Liu Yifei, Tang Chaoxin, Wen Jixiang, Guo Hongdong, Fan Henghui
College of Water Resources and Architectural Engineering, Northwest A&F University, Yangling 712100, China; Problematic Rock and Soil Museum, Northwest A&F University, Yangling 712100, China; School of Transportation, Southeast University, Nanjing 211189, China.
College of Water Resources and Architectural Engineering, Northwest A&F University, Yangling 712100, China; Problematic Rock and Soil Museum, Northwest A&F University, Yangling 712100, China; Powerchina Northwest Engineering Corporation Limited, Xi'an 710065, China.
Sci Total Environ. 2024 Apr 15;921:171111. doi: 10.1016/j.scitotenv.2024.171111. Epub 2024 Feb 23.
Loess exhibits poor engineering properties, such as low strength and poor water stability. Conventional materials used for improving loess, such as cement and lime, result in environmental pollution issues throughout their production and application processes. To assess the efficacy of bio-based materials, including calcium alginate (CA), xanthan gum (XA), cotton fibers (CO) and flax fibers (FA) in the treatment of loess, the improved soil's strength, disintegration, and water resistance were examined. Subsequently, an optimal amendment approach was determined, and dry-wet cycle tests and microscopic observation were performed. The results show that 1.0 % calcium alginate can effectively enhance the strength of loess, significantly improving its resistance to disintegration with almost no observable disintegration; permeability is significantly reduced, and water repellency is enhanced. 2.0 % xanthan can improve the strength and disintegration resistance of loess, but the improvement in strength is lower than that of calcium alginate. Additionally, the improved soil with XA experiences a flocculent disintegration in static water, which cannot maintain the soil structure. Cotton fibers and flax fibers can enhance both compressive and tensile strength of the soil. The content of 0.45 % flax fibers is considered the optimal choice as it has no effect on water stability. Combining the above results, the combination of 1.0 % CA and 0.45 % FA has been selected to improve the loess, which effectively improves the comprehensive mechanical properties and water stability of the composite improved soil. The decrease in strength and mass loss rate are significantly reduced after dry-wet cycle tests. Microscopic tests show that calcium alginate connects soil particles by Ca ionic bridges, which allows the cementing materials to fill the loess pores and exert the role of agglomeration and coagulation to enhance the integrity of the loess. This study shows that the bio-based material with calcium alginate as the main body can effectively improve the mechanical strength and water stability of the loess.
黄土表现出较差的工程性质，如强度低和水稳定性差。用于改良黄土的传统材料，如水泥和石灰，在其生产和应用过程中会导致环境污染问题。为了评估包括海藻酸钙（CA）、黄原胶（XA）、棉纤维（CO）和亚麻纤维（FA）在内的生物基材料对黄土的改良效果，对改良后土的强度、崩解性和耐水性进行了研究。随后，确定了最佳的改良方法，并进行了干湿循环试验和微观观察。结果表明，1.0%的海藻酸钙能有效提高黄土强度，显著增强其抗崩解性，几乎无明显崩解现象；渗透性显著降低，疏水性增强。2.0%的黄原胶能提高黄土强度和抗崩解性，但强度提升幅度低于海藻酸钙。此外，含XA的改良土在静水中会发生絮凝崩解，无法维持土体结构。棉纤维和亚麻纤维能增强土体的抗压和抗拉强度。0.45%的亚麻纤维含量被认为是最佳选择，因为它对水稳定性无影响。综合上述结果，选择1.0%的CA与0.45%的FA组合对黄土进行改良，有效改善了复合改良土的综合力学性能和水稳定性。干湿循环试验后强度降低和质量损失率显著减小。微观试验表明，海藻酸钙通过钙离子桥连接土颗粒，使胶结材料填充黄土孔隙，发挥团聚和凝聚作用，增强黄土的整体性。本研究表明，以海藻酸钙为主体生物基材料能有效提高黄土的力学强度和水稳定性。
