Physicochemical properties of high-content rubber modified bio-asphalt using molecular simulation

High-content rubber modified asphalt would let out lots of volatile organic compounds (VOCs), bio-oil was used to reduce the VOCs emission and mixing temperature of high-content rubber modified asphalt. The molecular model of high-content rubber modified bio-asphalt (HRMBA) was built to calculate the solubility parameter, free volume, molecular orientation, and radial distribution function. The effects of bio-oil on the physicochemical properties of HRMBA during VOCs emission process were studied deeply using molecular dynamic simulations and first principles. The differential scanning calorimeter (DSC), Fourier infrared spectrometer (FT-IR), and gel chromatography (GPC) were used to test the glass transition temperature, functional groups, and molecular aggregate and verify the simulated results. The results show that the optimum contents of waste tire in HRMBA is 35%, and bio-oil can promote the compatibility between rubber and asphalt. Free volume of HRMBA shows a strong correlation with the probe Connolly radius, and Connolly radius increases the molecular movements and dissolution of HRMBA. Moreover, the compatibility between bio-oil and rubber are good. Bio-oil can improve the dissolution of rubber into asphalt and inhibit the VOCs emissions of HRMBA. The compatibility between rubber and asphalt are damaged after VOCs emission. A new calculation method was used to evaluate the physicochemical properties of HRMBA, and experiment methods were also used to verify these.