Use of Dielectric Profiling System for Rapid Continuous Measurement of Asphalt Mix Density: Case Studies in Michigan

Abstract

Asphalt pavement density is a key indicator of its long-term performance and is usually measured through traditional coring methods. However, the coring process is labor-intensive, surface-destructive, and, most importantly, provides limited coverage. Moreover, cores may report densities from non-representative areas. This study evaluates the effectiveness of the dielectric profiling system (DPS) in measuring asphalt pavement density, comparing its accuracy with traditional coring methods. The DPS was used to measure dielectric on 25 projects; field cores and loose mix samples were collected to establish the cores and mix (puck) dielectric-density calibration curves. Additional quality assurance and quality control (QA/QC) field cores were also collected to validate the DPS-calculated density. The mix (puck) calibration method produced consistent and more reliable results than the core calibration results. QA/QC field core density and DPS-calculated density for most projects were statistically similar, indicating DPS’s ability to accurately measure the asphalt pavement density. Furthermore, the DPS results demonstrate repeatability. Additionally, mix calibration is consistent across different hot-mix asphalt production days, as minor fluctuations in mix composition do not affect the calibration curves relating surface dielectric values to air void contents. The DPS significantly reduces the risks of random sampling inherent in core-based QA/QC methods by providing full coverage of the asphalt layer density. This comprehensive assessment minimizes the likelihood of undetected low-density areas, particularly at critical points such as longitudinal joints. The study concludes that the DPS offers a reliable and efficient alternative to traditional methods, potentially transforming asphalt pavement QA/QC practices.