<title>Simple method for estimation of water content of roadbeds using multi-offset GPR</title>

Abstract

In this paper the possibility to measure moisture content in roadbeds using multi-channel GPR is described. GPR is a continuous and non-destructive method and its capabilities of providing information on soil and water content is well documented in the past. Most of these earlier described methods involve several time consuming measurements with a variety of antenna settings. A multi-channel radar system can however make more efficient measurements through the use of independently controlled transmitters and receivers in the antenna array.The results, from measurements with a 500 MHz GPR system, show a clear correlation between the GPR data and the soil water content in a Swedish roadbed. Further evaluation is, however, needed to compare different antenna frequencies and to calibrate the equipment together with reference velocity analysis.

NDT Transportation

“…There are several advantages, when data are collected using several antennas simultaneously: (1) high-frequency antennas with good resolution near the pavement surface and lower frequency antennas with greater signal penetration can be used at the same time, (2) multiple channels allow the use of antenna array techniques to determine signal velocities (Davis et al, 1994;Mesher et al, 1995;Emilsson et al, 2002) and (3) multichannel systems allow data collection using many antennas with same frequency to collect several survey lines simultaneously which facilitates the preparation of a 3D model of the surveyed structures (Davidson and Chase, 1998;Manacorda et al, 2002), or the configuration can be a mixture of any of these three. There are several advantages, when data are collected using several antennas simultaneously: (1) high-frequency antennas with good resolution near the pavement surface and lower frequency antennas with greater signal penetration can be used at the same time, (2) multiple channels allow the use of antenna array techniques to determine signal velocities (Davis et al, 1994;Mesher et al, 1995;Emilsson et al, 2002) and (3) multichannel systems allow data collection using many antennas with same frequency to collect several survey lines simultaneously which facilitates the preparation of a 3D model of the surveyed structures (Davidson and Chase, 1998;Manacorda et al, 2002), or the configuration can be a mixture of any of these three.…”

“…According to Fauchard et al (2003) this method provides sufficient accuracy of dielectric values for first two or three layers in road structures. Dielectric values have been also measured using different antenna array techniques (Davis et al, 1994;Emilsson et al, 2002). Dielectric values have been also measured using different antenna array techniques (Davis et al, 1994;Emilsson et al, 2002).…”

Permittivity Characterization of Unbound Granular Pavement Materials with a Modified Free-Space Approach

“…Although many researchers have applied multioffset techniques for soil moisture quantification (12,23,24), only a few have applied these techniques for moisture measurement for roads (25). However, several have used these techniques for mapping asphalt density variations (26) and for pavement thickness applications (27)(28)(29).…”