Performance evaluation of perpetual pavement after ten years

In 2005 the Kansas Department of Transportation constructed four perpetual pavement sections on US-75 as a viable alternative to full-depth asphalt pavements. These sections were designed to keep the horizontal tensile strain at the bottom of the Asphalt Concrete (AC) layer below the mixture fatigue endurance limit (assumed to be 70 με). In this study, structural performance of these perpetual pavement sections was evaluated after ten years based on the surface deflection measurements. This study used Falling-Weight Deflectometer (FWD) data collected in 2005 and 2016. The layer moduli were back calculated and mean effective Structural Number (SN_eff) was computed for both time periods. Statistical analysis was done for comparison. The results show significantly reduced mean SN_eff after ten years of service. These pavement sections were reanalyzed using the AASHTOWare Pavement ME Design software to investigate tensile strains at the bottom of the AC layer. Tensile strains were also computed using moduli back calculated from the FWD deflection data. Predicted strain values derived from the AASHTOWare software were lower than the tensile strains computed using the back calculated moduli. Full-depth cores collected from the crack locations on the pavement sections did not show any bottom-up cracking.