Effect of microstructure change on permeability of flax-fiber reinforced silty clay soaked with zinc-ion solution

Abstract

With the application of fiber-reinforcement technology, the mechanical properties of silty clay are improved with fiber reinforcement. However, the variation of permeability coefficient and other parameters of flax-fiber reinforced silty clay have not been sufficiently studied. In this study, the permeability of flax-fiber reinforced silty clay soaked with zinc-contaminated solution under different osmotic pressure was tested by a flexible-wall permeameter, and the effects of zinc-ion concentration and confining pressure on the permeability of flax-fiber reinforced silty clay were studied. Genius XRF was employed to detect the types and quantity of metal elements in the specimens, thereafter, the reasons for the change of permeability were explained from chemical and microscopic perspective. The results showed that the permeability coefficient of flax-fiber reinforced silty clay decreased significantly with the increase of zinc-ion concentration in a low concentration (about 1-10 mg L −1). While in a high concentration (about 100 mg L −1), the permeability coefficient of flax-fiber reinforced silty clay changed little with the increase of zinc-ion concentration. While the flax-fiber reinforced silty clay was not soaked with zinc-ion solution, the permeability coefficient of the specimen increased with the increase of confining pressure. However, when the flax-fiber reinforced silty clay was soaked with zinc-contaminated solution, the permeability coefficient first decreased and then tended to be constant with the increase of confining pressure. With the increase of confining pressure, the porosity of flax-fiber reinforced silty clay decreased, and with the increase of zinc-ion concentration, the porosity of flax-fiber reinforced silty clay first increased and then decreased. In recent years, with the rapid development of industry, the pollution degree of industrial development area has been increasing 1-3. There are some engineering projects built on the ground of demolished landfills, and residual contaminants in the subgrade always change the physical and chemical properties of the ground soil 4-6. Depending on the survey bulletin of soil pollution in China published on April 17, 2018, the survey covers all of China's inland farmland, which included woodlands, grasslands, unused land and construction land, about 6.3 × 10 12 m 2. The result showed that the environmental in industrial wasteland was seriously polluted, and the soil pollution was common around the world. Among those pollutants, one class of the most serious pollutants is heavy metals. However, the eight kinds of heavy metals, including Cr, Ni, Cu, Zn, As, Cd, Hg and Pb, which accounted for the main part of inorganic pollution, and the average concentrations of them were 63.

A study on the collapse characteristics of loess based on energy spectrum superposition method

“…However, this method was found to be inefficient as it could only identify a few minerals such as quartz and pyrite [ 37 , 38 ]. With the development of photoelectric technology, new techniques such as X Ray Fluorescence (XRF) [ [39] , [40] , [41] , [42] ], X Ray Diffraction (XRD) [ [43] , [44] , [45] , [46] , [47] ], Energy Dispersive Spectroscopy (EDS) [ [48] , [49] , [50] , [51] ], and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) [ 52 , 53 ], have been introduced for quantitative or semi-quantitative monitoring and analysis of mineral types in powder samples. However, these techniques cannot provide information on the distribution and enrichment of minerals in loess.…”