Effect of Styrene-Butadiene-Styrene on the Properties and Grading of Local Asphalt Binder in the UAE

Flexible pavements in the UAE are subjected to heavy traffic loading repetitions and severe weather conditions which are the main causes of local pavement deteriorate. Fatigue cracking and rutting are most common deterioration types. One effective solution to mitigate both pavement distresses is to use asphalt modifier technologies to improve the properties of asphalt binders used locally in the UAE. The main goal of this study is investigating the effects of Styrene-Butadiene-Styrene (SBS) on the rheological properties of local asphalt binder as well as its grade based on both penetration and Superpave grading systems. Three different SBS contents of 2.5%, 4.5%, and 6.5% by weight of asphalt binder were utilized. It was found that increasing SBS content increased the asphalt binder softening point and rotational viscosity and decreased the penetration value. SBS-modified asphalt binders were less susceptible to temperature changes. Superpave performance results showed that SBS-modified asphalt binders exhibited higher rutting parameter G*/Sin δ values as the SBS content increased for both unaged and short-term-aged conditions. Adding 2.5% SBS increased the asphalt penetration grade from 60/70 to 40/50 and the performance grade (PG) from 64 to 70. For the 4.5% and 6.5% SBS cases, the asphalt binder PG increased to 76 and 88 respectively. SBS-modified asphalt binders were found to possess significantly higher mixing and compaction temperature ranges compared to the control asphalt binder.