English -- Standard Method of Test for Comparative Qualitative Corrosion Characterization of Steel Bars Used for Concrete Reinforcement (Linear Polarization Resistance and Potentiodynamic Polarization Tests)

Abstract

Scope: This test method describes procedures to evaluate the comparative qualitative corrosion performance of uncoated Corrosion Resistant Reinforcing (CRR) M 334M/M 334 alloy steel bars to those of M 31M/M 31 or other selected reference bars, utilizing electrochemical polarization resistance and potentiodynamic polarization measurements in various test solutions. The test methods evaluate the corrosion performance of the uncoated CRR bars as a function of (1) pH of the environment and (2) concentration of chloride ions, in particular the [Cl–]/[OH–] threshold ratio.  Bars tested in accordance with these test procedures shall be characterized as corrosion-resistant when both of the conditions below are met: The ratio of the polarization resistance (Rp) measured at pH = 10 to the polarization resistance measured at pH = 13 is greater than or equal to (≥) 0.5, i.e., [Rp at (pH = 10)]/[Rp at (pH = 13)] ≥ 0.5, and  The measured pitting potential is greater than or equal to (≥) 250 mV vs. Ag/Ag Cl reference electrode at a [Cl–]/[OH–) ratio equal to 2.  The values stated in either SI or inch-pound units shall be regarded separately as standard. The inch-pound units are shown in brackets. The values stated might not be exact equivalents; therefore, each system must be used independently of the other.  This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety concerns associated with its use. It is the responsibility of the user of this procedure to establish appropriate safety and health practices and to determine the applicability of regulatory limitations prior to use.