ELECTROCHEMICAL AND PHYSICOCHEMICAL CHARACTERIZATION OF FLUORINATED ORGANIC COATINGS FOR STEEL AND CONCRETE PROTECTION - INFLUENCE OF THE PIGMENT VOLUME CONCENTRATION

In this paper the electrochemical and physico-chemical characterizatio n of fluorinated coatings was carried out. Their water permeability an d its dependence on the pigment volume concentration (PVC) was quantit atively investigated through electrochemical impedance measurements an d a linear relationship between the maximum amount of permeated water and the PVC was found. The impedance data analysis, performed through equivalent circuit modelling, on results obtained on undamaged and art ificially damaged coatings was used to evaluate the protective perform ance and the retention of the coating adhesion once exposed to aggress ive environments. It demonstrated that these properties are not remark ably affected by the PVC variation, even if the lower the PVC, the hig her the performance of the coatings. The influence of the pigment conc entration on some physico-chemical properties (water vapour diffusion coefficient, tensile strength, tensile strain and gloss) was also eval uated for the optimization of the coating formulation. (C) 1998 Elsevi er Science S.A. All rights reserved.