Evaluation of foaming performance for polymer modified and virgin asphalt binders

The pavement suffers rapid deterioration as a result of the weak bonding strength exhibited by the foamed virgin asphalt in the mixture. Consequently, it is crucial to develop a modified asphalt suitable for foaming. The expansion height and bubble size of foamed asphalt can be continuously and simultaneously monitored by binocular ranging equipment. By analyzing these dynamic responses, the evolution of the spatial domain expansion characteristics and the geometric features of the surface bubbles of foamed thermoplastic resin modified asphalt (TRA) was analyzed. Meanwhile, multi-stress creep recovery (MSCR) and bending beam rheometer (BBR) tests were conducted to analyze its rheological properties. Subsequently, the dispersibility of foamed TRA in the mixture was explored. The results showed that thermoplastic resin significantly improved the physical performance stability of foamed asphalt, as evidenced by an increase in its half-life by 2-3 times compared to the virgin asphalt when the dosage of thermoplastic resin reached 8 %. Foamed modified asphalt has fewer bubbles, but it has larger bubble sizes and more uniform distribution of bubbles. Meanwhile, the TRA exhibited excellent high-temperature deformation resistance and elastic recovery ability. The dispersion uniformity of foamed TRA in the mixture was superior to that of virgin asphalt. This study serves as a valuable reference for the exploration of foaming behavior in modified asphalt and the utilization of foamed modified asphalt in the mixture.