Influence of different fillers and SBS modified bituminous blends on fatigue, self-healing and thixotropic performance of mastics

The prediction of asphalt pavement performance is closely linked to the behaviour of mastic, consisting of filler and bitumen, which can be modelled as viscoelastic material. The purpose of this study is to investigate the effect of different fillers and bituminous blends on mastic fatigue response, considering recoverable phenomena in viscoelastic materials (thixotropy and self-healing) that concurrently occur. Three fillers (limestone, basalt and Portland cement) and three aged polymer modified bitumen contents (0%, 45% and 100%) were blended with a virgin polymer modified bitumen obtaining nine mastics characterised in terms of fatigue, self-healing and thixotropy using a Dynamic Shear Rheometer. Data obtained are analysed through a model previously adopted for polymer modified bitumens and mastics, allowing the determination of the fatigue endurance limit. Results show that the presence of filler with increasing particle density and/or Rigden voids causes a higher mastic stiffness without a clear trend on fatigue performance. In fact, great attention should be put on filler-bitumen interactions based on the physicochemical nature of filler. Moreover, whatever the filler considered, an enhancement in the fatigue endurance limit is detected in the mastics blended with a percentage of aged polymer modified bitumen (up to 45%), promoting the addition of Reclaimed Asphalt to obtain more performing and sustainable recycled mixtures.