Many corroding interfaces exhibit electrochemical impedance response similar to that of a polarization resistance associated with the corrosion process, in parallel with a Constant Phase Angle Element (CPE) having relatively large admittance. Such conditions are often encountered in the case of steel in concrete. While polarization measurements using a forward and reverse potential scan rate dV/dt can be helpful to subtract the contribution of an ideal interfacial capacitance C by using a C dV/dt correction, in concrete the pronounced frequency dispersion of the CPE complicates the time domain response and correction is not straightforward. A solution to the problem is presented in this paper and applied to evaluate the CPE parameters and estimate the polarization resistance of steel in concrete from cyclic-scan polarization measurements. The technique is demonstrated for experiments with plain steel and galvanized rebar in concrete.

Subject
Electric current, Electrochemical impedance spectroscopy, Cyclic polarization, Corrosion rate, Circuit potentials, Storage, Constants, Interfaces, Steel, Polarization resistance, Concrete, Step potential, Electrode potential
Keywords:
concrete, corrosion, constant phase angle element, cyclic polarization, modeling, reinforcing steel
© 1997 Association for Materials Protection and Performance (AMPP). All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means (electronic, mechanical, photocopying, recording, or otherwise) without the prior written permission of AMPP. Positions and opinions advanced in this work are those of the author(s) and not necessarily those of AMPP. Responsibility for the content of the work lies solely with the author(s).
1997
Association for Materials Protection and Performance (AMPP)
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