Optimization of physical and strength performance of cellulose-based fiber additives stabilized expansive soil

Expansive soils are known as geotechnically problematic soils and represent a significant challenge for both civil engineering and geotechnical applications. The primary issue with expansive soils is their susceptibility to moisture-induced volume changes, resulting in both shrinkage and swelling behaviors. This study presents a comprehensive investigation into optimizing the physical and strength properties of expansive soil through the use of cellulose-based fiber additives, namely bamboo fiber (BF), rice husk fiber (RHF), and wheat straw fiber (WSF). Various fiber dosages (5%, 10%, and 15%) and sizes (75 µm, 150 µm, and 300 µm) were employed in combinations to identify the optimal conditions and analyze the soil-fiber reinforcement mechanisms. The experimental design was leveraged by the Taguchi method to optimize conditions, focusing on key response factors such as the Atterberg limit test (PI, LL), free swell ratio (FSR), linear shrinkage (LS), and unconfined compressive strength (UCS) and statistical analysis for results were validated by Analysis of Variance (ANOVA). Additionally, cellulose content and water absorption capacity were assessed to confirm the suitability of cellulose-based fibers as soil stabilizers. Hence, the results demonstrate a substantial enhancement in both the physical and mechanical properties of the stabilized soil with the incorporation of cellulose-based fiber additives. Specifically, the Plastic Index (PI) improved by 85% when using RHF fibers at a dosage and size of 15% and 300 µm, respectively. The Free Swell Ratio (FSR) witnessed improvement with WSF fibers at a dosage of 15% and a size of 150 µm. Linear shrinkage exhibited remarkable improvement, exceeding 95%, with a combination of 15% and 75 µm fibers. Furthermore, the Unconfined Compressive Strength (UCS) values were improved by more than 100% when using 15% BF fibers with a size of 300 µm. Therefore, the findings of the study highlight that cellulose-based additives as highly effective and sustainable alternatives for soil stabilization, surpassing the engineering performance of traditional soil stabilizers.