Quantitative effect of droplet size and emulsion viscosity on the storage stability of asphalt emulsion

•The representative droplet sizes and viscosity that have a high correlation with storage stability are studied.•The empirical prediction model for the 1 d and 5 d storage stability of asphalt emulsion are established.•It is recommended that the 1 d and 5 d storage stability should be lower than 0.2% and 1% for asphalt emulsion with excellent storage stability.•The permissible maximum D90 of asphalt emulsion is analyzed to ensure a good storage stability of asphalt emulsion.