Low-temperature cracking in cold regions highlighted the necessity of producing asphalt binders that can perform against the traffic and environmental conditions in cold climates. Highly elastic asphalt binders (HEBs) are such binders that can exhibit superior performance in extreme low temperatures. The current study evaluates the rheological performance of HEBs produced using two control binders (PG 52-28 and PG 64-22). A high styrene-butadiene-styrene (SBS) polymer content of 7.5% by weight of binder and two types of softening agents were adopted in this study. HEBs were tested for their storage stability and for morphological characteristics. The linear viscoelastic rheological behavior was assessed using master curves of complex shear modulus (G*), and phase angle (δ). Low-temperature performance was evaluated using the bending beam rheometer (BBR) test. Rutting and fatigue performance was assessed using the multiple stress creep and recovery (MSCR) test and linear amplitude sweep (LAS) test, respectively. Results show that binders modified with softening agents show improved storage stability. Fluorescence microscopy showed that binders modified with softening agents have a more homogenous and less condensed polymer network distribution compared to high polymer–modified binders produced without any softening agents. Low-temperature cracking performance with corn oil–modified binders have shown superior performance compared to hydrolene oil–modified asphalt binders. ΔTc values indicate that stiffer control binders (PG 64-22) may not be applicable for the HEB modification approach. HEBs showed enhanced fatigue resistance compared to the control binders. In summary, HEBs exhibited enhanced intermediate- and low-temperature performance, with a marginal reduction in rut resistance, making this approach suitable for practical asphalt applications in cold regions.
Issa et al. (Thu,) studied this question.