Abstract
Using a modified permeameter, laterite samples that were corroded and permeated by alkaline solutions at different concentrations for varying amounts of time were subjected to triaxial compression tests, chemical composition analysis, particle composition tests, and microstructure analysis. The results showed that the strength parameters c, φ, and K of the laterite samples that were corroded by alkaline‐solution permeation were reduced with increasing corrosion time and alkaline‐solution concentration. The alkaline‐solution corrosion had a minor effect on the strength parameters n and Rf. The contents of Al2O3 and Fe2O3 in the laterite fluctuated and decreased with increasing alkaline‐solution concentration and corrosion time. There were no distinct patterns in the relationships between the SiO2 content and the increases in the alkaline‐solution concentration and corrosion time. Due to the corrosion during the alkaline‐solution permeation, the content of clay particles increased with increasing time and concentration of the alkaline solution. After the permeation with the alkaline solution, the soil particles became smaller and were arranged in an ordered state. The analysis suggested that the permeation effect of the alkaline solution changed the chemical composition of the laterite and the connecting strength of the soil particles, resulting in changes in its physical and mechanical properties.
Highlights
As national awareness of environmental protection increases, geotechnical engineering researchers are paying more attention to the environmental and geotechnical engineering issues associated with environmental science
Chen [5] studied the changes in the chemical composition, bonding force, and microstructure of laterite during alkaline-solution corrosion and found that the coefficient of compressibility and water permeability of the soil increased after corrosion, as did the shear strength, internal friction angle, and cohesive force
There are commercial permeameters, but their materials are generally copper or steel. us, chemical solutions have a corrosive effect on them, which has a great impact on the research conclusions. e specimen sizes of the existing permeameters are not suitable for triaxial shear test, and the triaxial shear tests cannot be performed after a permeation test. erefore, a device was designed and constructed for long-term permeation using chemical solutions that were suitable for the triaxial samples in this work
Summary
As national awareness of environmental protection increases, geotechnical engineering researchers are paying more attention to the environmental and geotechnical engineering issues associated with environmental science. Chen [5] studied the changes in the chemical composition, bonding force, and microstructure of laterite during alkaline-solution corrosion and found that the coefficient of compressibility and water permeability of the soil increased after corrosion, as did the shear strength, internal friction angle, and cohesive force. Yang et al [11] studied the effect of common phosphate-containing alkaline-solution contamination in sewage on the mechanical properties of laterite and found that the cohesive force of the contaminated laterite decreased, the internal friction angle decreased, and the compressibility increased. The existing research results generally showed that, during the corrosion by alkaline solutions, the permeability coefficient of laterite increases, the strength decreases, and the engineering properties of the soil generally show a deteriorating trend. A device for long-term permeation with a chemical solution was constructed for triaxial specimens, and the macromechanical properties of laterite after being corroded by alkaline-solution permeation under different concentrations and different cycles were studied; in combination with the chemical composition and microstructure analysis, the reasons for the permeation corrosion were discussed
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