Elastomeric Asphalt Extender – A New Frontier on Asphalt Rubber Mixes

The Reacted and Activated Rubber (RAR), as an Asphalt Rubber Binder, is
composed of plain soft bitumen, fine crumb rubber, and an Activated Mineral Binder
Stabilizer (AMBS) at optimized proportions. RAR is produced by a short- time hot blending
and activation in a specially designed process to form a dried granulated activated rubber.
RAR can be added to any type of Hot Mix Asphalt (HMA) – Dense, Open Graded, Gapgraded,
SMA, etc., for replacing part of the asphalt cement (bitumen) at different proportions.
In the mixing plant it is added directly to the pug mill or dryer drum, right after the bitumen
spraying, using existing feeders (i.e. fiber feeders for SMA mixes, etc.). This paper
summarizes an R&D Research effort showing that Asphalt Rubber HMA, produced with RAR,
outperforms conventional HMA and even regular modified and asphalt rubber mixes. In
general, it was found that RAR is an elastomeric asphalt extender that modifies the plain
bitumen by increasing its PG grading, resilience, softening point and recovery properties. As
shown in the paper, Different types of HMA mixes produced with RAR showed much better
Stability, Rutting and Fatigue resistance under attractive cost/benefit conditions.