Synopsis: The United States is a country known for its wasteful use of natural resources. Efforts to correct the results of past transgressions as well as to balance economic development against legitimate concerns of conservation are pervading almost all aspects of life, including the construction industry. Concrete, being the most widely used material worldwide, is a natural target for conservation of natural resources. The cement industry is a major producer of greenhouse gases and energy user. Recent research has led to the point where numerous by-products of industrial processes with pozzolanic properties can be substituted partially for cement, such as fly ash and ground granulated blast furnace slag. Also other recycled materials are finding increased application in concrete production. For example, recycled concrete has been used successfully in numerous projects, and crushed waste glass is now available as a valuable source of aggregate, since the problem of alkali-silicate reaction has been solved. The key to commercial success is beneficiation, i.e. the targeted utilization of specific properties of the recycled material, which adds value to the end product.