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

TLDR

Reclaimed asphalt pavement (RAP) has been explored for pavement subbases, yet its high cement‑based carbon footprint limits environmental appeal, whereas recycled concrete aggregate (RCA) is widely accepted. This study investigated blending RAP with RCA as a sustainable alternative pavement subbase material. Geotechnical laboratory tests were performed on RAP/RCA mixtures with 100, 50, 30, and 15 % RAP content. Laboratory results showed that a 15 % RAP blend satisfies repeated‑load triaxial criteria, while 100 % RAP fails field‑strength tests, indicating that RAP/RCA mixes may be suitable for low‑traffic applications such as haul roads and footpaths.

Abstract

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 was 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 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 it had insufficient strength requirements to meet local road-authority pavement-subbase requirements. RAP and RAP/RCA blends, although found in this study to be not fully compliant with the local road-authorities requirements, could be potentially considered for lower traffic usage, such as haul roads and footpaths.