In this paper, self-sensing cemented soil composites were prepared using multi-walled carbon nanotubes and nano-magnetite as conductive fillers. The effects of mono-doped and co-doped multi-walled carbon nanotubes and nano-magnetite on the early mechanical properties, electrical properties, and self-sensing properties of the cemented soil composites under different forms of loading were investigated. The influence mechanism of multi-walled carbon nanotubes and nano-magnetite on the cemented soil composites was explored by scanning electron microscopy. The results indicate that the incorporation of nano-magnetite has the potential to enhance the early mechanical properties of cemented soil composites. While multi-walled carbon nanotubes enhance the integrity of the conductive network within the cementitious soil, they also mitigate the influence of the polarization effect. The dispersion of multi-walled carbon nanotubes in cemented soil composites can be enhanced through the co-doped multi-walled carbon nanotubes and nano-magnetite, thereby increasing its electrical conductivity. Furthermore, the co-doped multi-walled carbon nanotubes-nano-magnetite not only enhances the stress sensitivity of the cemented soil composites but also sustains a favorable linear relationship between cracks and electrical resistance changes, thereby facilitating more precise and comprehensive crack monitoring.

Soil salinization poses a serious threat to sustainable ecological agricultural development. Most crops are susceptible to salt stress during the growth phase of seed germination and seedling emergence. Seed priming could activate the pre-germination metabolic processes, thereby improving seed germination and seedling growth under abiotic stress conditions. Moreover, multi-walled carbon nanotube (MWCNT), as an important class of carbon nanotubes, has been applied to promote plant growth by enhancing antioxidant defense systems and photosynthetic performance during the seedling stage. In this way, it is worth exploring the combination of pre-germination and post-germination treatments to reduce the damage of salt stress to crops. Therefore, in this study, rice seeds were firstly exposed to UV-B tube in a UV irradiation box for priming treatment (90 min). After emergence, the seedlings were transplanted into pots containing 150 mg L-1 MWCNT and 200 mM NaCl to evaluate the positive effects of nanomaterial on the growth of rice. The results demonstrated that after 28 days of salt stress exposure, the combination of UV-B priming and MWCNT significantly improved the growth performance of rice and minimized the adverse effects of salt stress, as compared with the single UV-B priming or MWCNT treatment, increasing biomass accumulation and the contents of osmoregulation substances, modulating antioxidant enzyme system, improving photosynthetic performance. This study suggested that the integration of seed priming with UV-B and soil application of MWCNT enhanced antioxidant capacity, which might increase photosynthesis and biomass accumulation, thereby improving the salt tolerance of rice.