Micromechanical response and pore-skeleton characteristics of oil shale waste-modified asphalt mixtures

Oil shale waste (OSW) has the potential to serve as an aggregate in asphalt pavements due to its unique porous structure and oil storage characteristics. However, in practical applications, these intrinsic properties and their reinforcing effects on asphalt pavement performance are often overlooked. To address this issue, the mechanisms underlying OSW’s performance enhancement as a fine aggregate in asphalt mixtures were investigated using X-ray computed tomography (CT) scanning and Particle Flow Code (PFC) numerical simulations, combined with laboratory mechanical tests. The CT results showed that the number of contact points between coarse aggregate and asphalt mortar in the OSW asphalt mixture (OSW-AM) was 26.44% higher than that in the basalt asphalt mixture (BS-AM), indicating a more uniform spatial distribution. In addition, the asphalt film thickness in the OSW-AM was 33.60% greater than that in the BS-AM, demonstrating the superior oil absorption capacity of OSW. Force chain analysis further revealed that the maximum contact force in the OSW-AM increased by 18.3% compared with that in the BS-AM, suggesting that the incorporation of OSW enhances the stability of the aggregate skeleton structure. These findings provide theoretical support for the application of OSW in road engineering.