Investigation into the mechanism of performance enhancement of solvent-based asphalt induced by microbial digestion

To address the insufficient early strength of solvent-based asphalt, we propose a bio-based strategy that employs hydrocarbon-digesting Pseudomonas spp. to selectively remove residual solvent and thereby accelerate curing. Gas chromatography–mass spectrometry (GC–MS) and rheometry reveal preferential depletion of C6–C9 fractions, a marked reduction in residual-solvent concentration, and a faster rise in modulus and viscosity, without compromising the asphalt matrix. Fourier-transform infrared spectroscopy (FTIR) and thin-layer chromatography (TLC) identify glycolipid (rhamnolipid-type) metabolites formed during microbial digestion (i.e., biodegradation via catabolism); together with KEGG-based pathway analysis, these results elucidate the mechanism of solvent digestion. A coupled diffusion–evaporation–digestion model implemented in COMSOL quantitatively describes the performance enhancement. Overall, microbial treatment promotes solvent loss via digestion, shortens curing, and improves the macroscopic performance of solvent-based asphalt. To the best of our knowledge, this is the first study to apply microbial technology to enhance asphalt pavement materials, offering a novel, sustainable route to eco-friendly, high-performance road infrastructure.