The best temperature for mixing bitumen 60/70 with aggregate depends on the type of bitumen and the desired mix (e.g., Hot Mix Asphalt). Here’s a general guideline:
Hot mix asphalt HMA
• Aggregate temperature: 150°C to 170°C
• Bitumen temperature: 150°C to 160°C
• Mixing temperature: 140°C to 160°C (ideal range for good coating and workability)
Warm Mix Asphalt (WMA)
• Mixing temperature: 100°C to 140°C
(WMA uses additives or foaming to allow lower temperatures.)
Cold Mix Asphalt
• Mixing temperature: Ambient temperature
• Used with cutback or emulsion bitumen—less common for high-traffic roads.
Key Considerations:
• Overheating bitumen (above 180°C) can lead to oxidation and hardening.
• Insufficient heating causes poor coating and weak bonding.
Chart of mixing temperature for various grades of bitumen
Here’s a visual chart showing the recommended mixing temperature ranges for both bitumen and aggregate across different bitumen grades. Solid lines represent bitumen temperature ranges, while dashed lines represent aggregate ranges.