Investigations on Flexural and Shear Characteristics of Geosynthetic-reinforced Asphalt Overlay

Abstract

Paving geosynthetics have been increasingly used as interlayer systems to mitigate reflective cracking; however, their effectiveness depends on the interaction between reinforcement tensile properties, interface bonding, and strain development within the asphalt overlay. This study investigates the mechanisms by which fiberglass (G-FG) and polyester (G-PET) geogrid composites mitigate reflective cracking using specimens extracted from full-scale experimental pavement sections at Salvador International Airport, Brazil. Cyclic four-point bending tests combined with Digital Image Correlation (DIC) were used to evaluate fatigue performance, strain development, and crack propagation, while interface shear strength (ISS) tests assessed interlayer bonding. Geosynthetic reinforcement increased fatigue life by approximately 3.5 to 13 times compared with unreinforced specimens. DIC results showed substantial reductions in tensile strain concentrations and delayed crack initiation, with strain reduction factors of 0.09 and 0.34 for G-FG and G-PET, respectively. Despite a slight reduction in interface shear resistance, adequate bonding was maintained. The results demonstrate that reflective cracking mitigation depends on the combined effects of reinforcement stiffness, strain mobilization, and interface bonding rather than tensile strength alone.