Phase morphology evolution and structural analysis of high viscosity modified asphalt during preparation and storage

The phase evolution and structural changes of high viscosity modified asphalt (HVMA) during preparation and storage were investigated in this paper. Firstly, the effects of high viscosity agent (HVA) dosage and stabilizer amount on conventional performance and microscopic phase morphology of HVMA during the preparation process were deeply analyzed by fluorescence microscopy and Fourier transform infrared spectroscopy (FTIR) test. Secondly, the effects of stabilizer amount on crosslinking degree and crosslinking reaction kinetics were quantitatively analyzed. In addition, the phase morphology evolution and aging degree of HVMA during high-temperature storage was studied. The results show that with the increase of the HVA content, the phase morphology of HVA in the asphalt phase gradually changes from isolated spherical to wormlike and then to continuous phase. When the HVA content is fixed at optimal dosage, the dispersion degree of HVA increases and the fineness of the structure becomes smaller with the addition of the stabilizer, indicating the co-continuous phase of HVMA becomes more stable. Crosslinking degree correlates linearly with stabilizer dosage, and the cross-linking reaction conforms to the first-order kinetic equation (the reaction rate constant k A = 1.48 × 10 −3 min −1 ). During HVMA storage at high temperatures, when the amount of stabilizer is < 2 ‰, the phase morphology of HVMA will gradually change from continuous phase to dispersed phase over time, forming a "sea-island structure". If the addition amount of stabilizer is ≥ 2 ‰, the co-continuous phase system gradually coarsens, but the HVA phase is still interconnected and there is a salami structure. FTIR analysis showed that with the extension of storage time, the functional group index in HVMA changed gradually, indicating that HVA has aged. The above research results provide an important theoretical basis and technical support for the preparation, storage, and performance optimization of HVMA. • The phase evolution and structural changes of high viscosity modified asphalt (HVMA) were studied. • The dosage of high viscosity agent (HVA) has a significant impact on the morphology of HVA phase. • Stabilizer can increase the dispersion degree of HVA, which enhances the stability of HVMA. • The reaction between stabilizer and HVA conforms to first-order kinetic equation. • HVMA undergoes aging during high-temperature storage, but HVA still maintains its interconnected structure.