The deteriorating ecological environment and the concept of sustainable development have highlighted the importance of waste reuse. This article investigates the performance changes resulting from the incorporation of shellac into asphalt binders. Seashell powder-modified asphalt was prepared with 5%, 10%, and 15% admixture using the high-speed shear method. The microstructure of the seashell powder was observed by scanning electron microscope test (SEM); the physical-phase analysis of the seashell powder was carried out using an X-ray diffraction (XRD) test; the surface characteristics and pore structure of shellac were analyzed by the specific surface area Brunauer-Emmett-Teller (BET) test; and Fourier infrared spectroscopy (FTIR) qualitatively analyzed the composition and changes of functional groups of seashell powder-modified asphalt. The conventional performance index of seashell powder asphalt was analyzed by penetration, softening point, and ductility (5 °C) tests; the effect of seashell powder on asphalt binder was studied using a dynamic shear rheometer (DSR) and bending beam rheometer (BBR) at high and low temperatures, respectively. The results indicate the following: seashell powder is a coarse, porous, and angular CaCO₃ bio-material; seashell powder and the asphalt binder represent a stable physical mixture of modified properties; seashell powder improves the consistency, hardness, and high-temperature performance of the asphalt binder but weakens the low-temperature performance of it; seashell powder enhances the elasticity, recovery performance, and permanent deformation resistance of asphalt binders and improves high-temperature rheological properties; finally, seashell powder has a minimal effect on the crack resistance of asphalt binders at very low temperatures. In summary, the use of waste seashells for recycling as bio-modifiers for asphalt binders is a practical approach.

The sustainability of resources is presently a major global concern. Sustainable construction materials can be produced by applying biological waste to engineering. Eggshells, as biological waste, are usually dumped in landfills or discarded. This causes many environmental problems including malodor, noise pollution, and serious waste of resources. To solve these problems, this study combined eggshell waste with bitumen materials for bio-roads construction. This paper investigated the impact of biological waste eggshell powder on the high- and low-temperature characteristics of bitumen materials. Scanning electron microscopy (SEM) revealed the microstructure of eggshell powder. The interaction between eggshell powder and asphalt was analyzed using Fourier transform infrared spectroscopy (FT-IR). The high- and low-temperature characteristics were investigated using conventional performance tests, and dynamic shear rheometer (DSR) and bending beam rheometer (BBR) experiments. These results indicate that eggshell powder (1) has a rough and porous microstructure; (2) has no apparent chemical reaction with asphalt; and (3) improves the consistency, hardness, and high-temperature characteristics. However, it reduces the plastic deformation capacity of asphalt, and the low-temperature crack resistance of asphalt cannot be improved. The research demonstrated that the application of eggshell powder in asphalt is feasible and has long-term resource and environmental advantages.

Green economy is a major them of sustainable development. The application of biological waste in engineering is conducive to green development. This study reveals the effect of recycled eggshell waste on the physical and chemical properties as well as nano-microstructure characteristics of asphalt. The hardness, thermal stability and ductility of asphalt were explored by the penetration, softening point and ductility tests. The distribution and relative content of protons in asphalt were revealed by nuclear magnetic resonance hydrogen spectrum (¹H-NMR). The microscopic characteristics of the particle morphology and surface structure of the eggshell powder were explored by scanning electron microscopy (SEM). An atomic force microscope (AFM) was used to analyze the evolution laws of asphalt nano-microstructures. The experiment results indicate that (1) the eggshell waste increases the hardness, thermal stability and reduces the ductility of asphalt; (2) the chemical environment in which the protons of the eggshell waste asphalt are located and the H index have no obvious changes; (3) the eggshell powder is characterized by a rough, wrinkled, porous and loosened structure; (4) the nano-microstructure of eggshell waste asphalt exhibits “bee-like structures”, and the different proportion of eggshell waste changes the maturity, size and quantity of the “bee-like structures” and roughness, which can be attributed to the interaction of the asphaltene-waxiness system.