Enhancing the mechanical properties and freeze–thaw durability of nanoclay-stabilized loess using coconut fibers

• Loess soil stabilized using nanoclay (NC) and coconut fibers. • NC increased resistance by generating viscous gel and filling the voids. • Coconut fibers improved UCS, ITS and durability under freeze–thaw cycles. • The collapse potential significantly improved by the use of NC and fibers. • Coconut fibers and NC, serves as an eco-friendly solution for loess stabilization. Loess soil is known for its low mechanical strength and high moisture sensitivity. Previous studies have shown that the addition of Nanoclay(NC) significantly improves the engineering properties of loess. However, the combined effect of NC and natural fibers on loess soil has not yet been thoroughly investigated. This study examines the combined impact of NC as a mineral additive and coconut fibers as a natural reinforcing element on the mechanical and geotechnical properties of loess. To this end, samples were prepared with different percentages of NC (0.5%, 1%, 1.5%, 2%) and coconut fibers (0.3%, 0.6%, 0.9%) and were subjected to compaction, Unconfined Compressive Stress(UCS), Indirect Tensile Strength(ITS), Collapsibility Potential(CP), and Freeze-Thaw(F-T) cycles tests. In addition, microstructural analyses were performed using Scanning Electron Microscopy(SEM), Fourier-Transform Infrared Spectroscopy(FTIR), X-Ray Fluorescence(XRF), and Energy Dispersive Spectroscopy(EDS). The results indicated that NC improved compactability and significantly increased the UCS and ITS by 74.76% and 184.40 %, respectively. With the combined addition of NC and coconut fibers, the UCS and ITS of the stabilized soil increased by 110.02% and 575.68 %, respectively. The CP of the loess improved from "Moderately Severe" to "Moderate" after adding NC, and further improved to "Slight" with the combined addition of coconut fibers and NC. These findings indicate that stabilizing and reinforcing loess with NC and coconut fibers not only enhances its mechanical properties and F-T durability, but also reduces its collapse potential. This combined treatment can be considered as an eco-friendly and sustainable solution for soil improvement.