Effect of Geosynthetic Material in Reclaimed Asphalt Pavement on Performance Properties of Asphalt Mixtures

Geosynthetic materials have been used effectively at the interface between asphalt pavement layers for waterproofing and mitigating crack propagation. When an asphalt pavement with a geosynthetic interlayer is rehabilitated, the asphalt surface layer as well as the underlying geosynthetic interlayer can be removed for new overlays. The reclaimed asphalt pavement (RAP) as well as the geosynthetic material is reused in new asphalt mixtures because the geosynthetic material cannot be removed from the RAP. This situation leads to the question of whether the presence of the geosynthetic material in RAP has a negative impact on the performance of the new asphalt mixtures. A study was conducted to answer this question. A two-layer test section with a geosynthetic layer installed at the layer interface was constructed. The sections were milled so that RAP with and without the geosynthetic material was collected. Superpave (R) mix designs were then produced: one with the RAP with geosynthetic material and the other with the control RAP. A variety of hot-mix asphalt (HMA) performance tests were conducted to determine whether the presence of the geosynthetic material in the RAP had an impact on the HMA performance concerning stiffness, moisture susceptibility, rutting resistance, and resistance to low-temperature cracking. The laboratory evaluation concluded that the presence of the geosynthetic material in the RAP did not have a significant impact on the RAP properties or the volumetric and performance properties of the asphalt mixture.