Innovative Pavement Design for Heavy-Haul Mining Roads Using Phosphate Mine Waste Rock: Dust Emission Control, Mechanical and Operational Performance Improvements

Conventional pavement design methods are generally intended for highways and are not suited to the extreme loading conditions experienced by mining haul roads. This study presents an innovative pavement design for a heavily trafficked phosphate mine haul road (≈22.35 kT·day−1) constructed entirely from phosphate mine waste rock (PMWR), offering a sustainable alternative to conventional aggregates. The proposed structure comprises a 0.35 m sub-base (0–100 mm), a 0.25 m base (0–63 mm), and a 0.07 m semi-granular asphalt concrete (BBSG 0–20 mm) wearing course designed to combine high mechanical performance with effective dust control. The design was validated through an integrated experimental program that included repeated load triaxial testing (RLTT), asphalt stiffness, fatigue and rutting tests, thermogravimetric analysis (TGA), and full-scale field trials involving EV2 plate-load testing, dust monitoring, and emergency braking tests using a Komatsu 730E haul truck. The results demonstrate that the proposed pavement provides excellent structural performance. The asphalt mixture achieved a stiffness modulus of 9160 MPa, a fatigue resistance of 139.6 µε, and a proportional rut depth (PRD) of only 2.2%. In the field, the compacted sub-base and base reached average EV2 values of 153 MPa and 181 MPa, respectively, confirming their high load-bearing capacity. The paved haul road reduced airborne dust emissions by approximately 91%, surpassing the mine’s target of 80%, while also enabling haul-truck operating speeds to double, with associated reductions in tire wear and maintenance. Despite these performance gains, the proposed solution remains economically attractive, with a construction cost of approximately 23.97 €/m2. Overall, the study demonstrates that phosphate mine waste rock can be successfully transformed into a durable, cost-effective, and environmentally sustainable pavement solution for heavy-haul mining roads, providing a practical example of circular economy principles in mining infrastructure.