Algorithm development for real-time thin asphalt concrete overlay compaction monitoring using ground-penetrating radar

Abstract

Ground-penetrating radar (GPR) is an effective, feasible, and non-destructive tool for real-time estimation of the density of asphalt concrete (AC) during compaction. When the AC pavement is thin, however, it is difficult to estimate the density due to the limited GPR signal resolution. In addition, the surface moisture, applied during compaction, has an effect on the GPR signal and hence impacts density prediction accuracy. In this study, a nonlinear optimization approach, based on gradient descent, was used to recover the AC pavement surface reflection. A “modified reference scan” approach was developed to remove the effect of surface moisture on GPR signals during density monitoring. The “modified reference scan” approach was first validated in a laboratory experiment setting, then validated in a field study near Chicago, IL, where GPR antennas were installed on the roller and data were collected during compaction. The results show that GPR is a prospective tool for real-time AC compaction monitoring.