Today, the construction sector experiences significant pressure to use green and sustainable materials. In this framework, using biological components derived from agricultural products is the most interesting topic for the stability of asphalt pavement construction materials. Furthermore, the escalation in demand for transportation infrastructure has resulted in a rapid surge in the volume of traffic and premature degradation of asphalt pavements. The primary objective of this study is to assess the efficacy of olive kernel ash (OKA) obtained from olive canning factories in modifying the characteristics of asphalt. The investigation of this function has not been explored in prior research. To this end, a comprehensive analysis of morphological, Thermogravimetric, chemical, and phase separation was conducted, in addition to physical and rheological testing, over three distinct temperature ranges: high, intermediate, and low. The results showed that OKA is thermally stable and has a slow decomposition. Also, using OKA, compared to most biomass employed in bitumen, exhibits a satisfactory amount of phase separation. Despite the enhanced shear strength, the modified samples incorporating OKA do not encounter any operational challenges regarding transportation and pumping. The findings from the rheological experiments indicate that incorporating 20 % OKA in bitumen can increase the shear modulus up to 71 % and recovery percentage up to 20 %. Therefore, it significantly enhances the resistance to permanent deformation under high temperatures. The increase in molecular weight and asphaltene phase creates a resistant binder against high temperatures. Meanwhile, the fatigue life of modified samples containing 20 % OKA decreased to 59 %. However, applying the highest shear stress to the sample containing OKA experiences demonstrates its ability to resist this stress for longer. Also, it was found that regulating the OKA dosage in bitumen can maintain its acceptable resistance level to cracking at low temperatures. This phenomenon is due to the positive effect of OKA on the viscoelastic characteristics of bitumen. Based on our assessments, it has been observed that incorporating OKA up to 20 % in bitumen consistently enhances its performance capabilities at high temperatures. Nevertheless, while using this modified bitumen in cold regions, limiting its utilization to a maximum of 5 % is advisable.
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