Periodic Reporting for period 1 - BALANCE (Biopolymer combine with vegetAtion soiL treAtmeNt for stabilisation of transport infrastruCture Earthworks)
Okres sprawozdawczy: 2023-01-01 do 2025-12-31
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.
Clay Polymer Network Formation: The interaction between biopolymers and clay particles results in the formation of a clay polymer network structure. This structure significantly reduces the compressibility of the sludge, with xanthan gum exhibiting the most prominent effect among the polymers utilized in the experiment. As the dosage of biopolymer increases, the structural yield stress of the modified sludge also increases, leading to a reduction in its compressibility.
Effect on Compression Index: The vertical effective stress significantly influences the compression index of the modified sludge. With increasing dosage, the compression index of the modified sludge further escalates. Notably, surpassing a specific threshold dosage (0.5% for xanthan gum, 1% for sodium alginate and cationic guar gum) results in the modified sludge having a higher compression index compared to the remolded sludge.
Impact on Permeability: Biopolymers exert a blocking effect on soil pores, causing a substantial decrease in sludge permeability. The permeability coefficient of the modified sludge diminishes as the biopolymer dosage increases. Xanthan gum, in particular, exhibits a remarkable effect, reducing soil permeability by two orders of magnitude at a dosage of 1.5%.
Pore Size Distribution: The primary pore size distribution of biopolymer-modified sludge ranges from 0.01 to 1 μm. With increasing content, the total pore volume decreases progressively.
These conclusions provide a comprehensive understanding of the properties of biopolymer-modified sludge. Further research endeavors will aim to develop corresponding design specifications based on these findings.