Analysis of iones (K%2b, Na%2b) migration paths in the concrete matrix; through an equivalent circuit associated to the loss of bond in the concrete-steel interphase

This work analyzed the degradation of the bond between steel and concrete under protection conditions (-1000 mV ≤ E ≤ -850 mV vs. Ag/AgCl) and overprotection (E <-1000 mV vs. Ag/AgCl) cathodic by impressed current are based on a model of paths in the concrete matrix and an equivalent circuit. Considering two mixtures immersed in a 3.5%25 solution of NaCl; the first with ordinary Portland cement (OPC) and the second replacing 15%25 cement with fly ash (OPCFA). Based on analysis obtained from the equivalent circuit showed greater continuous conductivity resistance path (CCRP), the specimens with protection potentials and charge transfer resistance (Rct). Marking a difference of protection and cathodic overprotection in the corrosion rate, and the increasing of the concentration of potassium, sodium (K%2b, Na%2b) ions; in the specimens submitted to levels of overprotection, which presented greater bond loss based on the results of the pull out test. ©The Electrochemical Society.

Cements; Charge transfer; Concretes; Fly ash; Portland cement; Timing circuits; Cathodic Overprotection; Charge transfer resistance; Concrete matrix; Impressed current; Migration path; Ordinary Portland cement; Overprotection; Protection potential; Equivalent circuits

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