Gilsonite in Stone Mastic Asphalt (SMA)

Stone mastic asphalt (SMA) uses a coarse stone skeleton filled with a rich mastic of binder, filler and fibers. It offers excellent rut resistance and durability.

Role of the binder

SMA contains more binder than dense mixes. A stiffer binder reduces drain-down and improves rut resistance.

Benefits of gilsonite in SMA

• Increases mastic stiffness
• Helps reduce binder drain-down (with fibers)
• Improves high-temperature stability

Formulation tips

• 5–10% gilsonite by weight of binder
• Keep cellulose or mineral fibers for drain-down control
• Verify with Schellenberg drain-down test

Applications

Motorways, heavy-duty urban roads and airport runways.

SMA basics

Why gilsonite helps in SMA

The rich mastic carries much of the load and must not flow in heat. A stiffer, gilsonite-modified binder improves mastic stability and reduces drain-down risk.

Construction tips

Use steel-wheel rollers, avoid over-rolling that can bring mastic to the surface, and control temperatures carefully.

See asphalt modifier gilsonite and mix design tips.