Reclaimed Asphalt Pavement and Recycled Concrete Aggregate Blends in Pavement Subbases: Laboratory and Field Evaluation

In recent years, efforts have been made to incorporate Reclaimed Asphalt Pavement (RAP) into pavement base or subbase applications by means of cement binder stabilization. This approach however may not be an environmentally friendly solution, due to the high carbon footprint involved in the production of Portland cement. Recycled Concrete Aggregate (RCA), on the other hand has been widely accepted in pavement applications. The sustainable solution of blending RAP with RCA was investigated in this research in an attempt to facilitate the usage of this blend as an alternative pavement subbase material. An extensive suite of geotechnical laboratory tests were undertaken on RAP with contents of 100%, 50%, 30% and 15% in blends with RCA. Results of the research study indicated that RAP/RCA blends when used with a low 15% RAP content meet the Repeated Load Triaxial requirements for use in pavement subbase layers. Results of field performance of a pavement subbase constructed with untreated 100% RAP at a private haul road field demonstration site confirmed that untreated 100% RAP had insufficient strength requirements to meet local road authority pavement subbase requirements. RAP and RAP/RCA blends, though found in this study to be not fully compliant with the local road authorities requirements for pavement subbases, could be potentially considered for lower traffic usage such as haul roads and footpaths.