Effect of polyphosphoric acid on physical properties, chemical composition and morphology of bitumen

The effect of polyphosphoric acid (PPA) on chemical composition, physical properties and morphology of bitumen was investigated. The morphology of the binders was characterized by atomic force microscopy. The results show that the influence of PPA on chemical composition, physical properties and morphology of bitumens depends on the base bitumen. The colloidal index shows an obvious effect on the chemical composition and physical properties as well as morphology of bitumen during PPA modification. A strong correlation is observed between morphology and chemical composition as well as physical properties for different bitumens after PPA modification.