DEVELOPMENT OF END-RESULT AND PERFORMANCE-RELATED SPECIFICATIONS FOR ASPHALT PAVEMENT CONSTRUCTION IN ILLINOIS

Illinois has been engaged in research over the past decade to develop quality control/quality assurance (QC/QA) specifications that maximize pavement construction quality, while minimizing the amount of agency testing required to execute the system. This paper describes recent efforts to develop and implement end-result and performance-related specifications (ERS/PRS) in Illinois. In the summer of 1996, a pilot study was conducted during the construction of an eight-inch overlay placed over rubblized concrete on Interstate 57 near Edgewood, Illinois, to collect data to support the development of ERS/PRS. A high sampling and testing frequency was followed to aid in the determination of typical variances and to help determine the minimum amount of samples required for QC and QA in the future. Fundamental properties of plant produced mixtures were also measured, including: fatigue, permanent deformation, resilient modulus, and tensile strength. Furthermore, a unique "properties map" was developed, where all measured quality characteristics for each subplot of material were mapped by station and by pavement lift. This map will facilitate the development of future linkages between quality characteristics, engineering properties, and measured distresses (rutting, cracking, moisture damage, etc.), which is essential for the development of a comprehensive PRS. Ongoing and planned research efforts in this area are also described, including an upcoming project involving the development and use of percent-within-limits (PWL) based pay factors for field density control, which utilize contractor test results, and the evaluation of a rapid, non-nuclear pavement density gauge.