Effectiveness of Repair Methods of Corroded Bridge Cables

摘要

It is important to repair the corroded bridge cables by proper methods so that corrosion does notrnprogress further. Six repair methods were proposed and applied to cable specimens. Then, thernspecimens were exposed to the severe corrosion environments and the effectiveness of the proposedrnrepair methods was compared. Two different types of test cables were used in this study: parallelrnwire strands and spiral strands. The parallel wire strand cables consist of 19 non-galvanized steelrnwires. This aimed at the main cables of suspension bridges. Six repair methods were applied tornthese cable specimens: coating with zinc or epoxy resin paint or zinc powder paste, filling withrnepoxy resin or oil, and dehumidification method. Then the specimens were wrapped with wet gauzernand kept at 40℃ for 15 months to accelerate corrosion. By investigating mass loss due to corrosionrnand appearance during this period, effectiveness of six repair methods was compared. As for thernsurface wires, the dehumidification method was the most effective followed by the epoxy resinrnpaint and filling, the zinc powder paste, and the zinc and epoxy resin paint on the surface. The oilrnfilling was not very effective compared with other repair methods. The corrosion of the inside wiresrnwas much less than those of the surface wires. The spiral strand cables consist of seven galvanizedrnsteel wires. This test aimed at hangers of suspension bridges and stays of cable-stayed bridges. Byrninvestigating mass loss due to corrosion and appearance of both inside and surface wires during thern16 month period, the proposed six repair methods were all very effective compared with those ofrnun-repaired strands. This study proves that, even if a cable is corroded, proper repair works arerneffective in preventing further corrosion.