Comparison of In-Place Versus Laboratory Aged HMA Binder Properties

Properties of asphalt binder are some of the contributing factors that affect the performance and life expectancy of hot mix asphalt (HMA). Analysis of test data of laboratory aged binder and recovered in-place binder helps to create selection criteria of proper type and grade of binder for future projects. In this study, HMA binder properties from laboratory-aged specimens were compared to those extracted from field specimens. The properties are absolute viscosity, penetration, bending beam rheometer creep stiffness, bending beam rheometer m-value and direct tension failure strain. The data for the study were collected from the project files of Clark County Public Works, Las Vegas, NV. The comparisons based on a statistical analysis show that (1) there is no difference between the field and laboratory specimens for absolute viscosity (2) there is a significant difference between the field and laboratory specimens for penetration (3) the comparison of other three properties is inconclusive. Significant differences between laboratory penetration test results and the inconclusive evidence in the results of BBR creep stiffness and BBR m value tests between the in-place and laboratory-aged samples show that laboratory tests may not reflect the changes in asphalt binder during its performance life.