Dielectric-based Index for Quality Evaluation of HMA Centerline Longitudinal Joint

A centerline longitudinal joint is constructed during the hot-mix asphalt (HMA) material paving process, where one lane is paved while traffic is maintained in the adjacent one. Since a poorly constructed joint can prematurely deteriorate an otherwise sound pavement, the service life of HMA pavements depends critically on the construction quality achieved at the joint. Improving the joint’s quality through better compaction during construction can help attain flexible pavements with longer service lives and fewer maintenance needs. Current quality control and quality assurance plans require destructive coring of the pavements; however, they provide limited coverage. A non-destructive alternative to traditional joint evaluation methods is using a density profiling system (DPS), which offers a rapid and continuous real-time assessment of the compaction levels achieved during construction in terms of dielectric values.

Further, using DPS necessitates the calibration and validation of the relationship between air voids and dielectric values of the HMA mixes, which involves the labor-, cost-, and time-intensive process of extracting field cores from pavements. This paper presents an index, the longitudinal joint quality index (LJQI), that can be used to evaluate the construction quality achieved at the joints without the need for calibrating the air void vs. dielectric relationship. The proposed index can be used significantly as a pass/fail criterion for joint acceptance when logistic/capacity issues limit pavement coring. Based on the sensitivity analysis presented, this study suggests a minimum LJQI value of 60 % for accepting a centerline longitudinal joint without penalty.