## 1 Introduction  
Bitumen modification has become a critical technique in the construction industry to improve the performance and durability of asphalt pavements. Conventional bitumen, although widely used, often lacks the mechanical robustness required to endure harsh environmental and loading conditions. This deficiency can lead to early-stage pavement failures such as rutting, cracking, and deformation. To address these challenges, various additives--such as polymers, fillers, and oils--are commonly introduced into the bitumen matrix to enhance its rheological properties. These modifications not only improve the mechanical properties of the asphalt but also contribute to its overall longevity [1, 2, 3, 4, 5]. One of the most widely used modifiers is styrene-butadiene-styrene (SBS), a thermoplastic elastomer known for its ability to improve the elasticity and thermal resistance of bitumen. The addition of SBS has proven effective in increasing the durability of bitumen under high-temperature and dynamic load conditions. In recent years, however, the focus has shifted towards more sustainable alternatives, such as waste materials and bio-based modifiers. Among these, animal bone ash (AB) and waste cooking oil (WCO) have gained attention due to their environmental benefits and their potential to further enhance bitumen properties. These sustainable modifiers provide an opportunity to not only improve performance but also reduce the environmental impact of road construction [6; 7; 8; 9]. The incorporation of waste cooking oil into bitumen has been extensively studied, with promising results regarding its impact on the rheological properties of asphalt binders. Previous studies, such as those by [PERSON] et al. [10] and [PERSON] et al. [11], have shown that chemically modified WCO can improve the viscosity, elasticity, and overall performance of asphalt, particularly in aged asphalt mixtures. Similarly, research conducted by [PERSON] et al. [12] highlighted the importance of the type and quality of WCO used, as these factors significantly influence the rheological properties of the modified bitumen. Furthermore, studies by [PERSON] et al. [13] emphasized the complex interactions between WCO components and bitumen, which further underscore the need for a comprehensive understanding of these modifications. The combination of WCO with SBS has also been explored as a means to enhance the performance of modified bitumen. Research by [PERSON] and [PERSON] [14] demonstrated that SBS, when combined with WCO, not only improves high-temperature performance but also enhances low-temperature cracking resistance. These findings are crucial for extending the service life of asphalt pavements under varying temperature conditions. Additional studies, such as those by [PERSON] et al. [15] and [PERSON] et al. [16], have focused on optimizing preparation methods and examining the temperature-dependent behaviors of WCO-modified bitumen, further contributing to the understanding of how these sustainable additives influence bitumen performance across different climates. Animal bone ash, though less studied, presents a promising avenue for enhancing the rheological properties of bitumen. While research has traditionally focused on other types of ash, such as palm oil fuel ash, the potential of animal bone ash as a modifier remains largely unexplored. Recent studies, such as those by [PERSON] et al. [17], have demonstrated that animal bone ash can significantly improve the mechanical properties of asphalt concrete. The incorporation of animal bone ash into asphalt concrete has been shown to increase Marshall stability and improve the bond between bitumen and aggregate particles, which is crucial for durability under various loading conditions. Also, recent studies, such as those by [PERSON] [18], have analyzed the effects of waste animal bone ash and Portland cement on bitumen.