The results of experiments on chemical modification of viscous road asphalts with atactic polypropylene (APP) obtained by polymerization over a titanium-magnesium catalyst are presented. It has been shown that the preparation of an asphalt-polymer binder (APB) in an asphalt melt at 140A degrees D is accompanied by the thermo-oxidative degradation of APP. The reaction scheme for chemical interaction of polyconjugated bitumen compounds with oxidized APP is presented. The APB materials with APP feature improved resistance to thermo-oxidative degradation and aging, high adhesion to mineral fillers, hardness, and heat resistance. A single-step technology for production of APB has been developed. The road concrete mixes with APP possess the lower water saturation and swelling in water, enhanced strength at 20 and 50A degrees D, a low coefficient of heat sensitivity and enhanced crack resistance. The possibility of preparation of stone mastic asphalt (SMA) without admixture of specialty stabilizing fibrous additives has been experimentally proven.