration at corrosion locations. Model analyses were
performed to verify and explain the experimental results. Based upon the results, it
was determined that unexpectedly higher chloride concentrations were present on
the top of the rebar trace than that to the side at the same depth and an inverse
concentration gradient (increasing [Cl-] with increasing depth) occurred near the top
of rebars. Also, coarse aggregate volume profile in close proximity to the rebar and
spatial distribution of these aggregates, in conjunction with the physical obstruction
afforded by reinforcement to chloride flow, complicates concrete sampling for Cl- intended to define the critical concentration of this species to initiate corrosion.
Modeling analyses that considered cover thickness, chloride threshold concentration,
reinforcement size and shape, and coarse aggregate type and percolation confirmed
the experimental findings. The results, at least in part, account for the relatively
wide spread in chloride corrosion threshold values reported in the literature and
illustrate that more consistent chloride threshold concentrations can be acquired
from mortar or paste specimens than from concrete ones.
concrete and reinforcement corrosion initiation have been studied with experimental
and modeling (finite element method) analyses. Once specimens were fabricated
and exposed to a chloride solution, various experimental techniques were employed
to determine the effect of reinforcement and coarse aggregate on time-to-corrosion
and chloride ingress and concentration at corrosion locations. Model analyses were
performed to verify and explain the experimental results. Based upon the results, it
was determined that unexpectedly higher chloride concentrations were present on
the top of the rebar trace than that to the side at the same depth and an inverse
concentration gradient (increasing [Cl-] with increasing depth) occurred near the top
of rebars. Also, coarse aggregate volume profile in close proximity to the rebar and
spatial distribution of these aggregates, in conjunction with the physical obstruction
afforded by reinforcement to chloride flow, complicates concrete sampling for Cl- intended to define the critical concentration of this species to initiate corrosion.
Modeling analyses that considered cover thickness, chloride threshold concentration,
reinforcement size and shape, and coarse aggregate type and percolation confirmed
the experimental findings. The results, at least in part, account for the relatively
wide spread in chloride corrosion threshold values reported in the literature and
illustrate that more consistent chloride threshold concentrations can be acquired
from mortar or paste specimens than from concrete ones.
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