Characterization of Styrene-Butadiene-Styrene (SBS)-Modified Asphalt Binders using the Bending Beam Rheometer and the Asphalt Binder Cracking Device

The addition of Styrene Butadiene Styrene to asphalt binders has led to enhanced performance in pavements across the entire range of working temperatures but have proven to be more difficult to characterize than unmodified binders. Low-temperature properties of asphalt binders are typically evaluated using the Bending Beam Rheometer (BBR) which was developed to measure the creep stiffness. Recent refinements to the BBR analysis have led to the development of ΔTc which is meant to provide insight into the relaxation properties of the binder. The Asphalt Binder Cracking Device (ABCD) was developed to improve on this characterization by taking into consideration the failure strength and coefficient of thermal contraction. It was found that the evaluation of the materials using ΔTc was inconsistent with binder type and generally indicated that SBS reduced cracking resistance while the ABCD critical temperature and the proposed ΔTf parameter generally showed an improved correlation with SBS concentration.