As outlined in Chapter 1, extensive field investigations of a large number of concrete structures in severe environments have been carried out in many countries. For most of these concrete structures, it has primarily been corrosion of embedded steel that has created the most severe problems to the durability and performance. In recent years, the increasing use of de-icing salt has created special problems for many concrete bridges (U.S. Accounting Office, 1979). Already in 1986, it was estimated that the cost of correcting corroding concrete bridges in the United States 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 U.S. bridges of up to about US$8.3 billion were estimated by Yunovich et al. (2001), and up to US$9.4 billion for the next 20 years by American Society of Civil Engineers (Darwin, 2007). 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.