Investigation on the effect of phase segregation on the mechanical properties of polymer modified bitumen using analytical and morphological tools

The mechanical strength of polymer modified bituminous mix which is evaluated in terms of stiffness reflects the deformation behaviour of bituminous mixture. The stiffness of the binder strongly depends on its chemical composition besides aggregate structure of the bituminous mixture. Compatibility of polymer with the base bitumen is considered as major strength enhancing factor in the case of polymer modified bituminous mix. To relate the factors affecting the mechanical strength of the binder a new approach in this research study was adopted in order to relate the compatibility of 80/100 pen bitumen with polymer Polypropylene (PP) using analytical and morphological tools. Morphological tools like Atomic Force Microscopy (AFM) and Transmission Electron Microscope (TEM) were used to study the changes due to the difference in compatibility of polymer with bitumen. It was observed that the presence of phase segregated layer as observed by AFM surface morphology was considered as the main strength enhancing factor of the bituminous mix. While the presence of lamella as observed in TEM scanned images of PP PMB revealed that addition of polymer forms localized network in the phase segregated layer which induces the stiffening effect in PMB. From the chromatographic method (SARA) analytical analysis Saturate, Aromatics, Resin and Asphaltene fractionate were determined in the blend. It was observed that chemical composition of the blend also has a profound effect on the rheological properties and on the morphology of polymer modified bituminous (PMB) blend. It was concluded that PP PMB gets benefited by phase segregated layer in the blend when the polymer concentration was kept below 3 as it sufficiently enhances the mechanical strength of the PMB binder as observed by dynamic creep results. © The Authors, published by EDP Sciences, 2017.