TY - JOUR A1 - Ebell, Gino A1 - Burkert, Andreas A1 - Lehmann, Jens A1 - Mietz, Jürgen T1 - Electrochemical investigations on the corrosion behaviour of galvanized reinforcing steels in concrete with chromate-reduced cements JF - Materials and corrosion N2 - The reduction of the chromate contents in cements affects the electrochemical reactions of galvanized reinforcing steels in fresh concrete. By means of electrochemical measurements and bar pull-out tests the effect of chromates on the formation of protective coatings at the zinc and the bond behaviour have been investigated using chromate-containing and chromate-reduced cements. The results have shown that the bond zone was affected as a result of chromate reduction for cement types CEM I and CEM II. The disturbance to the bond zone should be considered as long-term in relation to the pore structure which is formed. The effects on the bond are largely compensated for as the concrete ages. The results of the related bond strength with displacement paths of 0.1 and 0.5?mm, respectively, are still within the range of expected figures for non-galvanized reinforcing steel despite the structural disturbance. Under practical aspects it is not necessary that the existing structural disturbance with respect to bond strength is taken into consideration. KW - Cement KW - Chromate KW - Concrete KW - Electrochemical measurements KW - Galvanized steel KW - Polarization KW - Pull-out tests KW - Reinforcing steel KW - Zinc PY - 2012 DO - https://doi.org/10.1002/maco.201106311 SN - 0947-5117 SN - 1521-4176 VL - 63 IS - 9 SP - 791 EP - 802 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-26568 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Poltavtseva, Marina A1 - Ebell, Gino A1 - Mietz, Jürgen T1 - Electrochemical investigations of carbon-based conductive coatings for application as anodes in ICCP systems of reinforced concrete structures JF - Materials and corrosion N2 - Carbon-based conductive coatings are complex composites, consisting of an organic or inorganic binder and conductive carbon components, for application as anodes in impressed current cathodic protection systems of reinforced concrete structures. The electrochemical properties of three coatings at different humidity and in saturated calcium hydroxide solution were studied by electrochemical methods, such as electrochemical impedance measurement, measuring of open circuit potential over time and galvanostatic polarization. The dissolved organic and inorganic carbons in electrolyte solution were quantified by using a photometric method. The structures of the coatings were investigated before and after the electrochemical tests by microscopy and scanning electron microscope/EDX analysis. The results of the electrochemical impedance measurements show that the tested coatings all have a relatively low resistance, which is between 100 and 200 Ω. The binder and the surface porosity influence the degradation behavior of those coatings. Especially the organic binder reacts with the strong alkaline medium under dissolving of organic carbon. KW - Cathodic protection KW - Corrosion KW - Rebar KW - Reinforcement KW - Concrete KW - Potential PY - 2015 DO - https://doi.org/10.1002/maco.201407680 SN - 0947-5117 SN - 1521-4176 VL - 66 IS - 7 SP - 627 EP - 634 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-33709 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -