Study on improved ploypropylene modified bitumen by incorporating phosphoric acid

This study presents a research conducted to investigate the properties of polymer modified bitumen (PMB) by using bitumen 60/70 as original bitumen, polypropylene (PP) as modifier, phosphoric acid (H3PO4) as additives, and with wet mixing method combining high shear mix and low shear mix in order to determine the optimum binder-PP ratio PMB for applying in Hong Kong. 18 samples had been prepared in this study, of which the PP contents vary from 2~7% with 1%, 3% and 5% of H3PO4 content. In result, compatibility and stability between PP and bitumen is the control factor for determining the maximum content of PP that can be added into the PMB, and all the PMB sample resulted in better performance in every test conducted in this study except ductility. It is concluded that the optimum binder-PP ratio in terms of upgrading the original bitumen (bitumen 60/70) to grade PG82 for Hong Kong areas is 5% PP with 3% H3PO4