Large-scale laboratory study on geosynthetic interlayers to improve performance of asphalt overlays on jointed concrete pavements

This study utilized large-scale cyclic plate loading tests to evaluate the effectiveness of geosynthetic interlayers to improve pavement performance. Four test sections were constructed in a 2.2 m × 2.0 m × 2.0 m steel test box and evaluated under controlled laboratory conditions with and without simulated rainfall. This study used a standard hot mix asphalt (HMA) mix to investigate unreinforced and geosynthetic interlayer-reinforced with 50-mm thick HMA overlays over jointed concrete pavements. The geosynthetic interlayers included a fiberglass grid designed to provide tensile reinforcement and minimize strain concentration, and a composite grid that integrated a geogrid made from high-modulus polyvinyl alcohol (PVA) fibers in combination with a nonwoven geotextile for both reinforcement and moisture barrier functions. To assess the performance of these interlayers, permanent deformation at the center of loading, permanent deformation of the concrete slab, stress distributions at the interfaces between the slab and the aggregate base and between the base and the subgrade, tensile strain in the HMA overlay, and the overall improvement by the overlay with and without a geosynthetic interlayer were tested. The test results indicate that the geosynthetic interlayers significantly enhanced the overlay performance by reducing permanent deformations and vertical stresses. Comparative analysis between the unreinforced and reinforced sections demonstrated the superior performance of geosynthetic-reinforced overlays in extending pavement service life.