The deterioration of 100 years old coated steel bridges

Steel bridges have been widely built from the beginning of the XIX century. The structures were protected from the uniform atmospheric corrosion through Lead-containing coatings. These exhibited over the decades a very good resistance to degradation. Generally, a similar reduced corrosion was also observed for the rivets, which linked the structural elements. The degradation was mainly located in the regions directly exposed to rainfall or water flux. The formation of craters or exfoliation was only locally found. The enrichment of organic deposits promoted the permanence of humidity, which in turn, had an adverse effect on the steel conservation. Generally, the total coating thickness slightly decreased, and the long-therm protection was no longer attained. The content of Lead has a detrimental effect on the environment. Thus, the restoration works must consider the pollutant effect during its elimination and disposal.