Quantitative detection of polymer content in styrene‐butadiene‐styrene modified asphalt after aging

Abstract The identification of styrene‐butadiene‐styrene (SBS) content is crucial in engineering applications since the key to assessing the performance of aged‐modified asphalt is the SBS content. Six types of modified asphalts with various SBS contents were prepared, and physical, rheological, and Fourier‐transform infrared spectroscopy (FTIR) tests were conducted. The fitting relationship between aged‐modified asphalt indexes and SBS content was established, and the three methods' accuracy, simplicity, and efficiency were compared and analyzed. The results showed that the fitting relationship between SBS content and viscosity could exceed 0.83 after aging. However, the linear and quadratic fittings deviated from the measured values, and the softening point had no apparent law with the SBS content. The rheological index method significantly correlated with SBS content and is highly automated. However, FTIR was established based on the direct detection of SBS characteristic peaks compared with the physical and rheological indexes methods. It could directly reflect the SBS content and was not easily disturbed by SBS substitutes. In addition, after long‐term aging, the linear relationship between SBS characteristic peak index, A 966 /A 811 , and SBS content could exceed 0.97. The FTIR test exhibited high accuracy and fast detection speed and is the best detection method for SBS content.