The stability of soil in high-altitude regions is significantly affected by freeze-thaw cycles, which alter its mechanical and physical properties. This study investigates the impact of 12 consecutive freeze-thaw cycles on poorly graded sandy-silt soil collected from Arunachal Pradesh. To enhance soil resistance, a bio-slurry containing urea (60 g/L) and calcium chloride (111 g/L), along with vetiver and bamboo fibers (by soil weight), was introduced as a stabilizing agent. The durability of the treated soil was evaluated by measuring the weight fluctuations after each cycle and assessing unconfined compressive strength (UCS) after 5, 10, and 12 cycles. The results revealed that untreated soil experienced a 50% reduction in UCS, while bioslurry-treated soil retained 70-80% of its original strength after 12 freeze-thaw cycles. The greatest strength retention was observed in soil treated with bioslurry and bamboo fiber, which retained 80% of its strength, followed by vetiver-treated soil at 75% strength retention. Weight loss measurements indicated that untreated soil samples lost 9.5% of their initial mass, whereas bioslurry-treated samples exhibited only a 3-5% weight loss. The findings of the study highlight the potential of bioslurry and natural fibers in mitigating freeze-thaw-induced soil degradation, making them suitable for applications in geotechnical engineering in cold-climate regions.

The objectives of this study are to investigate the strength properties and permeability of soil specimens treated with microplastic at different concentrations and samples treated with both microplastic and plant roots. A clayey soil was treated with polyethylene terephthalate (PE-T) at a concentration range between 0.25 and 4% (by dry mass of soil). The findings revealed that true (undrained) cohesion is increased with the increasing amount of PE-T in soil. It was also found that soil treated with PE-T at concentrations of 1%, 2%, and 4% exhibited greater stress increments with strain values near 2%. As the concentrations of PE-T increase, the stress gradually increases and shows ductile behavior. The study also found that the shear strength significantly increased in the soil sample treated with both PE-T and roots. The PE-T and roots help to prevent particles from sliding over each other and improve the interlocking of soil grains. Moreover, the coefficient of permeability increases by 72% and 87% in the soil treated with 1% PE-T and 1% PE-T + roots, respectively, as compared with the clean soil (control). The higher increase in the soil sample with PE-T+ root is caused by the higher increase in void space which allows for higher volumetric expansion which eases the fluid flow. The current study demonstrates that the growth rate of roots gradually increases with the increase of PE-T in the soil samples as compared to clean soil. This is due to the ability of soil samples containing microplastics to hold more water. The microstructure of soil and PE-T was examined by images in the scanning electron microscope.

An increase in precipitation due to climate change has given rise to the number of landslide occurrences. Vetiver, which is a perennial grass, is becoming increasingly popular all over the world as a vegetation-based soil bioengineering tool for preventing landslides. Sunshine Vetiver grass, also known as Chrysopogon zizanioides is noninvasive and does not compete with other indigenous plants growing in the area. Even though it is a tropical grass, Vetiver can grow in a wide range of climate conditions, including those that are quite harsh in terms of both soil and climate. The roots can grow up to 3 m in length in a dense bushy root network under optimal conditions. In this review, the authors have studied the impact of Vetiver on landslide mitigation as a climate-adaptive slope repair tool based on the research undertaken so far. Furthermore, the authors have addressed the future potential and constraints associated with the use of Vetiver for landslide mitigation. It is seen that the use of Vetiver reduces pore water pressure. The high tensile strength of Vetiver roots provides reinforcement for slopes and enhances soil shear strength. Vetiver increases saturated hydraulic conductivity and reduces surface runoff and slip surface depth. Being a vegetation-based climate-adaptive technology, this grass exhibits great promise in its ability to effectively address landslide problems. However, the magnitude of the root impact diminishes as the depth increases, rendering Vetiver a more promising remedy for shallow landslide occurrences. In addition, Vetiver grass has a wide range of practical uses due to its unique characteristics, which provide additional benefits. Employment of Vetiver is cost-effective compared with traditional engineering methods, and it requires less initial maintenance, which implies that community-based initiatives can effectively address landslide prevention through Vetiver implementation. Vetiver grass has a long bushy network of roots that can grow up to 3 m in length. The Sunshine Vetiver grass is not invasive and does not compete with indigenous plants. Although Vetiver is a tropical grass, this grass can survive in various climates and soil conditions. Vetiver is a vegetation-based climate-adaptive technology that can prevent slope failure and reduce surface runoff. Additionally, growing Vetiver can generate income for local communities because the fragrant roots can be utilized in the extraction of essential oils for the perfume industry and from the manufacture and trade of other commodities derived from Vetiver. The grass's green leaves contribute to the aesthetic appeal of the landscape. Implementing Vetiver on slopes does not require heavy machinery and is cost-effective compared with traditional engineering methods. It also requires less initial maintenance, making it an ideal solution for community-based initiatives aiming to address slope failure prevention through Vetiver implementation.