Concrete structures are the most widely used construction in the world. Over ten times more concrete is produced than all other construction materials put together. Concrete structures were traditionally viewed as being maintenance-free with a practically unlimited life. However, over the past several decades, a number of durability related problems have emerged and stimulated research into the key factors relating to durability of concrete structures globally. It is now generally accepted that concrete structures deteriorate with time. Premature deterioration of concrete structures is a major and growing world-wide problem.