Types of Emulsified Asphalt

Aggregates

• Aggregates have a positive, negative or mixed charge on the surface, which delineate the different types of emulsified asphalts and their consistency. Fine asphalt aggregates are manufactured from sources of stone gravel or slag and course aggregates are manufactured from crushed stone, crushed gravel or crushed slag. Other types of aggregate may include limestone or sandstone, depending on the project.

Anionic

• Used in highway and road construction, anionic is characterized by negatively charged asphalt globules. On an atomic level, the negatively charged emulsifying agent pairs itself with the asphalt concrete. Because each globule of asphalt carries a similar charge, they repel each other, suspended individually in the water. Anionic emulsified asphalt works better in conditions of low humidity due to its long setting time.

Cationic

• Also used in highway and road construction, cationic is characterized by positively charged asphalt globules. The cationic emulsifying agent functions similarly to the anionic; the positively charged emulsifying agent pairs itself with the asphalt concrete, repelling similarly charged globules. Cationic emulsified asphalt works better in conditions of high humidity due to its rapid setting time.

Nonionic

• Nonionic is asphalt globules that have a neutral or no charge. This type of emulsified asphalt has typically been used in heavy industrial applications rather than road construction.