In response to the need to improve asphalt pavement performance, the Strategic Highway Research Program (SHRP) was initiated in 1987. Products from SHRP included performance-based specifications for asphalt binders and performance-based mix design tests and criteria for asphalt mixtures. The superpave asphalt binder specification addresses performance of in-service pavements for given environmental and traffic conditions. During the 1985 paving season in Indiana, the original asphalt binder and HMA (truck mix samples) from a number of pavements were sampled and retained. Cores were also taken from these pavements after seven or eight years of service. Conditions surveys were performed on these pavements, prior to coring. The study objectives were directed toward characterizing the original and extracted/recovered asphalt binders from the field samples using Superpave test methods and equipment. Taking this approach provided an early opportunity to examine a number of features of the Superpave system, including short (RTFO) and long-term (PAV) aging. Results of this research documented the difference in stiffness between RTFO aged and asphalts extracted and recovered from loose mixtures; in addition to, the difference in stiffness between PAV aged and in-service aged asphalts, in Indiana. Additionally, asphalt stiffness was related to pavement performance. A poor relationship was found between the stiffness of RTFO aged asphalts and rutting. On the other hand, a good relationship was found between stiffness of in-service asphalts and cracking. Collected weather data from seven counties indicated agreement between calculated PG grades for these counties and recommended Superpave PG grade, based on the environmental conditions. Based on the results of this research, recommendations were made to further investigate the short-and-long -term binder aging to better address variability and of these procedures, to address storage conditions sometimes unavoidable for field samples, and to validate PG grades requirements for Indiana.

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RTFO, PAV, agining, Superpave Binder Specifications, condition surveys, in-service asphalts, storage time, extraction, SPR-2077

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Performing Organization

Joint Transportation Research Program

Publisher Place

West Lafayette, IN

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