Increasing the Stability of Bitumen by using Polyphosphoric Acid

Modification of bitumen is one of the alternate solutions to improve the deficiencies of conventional bitumen. Modified bitumen fulfills many requirements and purposes cracking rutting etc are few failures in pavement which is due to high intensity of traffic, over loading of vehicles and significant variations in daily and seasonal temperature of the pavement. Investigations and literature has revealed that modifiers can be used to improve the properties of conventional bitumen and bituminous mixes to make it more suitable for pavement construction. Poly Phospheric Acid (PPA) is an example of reactive modifier that can be used by itself or in conjugation with suitable polymer. In general the concentration of PPA in bitumen is in the range from 0.2-1.2 wt% with an optimum 1.0wt%. The Marshall Stability test value is found maximum of 32.05KN for 12% poly phosphoric acid and 5.4% bitumen content which is more than plain bitumen. Mixes at bitumen content of 6% for 12% modifier and 6.5% for 0% modifier satisfies requirement of mix prepared with modified bitumen as per IRC: SP-53-2010. Modification of bituminous concrete mix has resulted in maximum stability with less bitumen content.