A systematic review on performance of reclaimed asphalt pavement (RAP) as sustainable material in rigid pavement construction: Current status to future perspective

Recently the waste of asphalt pavement materials has been increasing in day-to-day life by cost and economic criteria in the Indian environment. In this regard, the use of recycled asphalt pavement has grown worldwide reducing the use of virgin materials. Besides, the scarcity of natural aggregates, as well as the lack of eco-friendly materials, lead to an increase in the utilization of Reclaimed Asphalt Pavement (RAP) as an alternative material in road construction. This paper provides a comprehensive and insightful evaluation of the utilization of RAP aggregates based on characterization, strength, durability, and micro-structure properties along with life cycle analysis (LCA). For this purpose, a sequential characterization of the RAP materials is employed for a detailed analysis using physical and mechanical properties. Further, RAP aggregates' fresh and hardened properties, including durability properties, have been presented to show the potential utility as a partial substitute for natural aggregates (NA). Thus, the main objective of this critical review is to develop an extensive understanding of the present scenario in the utilization of RAP materials and identify the different properties needed for sustainability in pavement structures. Consequently, the various research gaps are highlighted based on the material properties, strength parameters, and circular economy of environmental impacts. Moreover, the optimum proportions of these substitute materials have been recommended for sustainable rigid pavement systems. The literature showed that the effect of RAP aggregates in concrete leads to loss of mechanical properties, which can be compensated by using various mineral admixtures or stabilizers to improve their strength and durability performance. Hence, this in-depth review will help the researchers, pavement engineers, and authorities of national and state highways with the effective use of RAP aggregates in rigid pavement construction.