A novel recovery method to derive cationic emulsified asphalt evaporation residues

Emulsified asphalt, lauded as a new eco-friendly binder, has gained widespread attention and use lately. The characteristics of emulsified asphalt evaporation residues are pivotal for assessing emulsified asphalt quality, highlighting the significance of their recovery methods. This research aims to discern the effect of various recovery methods on the qualities of emulsified asphalt residues, with the goal of selecting an optimal recovery method. Initially, three cationic emulsifiers (SBT, KZW, SHLH) were employed to prepare emulsions, followed by analysis of particle size and storage stability of them. Subsequently, three recovery methods were identified as the direct heat method (DHM), the low temperature heat method (LTHM), and the spin heat method (SHM). Following this, a number of evaluations were carried out on the residues, including physical property tests, temperature sweep test, bending beam rheometer test, multiple stress creep recovery test, and linear amplitude sweep test. Ultimately, aging degree of residues was assessed via Fourier transform infrared spectroscopy (FTIR) test and microstructural analysis was executed utilizing field emission scanning electron microscopy (FESEM) test. Comparing the performance of residues obtained through DHM and LTHM, those obtained via SHM exhibit superior performance in terms of high-temperature rheological and fatigue properties. FTIR results reveal that the emulsified asphalt recovery process only involves physical mixing and minimal aging of residues obtained by SHM among the three recovery methods. Additionally, less residual emulsifier is observed under low-temperature heating condition through FESEM, while abundant residual emulsifier is observed under spin evaporation condition. In summary, the results suggest that SHM can be used as an appropriate method for recovering emulsified asphalt residues. • SBT cationic emulsifier has better emulsification characteristics compared to KZW, SHLH. • Recovery method greatly affects the performance of the residues while emulsifier has a smaller influence. • SHM can reduce the low-temperature damage to the residues during the recovery process. • SHM can significantly reduce the degree of aging of the residues compared to DHM, LTHM.