IMPLEMENTATION OF A DYNAMIC DEFLECTION SYSTEM FOR RIGID AND FLEXIBLE PAVEMENTS IN OHIO. FINAL REPORT

Since 1984, the Ohio Department of Transportation has used Dynaflect deflection measurements to design asphalt concrete overlays on all four-lane pavements programmed for rehabilitation. Slight variations in these deflections on rigid pavement can result in substantial differences in overlay thickness when calculated with a two-layer elastic procedure. In this research, a Dynatest Falling Weight Deflectometer was correlated with the Dynaflect on three flexible and three rigid pavements. Various analysis procedures were used with these data to calculate layer moduli and overlay thicknesses. While differences occurred from pavement to pavement, deflections obtained with the Dynaflect and FWD correlated quite well on the average, pavement nonlinearity was not as significant as was anticipated, and the current ODOT procedure for designing overlay thicknesses appears to be reasonable. Based upon the results of this study, Ohio will continue to use Dynaflect deflection measurements for designing overlays in the near future and search will continue with the FWD to locate underlying pavement voids and quantify pavement nonlinearity.