Fundamental properties of bitumen binders containing novel cellulose-based poly-functional fibres

A series of Fibre-added bitumen compounds were subjected to conventional and rheological tests for investigating the effectiveness of modified fibres in improving the characteristics of bituminous binders. The studied fibres were novel composite cellulose-based poly-functional fibres with and without a plastomeric polymer and crumb rubber content, which blended with neat bitumen or SBS Polymer modified Bitumen (PmB). The test program included a primary stage of microscopic analysis by means of Scanning Electron Microscopy (SEM), for observing these composite fibres’ microstructure as well as the empirical test methods, and dynamic rheological analyses using Dynamic Shear Rheometer (DSR). According to the conventional test results, the addition of fibres increased the softening point and viscosity and reduced the penetration. From another perspective, while the addition of rubber decreased the softening point and viscosity, it increased the penetration of compounds in comparison to those containing fibres without rubber content. From the results obtained by Multiple-Stress Creep-Recovery (MSCR) and Frequency Sweep (FS) test, the isochronal graphs of complex modulus and creep-recovery curves showed the same trends in terms of increased stiffness. In addition, the phase angle curves confirm that the presence of rubber decreased the stiffness and increased the elasticity for PmB compounds in comparison to those of reference mixtures containing non-rubberized fibres.