Evaluation of storage stability of styrene–butadiene–styrene block copolymer-modified asphalt via electrochemical analysis

• Electrochemical analysis determines SBS content variation after hot tube storage.
• The method provides an accurate segregation assessment for SBS modified asphalt.
• The method reveals the thermo-oxidative degradation of SBS in modified asphalt.

The stability of styrene–butadiene–styrene (SBS) block copolymer-modified asphalt during hot storage and transportation is an important issue. Considering the shortcomings of the present storage stability test implementing softening point, an electrochemical technique was developed to evaluate the segregation behavior of SBS-modified asphalt. Quantitative analysis of SBS content in asphalt based on potentiometric titration was employed to determine the difference in SBS content between the top and the bottom samples taken from a hot tube storage test. An accurate variation of SBS content was traced with a fractional error of less than 0.5%, and the possible thermo-oxidative degradation of SBS during hot storage was also discussed. Results showed that electrochemical analysis can be a viable technique to evaluate the storage stability of SBS-modified asphalt directly as opposed to an indirect measurement with softening point.