The effects of six different biopolymers – xanthan gum, sodium alginate, cationic guar gum, chitosan, agar gum, and carrageenan – on the fundamental physical properties, compressibility, permeability, and shear strength of clay were thoroughly investigated. Simultaneously, the study delved into the durability of the modified clay under drying-wetting cycles, aiming to assess its prospective applications in practical engineering contexts. The work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far of this research are summarized as follows:
Analysis of Biopolymer Influence: The research extensively analyzed the impact of various biopolymers on the fundamental physical and chemical properties of clay. This involved a detailed examination of the biopolymer dosage's effects on the boundary water content, pH value, and specific gravity of the modified clay.
Study on Shear Strength, Compressibility, and Permeability: The study meticulously explored the undrained shear strength, compressibility, and permeability of biopolymer-modified clay. The influence of biopolymer modification on the undrained shear strength was investigated through a falling cone test. Additionally, employing a one-dimensional consolidation-permeability joint test, the study delved into the biopolymers' impact on the yield stress, compression index, and coefficient of permeability of the clay. The outcomes highlighted an enhancement in undrained shear strength alongside a reduction in the compressibility and permeability of the modified clay.
Microstructural Analysis: The research conducted an in-depth analysis of the biopolymer's effect on the microstructure of clay. This involved utilizing Scanning Electron Microscopy (SEM) and Mercury Intrusion Porosimetry (MIP) to scrutinize the microstructure and modification mechanism of the biopolymer-modified clay. The findings revealed a decrease in pore diameter and total pore volume in the biopolymer-modified clay.
Durability and Stability Assessment: The study comprehensively assessed the durability and stability of biopolymer-modified clay under drying-wetting cycles. Through a series of drying-wetting cycle tests, the research analyzed crack development and shear strength concerning varying dosages and cycle repetitions. Notably, the results indicated a reduction in the crack rate of modified clay with an increase in the drying-wetting cycle repetitions, coupled with a significant improvement in its shear strength. Furthermore, finite element numerical simulations illustrated a reduction in the displacement of biopolymer-modified slopes, accompanied by an enhancement in the safety factor of the modified slope. These findings provide valuable insights for evaluating the application potential of biopolymers in practical engineering scenarios.
