Effect of Carbon Nano Tube on performance of asphalt binder under creep-recovery and sustained loading conditions

Abstract

Abstract The present study aimed at evaluating the rutting performance of Carbon Nano Tube (CNT) modified asphalt binder under different loading conditions. CNT content was varied as 0%, 0.4%, 0.75%, 1.5% and 2.25% by the weight of control binder. Superpave rutting parameter (G*/Sinδ) and Shenoy parameter (G*/(1-(1/TanδSinδ))) were initially evaluated using temperature sweep test. Though both parameters showed a similar trend, the later one found to have more sensitivity towards evaluating unrecoverable strain value. Creep-recovery test was further conducted at four different stress levels (100 Pa, 3200 Pa, 5000 Pa, and 10000 Pa) to understand the effect of CNT under cyclic loading-unloading condition. Improvement in recovery value and a corresponding decrease in non-recoverable creep compliance value was observed with the addition of CNT. Further attempt was made to model the strain response from creep-recovery test using the Burgers model and Power model. Based upon the variation of viscous component of steady flow obtained from the Burgers model, CNT addition found to improve the rutting performance. Further, the power model also showed an excellent prediction of strain response under creep period, however, deviation from the experimentally observed response was observed in the recovery period. Modification to the power law model was done which significantly improved the strain prediction in the recovery period. Likewise, the effects of CNT under sustained loading condition was evaluated using a creep test at two different stress levels (100 Pa and 3200 Pa). Incremental dosages of CNT shifted the binder response from linear to nonlinear viscoelastic region at comparatively lower creep period. Significant decrease in deformation rate was also observed with CNT addition.