There are various methods for improving the engineering properties of weak soils among which the usage of chemical additives is one of the most important ones. Considering sepiolite as an environmental friendly material and its unique physiochemical characteristics, this substance has been used as an additive for soil improvement in this study. For this purpose, in addition to soil identification tests, in order to examine the effect of changes in the percentage of sepiolite additive, a set of tests has been done including Atterberg limits, modified compaction, uniaxial compressive strength, pH, direct shear and permeability test on sandy clay and clayey sand soils. Furthermore, scanning electron microscopy (SEM) and x-ray diffraction (XRD) tests have been performed to investigate the microstructure of non-stabilized and stabilized soil. According to the results, with increasing the additive percentage and the curing time, the uniaxial compressive strength of the soil increased. The uniaxial strength in the clayey sand soil rose up to six times larger than that of the initial strength of the soil. However, the maximum strength enhancement in the sandy clay soil was up to three times the initial value. Sepiolite (above 5%) has improved soil shear strength parameters including cohesion and internal friction angle. The increase in the additive content led to diminished permeability in soil. Further, the elevation of the sepiolite content in the soil resulted in enhanced liquid and plastic limits of soil. Microstructural investigations indicated that the reason of improvement in strength parameters of soil was the incidence of chemical reactions including ion exchange, flocculation and production of calcium-silicate-hydrate (CSH) and calcium-aluminate-hydrate (CAH) gels. Further, sepiolite fiber resulted in enhanced strength by filling the pores and void spaces of soil.

改善软弱土工程性质的方法有很多种，其中化学添加剂的使用是最重要的方法之一。考虑到海泡石作为一种环保材料及其独特的理化特性，该物质已被用作本研究中土壤改良的添加剂。为此，除了土壤识别测试外，为了检查海泡石添加剂百分比变化的影响，还进行了一系列测试，包括阿特伯格极限、改良压实、单轴抗压强度、pH、直剪和渗透性在砂质粘土和粘土质砂土上进行试验。此外，还进行了扫描电子显微镜 (SEM) 和 X 射线衍射 (XRD) 测试，以研究不稳定和稳定土壤的微观结构。结果表明，随着添加量和养护时间的增加，土的单轴抗压强度增加。黏性砂土的单轴强度比土体的初始强度大6倍。然而，在砂质粘土中的最大强度增强高达初始值的三倍。海泡石（超过 5%）改善了土壤剪切强度参数，包括内聚力和内摩擦角。添加剂含量的增加导致土壤渗透性降低。此外，土壤中海泡石含量的增加导致土壤的液限和塑限增强。微观结构研究表明，土壤强度参数提高的原因是化学反应的发生，包括离子交换、絮凝和生产水合硅酸钙 (CSH) 和水合铝酸钙 (CAH) 凝胶。此外，海泡石纤维通过填充土壤的孔隙和空隙空间来提高强度。