Research on the adsorption capacity between asphaltene and resin in asphalt with different aging degree: Experimental study and quantum-mechanical calculation

Abstract

The regeneration of aged asphalt requires not only softening the already hardened asphalt, but also improving the stability of the micelle structure in the asphalt. In the colloidal hypothesis of asphalt, micelles are assumed to have an asphaltene core and an outer shell composed of resin. Resin molecules can stabilize asphaltene molecules and suspend them in malthene. On this basis, the interaction capacity of asphaltene-resin will directly affect the stability of micelles in malthene. As a result, changes in the ability of asphaltenes and resins to interact with each other during the aging and regeneration of asphalt are gradually receiving a great deal of attention from researchers. However, research in this area is currently limited to molecular dynamics simulations and quantum mechanical calculations and has not yet been investigated using experimental methods. Therefore, in this paper, the changes in the structural stability of micelles during the aging of asphalt are evaluated through experimental studies and quantum mechanical calculations. In subsequent studies, the changes in the structural stability of micelles during the regeneration of ageing asphalt will be further investigated. Firstly, the static adsorption experiment was used to study the adsorption behavior between asphaltene and resin, and the effect of asphalt aging on their adsorption behavior was analyzed by ultraviolet–visible spectroscopy(UV–vis). Secondly, through chemical structure analysis (including GPC, elemental analysis, 1HNMR) and an improved Brown-Ladner(B-L) method, representative molecular models of asphaltene and resin were constructed. The rationality of the molecular models was verified by molecular dynamics simulation(MD). Finally, with the help of Gaussian calculation and Multiwfn analysis, we evaluated the adsorption capacity of asphaltene-resin in virgin and aged asphalt from the molecular level. The adsorption experimental results show that the ability of asphaltene to adsorb resin decreases after asphalt aging, which may reduce the stability of micelles in malthene. The simulation results show that the simulation value and literature value is close, which indicate the new model molecular structure of asphaltene and resin by the B-L method is reasonable. The Gaussian calculation and Multiwfn analysis results show that the asphaltene-resin interaction ability of aged asphalt is lower than that of virgin asphalt. This may be an important factor to reduce the adsorption capacity of asphaltene-resin in aged asphalt. This study provides an in-depth analysis of asphalt aging from the perspective of asphalt micelles and provides new theoretical guidance for the regeneration of aging asphalt.