Mechanical experiment evaluation of the microvascular self-healing capability of bitumen using hollow fibers containing oily rejuvenator

Smart microvascular self-healing bituminous composites are considered a promising approach to prolong pavement service life. The objective of this work was to investigate the microvascular self-healing capability of bituminous material by using hollow fibers with oily rejuvenator through a direct-tension mechanical experiment. The hollow fibers with oily rejuvenator were prepared using a wet-spinning approach by applying polyvinylidene fluoride material. The fixed-length hollow fibers with sealed ends were mixed in bitumen to form composite samples. Through a repetitive tensile method, the tension strength data were used to calculate the self-healing efficiency autonomously by considering crack closure and healing at various healing temperatures and times. The scanning-electron-microscope morphology showed that the polyvinylidene fluoride hollow fibers had a tight interfacial structure with bituminous material without debonding. X-ray computed tomography results indicated that the fibers were distributed homogeneously in bitumen. The fiber content and fiber orientation affected the self healing capability of bituminous samples at 0 degrees C. To simplify the influence of the above two factors of the fibers, only one fiber was placed in bitumen samples parallel to the tension direction. With an increase in temperature from 0 to 30 degrees C, the self-healing capability of the bitumen samples increased dramatically. This phenomenon is attributed to the accelerated penetration speed of rejuvenator in the bitumen. An increase in time increased the self-healing capability of the bitumen samples. The rejuvenator may have sufficient time to leak from the hollow fibers and penetrate the bitumen. The results provide a guide to the microstructural design of the vascular fibers and the application of hollow fibers in self-healing asphalt pavement. (C) 2019 Elsevier Ltd. All rights reserved.