## 4 Results and Discussion
### Rutting Properties  
Table 6 represents the %R, Jnr, and Jnr_diff values of the CB, CRMB, and PMB binders, corresponding to 0.1 and 3.2 kPa stress levels. Higher %R and lower Jnr values are desirable for the improved rutting performance of asphalt binder. As expected, higher %R and lower Jnr values were noticed with the CRMB and PMB binders than with the CB binders, irrespective of the stress levels. For instance, decreases in Jnr values by 2488.2% and 197.3% were observed for the CRMB and PMB binders compared to for the CB binder at a 3.2 kPa stress level. Thus, it can be concluded that the CRMB and PMB binders exhibited a higher resistance to rutting compared to the CB binder based on the %R and Jnr values. Further, based upon the Jnr value corresponding to the standard stress level of 3.2 kPa, a binder can be categorized for different classes of vehicular loadings, as per AASHTO MP19. Table 6 clearly indicates that the addition of modifiers resulted in changing the vehicular loading grading to higher traffic loading conditions. Additionally, the stress sensitivity is considered as one of the most important parameters and it is desirable to have lower degree of stress sensitivity in an asphalt binder, which in turn helps in extending the service life of the pavement. From the results, it is evident that the addition of modifiers resulted in an increase in the sensitivity of the control binder towards the varied axle loading pattern, but this was within the requirements of AASHTO TP70 (Jnr_diff \(\leq\) 75%). Figure 6 represents the rutting properties in terms of the rut depth and dynamic stability of the CB, CRMB, and PMB mixtures. The rut depths of the CB, CRMB, and PMB mixtures were 3.5, 2.7, and 3.1 mm, respectively. Similarly, the dynamic stabilities of the CB, CRMB, and PMB mixtures were 3049, 4015, and 3695 mm/min, respectively. The results indicate that the CRMB and PMB mixtures showed a lower rut depth and higher dynamic stability values than the CB mixture. For instance, increases in the dynamic stability values by 24.1% and 17.5% were observed for the CRMB and PMB mixtures compared to the CB mixture. Thus, it can be concluded that the CRMB and PMB mixtures were more rut-resistant compared to the CB mixture, due to fact that the CRMB and PMB mixtures exhibited higher VMA values and the addition of modifiers resulted in a stiffer mixture. Finally, it can be concluded that the CRMB mixture exhibited a better rutting resistance compared to the PMB mixture. This may be due to the higher viscosity of CRMB, which is advantageous for resistance to rutting [14,15]. The rutting results were  
Figure 5: Workability test results: (**a**) number of gyrations, (**b**) Compaction Densification Index (CDI) and (**c**) Traffic Densification Index (TDI) values. also analysed using the correlation between wheel tracking and the MSCR test, as shown in Figure 7. It is clearly evident that lower Jnr values indicated lower rut passes and a higher dynamic stability. Similarly, higher %R values indicate lower rut passes and a higher dynamic stability. The dynamic stability had a good correlation, with an R\({}^{2}\) of 0.991 and 0.959 with respect to the Jnr and %R values, respectively. Similarly, the rut depth had a reasonable correlation, with an R\({}^{2}\) of 0.811 and 0.728 with respect to the Jnr and %R values, respectively. In addition, it can be inferred that, for the same aggregate gradation, the increase in the rutting resistance of the mixture is basically contributed by the asphalt binder. This also shows that the increase in asphalt viscosity improves the high-temperature performance of the mixture. Figure 6: Rut test results: (**a**) rut depth and (**b**) dynamic stability.