Effect of Fly Ash on the Electrochemical Performance of 316L Stainless Steel Concrete Reinforcement in Saline Environments Attacked by Acid Rain

Abstract

The present study investigates the effect of fly ash (FA) as a corrosion inhibitor on the electrochemical performance of 316L stainless steel concrete reinforcement in a simulating concrete pore solution exposed to a coastal environment that is severely polluted by acid rain (AR). The corrosion behavior of 316L stainless steel is examined by means of cyclic (reverse) polarization in order to evaluate the susceptibility of 316L rebars to localized corrosion. A slightly alkaline solution simulating corroded concrete that has exposed the reinforcement directly to acid rain attack (pH ≈ 8) was chosen as electrolyte. The solution contained Ca(OH)2 partially replaced by FA (0 wt.% - 25 wt.%), an acid rain simulating solution and 3.5 wt% NaCl. The beneficial effect of FA partially replacing Ca(OH)2 (up to 20 wt.% FA) on the corrosion resistance of 316L rebars was manifested by slower corrosion kinetics, nobler corrosion potentials and less susceptibility to localised corrosion. However, these trends were reversed at 25 wt.% FA. The above performance was compared with the corrosion performance in the same electrolyte but without the addition of 3.5 wt.% NaCl.