California Department of Transportation
 

Resource Conservation Program

Flexible Pavement Recycling

Flexible Pavement Recycling - Caltrans recycles existing roadway pavement whenever possible. One innovative way to recycle the pavement is in place. This process involves removing existing roadway to varying depths and blending it with new material and then placing it back in place. This not only is re-using existing material but also reduces the amount of material to be hauled to and from the job site.

Hot In-Place Recycling (HIPR)

Hot In-Place Recycling (HIPR) is an on-grade method of pavement surface preservation that consists of softening the existing asphalt pavement with heat, milling or scarifying to a maximum depth of 2 inches, and thoroughly remixing, leveling, and compacting the milled or scarified material. HIPR can include the addition of recycling agents and virgin hot mix asphalt (admix) as needed.

HIPR - Hot In-Place Recycling illustration

Cold In-Place Recycling (CIPR)

Cold In-Place Recycling (CIPR) is an on-grade method of pavement rehabilitation that consists of milling the existing asphalt concrete pavement to a depth between 2 to 4 inches; mixing the cold milled material with emulsified recycling agent and other additives as needed; spreading and compacting the recycled mixture; and overlaying the recycled surface with a new lawyer of hot mix asphalt (HMA). Foamed asphalt can be used as a recycling agent instead of asphalt emulsion, but the fine aggregates may need to be added to the recycled mixture.

Cold In-Place REcycling (CIPR) image

Pulverization

Pulverization is an on-grade method of pavement rehabilitation that consists of pulverizing the existing asphalt concrete pavement and a portion of the underlying granular base to a maximum depth of 10 inches, grading and compacting the recycled mixture, and overlaying the recycled surface with a new layer of hot mix asphalt (HMA). Other materials including aggregate base, Portland cement, kiln dust, or fly ash may be added prior to mixing as needed.

Pulverization picture example

This page last updated June 3, 2013