Evaluation of the Self-Healing Capacity of Asphalt Concrete with Polymer Capsules Containing Rejuvenator Under...

Under the effect of cyclic load, calcium alginate (Ca-alginate) capsules can release the asphalt rejuvenator gradually, which provides asphalt concrete with a sustained healing ability during its service period. The rejuvenator release is significantly influenced by load cycles, pressure, and frequency, factors that have been overlooked in previous studies. To address this gap, this study investigates the self-healing performance of capsule-modified asphalt concrete under various cyclic load conditions. Calcium alginate capsules with rejuvenator are fabricated and characterized. The healing efficiency of concrete beams with capsules under different load patterns is evaluated. Additionally, the rejuvenator release rate from capsules after cyclic load is measured. The rheological behavior and the chemical composition of the extracted asphalt binder are also examined. Results show that the prepared capsules exhibit a multi-chamber structure and satisfy mechanical and thermal requirements. The healing ratio of specimen beams improves with increasing load cycles and pressure but decreases with higher load frequency. Under fixed load pressure (0.7 MPa) and frequency (1 Hz), the healing ratio of beams with capsules after 128,000 cycles of load can reach 75%. The rejuvenator is released gradually from the capsules. Under constant load cycles, the release ratio rises with greater load pressure but declines as load frequency increases. Under 64,000 cycles of load and 1 Hz of load frequency, the rejuvenator release ratio of capsules increases from 49.5% to 61.5% when the load pressure increases from 0.7 MPa to 1.40 MPa. The released rejuvenator enhances the flow ability of asphalt. Furthermore, it helps rebalance the chemical composition of asphalt by increasing the content of light components, thereby contributing to asphalt regeneration. This paper provides theoretical support for the service life of capsules under various traffic load conditions, facilitating their practical application and promotion in road engineering projects.