The Asphalt Pavement Analyzer (APA) is a laboratory scale accelerated load wheel tester. The interest in the use of the APA has grown in recent years, especially during the implementation of the Superpave mix design procedure. Currently, this mix design procedure is based on volumetric properties and has no strength test to evaluate the mixture's susceptibility to rutting.
This paper presents the findings of a laboratory study conducted to examine the sensitivity of the Asphalt Pavement Analyzer in measuring the rut depth due to changes in aggregate type and asphalt binder type. The results of the APA were also compared to the ones obtained from axial and indirect tensile creep tests. The scope of this study included a 19-mm Superpave mix, two aggregate types (limestone and sandstone) and four binder types. The four binder types were PG 64-22, an SB polymer modified asphalt meeting PG 70-22, a gelled (chemically modified asphalt meeting PG 70-22), and a SB polymer modified asphalt meeting PG 76-22.
The test results of mixtures with different aggregates and binder types indicated that the APA was sensitive to these factors. Mixes with sandstone aggregates exhibited lower permanent deformation properties, as defined by the tests considered, than similar mixes with limestone aggregates. The ranking of the APA test results and indirect tensile creep test results was generally consistent with the ranking of the binder stiffness G*/sinδ. The APA had a fair correlation with the indirect tensile creep test results.