Rheological and Performance Evaluation of Reclaimed Asphalt Pavement (RAP) in Flexible Pavement Construction

reinforced Growing demand for sustainable infrastructure has intensified interest in recycled construction materials, particularly Reclaimed Asphalt Pavement (RAP). RAP offers environmental and economic advantages by reducing demand for virgin aggregates and bitumen; however, aged binder stiffening and reduced flexibility can increase fatigue and cracking susceptibility if not properly managed. This study presents a laboratory evaluation of asphalt mixtures incorporating RAP at replacement levels of 0%, 10%, 20%, 30% and 40%, with binder contents between 5.0% and 7.0%. Testing included conventional binder characterisation (penetration, softening point, flash and fire point), Marshall stability and flow analysis, volumetric evaluation (air voids, VMA and VFA) and microstructural/chemical assessment using SEM, XRD and XRF. Results indicate that moderate RAP inclusion increases mixture stiffness and improves rutting resistance while maintaining acceptable durability indicators. At higher RAP contents, oxidative aging effects become dominant, increasing brittleness and raising fatigue-cracking risk. The study concludes that RAP can serve as both a sustainability intervention and a performance-enhancing material when proportioned optimally and supported by appropriate binder selection and quality control, aligning flexible pavement construction with circular economy objectives