Degradation of SMA-13 low-temperature performance under coupled dry and wet-salt corrosion

Abstract

To investigate the low-temperature performance of polyester fiber-modified asphalt mixtures under the influence of dry-wet-salt corrosion coupling, six different polyester fiber content levels (0%, 0.3%, 0.35%, 0.4%, 0.45%, and 0.5% by weight of the mixture) were chosen for preparing SMA-13 asphalt mixture specimens. The Ultrasonic non-destructive testing, semi-circular bending tests, and scanning electron microscopy (SEM) were employed to evaluate the low-temperature performance of these mixtures under dry-wet-salt corrosion conditions with varying cycle numbers (0, 2, 4, 6, 8 cycles). The results of ultrasonic non-destructive testing showed that the wave velocity exhibited a trend of initial increase followed by a subsequent decrease with the increase in polyester fiber content. It reached a maximum value of 4.06 cm/us at a fiber content of 0.4%. The semi-circular bending tests (SCB) revealed that the fracture toughness of the polyester fiber asphalt mixture decreased as the number of dry-wet cycles increased. The impact of salt-dry-wet coupling > water-dry-wet coupling. Notably, after undergoing 4 cycles of water-dry-wet exposure, the overall fluctuation in specimen fracture toughness was minimal, indicating that results after four cycles could be suitable for evaluating the long-term degradation performance of asphalt mixtures under extended water-dry-wet cycling. SEM test results demonstrated that a polyester fiber content of 0.4% led to the formation of a strong fibrous network structure within the asphalt mixture. This significantly reduced moisture and salt intrusion during the dry-wet cycling process, enhancing the low-temperature crack resistance of the specimens.