Relationships between Mixture Fatigue Performance and Asphalt Binder Properties

摘要

This paper deals primarily with research carried out as part of NCHRP 9-59. The primary purpose of NCHRP 9-59 was to develop an improved binder fatigue specification. In order to achieve this objective, a new model for the fatigue and fracture properties for asphalt mixtures and binders was developed, called the general failure theory for asphalt binders (GFTAB). Mixtures made using 16 different binders were subjected to both flexural and uniaxial fatigue testing. The resulting data, along with fatigue data from the Strategic Highway Research Program were analyzed using the GFTAB model and the results compared to the results of a variety of binder tests, including the Glover-Rowe parameter (GRP), double-edge notched tension (DENT) lest and the linear amplitude sweep (LAS). The analysis of this data showed that the GRP most closely correlated to strain capacity as calculated from the mixture fatigue tests at a given temperature and loading rate. The concept of the fatigue/fracture performance ratio (FFPR) was developed to indicate the inherent strain capacity of a binder relative to a typical binder; the higher the FFPR value, the higher the failure strain at a given modulus value. The best indicator of mixture fatigue FFPR was found to be the Christensen-Anderson R-value; as R-value increases, fatigue FFPR decreases. Layered elastic analyses (LEA) of two representative pavement structures containing a variety of binders suggested the fatigue performance of actual pavements is the result of complex interactions among binder and mixture modulus, binder phase angle and pavement structure, making the development of a simple and effective fatigue parameter difficult. However, establishing a maximum limit on GRP at an appropriate test temperature, and perhaps setting maximum limits on R-value, will help ensure that asphalt binders have the correct combination of properties to ensure adequate fatigue performance when used in asphalt pavements.