Improving the performance of Crumb Rubber bitumen by means of Poly Phosphoric Acid (PPA) and Vestenamer additives

Paralleled to the numerous researches on Crumb Rubber (CR) modified bitumen, some limited work-studies have also been implemented on the effects of specific chemical modifiers, such as Poly Phosphoric Acid (PPA) and Vestenamer, on the performance of bitumen. The main difference between present research and previous ones is simultaneous evaluation of these additives on bitumen performance grade. In this research, five samples of modified bitumen were prepared using PG58-22, PPA, Vestenamer, and various CR percentages. The samples were classified according to the superpave performance grading system. The results indicate that these modifiers have significantly improved the performance of bitumen.

Research highlights
► We evaluated the simultaneous effect of poly phosphoric, Vestenamer and crumb rubber on the performance of PG58-22 base bitumen.
► We found that CR/Vestenamer/PPA modification improves the performance grade of bitumen at high, intermediate and low temperatures. This type of modification is significantly better than modification of bitumen only by use of CR or PPA.
► Modification reduces the risk of cracking at low temperatures and rutting at high temperatures.
► The degree of modification generally increases with CR content.