Physical and Mechanical Properties of Reclaimed Asphalt Pavement (RAP) Incorporated into Unbound Pavement Layers

Against the backdrop of global warming and depletion of natural resources, new techniques and alternative materials need to be explored and integrated into road construction. Reclaimed Asphalt Pavement (RAP) is one of the waste materials that can be reused in new road projects if its behavior is better understood. Numerous researchers have studied the use of RAP in both bound and unbound pavement layers. However, the mechanical behavior and deformation characteristics of RAP in unbound pavement layers are not fully understood due to its unique properties. For this reason, this paper aims to investigate the performance of RAP in the construction of unbound pavement layers (base and subbase). The methodology used consists of two phases: (i) laboratory tests in terms of physical properties, bearing capacity and permanent deformations generated and (ii) a comparative analysis of the test results. For the laboratory tests, the RAP material was taken from the milling operation of a pavement section to be rehabilitated and blended with virgin aggregates (VA) in different proportions. In addition, a sample consisting of pure VA was used as a reference sample for the comparative analysis of the results. Overall, it is concluded that the use of RAP for admixture in unbound layers is feasible and meets the sustainability requirements of pavement materials and structures without compromising pavement strength. A highlight of the research findings is that RAP with percentages up to 40% is a rational approach for the development of RAP-VA mixes to be incorporated into unbound pavement layers. Nevertheless, the results of the present study support the statement that testing is required each time to define the capabilities of RAP considering local effects and material conditions.