Effect of Zinc Contamination on Engineering Properties of Clayey Soils

Abstract

Soil contamination due to heavy metals is very serious problem today due to increased industrial activities and over use of pesticides and chemicals for agriculture. These contaminants may bring in considerable changes in the geotechnical properties of soils. The most commonly found heavy metals at contaminated sites are lead (Pb), chromium (Cr), arsenic (As), zinc (Zn), cadmium (Cd), copper (Cu). This paper investigates the effect of zinc contamination on the index and engineering properties of black cotton soil. In this study, black cotton soil samples are contaminated artificially with different concentrations such as 5, 10 and 15 ppm using zinc nitrate solutions for varying curing periods of 7, 14, and 21 days. Atterberg’s limit test, Standard Proctor test, unconfined compression (UCS) test, California bearing ratio (CBR) test and direct shear test are conducted on uncontaminated and contaminated soil samples. Plasticity index and maximum dry density of soil is found to be decreasing on zinc concentration and curing period increment. Unconfined compressive strength, California bearing ratio and cohesion value increases with increasing zinc concentration and curing period. The enhanced UCS and CBR value suggest that the soil contaminated with zinc can be used as construction material for earthen embankments, fill material, etc.