Low-temperature self-healing of SBS-modified asphalt mixtures via acoustic emission and semicircular bending tests

This study investigated the low-temperature self-healing behaviour of asphalt mixtures modified with 5% Styrene–Butadiene-Styrene (SBS) and subjected to 10 freeze–thaw cycles, with and without a 12-hour resting period between cycles. Acoustic Emission and semicircular bending tests were conducted under three fracture modes (Mode I, Mode II, and mixed Mode I/II) at temperatures of −12°C. The Acoustic Emission tests revealed that SBS modification enhanced the self-healing index by 16% in samples with resting time and by 11% in those without. The semicircular bending tests showed that the healing index varied depending on resting time, mixture type, and fracture mode. SBS-modified mixtures demonstrated improvements of approximately 15% in fracture energy, 10% in secant modulus, 11% in stress intensity factor, and 12% in flexibility index compared to control samples. A comparison of the Acoustic Emission and semicircular bending test results indicated that the resting period in mixed Mode I/II fracture aligns with the findings from the Acoustic Emission tests.