Influence of Preparation Processes on the Droplets Size Characteristics and Storage Stability of Emulsified Asphalt

Emulsified asphalt is commonly used in highway engineering as a binder for interlayer bonding, slurry seals, micro-surfacing, and cold recycled asphalt mixtures. Its storage stability is a common technical challenge in the field. The preparation process of emulsified asphalt significantly impacts its storage stability. This paper examines the effects of emulsion pH, asphalt temperature, and shearing time on the storage stability of emulsified asphalt and the particle size of asphalt droplets. The morphological evolution of asphalt droplets was observed using fluorescence microscopy, and the principles of emulsion sedimentation were elucidated. Based on this, the optimal preparation conditions for emulsified asphalt were determined using response surface methodology. The results indicate that emulsion pH, asphalt temperature, and shearing time significantly affect the particle size of emulsified asphalt droplets and their storage stability. Emulsified asphalts with a larger number of droplets and smaller particle sizes exhibit superior storage stability. Furthermore, the correlation between the D50 particle size of asphalt droplets and the storage stability of emulsified asphalt is stronger than that of D10 and D90, making D50 a more suitable indicator for predicting and assessing the storage stability of emulsified asphalt. Finally, the response surface optimization identified the optimal preparation conditions for emulsified asphalt as an emulsion pH of 3.2, an asphalt temperature of 137.3 degrees C, and a shearing time of 74 seconds.