NCAT Test Track Section S1 paired a 50% RAP surface mixture with SIP-1111™ at 4.1% by weight of total asphalt binder. After one year of heavy truck traffic and about 4 million ESALs, the section had no visible surface cracking and less than 3.5 mm of rut depth.

Balanced mix design selected the field dosage

The 12.5-mm dense-graded design used 50% RAP and PG 67-22 virgin binder. IDEAL-CT testing at 25°C increased from a CT Index of 32.2 without rejuvenator to 57.7 at 4.1% SIP-1111™. The selected dosage exceeded the paper’s stated minimum CT Index of 50 for Alabama surface mixtures.

Hamburg testing checked the other side of the balanced-design decision. At 4.1% SIP-1111™, the mixture recorded 4.6 mm of rut depth after 10,000 passes, below the 10-mm ALDOT wearing-surface limit cited in the paper. Testing was performed at 50°C under AASHTO T 324.

One-year field results

A direct path from mix design to trafficking

Section S1 connects laboratory dosage selection, continuous-plant production, full-scale placement, and accelerated trafficking in one high-RAP program. Producers can evaluate the same 4.1% total-binder dosage across cracking, rutting, ride quality, and surface texture rather than relying on a single laboratory measure.

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Source Documents

• Epoxidized Soybean Oil Rejuvenator for High-RAP Asphalt Pavements, National Center for Asphalt Technology, 2026