Anionic contamination and its stabilization on the strength and plastic features of clay soils (vermiculite and sepiolite)

ABSTRACT

Utilizing fine-grained soils containing clay minerals in most of the structures due to the specific surface area, ion exchange capacity and high adsorption capacity of hazardous contaminants have always been considered with the geotechnical view of the environment. In this study, the effect of contamination and stabilization of anionic pollutants (As) on the most important mechanical and physical properties of Vermiculite and Sepiolite clay soils was evaluated. Various experiments were performed at different stages such as gradation, Atterberg limits, specific gravity, density, permeability coefficient, unconfined compression strength, determination of pollutant concentration, X-Ray diffraction, as well as X-Ray fluorescence on different treatments of soil and in two different treatment periods (7 and 28 days). Finally, by examining the results of different experiments, we analyzed the proportion of two soils as a liner and also contamination problems with regard to the application of engineering materials. It was concluded that by the passage of time, microstructure characteristics of soil constituents and soil soluble conditions affect the geotechnical properties of polluted soils with anionic factors; therefore, the soils used as engineering materials and exposed to contaminants should be evaluated for their geotechnical properties after contamination and modification, so that the decisions about their selection can be made more confidently. The analysis of experiments also indicates the change in soil properties due to contamination of soil with an anionic contaminant (increasing the plastic limit), as well as the improvement of most of the geotechnical properties after the modification and stabilization (reduction of plastic limit).

KEYWORDS:

• Arsenic
• contamination
• stabilization
• iron
• UCS
• Atterberg Limits