Improvement of the aging resistance of bitumen by addition of synthetic metal and polymer additives

Bitumen materials are one of the earliest engineering materials used for road pavement, as well as for many other applications. In today?s industrialized world and high living standards, the need for higher quality materials is evident within the framework of developing technology and changing needsThe mechanical and chemical properties of bitumen changes with time, as short-term aging during the mixing and paving process and as long-term aging during its service life as a pavement. The significance of studies on improving the resistance to aging can be represented by the fact that short-term aging comprises approximately 70% of aging process.The resistance of modified bitumens with metallic and polymeric additives to short-term aging was investigated in this study. Organic based Zinc (Zn), Calcium (Ca), Magnesium (Mg), Boron (B), Zinc phosphate (ZnPO4) and Manganese (Mn) were used as metallic group additives, and Diethylene Glycol based Boron and Triethylene Glycol based Boron were used as polymeric group additives.To determine the influence of metallic and polymeric additives on the aging resistance of the pure bitumen, the standard test methods (rotational viscosity, penetration, softening point, ductility at 15 and 25 o C) were carried out on the 50-70 pen type original bitumen, original aged bitumen, modified bitumen, and modified aged bitumen containing metallic and polymeric in optimum quantities determined by viscosity aging index. The short-term aging of bitumen binders was carried out using TFOT method. The degree of oxidation of bitumen was evaluated through FTIR spectroscopy. In addition, the performance analyses of original, modified and aged bitumens were performed using Marshall Stability and flow method.The test results indicate that all of the used additives improve the aging resistance of the bitumen. The metallic group additives decreased the viscosity and softening point, but increased penetration and ductility of the bitumen. The polymeric group additives increased the viscosity and softening point, but decreased penetration and ductility of the bitumen. From metallic additives group, 1 % of organic based zinc by mass was found to be the most effective against aging by decreasing the short term aging by %58,5. From polymeric additives group, 2% of Triethylene Glycol based Boron by mass was the most effective, which decreased the short term aging by %56,7.