Evaluation of different porous asphalt gradations based on aggregate packing and stiffness parameters

Aggregate gradation is crucial for understanding how porous asphalt responds to traffic loading. A porous asphalt mixture is a particle size distribution that permits infiltration of the runoff storm water due to its voids content. The current study investigates the unbound aggregate blend packing conditions concerning density and stiffness characteristics. A gradation-based framework to analyze the susceptibility and durability of asphalt mixtures with various aggregate gradations is empirically evaluated by maintaining a constant source for both the aggregates and the binder; the laboratory experiment was intended to isolate the impact of aggregate gradation. The effort involved testing and packing studies for considering two gradations for the eleven various asphalt mixtures. Marshal Method of mix design was carried out, and tests like indirect tensile strength (ITS), tensile strength ratio (TSR), Cantabro test, and drain down test (min and max binder content) were conducted. Results indicate that the testing procedure impacts how the porous asphalt mixture responds to loads. According to the design criteria, the TSR value for both gradations exceeds 80%. The 9.5 mm and 4.75 mm fractions affect the mixture's strength, and a correlation is shown between the Marshall stability and ITS as well as the TSR and wet IDT. The findings demonstrate that filler material significantly affects the air void content and stability of the skeleton and that gradations, particularly fractions with 4.75 to 2.36 mm. impact the performance of porous asphalt mixtures. These pavement kinds help reduce drainage issues, replenish the subsurface layers, and enhance vehicle safety.