Using steel in structures requires corrosion prevention. At present, there is no other effective corrosion prevention method than application of coatings. This holds true with structures installed in oceans and coastal areas that are highly corrosive environments such as constantly exposing the structures to atmospheric salinity or with those that require long durability. On the other hand, the durability of coatings is limited as they sustain deterioration by ultraviolet ray or thermal impact or chemical degradation by hydrolysis. As a result, structures need to be recoated every few, a dozen or so years, although the recoating cycle varies depending on environmental conditions. For this reason, the development of more durable corrosion prevention methods has been sought to replace coatings. To meet such a demand, we investigated the possible application of titanium that has an overwhelmingly superior durability against seawater. Our investigation led to the development of a method that covers structures with adhesive titanium foil. To confirm the performance of this corrosion prevention method, we carried out ten years exposure test at Rakuten elevated bridge on the Okinawa Highway involving actual steel structures thus treated. As an excellent test result was recently obtained after eleven years of exposure, taking one year longer than the original plan, we hereby report on the test result.
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