Rheological and micro-structural characterization of bitumen modified with carbon nanomaterials

To investigate the rheological and micro-structural properties of bitumen modified with carbon nanotubes (CNTs) and graphene (Gr), bitumen samples with different contents of CNTs and Gr were manufactured and characterized from both rheological and micro-structural perspective. A frequency sweep and multi stress creep recovery (MSCR) were conducted by dynamic shear rheometer (DSR) to investigate the rheological properties of CNTs and Gr modified bitumen. Differential scanning calorimetry (DSC) tests were applied to survey the glass transition temperature. The homogeneity of the dispersion and the interaction between bitumen and nanomaterials were observed by scanning electron microscopy (SEM). The results indicated that the incorporation of CNTs and Gr enhance the stiffness, rutting resistance, elastic recovery performance, pavement service life and high temperature performance of bitumen. The performance improvements were attributed to an increase in the crosslinking degree of the binders induced by the carbon nanomaterials. Bitumen binders modified with 1.5% CNTs and 1% Gr are found to be the optimal mixtures. Compared to CNTs, Gr is more compatible with neat bitumen and the effect of Gr modification is observed to exceed that of CNTs at the same content. This may be due to the sheet-like surface morphology and larger specific surface area of Gr.