Construction on silty sand soils on the riverbank, which are typically loose, can cause geotechnical problems. Therefore, it is essential to improve their short-term and long-term behavior. Sustainable development encourages geotechnical engineers to use eco-friendly materials in soil improvement. This study investigates the effect of Kenaf fibers (KF) and Persian gum (PG) biopolymer on stabilizing silty sand with low shear strength. Short-term behavior was assessed using standard Proctor compaction, unconfined compressive strength (UCS), and indirect tensile strength (ITS) tests, while long-term performance was evaluated through the direct shear test. The effects of initial moisture content, PG and KF percentages, curing time, and temperature on mechanical properties were analyzed. Additionally, ultrasonic pulse velocity (UPV) and scanning electron microscopy (SEM) tests examined the microstructure of the improved soil. Results showed that the optimum PG and KF contents were 2.5 % and 1 % by soil weight, respectively. The UCS of samples containing these additives increased by 75 % compared to unstabilized soil. The highest UCS was achieved at 50 degrees C, with 5.1 times increase, while at 110 degrees C, it decreased by 67 % due to thermal degradation. Direct shear tests confirmed that KF reinforcement consistently improved shear strength. The UPV showed a strong correlation with UCS, supporting its use as a non-destructive evaluation method. Also, SEM analysis showed that PG enhanced particle bonding, while KF reinforcement created a denser and more interconnected soil structure. This study highlights the effectiveness of PG and KF as sustainable alternatives for soil stabilization, showing improved soil properties and environmental issues.

Silty sandy soils usually have low shear strength due to their non-cohesive structure, weak internal bonds, and high porosity. Environmental challenges, such as freeze-thaw (F-T) cycles, also reduce the mechanical characteristics and instability of infrastructures and structures built on these soils. Biopolymers and fibers offer a sustainable solution to improve soil strength and F-T strength. However, while much research focuses on stabilizing silty sand, fewer studies examine the combined effects of biopolymers and fibers on soil properties under F-T cycles. Additionally, the correlation between ultrasonic pulse velocity (UPV) and unconfined compressive strength (UCS) in biopolymer-stabilized and fiber-reinforced soils still needs to be explored. This study examines the stabilization of silty sand using Persian gum (PG) (0.5-3%) and kenaf fibers (KF) (0-1.5%) with lengths of 6, 12, and 18 mm at the curing times of 7, 28, and 90 days. The samples were subjected to F-T cycles (0, 1, 2, 3, 6, and 12). The results showed that the highest UCS was achieved with 2.5% PG and 1% KF (12 mm) after 28 days. After 12 F-T cycles, the UCS reductions were 41% for sample with 2.5% PG and 34% for sample 2.5% PG and 1%KF. The swelling after freezing for the 2.5% PG and 1% KF sample and the 2.5% PG sample was 4.8% and 3.45%, respectively. A correlation between UPV and UCS after various F-T cycles was suggested. The scanning electron microscopy (SEM) analysis revealed increased voids, weakened polymer bonds, and cracks after 12 F-T cycles.

The aim of this work is to analyze the effectiveness of Bentonite, Kenaf and Pine Wood mixtures as enhancement materials for grounding system purposes. Grounding systems are designed to dissipate high-magnitude fault currents to Earth and provide safety to persons working in or living near power system installations. They are also necessary to protect equipment from being damaged caused by lightning strikes. The safety and reliable operation of various applications in an electrical system is highly depending on the effectiveness of the grounding system installed which could be achieved with a low resistance path, and this can be obtained by employing grounding enhancement materials to the surrounding soil of the installation site. Hence, this is highlighted in this work where NEM mixtures grounding systems were installed at a site near to SGS, UPM with a high resistivity soil profile. Kenaf is a natural fiber that has been shown to be effective in improving the performance of grounding systems as it has a high conductivity and a high dielectric constant. This means that it can carry electrical current well and it can also store electrical energy. Kenaf is also a relatively inexpensive material, which makes it a cost-effective option. The unique properties of Bentonite, a clay material, and Pine wood, a natural insulator, make them promising options for improving grounding systems. Six grounding systems were installed with 100% Bentonite, 100% Pine, Bentonite and Pine Mix, Bentonite and Kenaf Mix, Pine and Kenaf Mix, and Reference grounding systems. A comparison was made between them using daily measured earth resistance from 2nd March 2023 until 10th July 2023, i.e. for 130 days. It was found that mixtures of Bentonite and Pine Wood performed better than the 100% Bentonite.