Multiscale characterization of bio-based polyurethane modified asphalt: Macro-micro experiments and molecular dynamics simulations
Junfeng Gao, Guixiu Guo, Hainian Wang, Ning Xu, Dongzhao Jin
Abstract
This study conducted a multiscale investigation of bio-based polyurethane modified asphalt (Bio-PUMA) by combining macro–micro experiments with molecular dynamics simulations. Penetration, softening point, ductility, viscosity testing, temperature sweep test, bending beam rheometer (BBR) test, and cigar tube segregation test were conducted to evaluate the macro performance and storage stability of Bio-PUMA. Fourier-transform infrared spectroscopy (FTIR) and fluorescence microscopy (FM) were used to characterize the micro properties of Bio-PUMA. The study found that the difference in solubility parameter (λ) between Bio-PU and base asphalt at 120℃ is minimal, indicating the best compatibility at this temperature. The diffusion coefficient at 150 °C is 2.44 times higher than that of 120 °C, it is recommended to prepare Bio-PUMA at temperatures above 150 °C. Lower temperatures and higher Bio-PU content result in a more stable system. The compatibility problem of Bio-PUMA gradually emerges with the increase of Bio-PU content. Bio-PU enhances the high-temperature property and thermal stability of base asphalt, and it has a certain negative impact on the low-temperature performance of asphalt. It is recommended that the Bio-PU content should not exceed 9 %.