A State-of-the-Art Review of Mineral, Synthetic, and Natural Fiber Applications in Asphalt Mixes

This state-of-the-art review investigates the use of natural, synthetic, and mineral fibers in asphalt mixtures, including dense-graded (such as dense-graded bituminous concrete; DGBC), gap-graded (such as stone matrix asphalt; SMA), and open-graded (such as open-graded friction course; OGFC) mixtures. The study comprehensively examines the physical, chemical, and mechanical characteristics of different fibers, their manufacturing/extraction methods, and the effect of fiber parameters (such as length, dosage, and type) on asphalt mix performance. The study explores a broad spectrum of fibers used globally, including asbestos, basalt, polyester, polypropylene, carbon, glass, steel, jute, coir, sisal, banana, sugarcane bagasse, bamboo, kenaf, and cellulose fibers. The article's findings highlight that fiber reinforcement improves asphalt pavement performance, offering enhanced resistance to fatigue cracking, rutting, and moisture damage. In addition, the study assesses the economic and environmental impacts of fiber-modified asphalt, concluding that despite higher initial costs, the long-term performance advantages justify the investment. Finally, the study highlights the existing research gaps and suggests future research directions, with a particular emphasis on the potential of natural fibers to improve the sustainability and performance of asphalt pavements.