Effect of Polymer Dispersion on the Rheology and Morphology of Polymer Modified Bituminous Blend

Increase in axle wheel load and traffic volume led to the use of polymer modified bitumen (PMB) as the enhanced mechanical properties of PMB offers better results in terms of rutting, thermal and fatigue related problems. In this paper viscosity function of PMB obtained at 135°C were studied in context with the miscibility of polymer in PMB. Polypropylene was used as modifier for 80/100 pen bitumen. The morphological analysis using Scanning Electron microscopy (SEM), Atomic force microscopy (AFM) and Field Emission Electron microscopy (FESEM) were used as tool to unfold the truth about viscosity enhancement and thus the mechanical properties of the PMB. It was found that although polymer resin was not fully digested by virgin bitumen but significantly alter the Newtonian behavior of virgin bitumen to Non-Newtonian by the addition of polymer. SEM examination of polypropylene resin revealed that partial breakage of the periphery of resin enhances the viscosity of the PMB significantly which is being confirmed by viscosity results and creaming effect as observed by FESEM results. Thus the partial miscible polymer in the blend enhances the viscosity and there by induces a phase separated layer as being observed by AFM results. Thus it was revealed that mechanical characteristic of the binder would be enhanced when the concentration of polymer in the blend was kept till 3% of the weight of the bitumen