AEMA ITC: Let's Get Technical

Investigation on the wetting behavior of asphalt emulsion on aggregate for asphalt emulsion mixture —

The article titled "Investigation on the wetting behavior of asphalt emulsion on aggregate for asphalt emulsion mixture" explores the interaction between asphalt emulsion and aggregate surfaces, which is crucial for the performance of asphalt emulsion mixtures. The study focuses on understanding how different factors, such as the type of aggregate and the properties of the asphalt emulsion, influence the wetting behavior. This wetting behavior is essential for ensuring proper adhesion between the asphalt and aggregate, which in turn affects the durability and strength of the pavement.

The researchers conducted a series of experiments to analyze the wetting behavior under various conditions. They examined the contact angle between the asphalt emulsion and different types of aggregates, as well as the effect of temperature and emulsion composition on this interaction. The results showed that certain aggregates had better wetting properties, leading to improved adhesion. Additionally, the study found that modifying the composition of the asphalt emulsion could enhance its wetting ability, thereby improving the overall performance of the asphalt mixture.

In conclusion, the article highlights the importance of optimizing the wetting behavior of asphalt emulsion on aggregates to achieve better pavement performance. By understanding the factors that influence this interaction, engineers can design more effective asphalt mixtures that offer greater durability and strength. The findings of this study provide valuable insights for the development of improved asphalt emulsion formulations and the selection of suitable aggregates for road construction projects.

Meng, Y., Ouyang, J., & Ou, J. (2023). Investigation on the wetting behavior of asphalt emulsion on aggregate for asphalt emulsion mixture. Construction and Building Materials, 400, 132844. https://doi.org/10.1016/j.conbuildmat.2023.132844

A novel recovery method to derive cationic emulsified asphalt evaporation residues —

This article looks at three asphalt emulsion recovery methods and their contribution to changing the residual asphalt binder properties.  The researchers use three different cationic emulsifiers and three different recovery methods.  The recovery methods used were: direct heat method standard JTG E20-2011, test method T 0651-1993, low temperature heat method NBSH/T 0890-2014, and spin heat method, T 0727-2011. 

The asphalt used was AH-70A, having a penetration value of 69.2.  The emulsifiers were cationic slow set.  The emulsions were produced on a laboratory colloid mill.  Emulsions were tested for evaporation residues, particle size and storage stability.  After the three recovery methods, residues were tested for physical, rheological and FTIR Properties.

Residues from the emulsions were similar.  Particle size and storage stability data showed that only one of the emulsions was stable.  For physical properties, all recovery methods and emulsifiers increased softening point pretty similarly.  In seven of nine residues, penetration decreased from the starting binder.  Spin heat method was responsible for the two increases.  Ductility was lower in all cases, with the direct heat method having higher ductilities in two of the three emulsifiers. 

G* results varied greatly, but two of nine higher results were from spin heat method and G* was much more affected by the recovery method than the emulsifier.  For MSCR, three of the top four highest shear strains at 3.2kPa were from the direct heat method.  In BBR testing, S/m was used to quantify the binders.  At -12C, there was not one emulsifier or recovery method that stood out, however when looking at -18C, direct heat method had the two highest values and spin heat method had the two lowest.  The emulsifiers did cause some variance in this test.  Fatigue life was evaluated using the VECD model.  Fatigue life was highest for spin heat method and lowest for direct heat method across all emulsifiers.  FTIR results, when looking at carbonyl index, indicate that spin heat method has lower aging that the other two methods. 

In conclusion, the three recovery methods and emulsifiers did show differences in how they affected recovered asphalt binder testing.  The spin heat method, overall, had the smallest effect, outside of G*.  With a procedure time of three hours, it seems possible for field implementation.  For comparison, the direct heat method is 20-30 minutes and the low temperature heat method is 48 hours.

Chu, F., Zhang, H., Wu, C., Wu, C., He, Y., Li, Q., … Du, P. (2024). A novel recovery method to derive cationic emulsified asphalt evaporation residues. Construction and Building Materials, 453, 139021. https://doi.org/10.1016/j.conbuildmat.2024.139021