Correlations Between Superpave Asphalt Stiffnesses and In-Service Pavement Performance

One of the primary concerns in the state of Indiana is the early appearance of flexible pavement distresses. Early distresses may result in pavement failure, shorter pavement service life, or both. The Strategic Highway Research Program–developed Superpave asphalt binder specifications are directed toward in-service pavement performance. Superpave binder tests and associated criteria were selected to control distresses that effect in-service hot-mix asphalt performance, specifically, permanent deformation, fatigue cracking, and low-temperature thermal cracking. The Indiana Department of Transportation was interested in whether or not the changes in in-service asphalt can be related to pavement distresses. Several factors were examined, including the type and severity of distresses as documented by pavement condition surveys. Also, Superpave asphalt binder tests were conducted on the original and the recovered in-service binders. One important aspect of the study was how the changes of inservice asphalts can be related to such distresses as permanent deformation, fatigue cracking, or low-temperature thermal cracking. This study documents the relationship among in-service asphalt binder stiffnesses, as characterized by complex shear modulus or binder stiffness (G*), and in-service permanent deformation and cracking, as characterized by pavement maintenance management system deduct values. The study documents a poor relationship between in-service binder stiffness and in-service permanent deformation or rutting. The study also documents a good relationship between in-service stiffness and in-service cracking.