A review of recycled aggregates (RAP and RCA) as unbound base course material for sustainable highway construction

Abstract

This paper presents a review of unbound recycled materials, specifically recycled asphalt pavement (RAP) and recycled concrete aggregate (RCA), as road base course for sustainable highway construction. A total of fifteen recycled materials were collected for characterization and testing from across the USA. Compaction characteristics and resilient moduli of these samples were determined and predictive equations were derived. Test sections were constructed using recycled materials in the granular base layers at the MnROAD test facility. Large-Scale Model Experiments (LSME) replicating field-scale conditions were also conducted and scalability of various scale modulus measurements was investigated. When compared to conventional base course, RAP and RCA experienced higher modulus. Discussion includes mechanical and durability characteristics, and leaching behavior. Sustainability evaluation of material alternatives in a project is described.