Effect of fly ash on the corrosion performance and structural integrity of stainless steel concrete rebars in acid rain and saline environments

Abstract

The corrosion behavior of 304L stainless steel rebars in an alkaline solution simulating new concrete subjected to acid rain attack and a mildly to slightly acidic solution simulating corroded cover concrete that exposed the reinforcement to direct acid rain attack, was investigated by reverse polarization. Both solutions contained Ca(OH)2 and fly ash (0-25 wt.% of the dry mixture). Concrete cubes containing 0-25 wt.% fly ash and reinforced with 304L rebars were subjected to salt spraying for 4 m. Although the polarization behaviors in the two electrolytes were different, the relative trends with respect to the fly ash contents were similar. The beneficial effect of fly ash (up to 20 wt.%) on the corrosion resistance of 304L rebars was demonstrated. However, a deteriorating effect was realized at 25 wt.% addition. Partial replacement of cement by fly ash did not significantly affect the tensile properties of the 304L rebar before or after 4 m of salt spraying. The elastic modulus and percent elongation presented a slight decrease after 4 m of salt spraying, irrespectively of FA content. Corrosion-wise, 304L can replace 316L stainless steel provided that FA has been added to the concrete mixture, even at low contents (10 or 15 wt.%).

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

“…Nevertheless, even in this case, the very low current densities values in the passive regime in combination with the slightly nobler Ea/c tr values compared to the respective Ecorr values indicate a good corrosion resistance. The above trends are compatible with previous efforts on 316L [14,16] and 304L [15,17] immersed in various AR mimicking electrolytes containing Ca(OH)2 and FA, whilst poor in Cl -. The beneficial effect of the FA partially replacing Ca(OH)2 on the corrosion resistance of the 316L rebars is attributed to the increase in the pozzolanic and cementitious activities.…”

“…Previous studies by the authors have manifested the beneficial effect of FA on the corrosion performance of 316L in concrete pore solutions containing AR mimicking solutions [14][15][16][17]. An optimum content of FA addition (20 wt.%) was identified.…”

“…The agglomerates form thick deposits on the steel surface causing generation of differential aeration cells below them. Consequently, pits are formed that are filled with corrosion products from the interaction between Ca(OH)2, FA, AR, Cland steel [15][16][17].…”

“…In their vast majority, they concern the effect of seawater [6,7,18]. A limited number addresses the effect of acidic environments [14][15][16][17]. However, non-information can be found on the effect of coastal environments burdened by industrial and/or urban pollution, especially as far as restoration works of ancient monument and historical buildings are concerned.…”

Combined Corrosion Inhibitors and Mechanical Properties of Concrete Embedded Steel (AISI 316L) during Accelerated Saline Corrosion Test

“…Previous efforts have studied the electrochemical performance of stainless steels in electrolytes consisting of Ca(OH) 2 and sodium chloride [12] or acid rain solutions [13][14][15][16]. The favorable effect of fly ash (maximized at 20% replacement of Ca(OH) 2 ) has been manifested [13][14][15][16].…”