Nondestructive Monitoring Of Sub-Asphalt Water Content Using Surface Ground Penetrating Radar Techniques

Abstract

The strength of sub-asphalt aggregate layers is crucial to understanding the relationship between traffic loading and pavement damage. Because these strengths are greatly influenced by water content, and because there are currently no techniques available for obtaining reliable, non-destructive subasphalt water content estimates, pavement damage assessment is often inaccurate. Although Ground Penetrating Radar (GPR) methods have the potential to provide high-resolution, non-destructive water content estimates, the accuracy of this technique is largely unknown. Based on the successful results of a pilot study conducted under ideal conditions to estimate water content using GPR techniques, we applied this concept to estimate the sub-asphalt water content in two differently layered pavement sections. Both pavement sections were subjected to infiltration over several weeks, and GPR data were collected periodically throughout the infiltration period. By relating the changes in GPR response during infiltration to the water content of the aggregate layers, we can observe the movement of water in the sub-asphalt layers. Analysis of the GPR data indicates that the water content of the aggregate layers varies with depth, lateral location, and time. These results suggest that GPR techniques may provide an efficient and high-resolution method for obtaining non-invasive water content estimates.