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.

To clarify the wear degradation of airport cement concrete pavements under combined environmental and traffic actions, this study established an environment-tire-pavement multi-physics finite element model incorporating surface texture, freeze–thaw deterioration, temperature gradients, and aircraft lift during taxiing. Indoor rapid freeze–thaw tests, accelerated wear tests, and 3D texture scanning were further conducted to calibrate and validate the model. The results show that temperature gradients significantly amplify pavement wear. At 180 km/h and 1.2 million wear cycles, increasing the temperature gradient from 0 to 60 °C/m increased wear depth and wear mass by about 40% and 96%, respectively. Taxiing speed was negatively correlated with wear, mainly because higher speed reduced tire-pavement contact duration and effective vertical load. Freeze–thaw deterioration was the dominant factor affecting wear, and the coupled freeze–thaw–temperature–load condition produced the most severe damage. The experimental and simulation results agreed well, with R² values above 0.98. Based on the combined experimental-simulation dataset, an interpretable CNN-BiLSTM model was developed for wear-depth prediction, achieving RMSE values of 0.019 and 0.035 for the training and test sets, respectively. SHAP analysis further confirmed that freeze–thaw cycles contributed most to wear prediction. This study can provide a quantitative basis for the wear resistance evaluation, life prediction, and maintenance decision-making of airport pavements.

The calcium alginate/Fe₃O₄ capsules with multi-chamber structure can release interior rejuvenator under cyclic load and microwave irradiation; however, the rejuvenator release mechanism of capsules under two types of external activation is still unknown. Hence, this paper investigates the rejuvenator release mechanism of capsules in asphalt concrete under cyclic load and microwave irradiation. This research covers the synthesis of calcium alginate/Fe₃O₄ capsules and the evaluation of fundamental characteristics. The asphalt concrete containing capsules are subjected to cyclic load and microwave irradiation, respectively. The rejuvenator discharge ratio of capsules after external activation is determined using FTIR spectrum analysis. Furthermore, the structure characteristics of the extracted capsules are monitored after cyclic load and microwave irradiation. The findings indicate that the capsules present a sustained release feature under cyclic load. The outer capsule surfaces forms microcracks (diffusion channel) and inner chamber walls generate micropores (release channel) under cyclic load pressure. The capsules release inner rejuvenator rapidly under the microwave irradiation. The nano-Fe₃O₄ particles generate irregular movement and form microwave action spots under the action of microwave irradiation, and the micropores (release and diffusion channel) occur on the outer surface of capsules and inner chamber wall. This paper reveals the mechanism of long-lasting slow release under cyclic load and active release under microwave irradiation of dual-responsive capsules, which may provide a theoretical basis for the all-season service of the capsule and the long-term intelligent maintenance of asphalt pavement.