Performance of VG30 paving grade bitumen modified with polyphosphoric acid at medium and high temperature regimes

This research describes the observations made on VG30 paving grade bitumen modified with Polyphosphoric Acid (PPA). Bitumen is used as a binder in the construction of flexible pavements. In order to overcome the limitations of air blowing technique to enhance bitumen properties, modification with PPA has been suggested by various researchers across the globe. In the present study, a comparative performance of the acid modified bitumen and unmodified VG30 grade bitumen, has been studied with respect to fundamental properties like penetration, softening point, ductility and the rheological parameters like complex shear modulus and phase angle. Further, the micro structural investigations have been carried out using X-Ray diffraction & Scanning Electron Microscopic techniques for both modified and unmodified binders. The above investigations have also been carried out for Rolling Thin Film Oven Test (RTFOT) short term aged binder residues to study the efficacy of the modification. The results indicate that the PPA can be used as modifier to enhance the medium and high temperature performance of bituminous binders.