POLYMER BLENDS FOR ENHANCED ASPHALT BINDERS

Straight asphalt binders have been modified by addition of both high-d ensity polyethylene (HDPE) and a blend of HDPE and ethylene -propylene -diene-monomer (EPDM). The blend composition was fixed to 90/10 HDPE/E PDM to illustrate the possibility of adapting the polymer to be added to the asphalt binder for specific end-use applications. Linear viscoe lastic properties of unmodified and polymer modified asphalts at conce ntrations ranging from 1 to 5 wt% were studied before and after Thin-F ilm Oven Test (TFOT) aging. Temperatures ranging from -15 degrees C to 60 degrees C were considered. Standard tests such as Ring-and-Ball so ftening point, Fraass breaking point and TFOT aging were also performe d on the whole set of samples. It was found that addition of rubber-mo dified polyethylene (HDPE/EPDM) to the straight asphalt results in mat erials with enhanced overall properties, and most important, dispersed phase much more stable than the equivalent HDPE modified asphalt, mai nly before TFOT aging. Good results were obtained for 1% HDPE/EPDM sam ples. Optimum design is, however, required for the desired properties to be obtained.