The behavior of carbon nano-tubes (CNTS) as a modifier to resist aging and moisture damage in asphalt

Background: Moisture damage and aging take place together in asphalt binder as it is on road-pavement in service life and, therefore, quite challenging to overcome. Various techniques, such as crumb rubber, fibers, etc. have been applied to improve the behaviour of asphalt materials. The use of nanomaterials was found as one of the effective techniques to develop temperature performances of asphalt binder. Methods: This study investigated moisture damage and aging of asphalt binder mixing with the carbon nanotubes (CNTs) using Atomic Force Microscopy (AFM). The base binder was primarily modified with 4% SBS polymer. Later on, CNTs were mixed in different percentages (i.e. 0.5%, 1%, and 1.5%) by weight with the 4% styrene–butadiene–styrene (SBS) modified binders. A special functionalized (-NH3) AFM probe with spring constant 3.44 N/m was utilized to complete the study. Results: The results were compared with 4% SBS modified asphalt with and without CNT addition. The adhesion forces of dry samples were found smaller as compared to wet and aged asphalt samples of with and without CNT. However, the adhesion forces of wet and aged samples with the investigated percentage of CNT performed considerably better than those without CNT. Conclusion: This result indicated significant improvement of asphalt to overcome moisture damage and aging owing to exposure in the outdoor environment as a paving material. This study recommends any dosage (i.e. 0.5 to 1.5% by weight) of CNT with 4% SBS modified asphalt to resist moisture damage and aging in the field.