Thermal storage stability and performance degradation of high-dosage SBS-modified asphalt for highway maintenance

High-dosage styrene-butadiene-styrene (SBS) modified asphalt is widely applied in high-grade pavement maintenance due to its superior performance. However, repeated thermal cycling during production and construction can lead to performance degradation of SBS-modified asphalt. To investigate the thermal storage stability and performance degradation of high-dosage SBS-modified asphalt for highway maintenance, laboratory simulations were designed to replicate the storage conditions encountered in real-world maintenance projects. Conventional performance tests, high-temperature rheological measurements, and Fourier transform infrared (FTIR) spectroscopy were subsequently employed. The results indicate that under constant-temperature storage, performance degradation intensifies with increasing temperature and duration, with more pronounced deterioration observed at elevated temperatures. Under cyclic heating storage, the most severe damage occurred under the 160 °C (5 h)~150 °C (19 h + 2 d) cycle. Mechanistic analysis demonstrated that aging of the base asphalt had a negligible impact on performance degradation, whereas degradation of the SBS modifier exerted a more substantial influence. Among these factors, disruption of the cross-linked structure was identified as the most critical factor, dominating performance deterioration. The primary degradation mechanism during high-temperature storage involved SBS chain scission and oxidative degradation, which progressively destroyed the three-dimensional network structure formed by cross-linking between the SBS modifier and the asphalt matrix.