Performance of Aged Asphalt Mixes Containing Waste Oil Shale Filler

A sustainable asphalt mix design is imperative to keep the natural resources of pavement materials. This study investigates the performance of aged-asphalt mixes incorporating waste oil shale as a mineral filler (OSMF). A total of 144 testing samples were prepared by Marshall and Superpave design methods. The conventional limestone mineral filler of asphalt mixes was replaced with the OSMF at different percentages of 0% (control), 50%, and 100%. The samples were subjected to standard short-term and long-term aging conditions. The mixes were evaluated based on the average Marshall stability and flow, loss of Marshall stability, Indirect Tensile Strength (ITS), and water sensitivity test. Microstructural properties were also studied through Scanning Electron Microscopy (SEM) and Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (FTIR) analyses. Results revealed that utilizing 50% and 100% OSMF in asphaltic mixes enhances the mixes’ performance by reducing the average losses in Marshall stability and ITS of both design mixes. The Superpave mixes have higher stability and lower flow values at all combinations of OSMF% compared to the Marshall mixes. They also showed better performance in the loss of stability and loss of ITS than that with the Marshall mixes at both aging conditions. Moreover, microstructural analyses revealed the diminishment of microcracks in the modified mixtures compared to control. Although incorporating 100% OSMF reduced the stability and flow values of asphalt mixes, the results satisfied the required limits of Jordan’s specifications for heavy-traffic wearing courses. Thus, it would be recommended to consider the integration of waste OSMF in asphalt mixes.