الفهرس Only 14 pages are availabe for public view
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Abstract
The thermal oxidation of asphalt (bitumen) during asphalt aggregate mixing or asphalt polymer modification process at high temperature is believed to be one of the most important factors contributing to the failure of asphalt binder and the asphalt pavement. The hardening and embrittlement of asphalt binder are due to the oxidation of its molecules resulting in the formation of highly polar and strongly interacting functional groups containing oxygen. The major functional groups produced during oxidation of asphalt are carbonyl groups, sulfoxides and sulfones. Nine different antioxidants were synthesized, characterized and examined for asphalt. The structures of the synthesized antioxidants were confirmed using the different tools of analyses: including elemental analyses, FTIR and 1H-NMR. The base bitumen was modified by adding different concentrations of the prepared antioxidants and heating the mixture at 170o C while stirring for 4 h. The modified bitumen blends were examined through the changes in tota acid number (TAN), FTIR and other physical properties including penetration test at 25 oC, softening point and kinematic viscosity at 135 oC. V The most effective antioxidants were selected to inhibit the oxidation of asphalt binder during mixing with 5 % atactic polypropylene (APP) at 170o C for 4 hr. while stirring. The selected antioxidant/polymer modified bitumen blends were examined using TAN, FTIR and physical properties