Study on self-healing and rheological properties of fiber-microcapsule composite modified asphalt mastic

Abstract

Basalt fibers can significantly enhance the deformation resistance and structural strength of asphalt materials through mechanical reinforcement, but their crack repair capacity is limited. To further control the development of micro-cracks into macro-cracks, it is a feasible approach to repair micro-cracks with microcapsules. Therefore, this study selects microcapsules to carry out composite modification on fiber-modified asphalt mastic so as to improve its repair capacity. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and Thermogravimetric analysis (TGA) were used to characterize the morphology, chemical structure, and thermal properties of the microcapsules. Self-healing tests, dynamic shear rheology (DSR), and bending beam rheology (BBR) were carried out to test the self-healing ability and rheological characteristics of the modified asphalt mastic. The results indicate that the microcapsules possess well-defined spherical structures with distinct concave-convex textures on their surfaces, which enhance their interfacial adhesion with asphalt. Alkyl glycidyl ether (AGE) and epoxy resin are successfully encapsulated within the microcapsules, which maintain thermal stability at 150 °C. Self-healing test results confirm that the content of the microcapsules and the healing time positively influence the repair capacity; however, increased damage severity diminishes the self-healing ability of the asphalt mastic. The optimal self-healing temperature is 25 °C. Rheological test results demonstrate that the compositely modified asphalt mastic exhibits a higher modulus and improved rutting resistance, although it shows slightly reduced fatigue resistance and low-temperature crack resistance. Notably, the asphalt mastic modified with 4% microcapsules displays the best overall performance.