Yukihito ASANO

Research on corrosion of bridge where weathering steel include the followingˇˇHigh Nickel was used

Eiji IWASAKI

Recently, an important problem is to decrease the cost of the life cycle of the bridge.
Then, the weathering steel was paid to attention. it doesn't coat withˇˇpaint ˇ¤ˇˇThe weather proof steel can be used for a long term even. It has understood from a past research, if it is an environment of 0.05mdd(mg/dm2/day) or less rust that protects steel can be done. The distance of leaving the shore in which the salinity that divided the coast in the whole country into five and came flying did not have to be investigated was decided.
The weather proof steel that contains a lot of nickels has been used since 1997. Even if 0.05mdd is exceeded, this can be used. This steel material was in manufacturer's own right developed. As for this steel material, the alloy is different in each manufacturer. Therefore, a quantitative index that showed it was easy to corrode was made. It is not easy to corrode by the value of this index large. However, there is no standard when this steel material is used for the bridge. Because the analysis and the evaluation are done, the finding of the decision of the standard is obtained.
The followings are the results obtained by this study.
1) An increase of rust was able to be observed by investigating the monitor point. However, the corrosion of the thickness of the board was not able to be observed.
2) The difference is seen from the result of the thickness measurement of rust,the evaluation of externals, and the cellophane adhesive tape examination.
3) From the measurement result of the amount of corrosion, three bridges were estimated to be 0.5mm or less 100 years later.
4) It has been two and a half years from one and a half years since the
bridge was completed. Therefore, it is necessary to be going to investigate in the future.

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