Synthesis and characterization of compartmented Ca-alginate/silica self-healing fibers containing bituminous rejuvenator

Due to the effects of traffic loading and environmental parameters, micro cracks would generate and develop in asphalt pavements during its service life. Encapsulations containing liquid rejuvenator for improving the self-healing ability of bitumen has a bright prospect. To avoid the rupture of encapsulations during the mixing, paving and compaction of asphalt mixture, the wall of which must be excellent in thermal stability and mechanical properties. In this research, a novel compartmented Ca-alginate/silica self-healing fiber encapsulating rejuvenator was synthesized by microfluidic method. Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) confirm that the compartmented Ca-alginate/SiO₂ self-healing fibers are successfully synthesized, nano silica composites are incorporated into the “egg-box” structure of Ca-alginate by physical adsorption and intermolecular interaction. The optimum content of SiO₂ can be determined by the morphology analysis. Thermogravimetric analysis and long-term thermal stability test show that the addition of SiO₂ can significantly improve the thermal stability of compartmented Ca-alginate self-healing fibers. In addition, the compartmented Ca-alginate/SiO₂ fiber has no leakage in bituminous binder under the temperature of 180 °C for 1 h. Nanoindentation test indicates that the addition of nano SiO₂ can increase the stiffness and rigidity of Ca-alginate wall and decreases the deformation. Three-point bending experiment shows that the fibers can survive in the process of mixing and compaction of asphalt mixture. Meanwhile, the fibers enhance the self-healing property of asphalt mixture.