“…To meet these requirements, special grades are manufactured by treating the straight run residual asphalt by various means. Some of the methods used include the conventional air-blowing, which is used extensively to alter the chemical composition and improve its rheological properties via oxidation (Gun, 1973;Hobson and Pohl, 1973;Oyekunle and Adesanya, 2000;Oyekunle and Omatsone, 2004). Correspondingly, the controlled addition of elemental sulphur to residual asphalts also resulted in chemical 252 L. O.…”