Study on self-healing performance of asphalt under sodium salt erosion

Asphalt pavement performance is significantly affected by natural forces and repeated vehicle loads, with salty environments further exacerbating degradation. To explore the change rule and mechanism of self-healing performance of asphalt under salt erosion environment, this study independently created a simulated salt erosion test for asphalt to examine the effects of sodium salt erosion on the self-healing properties of asphalt. Three salt solutions, sodium chloride (NaCl), sodium sulfate (Na2SO4), and sodium acetate (CH3COONa), were selected to simulate salt erosion on asphalt. Employing a pull-out test as the foundation, a methodological framework was developed to assess the macroscopic self-healing characteristics of asphalt, with healing strength (HS) and healing time (HT) serving as key evaluation parameters. Microscopic perspectives on the erosion mechanisms of asphalt by salts were investigated using four-component analysis, Fourier-transform infrared spectroscopy (FT-IR) analysis, and scanning electron microscopy (SEM). The findings indicate that the self-healing ability of asphalt deteriorates after salt erosion, with a reduction in healing strength, a longer healing time, and significant changes in surface microscopic morphology. This deterioration is attributed to the disruption of the asphalt colloid equilibrium and changes in the content of the four components under the influence of salt erosion. Asphalt content increases when the content of saturates, aromatics, and resins decreases, inducing changes in the asphalt's surface microscopic morphology and a subsequent decline in its self-healing performance. The order of impact on asphalt self-healing by the three sodium salts is as follows: Na2SO4 > CH3COONa > NaCl. This work can be used as a reference for the durability research of asphalt pavements in salt erosion environments and has practical significance in enhancing the durability of asphalt pavements under adverse conditions.