Cracking the Problem of Asphalt Recycling
Every road tells a story. Over time, sunlight, oxygen, and traffic wear away at asphalt pavements, leaving cracks and brittleness in their wake. To save costs and resources, reclaimed asphalt pavement (RAP) is recycled into mixes for new roads. But there’s a catch: the more RAP you add, the more brittle and crack-prone the pavement becomes.
For years, the industry tried to solve this problem with rejuvenators—additives meant to bring aged binder “back to life.” Early solutions, like re-refined engine oil bottoms (REOB), looked promising. They softened mixes, lowered binder stiffness, and passed performance grade tests. But the honeymoon didn’t last. Roads began to crack prematurely. Investigations traced the failures back to the rejuvenators themselves.
It became clear that softening alone wasn’t enough. The industry needed more than a mask to cover the cracks; it needed an intelligently designed solution.
A New Class of Rejuvenators
Researchers at Iowa State University looked to the farm. Soybean oil, a renewable and abundant resource, showed promise as a binder plasticizer. But in its natural form, it lacked the reactivity needed to stabilize aged asphalt. Fully epoxidized soybean oil, meanwhile, was too viscous and poorly compatible.
The breakthrough came with partial epoxidation. By carefully controlling the process, the team developed sub-epoxidized soybean oil (SESO)—a material that combined the best of both worlds. SESO softened binders like natural soybean oil but also reacted chemically with oxidized groups on asphaltenes, preventing them from clumping back together.
This novel approach is known as reactive restorative modification (RRM) and is redefining rejuvenation: from temporary softening to permanent chemical restoration.
Proof on the Road
SESO moved quickly from lab to field. Across nine states, SESO was tested in county roads and parking lots with RAP levels as high as 45%. Pavements were evaluated with fracture mechanics-based tests such as the disk-shaped compact tension (DCT), Illinois flexibility index test (I-FIT), and IDEAL-CT. The results: pavements held up, resisting cracks and delivering the durability agencies demanded. With SESO, higher RAP use is not only possible—it is reliable.
A Commercial Solution: SIP-1111™
This innovation is available through our SIP-1111™, the first commercial RRM based on SESO technology. SIP-1111™ is more than an additive—it’s a tool that allows the asphalt industry to embrace recycling without compromise.
For an industry grappling with cost pressures, environmental consciousness, and material shortages, this is a turning point. With SIP-1111™, roads can tell a new story: one of durability, sustainability, and innovation.
