Nondestructive Testing and Evaluation of Flexible Highway Pavements

Abstract

The motion of vehicles over pavements makes the problem of predicting consequent effects time dependent. Present design procedures, however, account for this motion as a sequence of equivalent static conditions reduced to passes or coverages. A solution to this problem was obtained by verifying the following hypothesis: A pavement system operated upon by a vehicular input produces an output response. Relating the two is a time dependent transfer (TDT) function that contains within it the properties of the system. This function is obtained, in a mathematical sense, using Laplace transformations, without the need to simulate respective material performance or to determine values for preselected descriptors. The TDT functions can be employed to predict a pavement system's response and performance when subjected to an imposed load. The investigation was carried out by extending transfer function theory in connection with a finite convolution procedure to define the pavement's TDT functions. Full scale dynamic tests (moving trucks and aircraft) were performed in service environments (6 highway and 2 runway cross-sections). It has been shown that the TDT functions obtained do represent the characteristics of flexible pavements. Changes in parameters of the TDT function reflect changes in pavement performance and conditions. /FHWA/