Corrosion inhibitors for concrete from cactus extracts

Abstract

This research in progress includes results on the corrosion performance of reinforcing steel in alkaline media when two different dehydrated cactus (Opuntia Ficus Indica—Nopal) were used as an addition 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 linear polarization resistance (RP) measurements were performed at different time periods to characterize the possible corrosion inhibiting effect of the cactus additions tested. Results showed good corrosion inhibiting effect of dehydrated Nopal on reinforcing steel, in all tested solutions, when chloride ions are present. 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 from microscopic evaluation of the metal surface layer performed at the end of the research program. The preliminary findings suggest that adding Nopal in concentrations between 1% and 2%, by mass, might be suitable for durability enhancing applications in alkaline media, especially in concrete structures.