Abstract
Naphthenic acids, separated from a bitumen and a furfural extract by extraction with solution of ammonia in ethylene glycol, have been added to the bitumen for the investigation of the influence on its properties. The results indicate that the ductility of the bitumen decreased and its penetration increased after mixed with these naphthenic acids. The data obtained also show that the naphthenic acids of furfural extract with lower molecular weight have greater impact on the ductility of bitumen than the naphthenic acids of bitumen with higher molecular weight.