Elucidating the molecular compatibility mechanism to guide the optimization of Straw-Derived asphalt

Amid the growing focus on sustainable development, the integration of renewable materials, such as straw liquefied residue oil (SLRO), into asphalt engineering is gaining significant attention. However, the underlying compatibility mechanisms and their impact on performance remain inadequately understood. This study offers a thorough investigation of the SLRO-asphalt system by combining molecular dynamics (MD) simulations with multi-scale experimental techniques. MD simulations revealed that intermolecular interactions, primarily hydrogen bonding, increase with higher SLRO content, peaking at 10 wt.%, which facilitates the formation of the most cohesive molecular network. Experimental results confirmed that this enhanced network exerts a dual influence on performance. Dynamic shear rheometer (DSR) tests demonstrated that the 10% SLRO blend significantly improved high-temperature rutting resistance following short-term aging. In contrast, bending beam rheometer (BBR) tests on long-term aged samples indicated that the same stiffening mechanism reduced low-temperature thermal cracking resistance. This study clarifies the microscopic origins of this performance trade-off, suggesting that the optimal SLRO content is context-dependent, requiring a balance between rutting and cracking resistance rather than an absolute value. These findings provide a crucial mechanistic foundation for the rational design and performance-driven optimization of sustainable bio-asphalts.