Locating voids beneath pavement using a pulsed radar

This paper presents the results of a study to determine the feasibility of using pulsed electromagnetic wave technology (radar) for locating and sizing voids beneath Concrete pavements. A short pulse radar provides a signal return from a void that has unique features that can be extracted to provide information regarding the location, depth, and size of the void. The data processing techniques developed have been implemented on a microcomputer that can be operated by field personnel to provide information for void depth and sizing to ±1/2 inch and spatial location within ±6 inches. Measurements using pavement 9" thick over four base materials were made inside a laboratory controlled environment and outside measurements were made on a specially constructed highway test lane with built-in calibrated voids.