Little is known regarding the effectiveness of biopolymers in soil improvement, especially considering interactions among different clay minerals, porewater cations, and biopolymer polarities. This paper presents an experimental investigation of the effects and effectiveness of four biopolymers of varying polarity and structure (xanthan gum, guar gum, carrageenan, and dextran), on the liquid limit, undrained strength, and thixotropic hardening of soft clays consisting of predominantly kaolinite with lesser montmorillonite. The liquid limits were measured using the standard Casagrande cup method. Fall cone penetration was adapted to determine the development of undrained shear strengths of the samples with time and after remolding. Clay samples were amended by the four biopolymers with a range of concentrations as well as varying NaCl in the pore fluid. Results show different biopolymers affect the consistency and strength behavior of different clays to varying extents; such changes are dominated by the constituent clay minerals’ surface charges as well as the biopolymers’ polarity and structure. Addition of biopolymers to clays results in an immediate gain in undrained shear strength that stabilizes, and some biopolymers exhibit a concentration saturation. Moreover, the neutral biopolymers (guar gum and carrageenan) behave fundamentally differently from anionic xanthan gum and cationic dextran. Advantages and limitations of potential applications of biopolymers in terms of effectiveness, costs, and ease of application are discussed. This research can aid the decision-making processes for coastal geotechnical engineers to determine which of the tested biopolymers presents a safe, cost-effective soil improvement additive for reducing erosion of coastal cohesive soils.

关于生物聚合物在土壤改良中的有效性知之甚少，特别是考虑到不同粘土矿物、孔隙水阳离子和生物聚合物极性之间的相互作用。本文介绍了四种不同极性和结构的生物聚合物（黄原胶、瓜尔胶、角叉菜胶和葡聚糖）对主要由高岭石组成的软粘土的液限、不排水强度和触变硬化的影响和有效性的实验研究含少量蒙脱石。使用标准卡萨格兰德杯法测量液限。落锥穿透适用于确定样品不排水剪切强度随时间和重塑后的发展。粘土样品通过四种生物聚合物进行了修正，这些生物聚合物具有一系列浓度以及孔隙流体中不同的 NaCl。结果表明，不同的生物聚合物对不同粘土的稠度和强度行为有不同程度的影响；这种变化主要取决于组成粘土矿物的表面电荷以及生物聚合物的极性和结构。将生物聚合物添加到粘土中会立即获得稳定的不排水剪切强度，并且一些生物聚合物表现出浓度饱和。此外，中性生物聚合物（瓜尔胶和角叉菜胶）的行为与阴离子黄原胶和阳离子葡聚糖根本不同。讨论了生物聚合物在有效性、成本和易用性方面的潜在应用的优势和局限性。