Recycled and rubberized SMA modified mixtures: A comparison between polymer modified bitumen and modified fibres

In the presented research a series of Stone Mastic Asphalt (SMA) mixtures with and without Reclaimed Asphalt Pavement (RAP) and rejuvenating agent modified with SBS Polymer modified Binder (PmB) or composite Modified Fibres (MF) were optimized and investigated. In addition, beyond the common wet and dry methods of using waste tire rubber for producing asphalt mixtures, the rubber was added to the fibres with and without containing a plastomer polymer as a modifier. A comprehensive experimental programme including mechanical and performance tests were considered for evaluating the properties of the mixtures modified with PmB or MF with and without rubber and RAP. According to the test results, the SMA mixtures modified with MF were comparable with those of modified with PmB in most of the cases, however, the superiority of PmB mixtures were apparent in some cases. In the case of RAP addition, while it increased the tensile properties of corresponding mixtures observed by ITS and ITSM tests, it intensified the low-temperature sensitivity and reduced the fatigue life of mixtures containing rubberized fibres. Finally, the performance tests, moisture susceptibility and bitumen/aggregate, showed no significant difference between the tested mixtures in terms of moisture susceptibility and effectiveness of rubberized-fibres in bitumen binder's adhesion properties.