ABSTRACT
A metal spraying system applied to steel surfaces at room temperature had been developed about thirty years ago and the system would not raise the steel substratum surface temperature. The system has been applied to approximately three thousand real steel structure constructions in Japan.The sprayed zinc-aluminum pseudo alloy in the system has superior corrosion prevention effect for a long-term based on sacrificial anodic protection and atmospheric isolation.The outline, characteristics, steel corrosion prevention mechanism of the spraying system and the actual condition survey results of structures applied the system more than 10 years ago had been introduced in past IABMAS 2004, 2006, 2008 and 2010 proceedings. Furthermore, in 2012 proceedings a life cycle cost estimation of the spraying system had been discussed based on only limited data from three actual steel bridges applied the system.In this paper, the actual condition survey results for 39 steel bridges applied the metal spraying system about 5 to 20 years ago in Japan (from Hokkaido to Okinawa) have been reported to discuss in more detail durability of the sprayed zinc-aluminum pseudo alloy onto steel bridges. The surveyed bridges are in coastal zone, urban district and rural area. Classification estimation standard for degradation of the sprayed metal and coating on them has been established and deterioration degree has been quantitatively calculated. Deterioration phenomena for the evaluation includes the coating blistering, cracking, peeling and substratum steel rust. After that, on-site visual observation of the bridge appearance has been carried out.As a result, main degradation factors of the metal spraying system in the long-term can be pointed out environment of the construction location and elements of the structure. These factors more seriously influence the deterioration of steel bridges than mere time elapsed from the metal spraying construction.
