Gilsonite and other asphaltites are used as performance-enhancing agents for asphalt mixes. Gilsonite-modified paving mixes achieve higher performance grades (PG) and incorporate into an asphalt blend with no need for high shear milling as in the case with some other modifiers. The use of SBS (styrene-butadiene-styrene) polymers may be partially or totally replaced by, or complemented by, the presence of gilsonite. Gilsonite-modified asphalts can have higher stability, reduced deformation, reduced temperature susceptibility and increased resistance to water stripping as compared to non-modified asphalts. A difficulty in using gilsonite as an asphalt modifier is that it is a solid, which is more difficultly handled and incorporated into a viscous bitumen.
Asphalt mix additives
On the other hand, a wide variety of polymers have been used as additives in bitumen compositions and gilsonite is one of them. For example, copolymers derived from styrene and conjugated dienes, such as butadiene or isoprene, are particularly useful, since these copolymers have good solubility in bitumen compositions and the resulting modified-bitumen compositions have good rheological properties.
