Improving production temperature of polymer modified bitumen by waxy materials

Although polymer modification of road grade bitumens is widely used to improve the performance characteristics, the sustainable development consideration would propose a challenge in this way. Most of the polymers used in polymer modified bitumen such as SBS and EVA, would increase the viscosity in approximately considerable amount in all the temperature range, as a result mixing and compaction temperatures of these PMB’s would be so much higher than non-modified ones. In the other hand the use of waxy materials to produce warm mix asphalts and decreasing energy consumption and reducing the CO2 generation level is a new common practice especially in Europe.The aim of this research was to combine these two kinds of additives (Polymers and Waxy materials) to reach to high performance bitumen with the moderate production temperatures. Penetration grade tests and rheological analysis conducted with a dynamic shear rheometer (DSR) were used to assay the performance of the samples. Rotational viscosity measurements in a wide range of temperature were also performed using a Brookfield RV viscometer on the samples to observe the changes in the production temperatures.In this research SBS and EVA were used as polymer modifier and PE Wax and EBS were used as waxy materials. Much better performance characteristics such as higher G*/Sinδ and higher upper PG limit were resulted by the use of combination of polymers and waxy materials in contrast with each of additives alone. Considerable reduction in the production temperatures were seen by mean of adding waxy materials. PE wax was shown to be less effective than EBS in both cases. Improvement in the storage stability of polymers was also observed in case of using experimented waxy materials

Keywords:

warm mix asphalts , waxy materials , performance characteristics , storage stability , production temperatures