ABSTRACT
Reactive polyurethane-based bitumen modifiers are constituted by polymers with strong adhesive properties due to the presence of reactive isocyanate groups; bitumen elasticity as well as adhesion in the bitumen/aggregates interface are improved by chemical bonding to asphaltene stacks or to aggregate surface. A comparative study of the rheological properties of mixtures of a normal bitumen (penetration index 60/70) with MDI-based and a TDI-based reactive polyurethanes, as well as with polybutadiene is presented. It is shown that reactive polyurethanes can produce greater enhancement of the bitumen elasticity, as sensed by the elastic part of the complex shear modulus G(ω), as compared e.g. to butadiene modifiers in a w/w basis. This effect is stronger for MDI-based Polyurethane modifiers.
