Corrosion protection assessment of concrete reinforcing bars with a geopolymer coating

Steel reinforcing bars (rebars), with and without a geopolymer coating, were embedded in mortar and subjected to accelerated general corrosion using impressed current. The percent corrosion (mass loss) of the bar was estimated using Faraday's law in situ and confirmed by direct measurement of mass loss after extraction. Results are very encouraging and indicate that the geopolymer coating provides the means to reduce activity of the corrosion process. This reduction in corrosion activity would result in a decrease in maintenance and rehabilitation efforts and in an increase in service life of steel reinforced concrete structures with respect to corrosion. For example, after nine days of accelerated corrosion, the mortar specimen reinforced with a geopolymer-coated bar had about 5% corrosion, while the mortar specimen reinforced with a bar without a geopolymer coating had accumulated over 20% corrosion. Both reinforced mortar specimens were monitored using guided mechanical waves to nondestructively assess the interface conditions between the steel and concrete, with results provided.