"Long-Term
Performance of an
Organic Corrosion
Inhibitor"
"Corrosion Inhibition
Properties of a
Complex Inhibitor -
Mechanism of
Inhibition"
"The Effects of
Calcium Nitrite and
Mix Design on the
Corrosion Resistance
of Steel in Concrete"
"Modelling Chloride
Diffusion in Concrete.
Effect of Fly Ash and
Slag"
|
"Long-Term Performance of an Organic Corrosion Inhibitor", J. K. Buffenbarger, M. A. Miltenberger, B. D. Miller and H. L. Casal, International Congress on Advanced Materials, their Processes and Applications, Munich, Germany, September 2000
An organic corrosion inhibitor (OCI) comprising an aqueous emulsion of esters and amines is a mixed inhibitor, affecting both the anodic and cathodic reactions of corrosion through an active-passive mechanism. This study, extending over a decade, explores the active part of the OCI, which is a film-forming amine (FFA), using Fourier transform infrared spectroscopy (FTIR) in grazing reflection. The passive mechanism of the OCI reduces permeability by the hydrolysis of an organic, waterproofing ester (WP) and deposition of insoluble calcium salts of fatty acid within concrete pores. Low-carbon steel coupons were soaked in water or limewater with the OCI and its separate components. Iron oxides (Fe2O3 and Fe3O4 corrosion products) were observed on reference coupons but not on coupons treated with OCI. FFA and WP could be deposited from hexane onto the steel coupons and identified by FTIR, but only the WP could be washed off with hexane. Linear polarization tests showed very high resistance (i. e., low corrosion) for the OCI-treated coupons compared to the reference coupons, and this was confirmed by inactive corrosion potentials (from -198 to -226 mv vs. SCE) compared to -470 to -533 mv for the references. Electrical impedance spectroscopy (EIS) likewise showed the OCI-treated coupons to be very passive. Three reference concretes and one OCI-treated concrete were made in accordance with ASTM C-192 and G-109. Tests were performed to determine chloride flux, diffusion coefficient by chloride migration and capillary absorption rate. Conditions during diffusion in the first two tests are different but the OCI-treated concrete had lower diffusion coefficients in both - approximately 13% lower in chloride flux testing and 30% lower in chloride migration testing. A reduction of 56% in the capillary absorption rate was seen for the OCI-treated concrete. The OCI admixture reduces the chloride build-up rate, reduces the chloride diffusion coefficient, moderately increases the chloride threshold and slows the rate of corrosion after initiation. The result of all these effects is improved corrosion resistance and increased durability in chloride environments. |
Axim Concrete Technologies | Euclid Chemical Company | Grace Construction Products
BASF Admixtures | Sika Corporation
Arnie Rosenberg, Executive Director
Email: info@corrosioninhibitors.org
Phone: 301-340-7368