Investigating characteristics of antioxidant modified bituminous binders and effect on aging behaviour

In this thesis, several antioxidant modifiers with two types of asphalt bitumen and new performance testing techniques were utilized. The aim of adding antioxidant materials in to the base bitumen is to improve the physical and rheological properties of base bitumen as well as the mechanical properties and durability of asphalt mixture. In addition, the ability of antioxidants to reduce age hardening was investigated in this study. Thiourea (T), furfural (F) and zinc oxide (ZnO) materials were used as additives in bitumen at different contents. The modified binders were examined under the frame of Superpave system by evaluating the performance grade of each binder and comparing it with base bitumen's grade. Furthermore, physical properties of unmodified and modified binders were analyzed by conducting conventional tests before and after aging process in the laboratory to evaluate effect of antioxidant addition on aging. In order to examine effect of antioxidant modification on rutting resistance of binders, master curve of each binder has been established after conducting frequency sweep tests utilizing the dynamic shear rheometer (DSR). In addition, the importance of this study acquires more importance by following the scientific approach by introducing new techniques for evaluating the performance of both the bitumen and asphalt mix simultaneously. For this purpose, the Multiple Stress Creep Recovery (MSCR) test on asphalt binders and the DSR Creep test on asphalt mix samples prepared from Marshall specimens were carried out as new performance testing techniques in Turkey. As a result, the antioxidant treatment increases the stiffness of the bitumen and improves the visco-elastic properties. Also, antioxidant materials have improved aging resistance of base bitumen. Furthermore, mechanical performance testing of modified mixtures proved the positive influence of increasing creep deformation resistance.