Thermal Aging and Pressure Scanning Electron Microscopic Analysis of Polymer Modified Agbabu Natural Bitumen: Fid-Bau Portal

Thermal Aging and Pressure Scanning Electron Microscopic Analysis of Polymer Modified Agbabu Natural Bitumen

Bakare, Hassan O. / Olabemiwo, Ojeyemi M. / Agunbiade, Foluso O. / Haruna, Mohammad S. / Akanji, Samuel B. / Oladipo, Kayode D.

Abstract

Premature failure of road pavement due to oxidative aging of bitumen is a problem affecting the durability of bitumen in pavement. Therefore, this study investigates the morphologies (microstructures) of polymer-modified Agbabu Natural Bitumen (ANB) samples as well as the effects of aging on its chemical compositions and physical properties. The raw ANB sample was purified by moisture extraction and subsequent removal of impurities to form the base. The base was modified with High Density Polyethylene (HDPE), Polyethylene-vinyl-acetate (PEVA), Polystyrene-co-butadiene (PSCB) and Polyphosphoric acid (PPA) in percentage compositions of 2, 4, and 6wt.% using melt blend technique. Pressure Scanning Electron Microscopy (PSEM) was used to investigate the morphological changes. For long-term aging, base and 6wt.% polymer modified base samples at 60 °C were used to study its effects on chemical and physical compositions of samples. PSEM analysis showed that all the polymer have good compatibilities with the base bitumen at various percentage compositions. However, PSCB showed compatibility only at 2wt.%. Thermal aging generally reduced penetration values and increased the softening points of the base and modified base samples. In addition, its effects on chemical composition of base and 6wt.% modified base samples were found to be faster in the base sample compared to the modified base samples at various aging periods. Thus, the use of PEVA, HDPE and PPA for modification at the three percentage compositions is recommended. However, for PSCB, it is recommended only at 2wt.% due to poor compatibilities at 4 and 6wt.%.