Curiosities: How is concrete recycled?

A: Concrete generally is crushed into “recycled concrete aggregate,” or RCA, said Craig Benson, a distinguished professor of geological engineering and co-director of the Office of Sustainability at University of Wisconsin-Madison. Once steel is removed, old concrete can be crushed and used to replace aggregate (the mix of sand and gravel) in new concrete. Crushed concrete can also be used to replace gravel as fill or base layer in construction.