Preparation and characterization of self-healing microcapsules of asphalt

Abstract

Cracking is one of the main forms of damage to asphalt pavement. The self-healing process of asphalt pavement is the inverse process of crack formation and development. Strengthening the self-healing ability of asphalt materials could restrain cracking and prolong the service life of asphalt pavement. Microcapsule self-healing technology has achieved good results in the field of microcrack repair and has promising research prospects. In this study, two kinds of microcapsules, CA-mic and E-mic, were prepared by in situ polymerization with a self-developed rejuvenator CA and modified epoxy resin as core materials. The micromorphology, thermal stability and chemical structure of the microcapsules were characterized by fluorescence microscopy (FM), scanning electron microscopy (SEM), laser particle size analyzer (LPSA), thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR). The freeze-heating cycle test was adopted to evaluate the durability of the microcapsules. The results showed that the two prepared microcapsules were spherical in shape and uniform in particle size distribution, with compact encapsulation and good durability. Additionally, they could survive under high temperature during asphalt construction. The rheological test of bending beams showed that the low temperature crack resistance of asphalt was improved after adding two kinds of microcapsules. The “Fracture - Healing- Fracture” tests showed that the two microcapsules could enhance the self-healing ability of the asphalt, and the maximum self-healing rate of the CA-mic could reach 52% and that of the E-mic could reach 47%.