Oil shale waste as asphalt fine aggregate: multiscale insights into pore structure, rheology and molecular mechanisms

Oil shale waste (OSW), characterized by its porous structure and oil storage capabilities, exhibits significant potential as a fine aggregate. This study integrates microscopic pore analysis, rheological evaluation and molecular simulation to elucidate the interaction dynamics between OSW and asphalt. Results indicate that combustion-derived waste (CSW) possesses a more complex pore structure, with a fractal dimension 2.87% higher than that of distillation-derived waste (DSW). This structural complexity significantly strengthens the filler-asphalt interaction, increasing the storage modulus of CSW asphalt mortar by 29.2% compared to DSW mortar and reducing the self-healing temperature to below 45 °C. Molecular simulations reveal a distinct shape-selective adsorption mechanism where micropores preferentially adsorb light asphalt components, effectively enhancing the rheological performance. These findings highlight the potential for the high-value valorisation of OSW as a sustainable alternative filler, although future work is needed to fully clarify the competitive adsorption behaviours and chemical influence within the complex pore network.