Efficacy of octadecylamine-functionalized graphene versus graphene nanoplatelets and graphene oxide as asphalt binder modifiers for high-temperature performance

In this work, we comprehensively report on the synthesis of octadecylamine (ODA)-functionalized graphene (G-ODA) and compare its performance to those of graphene nanoplatelets (GNPs) and graphene oxide (GO) as asphalt binder modifiers. An exploration into the mechanisms through which asphalt binder properties are enhanced by each graphene-based material has been conducted, identifying the one that demonstrates superior compatibility with asphalt. The study systematically evaluates the performance of each modifier, analyzing viscosity, rheology, anti-aging properties, morphology, and chemical transformations within asphalt binders. Experimental results indicate that all three graphene-based modifiers enhance the high-temperature performance and aging resistance of the asphalt binder, with GO emerging as the most compatible material, exhibiting superior performance across all investigated responses. The rheological properties results show that GO can improve G*/sin(δ) for the unaged binder by about 120%, followed by G-ODA and GNP. On the contrary, multiple stress creep and recovery (MSCR) results indicate that both GO and GNP efficiently reduce permanent deformation, with reductions in Jnr of about 39% and 34%, respectively while the G-ODA shows a smaller reduction of − 10%. Additionally, GO excels in improving elastic response, showing a substantial increase in percent recovery at 297%, compared to 48.4% with GNP and 28.8% with G-ODA. Fourier-transform infrared spectroscopy (FTIR) analysis establishes the absence of evidence indicating chemical interaction between any of the graphene-based materials and asphalt molecules. This suggests that the improvement is solely attributed to physical interaction, specifically through π-π interaction. On the other hand, AFM phase images indicate that all graphene-based materials can alter the morphology of asphalt binders. They increase the projected surface area of the Peri/Catana phases, which can influence the rheological properties of the binder.