Self-healing is a biological phenomenon in which living organism responds to the suffered damage in a complex way. Inspired by the self-healing phenomenon in nature, various biomimetic healing methods rooted in intrinsic or extrinsic healing mechanisms have been explored. Research on novel self-healing asphalt materials with intelligent response is at the cutting-edge of materials science and offers a potential strategy for building long-life and low-carbon asphalt concrete infrastructure. This paper describes the progress of research on extrinsic self-healing asphalt materials and makes a clear distinction between intrinsic and extrinsic self-healing. The asphalt self-healing mechanism is interpreted by capillary flow theory, phase field theory, molecular diffusion theory and surface energy theory form various perspective. The extrinsic self-healing strategies including thermal induced healing and rejuvenator induced healing are proposed to enhance the healing level of cracked asphalt materials. A brief review of the methods including fracture-healing test and fatigue-healing test for assessing the efficacy of different extrinsic healing methods is presented. The thermal induced healing method bring high crack repair efficiency for asphalt concrete and the rejuvenator induced healing strategy not only improve the healing ratio of cracked asphalt concrete but also regenerate the ageing asphalt in situ. Important lessons for prospective research on the creation of novel self-healing asphalt materials are highlighted.@en

Layered double hydroxides (LDHs) can shield polymeric materials from UV light, which allows reducing material aging and erosion damage of bituminous pavement under physical and chemical action. In this study, the physicochemical properties, aging resistance, and erosion resistance to the aqueous solution of LDHs modified bitumen mastic (BM) were characterized by Fourier-transform infrared spectroscopy, basic physical tests, viscosity tests, a dynamic shear rheometer, and a bending beam rheometer. The results show that few chemical reactions occurred between LDHs and BM, indicating that a physical mechanism underlay the modification of BM by LDHs. Moreover, LDHs could increase the flow activation energy of BM by 0.12%, increase the high failure temperature from 69.07 °C to 71.07 °C, and decrease the low failure temperature from −10.50 °C to −12.39 °C. Therefore, LDHs could slightly reduce the temperature sensitivity of BM, while slightly enhancing the high and low-temperature rheological properties of BM. Compared with short-term aging and long-term aging, LDHs could significantly improve the UV aging resistance of BM. The above results are consistent with previous studies of LDHs-modified bitumen. Furthermore, water and pH 3 acidic solutions had the greatest degree of erosion to BM, and LDHs could improve the resistance to aqueous solutions. Overall, this study can help to investigate the effects of various environmental factors on the performance of LDHs modified bitumen pavements during long-term use.@en

As a kind of solid waste, using Prestressed High-Strength Concrete Pile Waste Concrete (PPWC) as the replacement for limestone filler in asphalt concrete can not only reduce the accumulation of PPWC and increase its utilization but also avoid the increased road construction costs and environmental degradation associated with limestone mining. This study aims to investigate the effect of using PPWC filler to replace limestone filler on the road performance of asphalt concrete. Firstly, PPWC was ground into filler particles with a diameter less than 0.075 mm. The particle characteristics such as surface morphology, particle size distribution and chemical composition of PPWC filler and limestone filler were compared. Then, PPWC filler was used to replace limestone filler with different volume fractions to prepare asphalt concrete, and the water damage resistance, high-temperature rutting resistance, low-temperature crack resistance, fatigue resistance and adhesion performance of asphalt concrete were tested. The results showed that PPWC filler has a smaller particle size and rougher surface than limestone filler, and it contains Ca(OH)2 produced by hydration. The addition of PPWC filler can effectively improve the mechanical properties of asphalt concrete without reducing its water damage resistance. PPWC filler can improve the high-temperature rutting resistance and low-temperature crack resistance of asphalt concrete, but reduce its low-temperature fatigue resistance. The low content of PPWC filler will enhance the adhesion between asphalt mortar and aggregate. However, when the content of PPWC filler exceeds 50%, Ca (OH)2 in PPWC will reduce the adhesion between acid asphalt mortar and alkaline basalt aggregate. Therefore, the use of PPWC as filler in asphalt mixtures provides a reliable solution for the sustainable development of road materials.@en