Can Gilsonite Be Used in Warm Mix Asphalt?

Warm mix asphalt (WMA) is produced at temperatures 20–40°C lower than hot mix, saving fuel and reducing emissions. Gilsonite increases viscosity, so how do the two work together?

The challenge

Gilsonite needs heat to dissolve in bitumen. At lower WMA temperatures, dissolution may be slower in the dry process.

Solutions

• Wet process: dissolve gilsonite in the binder at the terminal first, then use WMA additives.
• Chemical WMA additives: surfactant-based additives improve workability without needing much lower viscosity.
• Fine powder: use finer gilsonite for faster dissolution.

Benefits of combining

WMA reduces aging of the binder at the plant, while gilsonite provides rut resistance. Together they can offer a durable, lower-emission pavement.

Recommendation

Trial the combination in the lab, checking binder dispersion and mix performance.

WMA technologies

Compatibility notes

Chemical additives are generally the easiest to combine with gilsonite-modified binder. Always verify mix workability and compaction at the target lower temperature.

Benefits of the combination

Lower fuel use and fumes from WMA, plus rut resistance from gilsonite.

Use asphalt modifier gilsonite in the wet process. Read wet vs. dry process.