Abstract: A method is provided for improving high temperature performance grade properties of unblown asphalt by i) heating an asphalt cement to 200.degree. F. to 500.degree. F. (93.degree. C. to 260.degree. C.), ii) adding 0.1 wt. % to 10 wt. % ethylene-vinyl acetate copolymer based on weight of said asphalt cement to the heated asphalt cement, iii) adding 0.05 wt. % to 1.0 wt. % phosphorus-containing acid, e.g., polyphosphoric acid, based on weight of said asphalt cement and iv) mixing the resulting blend, thereby providing an unblown asphalt composition of greater useful temperature index (UTI). The invention further relates to asphalt compositions thus made and paving compositions containing these asphalt compositions.