Opuntia-Ficus-Indica (Nopal) mucilage as a steel corrosion inhibitor in alkaline media

This paper presents results on the corrosion performance of reinforcing steel in alkaline media when dehydrated Opuntia Ficus Indica (Nopal) was used as an admixture. The dehydrated Nopal material was mixed with saturated calcium hydroxide (SCH) at 0.5, 1.0, and 2.0% by weight. Half cell potentials and Linear Polarization Resistance (LPR) measurements were performed at different time periods to characterize the corrosion inhibiting effect of the admixture. Results showed good corrosion inhibiting effect of dehydrated Nopal on reinforcing steel. The polarization resistance (Rp) value increased from an average of 40 k Omega cm 2 for regular chloride-contaminated SCH solution, to an average of 150 k Omega cm(2) for Nopal-added chloride-contaminated SCH solutions. The addition of Nopal led to the 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 experiment.