In emulsified asphalt, pH value also has a certain influence on the demulsification rate. Before studying the influence of pH on the demulsification rate of emulsified asphalt, the demulsification mechanisms of anionic emulsified asphalt and cationic emulsified asphalt are explained respectively.

Cationic emulsified asphalt demulsification relies on the positive charge of the nitrogen atom in the amine group in the chemical structure of the asphalt emulsifier to be affinity with the negative charge of the aggregate. Thus, the water in the emulsified asphalt is squeezed out and volatilized. The demulsification of the emulsified asphalt is completed. Because the introduction of pH-adjusting acid will cause an increase in positive charge, it slows down the combination of the positive charge carried by the asphalt emulsifier and the aggregate. Therefore, the pH of cationic emulsified asphalt will affect the demulsification rate.
The negative charge of the anionic emulsifier itself in anionic emulsified asphalt is mutually exclusive with the negative charge of the aggregate. The demulsification of anionic emulsified asphalt relies on the adhesion of the asphalt itself to the aggregate to squeeze out the water. Anionic asphalt emulsifiers generally rely on oxygen atoms to be hydrophilic, and oxygen atoms form hydrogen bonds with water, causing the evaporation of water to slow down. The hydrogen bonding effect is enhanced under acidic conditions and weakened under alkaline conditions. Therefore, the higher the pH, the slower the demulsification rate in anionic emulsified asphalt.