Bitumen Emulsion Supplier — Cationic & Anionic Grades

Bitumen emulsion is a stable mixture of bitumen, water, and an emulsifying agent, in which fine droplets of bitumen are dispersed throughout water. Depending on the emulsifier charge, emulsions are classified as cationic (positive charge) or anionic (negative charge). Black Rock Bitumen supplies a full range including K1-40, K1-60, K1-70, CRS-60, CRS-70, CMS-2, RS-1, RS-2, MS-2, HFMS-1, HFMS-2, SS-1, and SS-1h grades for road construction, waterproofing, and pavement maintenance worldwide.

Cationic bitumen emulsion carries a positive electrical charge on the bitumen droplets, enabling strong adhesion to negatively charged aggregates like granite and basalt — it breaks faster and works well even on damp surfaces. Anionic bitumen emulsion carries a negative charge and bonds best with positively charged, electropositive aggregates such as limestone. Cationic grades (K1-series, CRS, CMS, CSS) are more widely used globally; anionic grades (RS, MS, HFMS, SS) are preferred for specific regional or application requirements.

The main cationic bitumen emulsion grades are: K1-40 and K1-60 (slow-setting, for prime coats and dust control), K1-70 (for tack coats and surface dressing), CRS-60 and CRS-70 (rapid-setting, for chip sealing and surface dressing), CMS-2 (medium-setting, for cold mix asphalt and patching), CSS-1 and CSS-1h (slow-setting, for slurry seals and fog seals), and CQS-1h (quick-setting hard, for tack coat applications). All grades are manufactured to ASTM D2397 / AASHTO M208 standards.

The main anionic bitumen emulsion grades are: RS-1 and RS-2 (rapid-setting, for tack coats and surface dressing), MS-2 and MS-2h (medium-setting, for cold mix asphalt and patching), HFMS-1, HFMS-2, HFMS-2s, and HFMS-2h (high-float medium-setting, for chip seal and surface treatment where drainage control is needed), HFRS-2 (high-float rapid-setting, for spray sealing), SS-1 and SS-1h (slow-setting, for slurry seals and diluted tack coats), and QS-1h (quick-setting hard). All grades comply with ASTM D977 / AASHTO M140 standards.

Bitumen emulsion is manufactured by heating bitumen to a fluid state, then pumping it through a colloid mill together with hot water and an emulsifying agent. The high-shear action of the mill breaks the bitumen into microscopic droplets (typically 0.5 to 10 microns in diameter) and coats each droplet with the emulsifier, giving particles a positive (cationic) or negative (anionic) charge. The resulting stable dispersion is cooled and stored in tanks ready for shipment.

K1-60 should be stored in clean tanks away from direct sunlight, preferably between 5°C and 50°C. Gentle circulation is recommended before use, and contamination with cement, lime, or debris should be avoided.

Bitumen emulsion grades are classified by their setting (breaking) speed: Rapid-setting (RS/CRS) grades — such as K1-70, CRS-60, CRS-70 — break within seconds to minutes of contact with aggregates, making them ideal for tack coats and surface dressing. Medium-setting (MS/CMS) grades — such as CMS-2, MS-2 — allow several minutes of working time, suited to cold mix asphalt and patching. Slow-setting (SS/CSS) grades — such as K1-40, K1-60, SS-1 — take the longest to break and are used for slurry seals, prime coats, and soil stabilization where extended mixing time is needed.

Key benefits include fast setting and breaking time, excellent adhesion to aggregates, application at ambient temperatures, reduced fuel consumption compared to hot bitumen, and safer, more environmentally friendly handling.