Forensic investigation of flexible pavements in Ohio

This paper presents the results of a forensic investigation initiated by the Ohio Department of Transportation in 2006 to determine the reasons for differences in performance of flexible pavements in Ohio. Ten projects with average performance and ten projects with excellent performance were selected for study. Falling Weight Deflectometer and ride quality measurements were taken along all projects to evaluate structural and ride parameters. Material samples removed from pavement, base and subgrade layers along a 500-feet (152 metre) length of representative pavement within each section were tested to determine various material and physical properties. Other data collected in the test sections included rut depth and Dynamic Cone Penetrometer measurements. Practices recommended to improve flexible pavement performance include: implement SHRP specifications for designing AC surface and intermediate mixes with PG grade asphalt cement, polymers and smaller midrange aggregate; construct uniform stiff subgrades; and maximise resilient moduli of AC base materials.