Technical Reference · 2024-06-25 · 9 min read
Emulsified asphalt is not a single product — it is a family of products with different formulations designed for specific road construction and maintenance applications. Understanding the different types and their appropriate applications is essential for road engineers and contractors to specify and use the right product for each job.
Classification System
Emulsified asphalt is classified by two main parameters:
1. Charge Type
- Cationic (C): Positively charged bitumen droplets
- Anionic (A): Negatively charged bitumen droplets
Cationic emulsions are more widely used because they work well with the negatively charged surface of most aggregates (siliceous aggregates). Anionic emulsions are used with positively charged aggregates (some limestone).
2. Breaking Speed
- Rapid-setting (RS): Breaks quickly on contact with aggregate
- Medium-setting (MS): Moderate breaking speed
- Slow-setting (SS): Slow breaking speed
The breaking speed is controlled by the type and concentration of the emulsifying agent.
Common Emulsion Types and Applications
| Designation | Type | Breaking Speed | Primary Applications | |---|---|---|---| | CRS-1 | Cationic | Rapid | Chip seal, surface dressing | | CRS-2 | Cationic | Rapid | Chip seal (high traffic) | | CSS-1 | Cationic | Slow | Tack coat, slurry seal | | CSS-1h | Cationic | Slow | Micro-surfacing, tack coat | | CMS-2 | Cationic | Medium | Prime coat, cold mix | | SS-1 | Anionic | Slow | Prime coat, tack coat | | RS-1 | Anionic | Rapid | Chip seal (limestone aggregate) |
Polymer-Modified Emulsions
Polymer-modified emulsified asphalts (PMCSS-1h, PMCRS-2) contain polymer additives (typically SBS or SBR latex) that improve performance:
- Higher elastic recovery: Better resistance to fatigue cracking
- Higher softening point: Better rutting resistance at high temperatures
- Lower glass transition temperature: Better cracking resistance at low temperatures
- Faster traffic opening: Especially important for micro-surfacing
Polymer-modified emulsions are specified for:
- Micro-surfacing
- High-performance chip seal
- Bridge deck waterproofing
- High-traffic road applications
Residue Content
The residue content (bitumen content after water evaporation) is an important specification:
- Standard emulsions: 55–65% residue
- High-residue emulsions: 65–70% residue (for chip seal requiring high binder content)
- Diluted emulsions: 30–40% residue (for prime coat and fog seal)
Storage and Handling
Emulsified asphalt requires careful storage and handling:
- Temperature: Store at 10–60°C; avoid freezing
- Agitation: Gently agitate during storage to prevent separation
- Contamination: Keep tanks clean; avoid mixing different emulsion types
- Shelf life: Most emulsions have a shelf life of 3–6 months
Quality Testing
Before use, verify emulsion quality with standard tests:
- Residue content: ASTM D6934
- Viscosity: ASTM D7496
- Sieve test: ASTM D6933
- Storage stability: ASTM D6930
- Breaking value: ASTM D6930 (for cationic emulsions)
Understanding the different types of emulsified asphalt and their appropriate applications is fundamental to producing high-quality road treatments that perform well throughout their design life.
Discuss Your Project
Contact Bridgent for equipment specifications and a project-specific quotation.
Topics
- emulsified asphalt types
- bitumen emulsion applications
- asphalt emulsion guide