چكيده به لاتين
With the ever-increasing global population, construction on problematic soils has become unavoidable, leading to a growing focus on soil improvement techniques. While mechanical and electrical methods are costly and require specialized equipment, chemical methods such as adding cement or lime have proven to be effective and economical in soil improvement. However, in recent decades, these traditional materials have raised significant environmental concerns, including increased carbon dioxide emissions, prompting civil engineers to seek alternatives. Among environmentally friendly materials, Persian gum, a plant-based polysaccharide biopolymer, has shown promising results in recent years. This gum is more abundant in Iran than other gums like agar and is exported in hundreds of tons annually. To further investigate the effectiveness of Persian gum in improving soil properties, this study examines the long-term strength improvement of Firouzkooh sand using Persian gum. Based on previous research, the optimal moisture content was selected, and samples were prepared with three gum percentages (0.5%, 1%, and 1.5%) and cured for 7 to 90 days. Direct shear tests were conducted on these samples, and the effects of normal stress, gum percentage, and curing time on cohesion, friction angle, peak shear stress, and tensile strength were investigated. Finally, microscopic images were provided for further analysis. The results indicate that, in general, increasing the gum percentage significantly increases cohesion and peak shear stress but decreases the friction angle. Curing time also increases cohesion and peak shear stress up to 30 days, but after 30 days, the samples experience a decrease in cohesion and strength
