Laboratory evaluation of hard grade bitumen produced with PPA addition

Abstract

The present research deals with the development of poly phosphoric acid (PPA) based bituminous binder and investigating the corresponding changes happening with physical properties, chemical fractions, rheological properties, short term aging kinetics and surface morphology; when compared with virgin binder. During the current investigations, straight run VG-30 (AC-30) binder was modified with PPA from 0 to 4.5% with an incremental dosage of 0.75%. Rheological investigations were also carried out on the modified as well as unmodified binders using Antonpaar’s dynamic shear rheometer (DSR). An increase in the dosage of PPA to straight binder has shown improved physical properties in terms of decreased penetration value and increased softening point. Asphaltenes fractions of binders were found to be increased with the increment in the PPA dosage. The aging kinetics of PPA modified binders was also improved when compared with the straight run binder. It was observed that a 4.5% PPA addition has resulted in high service temperature binder grade of PG 76 and 70V with a corresponding 23 dmm penetration levels. From the field emission scanning electron microscopy (FESEM) images, a clear morphological change was observed on the modified binders with the added PPA content, when compared with VG 30 bitumen. Thus, obtained results have shown that the addition of 4.5% PPA content was found to be optimum for the production of hard grade binder.