Laboratory performance evaluation of both flake graphite and exfoliated graphite nanoplatelet modified asphalt composites

This paper presents a laboratory investigation of the thermal, electrical, rheological and mechanical properties and performance of control and graphite (flake graphite and exfoliated graphite nanoplatelet (xGNP)) modified asphalt binder and mixture. For the graphite modified asphalt binder, the rolling thin film oven (RTFO) test and pressure aging vessel (PAV) test were utilized to simulate the short-term and long-term aging process of control and graphite modified asphalt binder, respectively. The bending beam rheometer (BBR) test and dynamic shear rheometer (DSR) test were conducted to evaluate the rheological properties of the control and graphite modified asphalt binder at low and high temperatures, respectively. The Fourier transform infrared spectroscopy (FTIR) was used to evaluate the oxidation group content in these asphalt binders. The thermal conductivity of the graphite modified asphalt binder increased with graphite content. For the graphite modified asphalt mixtures, both thermal and electrical conductivities also increased with added graphite modifiers. The measured dynamic modulus results of mixture performance tests indicated that the added graphite particles were capable of increasing their moduli at both high and low temperatures. The Hamburg wheel tracking device (HWTD) test results also showed an improved rutting resistance. As a result, the graphite modified asphalt mixture can improve multiple physical properties and high-temperature performance as promising conductive materials for many applications.