Crystallization kinetics and morphology of biochar modified bio-asphalt binder

Abstract

Crystallization of biochar modified bio-asphalt binder (BMBA) directly affects their intrinsic physicochemical properties, which can significantly impact their processing and application. This research aims to maximize recycling the pyrolysis products of biomass (biochar and bio-oil) and investigate the crystallization kinetics of BMBA to inhibit the second crystallization and phase separation. Specifically, the parameters of crystallization kinetics and free volume were quantified using molecular dynamic simulations (MD). Relative crystallinity was evaluated using dynamic shear rheometer (DSR). Crystallization structure was analyzed using X-ray diffraction (XRD) and Synchrotron radiation small angle scattering (SAXS), and high-temperature-induced crystallization and low-temperature-physical hardening were quantified using hot-table polarizing microscope (HTPM). Crystallization morphology was measured by environmental scanning electron microscope (ESEM) and atomic force microscope (AFM). The parameters of crystallization kinetics show that high temperature and stress could induce the crystallization of BMBA. The low-temperature-physical hardening and aggregation of molecules indicate that the shape of BMBA crystals tends to be spherical under isothermal conditions but lamellar crystals under the non-isothermal conditions. This study provides a better understanding of the mechanism of crystallization kinetics of BMBA and a theoretical basis for the application of sustainable materials in asphalt pavement.