Conventional binders cannot meet the current performance requirements of asphaltic pavements due to increase in traffic volumes and loads. Nanomaterials, due to their exceptional mechanical properties, are gaining popularity as bitumen modifiers to enhance the performance properties of the asphaltic concrete. Carbon Nanotubes (CNTs) are one of the most widely used nanomaterials because of their strength properties, light weight, small size, and large surface area. CNT addition results in improved substrate characteristics as compared to other modifiers. Due to high length to diameter ratio, dispersion of CNTs in bitumen is a complex phenomenon. In this study, dispersion of CNTs in bitumen was carried out using both dry and wet mixing techniques, the latter was selected on the basis of homogeneity of the resultant asphalt mixture. Scanning Electron Microscopy (SEM) was used to check the dispersion of CNTs in binder while Fourier Transform Infrared Spectroscopy (FTIR) was carried out to ensure the removal of solvent used for wet mixing. Conventional bitumen tests (penetration, softening point, and ductility), dynamic shear rheometer tests, rolling bottle tests, and bitumen bond strength tests were employed to check the improvement in the rheological and adhesion properties of bitumen while wheel tracker test was used to check the improvement in resistance against permanent deformation of asphalt mixtures after addition of CNTs. Results show that CNTs improved the higher temperature performance and permanent deformation resistance in both binder and mixtures. Improvement in bitumen–aggregate adhesion properties and moisture resistance was also observed.

With the increase in the demand for bitumen, it has become essential for pavement engineers to ensure that construction of sustainable pavements occurs. For a complete analysis of the pavement, both its structural and functional performances are considered. In this study, a novel material (i.e., Graphene Nano-Platelets (GNPs)) has been used to enhance both of the types of pavements’ performances. Two percentages of GNPs (i.e., 2% and 4% by the weight of the binder) were used for the modification of asphalt binder in order to achieve the desired Performance Grade. GNPs were homogeneously dispersed in the asphalt binder, which was validated by Scanning Electron Microscope (SEM) images and a Hot Storage Stability Test. To analyze the structural performance of the GNPs-doped asphalt, its rheology, resistance to permanent deformation, resistance to moisture damage, and bitumen-aggregate adhesive bond strength were studied. For the analysis of the functional performance, the skid resistance and polishing effect were studied using a British Pendulum Skid Resistance Tester. The results showed that GNPs improved not only the rutting resistance of the pavement but also its durability. The high surface area of GNPs increases the pavement’s bonding strength and makes the asphalt binder stiffer. GNPs also provide nano-texture to the pavement, which enhances its skid resistance. Thus, we can recommend GNPs as an all-around modifier that could improve not only the structural performance but also the functional performance of asphalt pavements.

Recycling of an asphalt pavement reduces construction cost as well as the environmental degradation. Adding the bitumen emulsion as a rejuvenator in aged and oxidised asphalt binder improves its viscosity and stiffness without significantly decreasing the carbonyl index. This results in a high aging rate of such asphalt materials. This study proposes Cereclor as an alternate rejuvenator in the replacement of conventional bitumen-based emulsion. The main objectives of this study were to investigate the effect of Cereclor on aged asphalt binder’s characteristics, aging resistance and on the durability of Reclaimed Asphalt Pavement (RAP) modified asphalt mixtures. Carbonyl index was calculated from IR spectra of samples before and after laboratory aging to evaluate the aging resistance. It was observed that a 9% by weight of Cereclor rejuvenates 40/50 pen grade aged asphalt binder to the level of 60/70 pen grade bitumen. For durability assessment of RAP and rejuvenated mixes, fatigue, rutting and moisture susceptibility tests were performed. Four-point beam fatigue test showed that a 9% dose of Cereclor has increased the fatigue life of RAP by almost two times as compared to emulsion. Rut depth for all samples was in the range of 3–4 mm satisfying the rutting failure criteria. Overall, this study revealed that Cereclor has higher rejuvenation potential as compared to bitumen-based emulsion and thus it can potentially be used in pavement recycling.