Abstract
Abstract This paper shows the analysis performed on the corrosion parameters of three groups of reinforcing steel bars, two of these coated by electroplating process with Zinc (Zn) and Zinc-Nickel (Zn-Ni), and the other without any coating. It was used reinforced concrete specimens, which ones were grouped and then subjected to two different corrosion accelerating methods: aging wetting/drying cycles and salt spray exposure. Corrosion potential was measured to qualitative monitoring of the process and, after the end of the tests, corrosion rate was estimated by measuring the mass loss, to quantitative analyses. As it was expected, coated bars presented a better performance than the average bars regarding the corrosion resistance in chloride ions containing environments. It was also observed that the drying/ NaCl solution wetting cycles seems to be more severe than salt spray fog apparatus with respect to the acceleration of corrosion process.
Highlights
Corrosive processes in reinforced concrete structures put at risk the integrity of their users and have become usual in Brazil, mainly in coastal constructions since most of Brazil’s population lives along the coast [1]
This paper shows the analysis performed on the corrosion parameters of three groups of reinforcing steel bars, two of these coated by electroplating process with Zinc (Zn) and Zinc-Nickel (Zn-Ni), and the other without any coating
The zinc (Zn) is the metal more frequently used in these coatings [3], mainly because of its ability to create a dense and adherent protective film on the bar surface, causing the corrosion rates to become lower than the ones observed in ferrous materials
Summary
Corrosive processes in reinforced concrete structures put at risk the integrity of their users and have become usual in Brazil, mainly in coastal constructions since most of Brazil’s population lives along the coast [1]. The steel bar is immersed in molten Zinc, while in the second one ions of a more noble metal are deposited on the substrate due to the application of an electric current This last method is a quite common process in the industry, producing a layer that is extremely thin and relatively free of pores, avoiding material waste [5,6,7]. Since the interpretation of the results from the electrochemical procedures will be influenced by the change in the potentials of Zinc, Zinc-Nickel and steel, it is fundamental to know how to interpret these Zinc and Zn-Ni values, because the standard corrosion and passivation ranges do not suit them [4] As it was observed before by Sherine et al [11] and Panek et al.[12], when steel is electroplated with Zinc, its potential of corrosion regarding the saturated calomel electrode gets lower values to indicate high probability of corrosion, that is below -1.043 V, and passivation state, which is above -0.650 V. Still according to Panek et al [12], the potential of corrosion that indicates high probability of corrosion of the steel electroplated with a Zinc-Nickel alloy is
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