How is particle charge test used to verify compatibility between bitumen emulsion and aggregates?

Particle charge confirms whether the emulsion droplets are predominantly cationic or anionic and whether the system maintains its intended charge. This matters because aggregate surfaces have chemical characteristics that can favor or resist certain emulsion types. If charge is wrong or unstable, the emulsion may break too early in the sprayer or fail to adhere properly on aggregate. In procurement and plant QA, charge testing is used alongside breaking behavior and coating tests to confirm the emulsion will interact correctly with the targeted aggregate source.