Performance Deterioration of SBS-Modified Asphalt Mix: Impact of Elevated Storage Temperature and SBS Concentration of Modified Binder

Abstract

This study elucidates the important role of styrene-butadiene-styrene (SBS) concentration and storage temperature on the extent of property deterioration in SBS-MBs and their corresponding mixes. SBS-MBs with varying SBS content (3%, 4.5%, and 7% by weight) were first stored in closed metal containers at 150°C and 180°C. It was observed that the properties of the SBS-MBs remained stable at 150°C, but erosion was evident when stored at 180°C due to SBS degradation. The conventional, rheological, and morphological analysis demonstrated that the magnitude of property erosion at 180°C strongly depended on the concentration of the SBS polymer. SBS-MB with 4.5% by weight SBS polymer exhibited the maximum deterioration in the properties, while binder with 3% and 7% by weight SBS content showed subdued property erosion at 180°C. Asphalt mixes were prepared using the fresh and stored SBS-MBs with varying SBS content. Results showed a substantial drop in mixes Marshall stability, indirect tensile strength, fatigue, and rut resistance properties after using 4.5% by weight SBS-MBs that were stored at 180°C for 7 days. The consequential outcome of such property deterioration of asphalt mixes may impede pavement stability and service life. Meanwhile, only ≈10% property reduction took place in asphalt mixes that were prepared using 3% and 7% by weight SBS-MBs stored at 180°C. The findings from the study are practically significant while using SBS-MBs for pavement construction. Results also illustrate that the trend in deterioration is similar for SBS-MBs irrespective of grade and source of the base binder.