Soil Stabilization Using Chemically Treated Palm Fiber Reinforced Soils

Expansive soils (ES) are a major concern in geotechnical engineering, as their tendency to expand and contract with moisture variations can result in instability and a loss of structural integrity. Current study investigated that the stabilization of ES using natural palm fibers (PF), both in their untreated form and chemically treated using a combination of sodium hydroxide (NaOH) and hydrogen peroxide (H₂O₂). It also focuses on evaluating the improvement in mechanical behavior and degradation resistance of reinforced soil at two fiber content levels: 0.5% and 1.0% by weight of soil. Comprehensive laboratory tests, namely UCS as well as Triaxial compression tests were performed before and after subjecting the samples to degradation cycles of 7, 15, and 30 days. It was observed that from the triaxial test results the unreinforced soil (US) strength improved from 94.7 to 265.0 kPa. with UPF (1.8 times) reinforcement and further to 351.7 kPa. by reinforcement of chemically treated palm fiber (CPF), i.e., 2.71 times improvement, where CPF exhibited 0.33 times higher strength than UPF, confirming superior reinforcement efficiency, leading to minimum percentage of fiber degradation and maximum percentage of fiber degradation resistance after 30 days of immersion period. It is attributed that NaOH-H2O2 treatment removed lignin/hemicellulose, enhanced surface roughness, and improved fiber-soil bonding, making treated PF a sustainable and effective ES reinforcement. This eco-friendly approach ensures long-term strength, low coast, and offers a viable alternative to synthetic stabilizers in regions rich in agricultural waste.