Experimental Analysis of Changes in the Plasticity Index and Filtration Coefficient of Soils Under Gypsum Leaching Conditions
Keywords:
gypsum soils, plasticity index, filtration coefficientAbstract
This study experimentally analyzes the changes in the physical and mechanical properties of gypsum-containing soils under the influence of water, focusing particularly on the dynamics of plasticity index (Ip) and filtration coefficient (Kf). Fourteen natural soil samples (clayey sand and sandy clay) collected from the Sardoba reservoir area were selected as the research objects. Based on GOST and ASTM standards, the plastic limits, gypsum content, and water permeability parameters were determined.
According to the results, when the gypsum content in the soil decreased from 20% to 2.5%, the plasticity index increased from 4.4 to 12.7, while the filtration coefficient decreased from 9.0×10⁻⁵ m/s to 1.0×10⁻⁶ m/s. These changes are attributed to the densification of the soil structure and the closure of pores. A linear regression analysis revealed a correlation between Ip and Kf with an R² value greater than 0.93.
These findings, when compared with international research, confirm a sharp decline in filtration stability and an increase in deformability in gypsum soils. Based on the results, it is scientifically and practically concluded that gypsum soils with Ip > 7.5 may pose risks for foundations of hydraulic structures.
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