RECYCLING AGENTS FOR RECYCLED BITUMINOUS BINDERS--EXECUTIVE SUMMARY

Salvaged asphalt treated pavement materials were obtained, analyzed and combined with recycling agents. Laboratory tests were performed on the field aged mixtures, field aged asphalts, recycling agents, aged asphalt-recycling agent blends and recycled mixtures. Results from these tests suggest that recycling agents can restore aged asphalts to desired consistency levels and can be used to produce recycled mixtures with acceptable properties. However, the type of recycling agent and the nature of the aged asphalts will determine the temperature susceptibility of the blended binder. Potential aged asphalt-recycling agent compatibility problems exist. Tests and/or criteria need to be developed to more accurately recognize this potential problem. In the interim a laboratory oven aging test conducted on the blend of the aged asphalt and recycling agent is suggested for use. Recycled mixture properties can be adjusted by controlling the amount of recycling agent added. The properties of recycled mixtures are dependent upon the method and temperature of sample preparation as the blending of the recycling agent with the aged asphalt is both time and temperature dependent. Pavement performance has been predicted from existing pavement design methods using recycled mixture characterization data. A recommended specification for recycling agents and a method for the design of recycled mixtures is contained in the unabridged final report (FHWA/RD-82/010, NTIS No. PB82-197856). (FHWA)