Comparative Performance of Flexible Pavement Sublayers using AASHTO Design and Finite Element Modeling

Flexible pavement behavior is influenced by material characteristics and layer arrangement. Flexible pavement sections with equivalent structural numbers were evaluated using different base and subbase configurations consisting of crushed aggregate and reclaimed asphalt pavement. The investigated sections were constructed over subgrades with California bearing ratio values of 2% and 17%. Laboratory testing determined the California bearing ratio, resilient modulus, and shear strength parameters of all materials. Finite element analysis was conducted under a 400 kPa wheel load to assess vertical deformation and effective stress distribution within the pavement structure. The reclaimed asphalt pavement material exhibited lower California bearing ratio and resilient modulus values than crushed aggregate. The numerical analysis indicated that the pavement section containing a base layer only provided better structural performance than the other investigated configurations. Subgrade strength significantly affected pavement response in terms of deformation and stress values. Sections constructed with reclaimed asphalt pavement showed economic benefits despite reduced mechanical performance compared with crushed aggregate sections. The findings demonstrated that pavement sections with equivalent structural numbers could exhibit different mechanical responses depending on material properties and layer arrangement. The results highlighted the limitations of empirical pavement thickness design when stiffness variation and stress distribution were not considered.