DYNAFLECT EVALUATION OF LAYER MODULI IN FLORIDA'S FLEXIBLE PAVEMENT SYSTEMS

Research conducted to investigate the nondestructive testing (NDT) characterization of in-place pavement materials has resulted in the development of a modified sensor spacing for the Dynaflect. The modified testing configuration provides the capability to separate the deflection response contributed by the subgrade, the stabilized subgrade, and the combination of base and asphalt concrete for typical Florida flexible pavement systems. Analysis of Dynaflect data for in-service pavements using an elastic layer computer program resulted in the development of simple power law regression equations to predict layer moduli from modified sensor deflections. This paper presents the development of the simplified layer moduli prediction equations, and the recommended testing and analytical procedures for pavement evaluation investigations. The use of this simplified approach allows a large number of test locations to be analyzed by eliminating the use of computer-iterative programs which are usually time consuming, expensive, and often subject to substantial errors.