Shrinkage and Consolidation Characteristics of Chitosan-Amended Soft Soil—A Sustainable Alternate Landfill Liner Material

Abstract

Kuttanad is a region that lies in the southwest part of Kerala, India, and possesses soft soil, which imposes constraints on many civil engineering applications owing to low shear strength and high compressibility. Chemical stabilizers such as cement and lime have been extensively utilized in the past to address compressibility issues. However, future civilizations will be extremely dependent on the development of sustainable materials and practices such as the use of bio-enzymes, calcite precipitation methods, and biological materials as a result of escalating environmental concerns due to carbon emissions of conventional stabilizers. One such alternative is the utilization of biopolymers. The current study investigates the effect of chitosan (biopolymer extracted from shrimp shells) in improving the consolidation and shrinkage characteristics of these soft soils. The dosages adopted are 0.5%, 1%, 2%, and 4%. One-dimensional fixed ring consolidation tests indicate that consolidation characteristics are improved upon the addition of chitosan up to an optimum dosage of 2%. The coefficient of consolidation increases up to seven times that of untreated soil, indicating the acceleration of the consolidation process by incorporating chitosan. The shrinkage potential is reduced by 11% after amendment with 4% chitosan and all the treated samples exhibit zero signs of curling. Based on the findings from consolidation and shrinkage data, carbon emission assessments are carried out for a typical landfill liner amended with an optimum dosage of chitosan. In comparison to conventional stabilizers like cement and lime, the results indicate that chitosan minimized carbon emissions by 7.325 times and 8.754 times, respectively.

Target reliability-based design optimization studies on cohesive soil amended with chitosan and casein for liner applications

“…Under this phenomenon, the hydraulic conductivity increased by manifold and affected the liner functionality 16 . Chitosan has effectively controlled the desiccation cracking in fine-grained soils for dosages of 0.5–4% 17 . Steadily, a paradigm shift has been witnessed from the usage of chemical amendments to novel materials in recent years 18 – 23 .…”

“…Steadily, a paradigm shift has been witnessed from the usage of chemical amendments to novel materials in recent years 18 – 23 . Hydrophobic and waste-derived biopolymers such as chitosan have proven their worth in amending the soil to suit liner requirements at optimal dosages 17 , 23 . By natural selection, these materials tend to be resilient and relatively sustainable compared to other chemical stabilizers 24 .…”

Experiment and Analysis of Variance for Stabilizing Fine-Grained Soils with Cement and Sawdust Ash as Liner Materials

“…However, clay liners are susceptible to cracking and shrinking due to moisture content and temperature changes, which can compromise their performance and durability [5][6][7]. Therefore, improving the geotechnical properties of clay liners, such as strength, permeability, and shrinkage, is necessary to enhance their effectiveness and reliability [8][9][10]. One of the methods to improve the quality of clay liners is to stabilize them with additives, such as cement and sawdust ash (SDA) [11,12].…”

Embodied Energy in the Production of Guar and Xanthan Biopolymers and Their Cross-Linking Effect in Enhancing the Geotechnical Properties of Cohesive Soil

“…Soil treated with chitosan has displayed a considerable improvement in compressive strength of 4 MPa with an extended curing period of 90 days. Chitosan at high dosages was used for canal lining and was proven to be effective in holding and retaining water [25,26].…”