Asphalt Modification with SBS and Ethylene Copolymer Blends

The patent uses a composite modifier system combining SBS block copolymer (provides elasticity and rut resistance) with ethylene copolymer (provides stiffness) and wax (provides low-temperature flexibility). This composite approach allows the modified asphalt to achieve high rut resistance through SBS and ethylene copolymer while the wax component prevents excessive viscosity increase by providing lubrication and flexibility at lower temperatures.

The patent applies different polymer components to address different temperature conditions locally: SBS and ethylene copolymer dominate at high temperatures to provide rut resistance, while the wax component becomes more active at lower temperatures to maintain flexibility and reduce viscosity. This local quality differentiation allows the single modified asphalt formulation to perform optimally across a wide temperature range without excessive viscosity throughout.

The patent combines SBS block copolymer (high elasticity, good for rut resistance) with wax (high low-temperature flexibility) in the same modifier system. The SBS provides the stiffness and elasticity needed for rut resistance at high temperatures, while the wax component ensures adequate flexibility and cracking resistance at low temperatures. This composite material approach resolves the contradiction by having different components excel at different temperature extremes.

The patent changes the physical state parameters of the modifier components through temperature-dependent behavior. The wax component transitions from a more rigid state at high temperatures (contributing to stiffness) to a more flexible, plastic state at low temperatures (providing crack resistance). This parameter change with temperature allows the same formulation to satisfy both high-temperature rut resistance and low-temperature cracking resistance requirements.

The patent creates a cost-effective composite modifier where each component contributes differently to performance: SBS provides elasticity and fatigue resistance, ethylene copolymer provides stiffness and temperature stability, and wax provides flexibility and processability. This synergistic composite allows achieving high fatigue resistance with a balanced formulation rather than using excessive amounts of a single expensive polymer, thereby controlling manufacturing costs while maintaining high performance.

The patent uses relatively small amounts of each polymer component (typically 3-10% total by weight of asphalt) to achieve the desired performance improvement. Rather than using large quantities of a single polymer, the partial action of multiple components working together provides cumulative fatigue resistance enhancement at lower total polymer dosage, thus reducing manufacturing cost while maintaining high fatigue resistance.

The patent employs a composite modifier system where SBS block copolymer provides high elasticity through its microphase-separated structure, while ethylene copolymer provides stiffness through its crystalline regions. The combination of these two polymers with different mechanical properties creates a balanced modified asphalt that exhibits both high stiffness (from ethylene copolymer) and high elasticity (from SBS), resolving the contradiction between these two opposing properties.

The patent applies different polymer functions to different structural levels: SBS provides elasticity at the molecular chain level through its block structure, while ethylene copolymer provides stiffness at the macro level through its crystalline domains. This local quality differentiation allows the modified asphalt to simultaneously exhibit high elasticity and high stiffness without one property sacrificing the other.