Asphalt concrete density monitoring during compaction using roller-mounted GPR

Abstract

A direct relationship exists between asphalt concrete (AC) density and pavement performance. In the United States, quality thresholds have been established for AC density by Departments of Transportation (DOTs). During flexible pavement construction, remedial actions become limited as AC cools. Therefore, it is crucial to monitor AC to achieve the desired density during compaction. Ground-penetrating radar (GPR) technology can be used to monitor AC densification during construction. Contractors and agencies may use GPR for quality control/acceptance practices. This paper developed a roller-mounted GPR prototype and used it to perform small- and large-scale laboratory tests. Advanced algorithms were used to predict AC density while isolating roller vibration and other signal interference effects. The GPR results were verified using ground-truth cores and nuclear gauge measurements. An average absolute error of $\pm 0.7\%$ in determining AC percent compaction was achieved. The use of recycled materials/additives in AC was not considered in this study.