Profiling Flexible Highway Pavement Continuously with Rolling Dynamic Deflectometer and at Discrete Points with Falling Weight Deflectometer

Nondestructive testing of pavements plays an important role in the management of pavement infrastructure. Nondestructive testing techniques have been widely utilized in the United States during the past decade to characterize pavement systems at discrete points. Discrete-point testing is, however, not feasible for routine use as a means of continuously characterizing pavement systems. A new nondestructive testing technique for continuously profiling pavements has been developed, namely, the rolling dynamic deflectometer (RDD). The RDD is a large truck on which a servohydraulic vibrator is mounted. The vibrator is used to apply large vertical dynamic loads to the pavement with loading rollers, and the induced dynamic displacements are measured at multiple locations with rolling sensors. This arrangement permits continuous measurements at multiple locations on the pavement surface in a fraction of the time required for typical discrete-point testing at a few points along the section. In this paper, the configuration of the RDD and the procedure used to analyze RDD data are discussed. Continuous deflection profiles are presented from a test section of a flexible Interstate highway pavement, which contains several distinctly different pavement structures. The effects of the structures on measured deflections are discussed, and the capability of the RDD to delineate the extent of each feature is presented. The importance of loading frequency and resonances in the pavement structure is shown. In addition, results from the RDD are compared with results from falling weight deflectometer (FWD) tests performed at the same locations.