Polyphosphoric acid 115%
Polyphosphoric acid has different applications. In the road construction it is used to modify the bitumen, to enhance its basic characteristics.
Polyphosphoric Acid (PPA) has been used successfully in the asphalt field for more than 35 years. Extensive use of PPA either as a solo asphalt binder modifier or in combination with synthetic polymers has been practiced for more than 10 years. PPA is increasingly being used worldwide to meet the high performance requirements for binders in SuperpaveTM applications. PPA modified asphalt binders have been used to pave roads all across the world under a wide variety of traffic and weather conditions. These roads are performing as expected in terms of reliability and durability.
PPA is currently used in the air-blowing oxidation process, as an additive in reactive polymer applications, and as a direct binder modifier. PPA is classified as a chemical modifier because it reacts with some of the components of asphalt. The other broad category of asphalt modification is referred to as polymer modification and involves the use of specific elastomeric polymers. Both approaches are increasingly used. In neat asphalt, PPA increases the high temperature Performance Grade (PG) rating of the asphalt binder without affecting the low temperature properties. Significant improvement in the water-sensitivity of mixes is also obtained. In polymer-modified asphalt, PPA provides these same benefits and also allows for a significant reduction in the level of polymer required to meet elastic recovery requirements.
The use of PPA in asphalt modification was first reported in 1973. Earlier work dealt with the use of phosphorus pentoxide (P2O5) as a catalyst in the air-blown oxidation of asphalt. Significant research on the use of PPA with polymers to modify asphalts, conducted since the late 1990s, is illustrated in several patents.Considerable interest continues in understanding how PPA interacts with binders and developing technology to optimize its performance.