Concrete Pavement Recycling Practices in the US

Concrete pavements are recycled for paving applications in at least 41 U.S. states and production of recycled concrete aggregate (RCA) in the U.S. currently averages about 140 million tons (127 million metric tons) per year. The primary application of RCA has been subbase materials, but it also has been used in concrete and asphalt concrete paving layers, high-value rip-rap, general fill and embankment, and other applications. This paper discusses current U.S. concrete pavement recycling practices and briefly describes the physical, mechanical and chemical properties of RCA and the impacts on these properties on the properties of plastic and hardened concrete. It also describes current thinking concerning pavement mixture designs that can offset the effects of using RCA in concrete paving mixtures. Examples of successful recycling projects are provided to illustrate the varying approaches to using RCA in concrete pavements, including the use of RCA produced by recycling pavements that were severely damaged by D-cracking or alkali-silica reactivity (ASR) damage.