Ryuichiro NAKAJIMA
Research on the Long-term Corrosion Prediction by the Short-term Exposure Examination of Weathering Steel
Prof. Eiji IWSAKI
In recent years, public investment in Japan is reduced, and low-cost and durable structures are used intensively. The number of construction using weathering steel, unpainted weathering steel has been increasing.
Regarding weathering steel, it is important to use weathering steel it in consideration of the environmental conditions of a construction site. It is needed to evaluate carefully its application in a certain construction condition before usage. At the moment, local exposure examination is known as one method to evaluate the application of weathering steel. In case of local exposure is 30 ¦Ìm or less in the amount of corrosion for one year, application of weathering steel is possible. However, in the short-term exposure examination, during the exposure examination, there is no index at starting time and end time, and the influence of observed time is not considered.
In this research, we aimed to clarify the influence of the observed time at which a piece of weathering steel is installed in a weathering steel exposure examination. And, we aimed to draw the changes of the long-term corrosion prediction accompanying it. Specifically, we investigated by shifting the starting time of Airborne salt investigation, wind direction and velocity investigation, and an exposure examination for several months. From the results, the relations between the change of the amount of corrosion and other corrosion factors and exposure time were considered. Moreover, the relation of each corrosion factor in the corrosion environment of a researched bridge was grasped, and it proposed about the method of verifying the influence of exposure time on the exposure examination by exposure time.
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