1. Rapid Setting (RS) Emulsions
Characteristics: These emulsions break down and set very quickly after application.
Applications:
- Tack Coats: Ideal for providing a rapid bond between asphalt layers, minimizing the open time for subsequent paving operations.
- Prime Coats: Suitable for priming surfaces where rapid drying is essential, such as in areas with high humidity or frequent rain.
- Chip Seals: Used in chip seal applications where quick setting is required to minimize the risk of stone loss.
Property:
- Absolute Viscosity, Poise
- Residue on 600 Micron, %
- Storage Stability, hrs
- Particle Charge
- Mixing
- Dilution Ratio
2. Medium Setting (MS) Emulsions:
- Characteristics: These emulsions exhibit a moderate setting time, providing a balance between workability and rapid setting.
- Applications:
- Slurry Seals: Widely used in slurry seal applications, allowing for proper mixing and placement while ensuring a timely setting of the seal.
- Micro-Surfacing: Suitable for micro-surfacing applications where a controlled setting time is required to achieve the desired surface texture.
- Patch Repairs: Used in patch repair applications where a moderate setting time allows for proper compaction and shaping of the repair.
Property:
- Absolute Viscosity, Poise
- Residue on 600 Micron, %
- Storage Stability, hrs
- Particle Charge
- Mixing
- Dilution Ratio
3. Slow Setting (SS) Emulsions:
Characteristics: These emulsions have a slow setting time, allowing for extended working times.
Applications:
- Prime Coats: Suitable for priming porous surfaces where deeper penetration of the emulsion is desired.
- Stabilized Bases: Used in the construction of stabilized bases where a gradual setting time is beneficial for proper compaction and strength development.
- Cold Mixes: Employed in the production of cold mix asphalt where a slow setting time allows for proper mixing and placement of the aggregate.
Property:
- Absolute Viscosity, Poise
- Residue on 600 Micron, %
- Storage Stability, hrs
- Particle Charge
- Mixing
Factors Affecting Setting Time:
- Emulsion Properties: The type of emulsifier, bitumen grade, and droplet size significantly influence the setting time of the emulsion.
- Environmental Factors: Temperature, humidity, and wind can affect the rate of water evaporation and, consequently, the setting time of the emulsion.
- Aggregate Properties: The type and gradation of the aggregate can also influence the setting time of the emulsion.
By carefully selecting the appropriate setting time for a specific application, road engineers can optimize construction operations, improve pavement performance, and minimize the risk of construction delays.