Triaxial Shear Behaviour of Discrete Fibre-Reinforced Low-Plasticity Clay: A Comparative Assessment of Human Hair, Coir, Jute and Polypropylene

2026-10-10T10:36:39+07:00

Discrete fibre reinforcement is a low-carbon alternative to chemical stabilisation for weak cohesive subgrades and fills, yet the performance of waste and natural fibres relative to a synthetic benchmark under effective-stress conditions is poorly documented. This study compares human hair, coir, jute and polypropylene (PP) fibres at 0.5 and 1.0% by dry mass in a low-plasticity (CL) clay using consolidated-undrained triaxial tests with pore-pressure measurement at 50, 100 and 200 kPa. All fibres increased the peak deviatoric stress at every confinement; the largest gains were obtained with PP 1.0% (51–60%) and coir 1.0% (30–41%), while human hair 1.0% gave 19–35%. The pore pressure at peak, normalised by confining pressure, remained between 0.28 and 0.32 for every mixture, indicating that the strength gain arises from increased deviatoric resistance rather than altered pore-pressure generation. The effective cohesion intercept increased from 11.4 kPa (control) to 20.0 kPa (PP 1.0%); the accompanying rise in φ′ (31.5° to 37.0°) is sensitive to the three-point failure envelope and is reported with uncertainty bounds. The leading positions in the comparative ranking were unchanged under alternative weighting schemes and simulated measurement uncertainty. For practice, 1.0% PP or coir offers a meaningful short-term gain in strength and ductility for low-plasticity clay subgrades, and human hair is a credible waste-derived alternative, but the long-term durability of natural fibres must be verified before permanent use. Because each mixture–pressure condition was tested once, the findings are comparative trends rather than statistically replicated effects.

Optimization Vetiver Root Growth Using Modular and Root Biostimulants Combination in Soil Bioengineering Method for Slope Reinforcement

2026-09-30T15:22:49+07:00

The degradation of slope stability caused by earth-cutting activities during highway construction is a geotechnical problem that requires systematic, sustainable management. Conventional concrete-based slope stabilization methods, while structurally effective, generate significant CO₂ emissions, thereby contradicting the principles of sustainable development. This study aims to examine the effectiveness of soil bioengineering methods that integrate vetiver (Chrysopogon zizanioides) with modular jute fiber geotextiles, arbuscular mycorrhizal fungi (AMF) biostimulants, and soil moisture control to optimize root system development for slope stabilization. The study was conducted on a laboratory scale with eight treatment combinations covering variations in the use of jute fiber modular units, application of mycorrhizal biostimulants, and two soil moisture regimes (25–35% and 35–45%), with observations at 30, 60, and 90 days after planting (DAP). The parameters analyzed included vegetation biometrics, side root area ratio (RAR_side), root tensile strength, and shear strength of vegetated soil. The results showed that the combination of jute fiber modules and a mycorrhizal biostimulant produced the highest root growth response, with root length reaching ±54 cm and RAR values up to 29% at 90 DAP, and a strong positive correlation between root length and RAR_side (R² = 0.9216). The highest root tensile strength was obtained in the treatment combining modular geotextiles and a mycorrhizal biostimulant at a soil moisture content of 25–35%, reaching 72.5 MPa at a root diameter of 0.4 mm. At 90 days after sowing, treatment A1 achieved the highest cohesion value of 7.70 ± 0.32 kPa, with a root weight of 4.24 ± 0.07 grams, representing an increase of approximately 3.6 times compared to the control. The research results indicate that synergy among modular geotextiles, mycorrhizal biostimulants, and optimal moisture management has the potential to be an effective, environmentally friendly slope-stabilization solution for highway infrastructure projects in Indonesia.

Geotechnical Engineering Journal of the SEAGS & AGSSEA

Triaxial Shear Behaviour of Discrete Fibre-Reinforced Low-Plasticity Clay: A Comparative Assessment of Human Hair, Coir, Jute and Polypropylene

Optimization Vetiver Root Growth Using Modular and Root Biostimulants Combination in Soil Bioengineering Method for Slope Reinforcement