Feasibility for the Use of Non-contact Ultrasound for Application in Asphalt Concrete Materials

Abstract

A rapid quality control test method of hot mix asphalt (HMA) during the production and placement phase of roadway construction can be extremely valuable for the successful completion of a roadway construction project to keep it on schedule and under budget. Non-contact ultrasound technique has been used to characterize properties of ceramic and metallic materials. Prior to this study, the non-contact ultrasound technique was not used for constructions materials such as HMA. Until recently, the transmission of non-contact ultrasound through the air prior to propagation into a material such as the highly attenuating HMA was not possible. This study was conducted using a newly-developed low frequency ultrasound non-contact transducers in order to investigate the feasibility of correlating the bulk specific gravity of HMA to non-contact ultrasound measurements. HMA specimens were prepared with varying gradation and asphalt cement proportions. The data revealed that it was indeed possible to correlate non-contact ultrasound measurements to the of the bulk specific gravity of HMA. This work provides the foundation for future research for the utilization of the non-contact ultrasound technique as a viable, cost saving tool for quality control application in asphalt concrete plant production and construction of asphalt concrete pavements. It may very well be possible to reduce significantly the conventional testing by developing ultrasound equipment for density, gradation, and binder content with one signal transmission.