TYPICAL CURVES FOR EVALUATION OF PAVEMENT STIFFNESS FROM DYNAFLECT MEASUREMENTS

Currently, no direct solution exists that provides the pavement in situ layer moduli from deflection measurements. Current methods evaluate the pavement layer moduli from deflection measurements by using either empirical approaches or static layered elastic computer programs with iterative solutions. In this study, mechanistically based typical curves and tables are developed to evaluate the moduli of the four highway pavement layers--surface, base, subbase, and subgrade--from the Dynaflect measurements based on both static and dynamic analyses. The curves and tables are developed by using the Chevron computer program for the static analysis and the DYNAMIC computer program for the dynamic analysis. The results are applicable to a large number of typical combinations of layer thicknesses and material moduli. If the layer thicknesses are known and the Dynaflect measurements are determined, the four moduli of the pavement layers can be evaluated. The curves and tables developed are simple to use, without the need for previous empirical relationships or computer analysis. The study demonstrates that the static and dynamic predictions of the layer moduli are different in most cases. However, the research technique used in this study needs field verifications or other independent validation procedures to support the obtained results.