Unveiling optimal performance of SBS-modified asphalt mixture: crucial impact of elevated storage temperature and duration of binders

SBS-modified binders (SBS-MB) are susceptible to degradation when exposed to temperatures above 200 °C during manufacturing, transport and installation due to minimal oxygen. Without proper controls, this can lead to a substantial decline in binder properties, negatively affecting pavement quality. Therefore, a humble effort has been made in this study to recognize the role of elevated temperature and storage duration of modified binders on the properties of the prepared mixes. Studies were carried out by storing 4.5 wt% SBS-modified bitumen in a sealed tin container at 150 °C, 180 °C and 210 °C separately, for 1, 3, 7 and 14 days. After the stipulated storage time, the rheological properties of the SBS-modified binders were measured. Results highlighted that the aforementioned storage condition of binders played a key role in the observed property erosion of the modified mix. It had been found that in storage at 150 °C up to 14 days, the properties of the modified binder and corresponding mix remain unaffected. Notably, consequential erosion in asphalt mix performance was observed through Marshall stability, moisture susceptibility, tensile strength and stiffness modulus value when using mixes prepared with SBS-MBs stored at 180 °C and 210 °C. The severity of erosion corresponded to the duration of binder storage days. Storing the binder at temperatures of 180 °C for 3, 7 and 14 days resulted in 8.9%, 11.7% and 13% more abrasion loss, respectively, compared to fresh (unstored) SBS-MB. Moreover, within only 1 day of storage at 210 °C, a significant 20% reduction in the mixes' dynamic stability (DS) value was observed. The FM results clearly indicate that storing SBS-MBs at elevated temperatures (≥ 180 °C) will lead to the disintegration of the polymer network, thereby eroding the properties.