Research on Installation Technologies of Corrosion Protection for Steel Structures
Keywords:preparation level of steel surface, steel protection from corrosion, painting systems, salt spray test, adhesion test
Rusted S275 steel profiles were used in the experimentation. According to standard ISO 8501-1 the steel rust grade - B. The steel was cut into nine samples with dimensions 150x150 mm. and brought into three groups with three samples in each group. In each group the surface for anticorrosive coating of specimen was prepared in three different methods. The steel surface was sandblasted using quartz sand with fraction 0-0,8 mm. Using this method the preparation level of surface Sa 3 according to standard 8503-1 was achieved. The specimen in second group were prepared by mechanical method using the wiry brush. The level of surface St 2 was achieved according to standard ISO 8503-1. In third group the specimen have not been prepared in any method. According to the standard ISO 12944-5:2007 three different anticorrosive coating systems were selected: one component alkyd paint system, two component epoxy and polyurethane paint system and two component zinc, epoxy and polyurethane paint system. The paint systems were selected considering the category of corrosion C3 and C4. The coating of paint systems were performed using the airless painting equipment. The thickness of each layer, wet and dry, were controlled. The thickness results of dry coating were measured with digital device “Positector”. To accelerate the process of corrosion, the aggressive artificial atmosphere was created according to the standard ISO 9227:2017 Corrosion tests in artificial atmospheres – Salt spray tests. Neutral salt spray test is the method in which 5 % neutral sodium chloride melting is automated in controlled environment. The sufficient amount of sodium chloride is melted in distilled water with specific conduction not exceeding the 20 µS/cm at 25 0C ± 2 0C to get the concentration of 50 g/l ± 5 g/l. The steel samples were kept in artificial atmosphere for 500 hours. Anticorrosive coating characteristics for differently prepared surfaces were analysed by testing the adhesion according the standard ISO 4624:2016 using digital adhesion gauge “Elcometer 506”.
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