ABSTRACT
In many countries, extensive field investigations of a large number of important concrete structures in severe environments have been carried out. The results of all these investigations have been reported in comprehensive reports and published in numerous papers in journals and proceedings from various international conferences over a long period of time. For most of the concrete structures, it has primarily been electrochemical corrosion of embedded steel due to use of de-icing salt which has created the biggest and most severe problems (United States Accounting Office, 1979). Already in 1986, it was estimated that the cost of correcting corroding concrete bridges in the USA was US$24 billion with an annual increase of US$500 million (Transportation Research Board, 1986). Later on, annual costs of repair and replacement of US bridges of up to about US$8.3 billion have been estimated by Yunovich et al. (2001) and up to US$9.4 billion for the next 20 years by the American Society of Civil Engineers (Darwin, 2007). Already in 1998, annual costs of US$5 billion for concrete structures in Western Europe were estimated (Knudsen et al., 1998), and similar durability problems and extensive expenses from a large number of other countries have also been reported.
