1DDevelopment of new recoating systems to reduce environmental loads for steel railway bridges
  • Development of new recoating systems (ECO) to significantly reduce environmental loads
  • Achievement of lead-free paint to cut hazardous chemical substances by about 70% and VOC by about 80%
  •    Steel railway bridges and other structures are painted to prevent corrosion, with the method and coating systems selected to conform to the "Manual of Painting-Design and Application to Steel Structures" compiled by the Railway Technical Research Institute (RTRI).
       Since the guidelines were revised in 1993, heated discussion has occurred on the problems of human health and global and local environments, and it is now paramount to consider environmental factors when developing new materials. To this end, the RTRI formulated new recoating systems for steel structures to eliminate lead and chromium compounds, cut hazardous chemical substances specified by the PRTR law by about 70% in comparison to conventional methods, and reduce volatile organic compounds (VOC) that have posed serious problems in recent years by about 80%. These values far exceed the target of 30% specified by the Ministry of the Environment. To emphasize the objective of reducing burdens on the environment, the coating systems as a whole have been given the name of ECO.
       The ECO coating systems have been adopted for the intermediate and finish coating of steel structures, using the new paint with water as a solvent to satisfy the performance required for steel bridges. A painting test on an actual bridge (Fig. 1) showed that the specifications could be applied without problems. A combined cycle test performed by the RTRI indicated that the durability of painting according to ECO guidelines was higher than that using conventional specifications (Fig. 2), suggesting that reductions in life cycle costs are possible.
       Based on these findings, the "Manual of Painting-Design and Application to Steel Structures" were revised in 2005 to introduce coating systems for low environmental impact and new performance rules. The coating systems will be introduced by JR companies in 2006.


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