Assessment of Paint Layers Quality 1. Field investigations on a railway bridge

摘要

By electrical determinations, digital microscopy and visual observations, the anticorrosive insulation capacity of the paint layers applied to the three sections of a bridge over the Tisza River was assessed. The visual observations have highlighted the fact that on the Eastern section repainted in 2013, biofouling increases are significant (covers up to 10 % of the surface) - both ferns have been identified (Hypogymnia physodes and Xanthoria parietina), filamentous molds (Aspergillus fumigatus and Aspergillus niger) as well as algae and moss (green - capable of photosynthesis). On paint applied in 1986, no bio fouling was visible but the painting material is aged and shows rust traces (5-10 % of the surface) and exfoliation between the paint layers (10-20 % of the surface). No bio fouling and/or exfoliation/degradation of the paint layer have been observed on the paint applied in 2014. Determinations of electrical insulation resistance correlated with those of the paint layers' thickness are closely related to the visual observations. The values obtained for the specific resistivity of the paint layers applied in 2013 (with bio fouling increases) are approx. 38 times lower than those applied in 2014. These findings suggest that the painting material used in 1983 for the top coat realization, showed major qualitative vices.