| The area of Pingtan city,Fujian province is the highest salinity region in China. With the further development of cooperation in economic between the two sides of the Taiwan Strait, a large number of projects such as the construction of the bridge across the sea are gradually being carried out.Trestle bridge of steel is the basic guarantee to ensure the safety and smooth development of the cross sea bridge construction. Experience in engineering construction shows that the corrosion of the coastal steel trestle bridge in Pingtan city is serious. So, this paperlaunchesresearchonthe corrosion of the steel in the actual project of trestle bridge.Use the method of combining theoretical research and experimental verification to study on the corrosion mechanism and present situation of the steel trestle bridge component in Pingtan. And then explore the anti-corrosion technology suitable for Pingtan steel trestle bridge. Finally, the key theories, methods and key technologies to ensure the safety of the existing and newly built trestle bridgecorrosion are provided.First of all, the corrosion of steel trestle bridgein Pingtan has been evaluated. The observation of surface morphology results show that the steel surface deterioration is serious and has lost its original features. The whole silvery white steel is rust into red brown, and surface oxide skin has convexed. Testing the removal of corrosion products of steel shows that corrosion rate was between 0.11mm/a~0.69mm/a. The corrosion rate from high to low is groove steel, steel pipe pile and I-beam. The tensile test of corrosion specimens results show that the corrosion does not affect the tensile strength of the steel, but the serious corrosion has a great influence on the elongation of steel and make the steel toughness significantly reduced. The corrosion of components with higher carbon content is more serious. Groove steel pitting corrosion has further exacerbated the trend. I-beam showed uniform corrosion and the rate is relatively stable.Secondly, explore the corrosion protection technology for steel trestle bridge in Pingtan. Epoxy coal tar pitch and epoxy resin glass fiber cloth were optimized, and the accelerated corrosion test system was designed to simulate the corrosion environment in Pingtan. The corrosion test specimens were prepared by accelerated corrosion test system. The test was carried out by controlling the temperature, humidity, dry wet cycle times, water and salt spray. Then based on the corrosion kinetic equation to calculated accelerated factor. Finally, accelerated corrosion test was carried out according to the method, and the microstructure and morphology of the coating were observed at different stages. Results show thatthe anti corrosion effect of epoxy resin glass fiber cloth in atmosphere, epoxy coal tar pitch in the whole leaching area and tidal zone is better.Third, the corrosion protection effect of different corrosion protective coatings was characterized by electrochemical characterization. Study on the electrochemical characteristics of different corrosion time specimens by using the method of half potential, constant potential polarization and electrochemical noise.Results show thatred lead paint, coal tar epoxy and epoxy glass fiber cloth three kinds of coatings have antiseptic effect on steel substrate,but the coal tar epoxy and epoxy resin and glass fiber cloth on the inhibition effect of the specimen is far better than the red lead paint. The three coatings have barrier effect on the erosion ions. The blocking effect of epoxy coal tar paint is the best. Although epoxy resin anti permeability performance and rustproof paint are poor, but epoxy resin with the surface of the substrate and the binding force is the largest. There is no further corrosion occurs. |
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