Zairyo-to-Kankyo
Online ISSN : 1881-9664
Print ISSN : 0917-0480
ISSN-L : 0917-0480
Influences of High Pressure Water Washing on the Characteristics of Rusts and the Corrosion Rate of Weathering Steels
Suppression of Deicing Salt-Induced Corrosion of Weathering Steel Bridges by Water Washing (2)
Shuichi HaraMasazumi MiuraYasushi UchiumiToshiaki FujiwaraMasataka Yamamoto
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JOURNAL FREE ACCESS

2005 Volume 54 Issue 7 Pages 344-349

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Abstract

To prevent the deicing salt-induced severe corrosion of weathering steel bridges, shikoku Regional Bureau of Japan Highway Public Co. (JH-Shikoku) performed water washing test of 2 bridge girders for 3 years. The supplied water pressure was 2-4MPa and the flow rate was 3-5.5l/min. The periodical water washing was done at the beginning of April after the seasonal sprinkling of deicing salts in every year. The rust layer formed on the washed part was characterized in a manner similar to the previous paper and was compared to the rust layer on no-washed part. The rust layers were characterized at two times, i. e.: the day (beginning of April) after the water washing was finished and the day (beginning of November) before the seasonal sprinkling of deicing salts. After the water washing, the concentration of soluble chloride ion of the rust layer decreased to approximately half of the seasonal peak in winter. The increase of rust layer thicknesses and the mass of rust per unit area on the washed parts were constantly suppressed during the experimental period. The corrosion loss of the steel with washed rust layer was smaller than the steel with no-washed rust layer. The specific surface area (SA) of the rust particles formed on the washed part was kept larger even in summer, when SA decreases in general by the high concentration of residual chloride ion. It is suggested that water washing has preserved the protectiveness of rust layer by the suppression of size growth of rust particles owing to chloride ion. Periodical water washing as a prevention technique to deicing salt-induced corrosion is useful for the maintenance of weathering steel bridges.

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© Japan Society of Corrosion Engineering
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