RAP Asphalt: What It Is and How Much a Mix Can Use

RAP is the old, reprocessed material, and asphalt is the finished mix it goes into. FHWA describes RAP as removed or reprocessed pavement material containing asphalt and aggregates, typically 3 to 7 percent asphalt by weight and usually crushed or milled to 1.5 inches or less.

New hot mix is aggregate coated with virgin asphalt binder. RAP is aggregate that is already coated with aged binder, so when it goes in the mix it replaces some of both. NAPA reports that 101.4 million tons of RAP were recycled into new asphalt mixtures in 2024, and that 99% of RAP is put back to use. About 89% goes into new mixtures and about 11% into other uses such as unbound aggregate bases.

That second group includes the loose millings property owners buy for driveways. See recycled asphalt millings for that side of it, and the glossary entry for the short definition.

Nationally the average is 21.9% RAP in new mixtures, and what a specific job can take is set by the agency specification and the plant. The binder rule of thumb changes at two points, 15% and 25%.

NAPA reports that the national average of 21.9% RAP saves $9.98 per ton of mix compared with all-virgin mixes, and that RAP saves $4.3 billion a year.

Above 25% RAP, the main risk is a stiffer mix that cracks. FHWA notes that adding high RAP usually increases mixture stiffness, which may contribute to low-temperature cracking in cold climates, and that there is still uncertainty about how the virgin and RAP binders interact during plant mixing.

That is why high-RAP work leans on mix design. The same page says the NCHRP 9-46 procedure is expected to address permanent deformation, fatigue cracking, low-temperature cracking and moisture susceptibility. Agencies have run high-RAP field projects for years. FHWA's list includes Florida at 45% and South Carolina at 30 and 50%, both reported in 2007, and Illinois allowing 10 to 50% in 2008.

Keep RAP sources separate, process it consistently, and keep it dry. FHWA points to NAPA's Quality Information Series 124 for material management and RAP processing, and says a screen is used to keep large particles out of the mix and a loader is used to blend the stockpile periodically.

The best field data is old, but it is specific. An NCAT survey of 81 operations in 26 states, published in 2008, found that 74% crushed all RAP to a single size and only 4% fractionated it. Half combined all RAP sources into one pile, and 53% used no special stockpiling practices.

The survey notes that cutting RAP moisture allows higher production rates, lower superheating temperatures and less fuel per ton of mix. That last part matters more when diesel is expensive. Practice may have moved since 2008, so ask the plant what it does now.

A small number so far. As of October 2026, 19 plants in our directory report a maximum RAP percentage: 18 in California, ranging from 12% to 50%, and one in Florida at 40%. That is far too few to describe a market.

A plant's page shows its figure where we have it, and you can find plants in your area with the asphalt plant finder. If you know a plant's number, you can send it from that plant's own page, under verified sources and corrections.

RAP is the largest single lever a plant has on binder and aggregate cost, and the tiers at 15% and 25% are where the binder decision changes. Know your agency's limit, know what your plants actually run, and treat stockpile moisture and consistency as cost items, not housekeeping.

Figures on this page were checked on October 11, 2026. The binder guidance tiers and the stockpile survey are older and are dated where they appear.