Investigation of factors affecting modified asphalt binder development and performance using the poker chip test

Abstract

With the surge in the use of modified asphalt binders throughout the world, it is important to examine these materials for performance outside of their linear viscoelastic (LVE) range. Modified asphalt binders, which are usually costlier, are expected to increase the service life of asphalt pavements. The current paper utilizes two approaches to evaluate the nonlinear viscoelastic and failure performance of eight binders including six novel modified asphalt binders. First, the poker chip test for cracking performance evaluation was conducted at different loading rates and aging levels. The results conclude the efficacy of the poker chip test to differentiate and rank the best performing modified asphalt binders. Furthermore, the impact of varying the loading rates, aging levels, modifications, and performance grades was also studied. These results indicated that loading rates ranging from 1 to 4 N/s can be used to differentiate modified binder performance with similar ranking, which allows a wider range of machines to be used to do this test. In addition, the impacts of aging were studied to introduce differentiation between modifiers which are sensitive to aging. Apart from this, the Multiple Stress Creep Recovery (MSCR) test was conducted to evaluate the rutting performance. MSCR results further augmented the confidence in initial rankings as polymer-modified binders showed superior performance to other modifier types. It was observed that the top two binders in terms of poker chip results also had the best MSCR performance. Hence, instead of balancing the performance, like is done for mixtures, between rutting and cracking, an optimum binder can be synthesized which has excellent performance against load-related cracking and permanent deformation. This sets the stage for a balanced binder selection and design process to be implemented into future specifications and research efforts.