Gilsonite Dosage in Hot Mix Asphalt
How much gilsonite should you add to hot mix asphalt (HMA)? The answer depends on the base binder, climate and traffic level.
Typical ranges
| Basis | Typical range |
|---|---|
| % by weight of binder | 4–12% |
| % by weight of total mix | 0.3–0.8% |
Factors that affect dosage
- Base binder grade: softer binders need more gilsonite.
- Climate: hot regions need higher stiffness.
- Traffic: heavy truck routes, intersections and bus lanes need more rut resistance.
- Layer: base and binder courses often use more gilsonite than wearing courses.
Adjusting the mix
Gilsonite stiffens the binder, so a slight increase in binder content is sometimes used to keep workability and durability. Always run a mix design.
Lab tests
- Softening point and penetration of modified binder
- Dynamic shear rheometer (DSR) for PG grade
- Marshall stability and flow
- Wheel tracking for rut resistance
Converting between bases
If a mix has 5 % binder, then 8 % gilsonite by weight of binder equals 0.4 % by weight of total mix (5 % × 8 %). Always make clear which basis a specification uses.
Practical dosage examples
| Situation | Typical dosage (by binder weight) |
|---|---|
| Moderate climate, normal traffic | 4–6 % |
| Hot climate, heavy traffic | 6–10 % |
| Intersections, ports, high-modulus base | 8–12 % |
These are starting points; confirm in the lab.
Use our asphalt modifier grade gilsonite. Read gilsonite for rutting resistance.
Recommended product
Asphalt Modifier Grade Gilsonite
| Property | Typical value | Test method |
|---|---|---|
| Appearance | Black powder or granules | Visual |
| Softening point (R&B) | 150 – 200 °C | ASTM D36 |
| Ash content, max | 8 % | ASTM D3174 |
| Moisture, max | 1 % | ASTM D95 |
| Solubility in TCE, min | 95 % | ASTM D2042 |
| Specific gravity @ 25°C | 1.04 – 1.10 | ASTM D70 |
| Particle size | Powder ≤ 200 mesh / granular 1–5 mm | Sieve |
| Typical dosage | 4 – 12 % by weight of binder | |
| Packing | 25 kg bags, meltable bags or 1 MT jumbo bags. | |
Typical values. The final specification is confirmed in the COA of each shipment.
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