Evaluation of the Proposed European Test Procedure for Ranking Stainless Steel Rebar

A modified version of EN 480-14 potentiostatic test procedure has been proposed as a rapid “pass/fail” screening test for the range of stainless steel reinforcing alloys currently available. The purpose of the present work was to determine if the proposed experimental details of the test are the most appropriate and result in the same ranking of the alloys as obtained in longer-term, conventional tests. To that end, some of the details of the experimental procedure were modified to allow a more direct comparison with the authors’ results of long-term testing of the same range of stainless steel grades. To this end, the admixed chloride content and applied potential were varied and the bars were embedded in the same concrete mixture (based on an ordinary Portland cement [OPC]/slag blend with 0.40 water/cementitious materials [w/cm] ratio) as in the long-term tests, rather than in OPC mortar with a 0.50 w/cm ratio. For comparison, tests were also conducted on bars cast into a plain OPC concrete with the same aggregates and w/cm ratio. The results illustrate the importance of concrete mixture design, with the steels exhibiting better performance in the OPC concrete than in the OPC/slag concrete under the same conditions. Furthermore, it is concluded that the use of the same constant applied potential for all grades of stainless steel may not be the most appropriate because of the wide range of half-cell potentials exhibited by the different rebar grades. Instead, it is recommended that the same anodic polarization (i.e., the same difference between the half-cell potential and the applied potential) be considered.