Multi-scale modeling and mechanistic-empirical analysis of basalt fiber-reinforced asphalt concrete: Linking linear viscoelasticity to structural pavement design

Although basalt fiber (BF) reinforcement can improve the micromechanical and linear viscoelastic (LVE) properties of asphalt mixtures, these material-level changes are rarely translated into structural design guidance for asphalt concrete surface courses with a 12.5 mm nominal maximum aggregate size (AC12.5). To connect laboratory performance with pavement-level prediction, this study couples rheological modeling with mechanistic-empirical (M-E) pavement simulation. An integrated experimental and modeling framework was used to characterize AC12.5 mixtures modified with BF dosages ranging from 0.0–0.5% by total mixture mass. Scanning electron microscopy (SEM) observations showed that binder absorption by BF establishes a continuous three-dimensional (3D) fiber network, increasing the optimum asphalt content from 4.6–5.4%. Mechanical characterization showed a non-linear dosage response, with 0.3% BF producing the highest flexural tensile strength (10.19 MPa), whereas 0.4% BF produced the highest Marshall Stability (MS > 13.6 kN) and static elastic modulus (560 MPa) derived from the 2S2P1D framework. M-E simulations indicated that these rheological changes corresponded to measurable structural effects under the modeled National Highway 32 conditions. Replacing a conventional 5 cm AC surface with a 4 cm BF-modified layer at 0.4% BF produced comparable rutting and fatigue predictions over a 15-year design life. These results support BF as a technically feasible modifier for reducing the modeled AC12.5 surface-layer thickness, although project-level economic benefits should be verified through life-cycle cost analysis (LCCA).