Comparative Strength Performance of Stone and Asphalt Wearing Courses for Low-Speed Urban Roads

Conventional asphalt wearing courses remain the dominant surface material for urban roads; however, their performance is often compromised in low-speed environments characterized by frequent braking, concentrated loading, and moisture exposure. Under such conditions, asphalt surfaces are susceptible to rutting, stripping, and strength degradation, prompting renewed interest in alternative surfacing materials with higher mechanical durability. This study presents a comparative evaluation of the strength performance of stone and asphalt wearing courses using laboratory-based mechanical indicators. The objective is to assess the relative suitability of both materials as wearing course layers based on their resistance to crushing, impact, abrasion, and tensile loading. Stone strength performance was evaluated using Aggregate Impact Value (AIV) and Aggregate Crushing Value (ACV) tests under both dry and wet conditions, together with the Los Angeles Abrasion test to assess durability. Asphalt wearing course performance was assessed through Marshall Stability, Indirect Tensile Strength (ITS), and Unconfined Compressive Strength (UCS) tests, representing load-bearing capacity, tensile resistance, and compressive behavior, respectively. All tests were conducted following relevant international standards to ensure consistency and comparability. The results indicate that stone exhibits superior resistance to impact, crushing, and abrasion, particularly under dry conditions, reflecting its strong compressive-dominated mechanical behavior. Asphalt demonstrates higher tensile strength and better resistance to crack initiation, attributable to its viscoelastic binder-controlled response. Moisture exposure was found to reduce strength indicators for both materials, with a more pronounced effect observed in asphalt mixtures. From an engineering perspective, stone wearing courses are more suitable for low-speed urban roads, intersections, and braking zones where compressive and abrasion stresses dominate, while asphalt wearing courses remain preferable for applications requiring higher tensile resistance and riding comfort.