State of the Art on Cactus Additions in Alkaline Media as Corrosion Inhibitors

A A Torres-Acosta,W Martínez-Molina,E M Alonso-Guzmán

doi:10.1155/2012/646142

Abstract

This research in progress includes results on the corrosion performance of reinforcing steel in alkaline media when two different dehydrated cacti (Opuntia ficus-indica—Nopal—and Aloe Vera) were used as additions in pH 12.5 and 13.3 solutions and in concrete. The dehydrated cactus addition was mixed at different concentrations by either solution or cement mass (0.10%, 0.25%, 0.5%, 1.0%, and 2.0%). Half-cell potentials and LPR measurements were performed at different time periods to characterize the possible corrosion inhibiting effect of the cactus additions tested in such alkaline media. Results showed good corrosion inhibiting effect of dehydrated Nopal on reinforcing steel, in all tested solutions, when chloride ions are present. Aloe Vera did show also corrosion inhibiting improvements in some extent. The addition of such cactus led to an apparent formation of a denser and more packed oxide/hydroxide surface layer on the steel surface that decreased corrosion activity. This oxide/hydroxide layer growth was confirmed by microscopic evaluation of the metal surface layer performed at the end of the research program. The preliminary findings suggest that adding Nopal at concentrations between 1% and 2%, by mass, might be suitable for durability enhancing applications in alkaline media, especially in concrete structures.

Highlights

IntroductionCorrosion inhibitors are widely used in concrete, where conventional formulations often include species (such as nitrite or benzoate) that have significant toxicity [1]
Corrosion inhibitors are widely used in concrete, where conventional formulations often include species that have significant toxicity [1]
The results shown indicated that Nopal additions inhibit the corrosion activity of reinforcing steel when chloride contamination is present

Summary

Introduction

Corrosion inhibitors are widely used in concrete, where conventional formulations often include species (such as nitrite or benzoate) that have significant toxicity [1]. As a result, they are being scrutinized by environmentalists and could be stopped from being used in the near future since they are significant biohazards and pollutants. The ones extracted from cactus plants are the most promising ones [2]. Native to Mexico, today the cactus is commercially grown in Mexico, Chile, Argentina, Morocco, Italy, and parts of California, Texas, and Florida [3]

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Discussion

Conclusion