Prediction of Fatigue Behaviour of Asphalt Mix from Tests on Asphalt Mastic

Abstract

With the introduction of the EN 13108-xx in 2008, it became possible to use performance-based test methods for the assessment of asphalt mixtures also in contracts. There are various test methods for addressing the performance characteristics of asphalt mixtures (i.e. low temperature cracking resistance, stiffness, resistance to fatigue and to permanent deformation). They are specified in the EN 12697-xx. However, these rather complex test methods require a large test effort compared to empirical tests; in the special case of fatigue tests, a substantial amount of material and time for specimen preparation is needed. Therefore, it is the main goal of an on-going research project to assess fatigue resistance on the mastic level by Dynamic Shear Rheometer (DSR), since mastic is the relevant binding component in asphalt mixtures. In this research, asphalt mixes with ten different types of bitumens and three different types of aggregates were produced and tested for fatigue on the four-point bending beam (4PB). The mastic components of each asphalt were mixed and tested for fatigue in the DSR. The results and analyses show a good correlation between the fatigue tests on both levels. With the shear stress level for 10⁶ fatigue load cycles and the initial stiffness on mastic level, the strain level at 10⁶ fatigue load cycles (ε₆) for the respective asphalt mix can be assessed with a very small deviation.