hamed seyfi - Department of Civil Engineering, Payam Noor University (PNU), Tehran, Iran
shahin shabani - Department of civil engineering, Payame Noor university (PNU), P.O.Box: ۱۹۳۹۵-۴۶۹۷, Tehran, Iran.
somayyeh gazaz - Chemistry Engineering Department, Payam Noor University (PNU), Tehran, Iran

Bitumen and asphalt mixture, cellulose fibers have attracted more attention of researchers due to their lower price and availability; the purpose of this research is to investigate the possibility of using cheap waste materials from paper factories to replace expensive modifiers, which can increase the life of asphalt pavement and reduce the need for its frequent repairs . In this research, the physical properties of the bitumen modified with cellulose fibers and black liquor have been investigated. The results showed that the increase in stiffness of the bitumen containing cellulose micro fibers and liquor. The increase in bitumen stiffness has decreased the degree of penetration and increased the softening point in the modified bitumen. The viscosity of the modified bitumen also increased with increasing stiffness. The results also showed the improvement of the high-temperature performance  of all the samples modified with cellulose micro fibers and liquor. However, the improvement of the low temperature of the modified bitumen is limited to the use of ۴ to ۶% cellulose microfibers. Increasing the resistance to rutting of the modified bitumen showed the positive effect of using cellulose micro-fibers in order to modify the properties of the base bitumen; Therefore, by using the wastes of paper factories, it is possible to achieve favorable results in reducing the common failures of asphalt pavements, including rutting at high temperature and cracking at low temperature, and reducing the costs of modifying bitumen and asphalt mixtures.

cellulose fibers, Black Liquor, Rheological properties, Dynamic shear rheometer test, bending beam rheometer test