Wednesday, March 19, 2008 - 4:45 PM
Convention Center, Second Level, 220 (Ernest N. Morial Convention Center)

CACTUS ADDITIONS IN ALKALINE MEDIA AS CORROSION INHIBITORS

Andres A. Torres-Acosta, Universidad Marista de Queretaro AC

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- 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.  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 from microscopic evaluation of the metal surface layer performed at the end of the research program.  The preliminary findings suggest that adding Nopal or Aloe Vera in concentrations between 1% and 2%, by mass, might be suitable for durability enhancing applications in alkaline media, especially in concrete structures.