Utilizing Asphaltenes and Polyethylene Terephthalate Fibres in Developing High-Performance Asphalt Concrete
Creators: Ahmed, Nirob
Publisher: name: University of Alberta Library
Year: 2024

<p>Asphalt pavement performance is significant in order to ensure safety, longevity, cost-effectiveness, environmental sustainability, and the overall socio-economic well-being. A substantial amount of financial allocation is dedicated every year to enhance the performance of asphalt pavement in a more sustainable manner, due to the increasing global concern for sustainable infrastructure development. This has stimulated investigations into waste materials and different methodologies that reduce environmental footprints while simultaneously enhancing the lifespan of asphalt pavement with improved capacity. In this context, this research explored the incorporation of waste additives, specifically asphaltenes and polyethylene terephthalate (PET) fibres, in the development of high-performance asphalt concrete (HPAC). HPAC is an innovative paving material for high-traffic roads, known for its superior strength, rutting resistance, and fatigue resistance.<br>
In the initial stage of this study, asphaltenes, a sustainable and cost-effective waste material, was used as an additive in the asphalt binder modification process. Two different asphalt binders were used in this study—one derived from crude oil and the other from Alberta oilsands bitumen. The binders were modified with an optimum concentration of 12% (by weight of binder) asphaltenes to assess their rheological and aging properties utilizing multiple stress creep recovery (MSCR) and frequency sweep (FS) tests. These tests were conducted on a dynamic shear rheometer (DSR) device with different plate geometry. MSCR test results demonstrated that binders modified with asphaltenes exhibited a reduction in non-recoverable creep compliance (J<em>nr), satisfying the criteria for extremely heavy traffic conditions, as evidenced by J</em>nr values consistently below 0.5 kPa-1. All the binders met the stress sensitivity requirement, with J<em>(nr diff) values being lower than 75%. J</em>(nr slope) results, on the other hand, indicated lower stress sensitivity in the asphaltenes-modified binders. Results from the FS tests revealed improved rutting resistance in the asphalt binders post asphaltenes modification with increased complex shear modulus and rutting parameter values. Lower phase angle values strongly indicated a shift toward increased elasticity and reduced viscous behaviour in binders subsequent to the asphaltenes incorporation. Additionally, complex shear modulus aging index (CAI) results demonstrated that the asphaltenes-modified binders were better resistant to short-term aging.<br>
Finally, asphalt mixes were prepared with the inclusion of asphaltenes, and three different lengths of PET fibres. An indirect tensile cracking test (IDEAL-CT) was performed to evaluate the cracking resistance properties of these mixes using a universal testing machine (UTM). The tests were performed at a typical intermediate temperature of 25 °C. Another target test temperature of 37 °C was determined based on the PG of the asphalt binder. The test results showed a clear impact of PET fibre incorporation at 37 °C, with significant improvement in the cracking tolerance (〖CT〗_Index values for control asphaltenes-modified, 6-mm, 12-mm, and 18-mm PET fabricated samples were found to be 61, 87, 105, and 99, respectively) and failure energy (5,475 J/m2, 6,752 J/m2, 7,005 J/m2, and 6,902 J/m2 for control asphaltenes-modified, 6-mm, 12-mm, and 18-mm PET fabricated samples, respectively), with this effect becoming more pronounced with increasing fibre length. </p>