A Sustainability Perspective for Unbound Reclaimed Asphalt Pavement (RAP) as a Pavement Base Material

The present study aims to investigate reclaimed asphalt pavement (RAP) materials for utilization for a pavement base layer material with the goal towards increasing the reutilization of materials and the movement towards increased pavement sustainability. Reduced cost for materials and transportation of materials, overall environmental benefits and many other advantages have led to increased interests in utilizing RAP in pavements including as base materials for highway/roadway construction projects. The potential advantages of utilizing RAP as an unbound base material are known; however, its overall application is still limited partially due to the lack of systematic evaluation studies for the parameterization of RAPs mechanical behavior in pavement design. With this in mind, the current investigation focuses on the resilient modulus (Mr) properties of RAP aggregates in terms of a material’s elastic response. Experimental data from tri-axial stress tests on specimens consisting of RAP, aggregates and a mixture of both materials are investigated. A number of constitutive models for the description of mechanical behavior of RAP materials are investigated. The required procedures for determining the constitutive constants of the constitutive models is outlined for the aforementioned materials. A comparative analysis is applied, and the related results are evaluated. The main conclusion is that RAP materials can be utilized as a base material in the framework of pavement sustainability, as its behavior under loading conditions are similar to virgin aggregate (VA) materials and can be simulated by using appropriate constitutive models for pavement design processes.