Laboratory study of the surface-physical behavior of asphalt mixtures containing LECA and modified with nano-AL2O3

The surface-physical performance of asphalt pavements, including sound absorption, skid resistance, texture, and resilient modulus, is crucial for road safety and durability. This study investigates the combined effects of lightweight expanded clay aggregate (LECA) and nano-Al₂O₃ on the mechanical and surface-physical properties of asphalt mixtures. Asphalt samples were prepared with LECA contents of 0%, 25%, and 50% by weight of aggregates and nano-Al₂O₃ at 0%, 1%, 2%, and 3% by weight of bitumen. Laboratory tests, including indirect tensile resilient modulus, sound absorption coefficient, British pendulum test, and mean texture depth (MTD) measurement, were conducted. Results indicated that nano-Al₂O₃ significantly increased the resilient modulus, with the 50% LECA + 3% Al₂O₃ mixture increasing modulus by 22%, 18%, and 25% at 25, 15, and 5 °C, respectively. LECA-containing mixtures exhibited higher sound absorption, particularly at high frequencies, and 50% LECA samples performed best. Skid resistance tests confirmed acceptable performance for 25% and 50% LECA mixtures. MTD results showed all samples exceeded the minimum requirement, ensuring adequate friction at various speeds. Overall, combining LECA and nano-Al₂O₃ substantially enhanced both surface-physical and mechanical properties. Furthermore, economic analysis revealed that although initial construction costs were higher, increased durability and reduced maintenance needs made these mixtures cost-effective over the pavement lifecycle. These findings demonstrate the potential of advanced materials to improve pavement performance, safety, and sustainability, providing practical guidance for engineers and policymakers.