The depletion of petroleum reserves and increasing environmental concerns have driven the development of eco-friendly asphalt binders. This research investigates the performance of natural asphalt (NA) modified with waste engine oil (WEO) as a sustainable alternative to conventional petroleum asphalt (PA). The study examines NA modified with 10%, 20%, and 30% WEO by the weight of asphalt to identify an optimal blend ratio that enhances the binder’s flexibility and workability while maintaining high-temperature stability. Comprehensive testing was conducted, including penetration, softening point, viscosity, ductility, multiple stress creep recovery (MSCR), linear amplitude sweep (LAS), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). The results reveal that WEO effectively softens NA, improves ductility, and enhances workability, with the 20% WEO blend achieving the best balance of physical and rheological properties. Chemical analysis indicates that WEO increases carbon content and reduces sulfur and impurities, aligning NA’s composition closer to PA. However, excessive WEO (30%) compromises thermal stability and deformation resistance. The findings underscore the potential of WEO-modified NA for sustainable pavement applications, with 20% WEO identified as the optimal content to achieve performance comparable to conventional petroleum asphalt while promoting environmental sustainability.

High temperatures combined with heavy traffic load necessitate asphalt binder modification to enhance its performance and durability. This research examines the effects of polyphosphoric acid (PPA) on the physical, rheological, and chemical properties of styrene-butadiene-styrene (SBS)-modified asphalt binders. Asphalt binders were prepared by adding 3% SBS and varying PPA dosages of 0.3%, 0.6%, and 0.9% by weight of asphalt cement. The experiment investigated the physical properties (penetration, softening point, ductility, viscosity, and specific gravity), the rheological properties (the performance grading (PG), multi-stress creep recovery (MSCR), and linear amplitude sweep (LAS)), and the microstructure and chemical composition of the modified asphalt binder. The results demonstrated impressive improvements in rutting resistance and stiffness. Adding 3% SBS and 0.9% PPA increased the rutting factor (G*/sin δ) by 165% and the high-temperature PG from 74.2 °C to 93.6 °C compared to the virgin asphalt binder. However, the optimum fatigue resistance was obtained by adding 0.3% PPA to the SBS asphalt binder. The microstructure and composition analysis revealed that using SBS and PPA together enhanced binder homogeneity and reduced voids. Lastly, an Overall Desirability (OD) analysis suggested the 3% SBS and 0.3% PPA to be the most effectively balanced formulation for the demand of high temperature and heavy traffic conditions. However, further field studies are recommended to validate the results under real-world conditions.

Journal Communications - Scientific Letters of the University of ?ilina is now a well-established open-access scientific journal aimed primarily at the topics connected with the field of transport.

Biobinders are increasingly gaining attention in the pavement community as sustainable alternatives to conventional petroleum-derived asphalt binders. While complete replacement of asphalt binder remains challenging, growing environmental concerns and energy crises demand at least partial substitution with renewable and ecofriendly materials. In this context, this study explores the use of pomegranate molasses (PM), a natural biobased product, as a novel asphalt binder modifier. A comprehensive experimental program was conducted to evaluate the chemical, thermal, rheological, and mechanical effects of PM incorporation at three dosages (10%, 20%, and 30% by weight of asphalt binder) compared with a reference binder. Fourier transform infrared spectroscopy confirmed the presence of oxygenated functional groups (O─H, C═O, S═O) introduced by PM, while thermogravimetric analysis showed that the modifier is thermally stable under asphalt mixing and compaction temperatures. Binder-level testing revealed improved viscosity and high-temperature performance with PM addition, along with enhanced fatigue life at moderate dosages. At the mixture level, Marshall stability increased by about 11%, wheel-tracking results showed up to a 45% reduction in rut depth, and cracking resistance evaluated through the asphalt flexibility ratio improved at PM10% and PM20% before declining at PM30%. The tensile strength ratio (TSR) remained above the 80% threshold for all mixes, while the resilient modulus increased with PM content. One-way ANOVA confirmed that PM had a statistically significant effect on rutting resistance ( p - value = 0.011 ) but no significant effect on fatigue, TSR, or stiffness. Overall, PM demonstrated strong potential as a sustainable biomodifier, with 20% PM (by weight of the asphalt binder) identified as the optimum dosage, offering the best balance of resistance to rutting, fatigue, cracking, and moisture damage. Further field validation is required to translate these laboratory findings into practical applications.