Electrically conductive nanocomposite bituminous binders containing carbon nanotubes and multilayer graphene

In the modern literature, there are practically no data on the electrical characteristics of bituminous binders modified with carbon nanotubes and graphene nanoplates, while they are necessary for the design and development of innovative asphalt pavement compositions sensitive to the super-high-frequency microwave radiation. Contemporary bituminous binders are multi-component systems that may contain polymers, rubbers, synthetic or natural resins, inorganic salts, and even fragrances. As a result of application of modifying additives, bitumen acquires high performance characteristics. A special class of modifiers are micro- and nano-sized electrically conductive fibers and particles (steel wool, carbon fibers, carbon black, carbon nanotubes, graphene nanoplates), the use of which makes it possible to ensure the sensibility of bituminous binders to super-high-frequency microwave radiation and the implementation of the process of healing cracks in an asphalt pavement with its subsequent regeneration. As part of the study, the authors developed an original technique to produce bituminous binders modified with carbon nanotubes and multilayer graphene. Modified bituminous compositions in the concentration range from 0.2 to 6 and from 0.2 to 11 wt. % for multi-walled carbon nanotubes (MWCNT) and multilayer graphene nanoplates (MG), respectively were experimentally obtained. For the first time, the dependence of the specific volume electrical conductivity of bitumen-based nanocomposites on the concentration of nanostructured carbon filler (MWCNT and MG) was researched. The maximum values of electrical conductivity were 4.76×10⁻⁴ S/cm and 3.5×10⁻⁴ S/cm for nanocomposites containing 6 wt. % MWCNT and 11 wt. % MG, respectively. The study determined the filler volume fractions at the percolation threshold for nanocomposites containing MWCNT and MG. They amounted to 0.22 and 2.18, respectively. The formation of a percolation contour in nanocomposites containing MWCNT occurs at significantly lower filler concentrations compared to bituminous compositions containing MG.