Gilsonite in Base and Binder Courses

Much of the rutting in heavy-duty pavements occurs in the lower asphalt layers, not just the surface. Modifying base and binder courses with gilsonite can extend pavement life.

Why lower layers matter

Under heavy trucks, stresses reach deep into the pavement. Soft binder in lower layers can deform, creating ruts that show at the surface.

Benefits

• Higher stiffness modulus
• Better load spreading
• Reduced rut depth

High-modulus asphalt

Some countries use high-modulus asphalt (EME) with very hard binders. Gilsonite is one way to harden binders for these mixes.

Dosage

6–12% by weight of binder, often via dry process using granular gilsonite.

Design considerations

Check fatigue resistance; stiffer layers need adequate binder content.

Related: high-modulus asphalt with gilsonite.

Layer-by-layer approach

Design note

Stiffer lower layers reduce strains at the bottom of the asphalt and stresses on the subgrade, which can extend pavement life when designed properly.