Mechanical performance and global warming potential of waste and synthetic fiber-reinforced warm mix asphalt for hot-arid climate

This study evaluates the mechanical and environmental performance of fiber-reinforced warm-mix asphalt (FRWMA) under the hot-arid conditions of the Arabian Gulf, where high temperatures and high humidity coexist, along with heavy industrial traffic loading and inferior aggregate quality. Stone mastic-WMA (binder 5.7%, fiber 0.3%) was reinforced with commercial polyacrylonitrile (PAN), waste cellulose, waste jute, or recycled pillow fibers and tested for volumetrics, fatigue, dynamic creep, and moisture damage. A scanning electron microscope (SEM) was used to examine the microstructure and thermal stability, and cradle-to-gate impacts were assessed using life-cycle assessment (LCA). PAN and cellulose delivered the most favorable balance of properties, with stability of 13.7 and 13.1 kN, tensile strength ratio (TSR) of 96% and 91%, fatigue lives of 22,580 and 19,290 cycles, high creep stiffness (64 and 60 MPa), and low creep-strain slopes, respectively. Jute showed intermediate gains, whereas pillow fiber performed poorly (TSR 57%, shortest fatigue life, highest creep slope) due to clumping, weak wetting, and asymmetric crack paths observed in crack-mapping and SEM. TGA confirmed all fibers are stable within the WMA production window (115-140 °C); thus, performance differences stem from dispersion and fiber–binder interfacial quality rather than thermal degradation. Relative to typical HMA, FRWMA reduced burner fuel to 6.3 L ton^-1, CO₂ to 16.9 kg ton^-1, and global warming potential (GWP) to 27-30 kg CO₂-eq ton^-1 (40-50% lower), with waste-fiber mixes achieving the lowest GWP. Overall, PAN- and cellulose-reinforced FRWMA provide superior fatigue and rutting resistance at reduced production temperatures while advancing circular-economy and decarbonization targets for hot-arid road networks.