ABSTRACT
ABSTRACT: In this study, first of all, the physical and chemical effects of polypropylene fiber modification on bitumen samples were investigated. Then, the amount of “optimum” polypropylene fibers was determined. In order to determine this value, first, static creep tests and Marshall tests were carried out and then, digital images of the modified binders under fluorescence microscopy were examined. The addition of the polypropylene fibers into the asphalt mixture enhances the mixture properties in a very favorable manner. The decrease of the accumulated strains at the end of the static creep tests correspond to approximately 60%. The initial and final creep stiffness values have increased by 129% and 149% correspondingly. Besides, the polypropylene modification ends up with a 30% economy from bitumen which deserves attention. Finally the optimal polypropylene addition amount was determined as 5.5% by weight of aggregate based on the static creep, Marshall tests and stereo microscopy analyses.
