Evaluation of the sensitivity of the rheology characteristics of bitumen and slurry seal modified with cellulose nanofiber solution

Abstract

Asphalt pavements account for a significant share of the world's pavements, these pavements will cause the waste of many unacceptable renewable resources along with the emission of greenhouse gases. Therefore, in order to reduce environmental risks and reduce costs, the use of protective asphalt has received more and more attention in recent decades. Slurry seal is used as an environmentally friendly product to delay pavement failures. Improving the properties of this type of preventive asphalt by changing the characteristics of the bitumen emulsion has attracted the attention of researchers in the last few years. Therefore, in this research, it has been tried to improve the quality of emulsion as an important and influential member on the performance of slurry seal using CNF (cellulose nanofiber solution. This research is based on laboratory and analytical method on modified bitumen emulsion and slurry seal containing it. In this research, 5 types of modified bitumen emulsions with CNF, including CNF0, CNF3, CNF5, CNF7, and CNF9, were proposed for the construction of slurry seal mixture. Bituminous specimens were subjected to physical, microstructure and rheological tests including saybolt furol viscosity, softening point, penetration degree, surface free energy (SFE), fourier transform infrared spectroscopy (FTIR), multi-stress creep recovery (MSCR) and elastic recovery (ER) tests. Then, the modified asphalt mixtures were evaluated with the wet cohesion, wet track abrasion, loaded wheel-displacement and loaded wheel-sand adhesion tests. Among the 5 specimens, CNF5 and CNF7 had the best results in bitumen and asphalt qualitative tests. These results showed that CNF5 with cellulose nanofibers of 5% can be considered as the optimal percentage because the properties of asphalt such as adhesion, deformation, bleeding, wear caused by moisture can be improved by 22.7%, 42%, 28.7% and 42.7%, respectively. It improved 8% to the control sample in residual bitumen.