Traditional repair methods suffer from poor penetration and limited effectiveness. This study uses SK-70 base asphalt as the matrix, incorporating 5% N-isopropylacrylamide-based temperature-sensitive hydrogel with particle size of 50~80 micrometers, lower critical solution temperature of 33°C, and crosslinking degree of 0.45% to prepare modified asphalt. A 7.0T MRI system was employed to dynamically track the crack healing process, combined with three-point bending tests and rheological measurements to evaluate its self-healing and pavement performance. Experimental results show that when triggered at 40°C, the relative signal intensity ratio in the crack region increased rapidly from 0.32 at 0 min to 0.68 at 30 min, reaching 0.91 at 240 min, and stabilizing at 0.92~0.95 at 480 min, with cracks completely disappearing from MRI images. Macroscopic self-healing efficiency improved with healing time, reaching 38.5% at 2 h, 67.2% at 4 h, and 89.3% at 8 h. Rheological tests demonstrate that the complex modulus of modified asphalt exceeds that of base asphalt at 20~35°C, with the modulus decline rate slowing at the 33°C phase transition temperature, indicating superior pavement performance. MRI enables intuitive and precise tracking of the entire micro-crack healing process. Temperature-sensitive hydrogel modified asphalt, leveraging its temperature-responsive phase transition characteristics, can efficiently fill micro-cracks, providing a reliable microscopic characterization method and novel technical pathway for asphalt pavement self-healing technology.
