Polymer modified-natural bitumen thermal aging resistance studies

Abstract

Bitumen is used as a binder in flexible road pavement but it reacts with atmospheric oxygen and hardens leading to road failures. This study therefore investigates the viability of using some polymers/modifiers to modify Agbabu natural bitumen (ANB) to reduce its susceptibility to oxidation and hence gives its road pavement longer service life. Purified ANB (base) sample was modified using melt blend technique. Three polymers: High-Density Polyethylene (HDPE), Poly(ethylene-co-vinyl-acetate) (PEVA) and Poly(styrene-co-butadiene) (PSCB) were used in 2, 4, and 6wt% for modification. Thereafter, long-term aging was thermally simulated on the base and polymer modified ANB samples at 60 oC. Both aged and unaged samples were then subjected to Fourier Transform Infrared (FTIR) Spectrometric Analysis and Oscillating Disc Rheometer (ODR) test to study the effects of aging on physicochemical and rheological properties of the samples. Our finding showed that PEVA modified samples at 2 and 6wt.% showed comparatively, improved resistance to fatigue cracking and rutting. However, the three modifiers used are capable of reducing the rate of thermal aging of the base sample.

Keywords:

• Carbonyl index
• sulphoxide index
• infrared spectrometric analysis
• melt blend technique
• oscillating disc rheometer
• long-term aging

Acknowledgements

The first author would like to thank the Management of Tertiary Education Trust Fund (TETFUND) for providing research grant for this study. Also, the corresponding author expresses appreciations to the Executive Vice Chairman/CEO, National Agency for Science and Engineering Infrastructure (NASENI), M.S. Haruna, for granting him a study leave.