performance evaluation of bitumen containing cellulose microfibers and SBS and SBR polymers

A key issue to the development of using modified bitumen is the high price of additives, including fibers, which in turn, can increase the cost of bitumen and modified asphalt mixtures. In contrast to other research, in this study, cheap waste materials obtained from paper-making manufacture, including Liquor and cellulose microfibers (obtained from waste pulp mills) are used to improve the properties of modified bitumen while reducing the cost of producing modified bitumen. Further, bitumen modified by styrene-butadiene-styrene (SBS) and styrene-butadiene rubber (SBR) were examined in this study in order to compare with bitumens modified by cellulose microfibers. For this purpose, SHRP tests, including dynamic shear rheometers and bending beam rheometers, were performed on polymer and fiber modified specimens. Based on the results of this study, all modified samples displayed a significant increase in bitumen hardness. Tests of classical bitumen and rotational viscosity demonstrated that polymers of butadiene-styrene-styrene and styrene-butadiene rubber significantly enhanced the viscosity and hardness of bitumen in comparison with other polymers. Consequently, the mix and compaction temperature of the modified samples with these additives have significantly increased. Results revealed that Liquor-containing bitumen improved its high-temperature performance, but it had a negative effect on the bitumen's low-temperature performance. Furthermore, cellulose microfibers had less effect on improving bitumen's properties than polymers such as styrene-butadiene-styrene and styrene-butadiene-rubber. However, cellulose microfibers' capabilities to modify the properties of bitumen, including a lower mixing and compaction temperature of asphalt mixtures than polymers and cheaper production and implementation of asphalt pavements due to the use of cheap waste materials, cannot be overlooked.