Key Engineering Materials Vol. 1000

Abstract: This study examined the performance of an unpaved road reinforced with a triaxial geogrid built on a soft clay subgrade. The test setup featured a fully instrumented unpaved road model comprising a 0.2-m-thick crushed rock base supported by a 0.8-m-thick soft clay subgrade. The triaxial geogrid was positioned between the base and subgrade layers. Plate bearing tests were performed following ASTM standards. The thickness of the triaxial geogrid-reinforced base layer played a critical role in determining the unpaved road model’s ultimate bearing capacity and failure modes. Results showed that the reinforced model with a base layer of 0.2 m thick exhibited the highest bearing capacity compared with the unreinforced model, with an enhancement factor of 1.44. Furthermore, the reinforced section outperformed the unreinforced one, even with a reduced base thickness of 0.15 m. This suggests that triaxial geogrid reinforcement offers a viable solution for enhancing the sustainability of unpaved road construction on weak subgrades.

Abstract: Red mud, a by-product of the aluminum industry, poses a threat to the environment with its high alkalinity and heavy metal content and may seep into the soil and groundwater, endangering ecology and health. Effective utilization of red mud can reduce pollution and achieve resource recycling. In this study, a metakaolin/red mud geopolymer was prepared by phosphoric acid excitation to investigate its adsorption capacity for lead ions. The ratio of metakaolin to red mud and the additions of phosphoric acid and water were optimized, and the optimal formulations were 3/7 mass ratio of metakaolin to red mud, 2.2 molar ratio of H₃PO₄/Al₂O₃, and 0.5 water-solid ratio, which demonstrated good stability and operability.

Abstract: Red mud may cause serious pollution to soil, water, and air. Lead can seriously harm biological and even human health. This chapter summarizes the adsorption properties of metakaolin/red mud base polymer for Pb (Ⅱ). Under optimized conditions, with 0.6g/L adsorbent, pH value of 5, and adsorption time of 120 minutes, the adsorption capacity reached 122.58mg/g, and the removal rate was 73.55%. This will help to mitigate the threat of red mud and lead wastewater to human health and the environment, providing an important reference for water pollution control.

Abstract: With the rapid advancement of global industrialization, there is an increasing year-on-year demand for oil in society. The occurrence of oil spills during the processes of development, refining, and transportation has become an urgent issue that needs to be addressed. Electrospun fiber separation using selective oil/water absorption represents a relatively new yet promising technology. However, despite the lipophilic nature of the membrane for oil absorption, the rate of oil absorption is slow. There are still challenges in meeting the needs of developing communities. The plant employs a strategy of multi-branching with narrowed pores, which serves to enhance the efficiency of water and nutrient transfer. Inspired by plant transpiration, we adjusted the parameters of electrospinning and constructed a PVDF biomimetic nanofiber membrane with gradually reduced pore size through a bottom-up layer-by-layer spinning strategy. This PVDF biomimetic nanofiber membrane conforms to Murray's law. The experimental results showed that the oil absorption of carbon tetrachloride by PVDF Murray membrane was 3.06 g/g. Significantly, the PVDF Murray membrane demonstrates rapid adsorption of the oil slick (0.3 mL, n-hexane) in just 13s, as compared to 24s without the Murray structure. Therefore, the one-step preparation of the PVDF Murray membrane indicates a promising potential for its future application as a sustainable and quick oil-absorbent membrane.