USE OF ASPHALT EMULSION AND FOAMED ASPHALT IN COLD-RECYCLED ASPHALT PAVING MIXTURES

Increased interest in improving the quality of cold-recycled asphalt paving mixtures has made it necessary to understand the behavior of these mixes better. This laboratory study investigates the long-term behavior of cold-recycled asphalt paving mixtures by using asphalt emulsion and foamed asphalt as the added binders. An artificially aged paving mixture was used to make the recycled mixes for this study. Specimens of the recycled mixes were compacted with the gyratory testing machine. The resilient modulus, Hveem stabilometer R-value, and Marshall stability were obtained on the compacted recycled mixes at various levels of compactive effort, added binder, testing temperature, and curing time. Results indicate that most of the rejuvenating action of the added binder on the old binder takes place during the compaction process. The binders of the recycled mixes that undergo the initial softening during the compaction process generally increase in stiffness with increasing curing time. The recycled mix with foamed asphalt added had properties comparable to those of the mix with asphalt emulsion added. However, slightly more added binder is needed when foamed asphalt is used. The structural performance of these recycled mixes as a stabilized base in a typical low-volume road was also evaluated and compared with that of a standard asphalt concrete by using a linear elastic multilayer analysis. (Author)