Many have found RAP to be a valuable resource for hot asphalt mixes, cold asphalt mixes, full-depth recycling and aggregate replacement. RAP in Hot Mix RAP is useful for hot asphalt overlays if the agency develops a mix design that meets criteria established by State and Federal specifications. The limiting factor is the percentage of RAP which asphalt companies are able to use to produce high performance asphalt mixes. Many engineering firms and some asphalt suppliers can analyze an agency's RAP and develop a mix design. Other common uses of RAP require less engineering and are lower in cost.
Cold mixes perform well when gradation is controlled.
The RAP is crushed and sized to meet the typical hot mix gradation requirements. The residual asphalt content determines the amount of emulsion added to the material to create a stable mix. If the road was old and oxidized, the residual asphalt content could be quite low. Because of the variable asphalt content, the resulting mix could require from 3-10 gallons of asphalt emulsions to create a stable cold mix. It is therefore recommended that cold mix be made only from tested materials.