INFLUENCE OF POLYMERIC MODIFICATION ON THE CONVENTIONAL PROPERTIES OF BITUMEN SOURCED FROM AGBABU AND LODA IN NIGERIA: A STATISTICAL APPROACH

Abstract

Natural bitumen requires modification to qualify as a binder in pavement construction.However, the effects of modifiers on bitumen vary depending on the bitumen composition, polymer type, and dosage applied. The effects of bitumen geographical location (Agbabu, L1 and Loda L2), dosage (0 - 6 wt.%) and polymer types(polypropylene (PP), polyethylene (PE), poly-ethylene-co-vinyl-acetate (PEVA),poly-styrene-co-butadiene (PSCB) and butyl acrylate (BA) were investigated on conventional properties of Nigerian bitumen. This study identified the most suitable modifier and optimum dosage levels as a preliminary attempt towards promoting Nigerian bitumen for road construction. Thermal degradation, functional groups,surface morphology and chemical composition of purified and modified bitumen were done using thermal gravimetric analyzer, Fourier Transform infrared technique,Scanning electron microscope and Thin Layer chromatography respectively.Conventional properties were analyzed using standard procedures and the results obtained were statistically analyzed using Statistical Package for Social Sciences (SPSS). Significant differences were noticed between the geographical areas, types and dosage of polymer (p< 0.05). Samples from L1 responded well to modification than those from L2. PSCB performed better at L1 and PP outperformed others at L2 regarding softening and penetration points. Polymeric modification improved the ductility of base bitumen regardless of location. Except PEVA, polymeric bitumen exhibits a lower fire point value compared to base samples. A dosage as low as 2 wt.% additives was found to be adequate in terms of ductility and flash point irrespective of sample location. Dosages of 4 and 6 wt% are optimum and significant (p< 0.05) at L1 and L2, respectively for other properties. Regarding the viscosity, only BA showed positive effect on viscosity reduction, other polymers tend to absorb oily components from bitumen and swell, resulting in higher viscosity. The findings of this study establish optimal polymer dosages for bitumen modification at Agbabu and Loda,Nigeria, providing a robust baseline for future enhancement using binary or ternary modifiers to improve road performance and pavement service life.