ABSTRACT
Concrete has been used as a construction material in a wide variety of structures ranging from buildings and parking structures to bridges, dams, earth-retaining structures, pressure vessels, tanks, boats, and offshore platforms. Today, it is the most widely used construction material. As with other forms of infrastructure, there is an ever-increasing need to evaluate and repair concrete structures. Repairs may be required for a variety of reasons, ranging from a change in the space requirements of the structure to the deterioration of concrete and corrosion of the steel reinforcement. Although most concrete structures have good long-term performance records, deterioration problems have occurred because of poor construction practices, poor design, lack of quality materials, and aggressive environmental exposure. Perhaps the most-cited statistic in the technical concrete literature concerns the extent of deterioration of this
Association of State Highway and Transportation Officials (AASHTO) rates 40% of U.S. highways as below minimum standards of engineering. According to the U.S. Department of Transportation, 230,000 out of the 575,000 bridges on primary and secondary roads are structurally deficient or functionally obsolete. It has been estimated that between $18 billion and $21 billion is spent by owners for repair, protection, and strengthening (Strategic Development Council, 1996). The value of the concrete-based infrastructure in the United States is estimated to be $8 trillion. And, as was so simply put in a Smithsonian article, “a lot of that concrete needs fixing” (Wolkomir, 1994).
