A.Bill Palmer, editor of Concrete Construction magazine, responds: Recycled concrete has been used extensively as aggregate in highway work around the country. A recent study by the Federal Highway Administration's Pavement Recycling Team looked at the use of recycled concrete aggregate (RCA) in five states; all five reported that RCA used as a base material performs as well as or better than virgin material.

As an added bonus, using RCA as a base keeps it out of landfills. The Texas Department of Transportation recycles nearly 100 percent of its concrete rubble. In the Denver area, about 6 million tons of concrete from the old Stapleton Airport runways has been recycled for various purposes.

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