Comparative analysis of 60/70 bitumen to polymerized modified bitumen (SASOBIT) in flexible road pavement.

Abstract

Nigeria roads are susceptible to rutting and fatigue crack caused by exceptionally high wheel loads, a wide temperature range between seasons, and sometimes even between day and night on the same day. To improve the properties of asphalt concrete as a whole, many types of modifier polymer have been added to asphalt materials. This study was conducted to investigate the effect of varying Sasobit content in bitumen on the properties of bitumen at intermediate temperatures. Thus, this research paper presents the result of the effect of modified bitumen on penetration, softening point, flash point, specific gravity and Marshall stability of polymerized modified bitumen for use in pavement construction. Grade 60/70 bitumen was chosen for this research and modified with 1%, 1.5%, 2%, 2.5%, 3%, 3.5% and 4% Sasobit content. The results show an increase in softening point from 49.3oC at 0% to 85.4oC at 4%, specific gravity ranging from 1.04 at 0% to 1.06 at 4% and Marshall stability from 9.9 kN at 0% to 13.9 kN at 4%, while penetration decreased from 63.2 at 0% to 22.0 at 4% as well as flash point where a retrogressing trend was recorded from 275oC at 0% to 254oC at 4% as Sasobit content increased. Therefore, Sasobit as bitumen modifier in asphalt production enhances the rheological, mechanical and viscoelastic properties of bitumen as well as the overall performance of flexible road pavement. Hence, the research recommends Sasobit content at 2.5% for use as additive in asphaltic concrete. This recommendation is based on current industry practice and field experience.