Relations between colloidal indices and low-temperature properties of reclaimed binder modified with softer binder, oil-rejuvenator and polybutadiene rubber

Abstract

Asphalt binder properties play an important role in the behavior of asphalt concrete pavements at low temperature and should be studied using laboratory tests. This research investigates the relationship between chemical properties and low-temperature performance of asphalt binders at RAP contents of 15%, 30%, 50 and 100% by weight. The asphalt is also modified with a softer binder, oil rejuvenator and polybutadiene rubber (PBR 1220) modified binder. Binder testing includes penetration test, softening point, bending beam rheometer (BBR) and Fraass breaking point. Moreover, saturate, aromatic, resin, and asphaltene (SARA) fractionation is used to study the induced changes in the chemical composition of binders after adding RAP. The results show that binders modified with oil-rejuvenator have better resistance to low temperature cracking in comparison with softer binder and polymer modified binder (PMB), particularly at high percentages of RAP. Using a softer virgin binder also demonstrates improvements in the low-temperature performance of RAP binder. Moreover, PBR 1220 blended with RAP binder showed poor resistance to low-temperature cracking, it means that having a low Tg (for polymer) would not necessarily lead to a good low temperature cracking of the polymer-modified binder. Finally, some promising statistical correlations are found between colloidal indices and low-temperature performance of samples with RAP content.