Aging effects on microstructures and micromechanical properties of vulcanized eucommia ulmoides gum modified bitumen

To reveal influence of thermo-oxidative aging on the microstructures and micromechanical performance of vulcanized eucommia ulmoides gum (VEUG) modified bitumen, atomic force microscope (AFM) tests were performed on virgin bitumen and VEUG modified bitumen before and after aging. Results indicate that the number and volume of “bee structures” in VEUG modified bitumen are reduced after the incorporation of VEUG. Also, the microstructures of VEUG modified bitumen are not obviously changed after aging as compared with those of virgin bitumen. All roughness indexes and their increments of VEUG modified bitumen are less than those of virgin bitumen before and after aging. Both VEUG incorporation and bituminous thermo-oxidative aging reduce the adhesive force and energy dissipation, but increase the Young's modulus of VEUG modified bitumen, and these changing amplitudes are less than those of virgin bitumen. The VEUG incorporation improves the aging resistance of bitumen. This study provides a perspective to reveal the modification mechanism of VEUG on bitumen from the perspectives of microstructures and micromechanical properties.