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

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.

Effect of Organic and Inorganic Corrosion Inhibitors on Strength Properties of Concrete

“…Corrosion inhibitors forms shielding hydrophobic film on the rebar surface in high alkalinity concrete environment by adsorbing the ions of inhibitors on to the surface which eventually delays the rate of corrosion by obstructive cathodic /or anodic reactions [7]. More technically, inhibitors forms coordinate bonds by contributing electrons to available d-orbitals of iron atoms and ultimately encouraging the adsorption of anti-oxidant molecules on the surface of rebar developing a protective layer around rebars inhibiting electrochemical process reactions such as anodic process (iron oxidation) and cathodic process(oxygen reduction) [8]. The success of inhibitors is governed by primarily the molarity or the concentration of inhibitor used.…”

Opuntia ficus-indica (Nopal Extract) as Green Inhibitor for Corrosion Protection in Industrial Steels

“…Chandra [66] and Torres Acosta [17] studied the effects of dehydrated Nopal and Aloe vera powder in the electrochemical performance of reinforcing steel in chloride contaminated concrete. Preliminary results suggest that adding these powders in small concentrations might be suitable for enhancing corrosion resistance of steel in concrete.…”

Effect of the Addition of Dried Opuntia Cactus Fibers-Setting Times and Mechanical Resistance in Portland Cement Mortar Base

“…An important feature of the nopal is its high content of carbohydrates (glucose), which are grouped in large starch chains, which when considered as an additive in the manufacture of mortars for mixing water retention, promote the setting [10,11,19]. Cement pastes decrease the permeability, improve durability and increase the compressive strength [9,20].…”