دانلود رایگان مقاله انگلیسی قطبش الکتروشیمیایی و امپدانس بتن آرمه و بتن مسلح ترکیبی تحت شرایط ماتریکس - الزویر 2018

Abstract:

In this paper, we investigate the influence of cementitious matrix cracking on the electrochemical polarization and impedance behaviors of corroding reinforced concrete and crack-resistant reinforced hybrid fiber-reinforced concrete (HyFRC). Samples were exposed to a chloride environment for 2.5 years while in either a continuous tensile stress state or in a nonloaded condition, and were periodically monitored for Tafel polarization responses. Electrochemical impedance spectroscopy (EIS) was additionally performed at the conclusion of the test program. Greater severity of corrosion-induced splitting matrix cracks along the length of embedded steel reinforcing bars and subsequent formation of anodic surfaces were found to affect several electrochemical parameters, including increase of the corrosion current and decrease of the ohmic resistance of concrete. Cathodic and anodic Tafel coefficients and Stern-Geary coefficients for passive and active samples are also reported, highlighted by a Stern-Geary coefficient of B=28.1 mV for active corrosion.

5 Summary and conclusions

The corrosion behavior of conventional reinforced concrete and reinforced hybrid fiber reinforced concrete (HyFRC) was found to be highly dependent on the cracked state of the composite matrix. A corrosive environment was prepared by allowing 3.5% w/w NaCl solution to permeate the porous cementitious matrix of samples containing a single steel reinforcing bar (rebar) in a wet-dry cyclic manner over a 2.5-year experimental duration. To account for cracks that are present in civil engineering structures in service, subsets of specimens were subjected to the same applied tensile load during environmental exposure. Corrosion potential measurements, linear polarization tests, and Tafel polarization tests were periodically conducted to monitor the electrochemical response of samples during the experiment. In addition, electrochemical impedance spectroscopy (EIS) was performed to evaluate the differences in the impedance responses between samples as a result of accumulated matrix cracking.